<?php

// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Classes representing HTML elements, used by $OUTPUT methods
 *
 * Please see http://docs.moodle.org/en/Developement:How_Moodle_outputs_HTML
 * for an overview.
 *
 * @package   moodlecore
 * @copyright 2009 Tim Hunt
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */


/**
 * Interface marking other classes as suitable for renderer_base::render()
 * @author 2010 Petr Skoda (skodak) info@skodak.org
 */
interface renderable {
    // intentionally empty
}


/**
 * Data structure representing a user picture.
 *
 * @copyright 2009 Nicolas Connault, 2010 Petr Skoda
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class user_picture implements renderable {
    /**
     * List of mandatory fields in user record here.
     * @var string
     */
    const FIELDS = 'id,picture,firstname,lastname,imagealt';

    /**
     * @var object $user A user object with at least fields id, picture, imagealt, firstname and lastname set.
     */
    public $user;
    /**
     * @var int $courseid The course id. Used when constructing the link to the user's profile,
     * page course id used if not specified.
     */
    public $courseid;
    /**
     * @var bool $link add course profile link to image
     */
    public $link = true;
    /**
     * @var int $size Size in pixels. Special values are (true/1 = 100px) and (false/0 = 35px) for backward compatibility
     */
    public $size = 35;
    /**
     * @var boolean $alttext add non-blank alt-text to the image.
     * Default true, set to false when image alt just duplicates text in screenreaders.
     */
    public $alttext = true;
    /**
     * @var boolean $popup Whether or not to open the link in a popup window.
     */
    public $popup = false;
    /**
     * @var string Image class attribute
     */
    public $class = 'userpicture';

    /**
     * User picture constructor.
     *
     * @param object $user user record with at least id, picture, imagealt, firstname and lastname set.
     * @param array $options such as link, size, link, ...
     */
    public function __construct(stdClass $user) {
        global $DB;

        static $fields = null;
        if (is_null($fields)) {
            $fields = explode(',', self::FIELDS);
        }

        if (empty($user->id)) {
            throw new coding_exception('User id is required when printing user avatar image.');
        }

        // only touch the DB if we are missing data and complain loudly...
        $needrec = false;
        foreach ($fields as $field) {
            if (!array_key_exists($field, $user)) {
                $needrec = true;
                debugging('Missing '.$field.' property in $user object, this is a performance problem that needs to be fixed by a developer. '
                          .'Please use user_picture::fields() to get the full list of required fields.', DEBUG_DEVELOPER);
                break;
            }
        }

        if ($needrec) {
            $this->user = $DB->get_record('user', array('id'=>$user->id), self::FIELDS, MUST_EXIST);
        } else {
            $this->user = clone($user);
        }
    }

    /**
     * Returns a list of required user fields, usefull when fetching required user info from db.
     * @param string $tableprefix name of database table prefix in query
     * @return string
     */
    public static function fields($tableprefix = '') {
        if ($tableprefix === '') {
            return self::FIELDS;
        } else {
            return "$tableprefix." . str_replace(',', ",$tableprefix.", self::FIELDS);
        }
    }
}


/**
 * Data structure representing a help icon.
 *
 * @copyright 2009 Nicolas Connault, 2010 Petr Skoda
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class help_icon implements renderable {
    /**
     * @var string $page name of help page
     */
    public $helppage;
    /**
     * @var string $title A descriptive text for title tooltip
     */
    public $title = null;
    /**
     * @var string $component Component name, the same as in get_string()
     */
    public $component = 'moodle';
    /**
     * @var string $linktext Extra descriptive text next to the icon
     */
    public $linktext = null;

    /**
     * Constructor: sets up the other components in case they are needed
     * @param string $page  The keyword that defines a help page
     * @param string $title A descriptive text for accesibility only
     * @param string $component
     * @param bool $linktext add extra text to icon
     * @return void
     */
    public function __construct($helppage, $title, $component = 'moodle') {
        if (empty($title)) {
            throw new coding_exception('A help_icon object requires a $text parameter');
        }
        if (empty($helppage)) {
            throw new coding_exception('A help_icon object requires a $helppage parameter');
        }

        $this->helppage  = $helppage;
        $this->title     = $title;
        $this->component = $component;
    }
}


/**
 * Data structure representing a simple form with only one button.
 *
 * @copyright 2009 Petr Skoda
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class single_button implements renderable {
    /**
     * Target url
     * @var moodle_url
     */
    var $url;
    /**
     * Button label
     * @var string
     */
    var $label;
    /**
     * Form submit method
     * @var string post or get
     */
    var $method = 'post';
    /**
     * Wrapping div class
     * @var string
     * */
    var $class = 'singlebutton';
    /**
     * True if button disabled, false if normal
     * @var boolean
     */
    var $disabled = false;
    /**
     * Button tooltip
     * @var string
     */
    var $tooltip = null;
    /**
     * Form id
     * @var string
     */
    var $formid;
    /**
     * List of attached actions
     * @var array of component_action
     */
    var $actions = array();

    /**
     * Constructor
     * @param string|moodle_url $url
     * @param string $label button text
     * @param string $method get or post submit method
     */
    public function __construct(moodle_url $url, $label, $method='post') {
        $this->url    = clone($url);
        $this->label  = $label;
        $this->method = $method;
    }

    /**
     * Shortcut for adding a JS confirm dialog when the button is clicked.
     * The message must be a yes/no question.
     * @param string $message The yes/no confirmation question. If "Yes" is clicked, the original action will occur.
     * @return void
     */
    public function add_confirm_action($confirmmessage) {
        $this->add_action(new component_action('click', 'M.util.show_confirm_dialog', array('message' => $confirmmessage)));
    }

    /**
     * Add action to the button.
     * @param component_action $action
     * @return void
     */
    public function add_action(component_action $action) {
        $this->actions[] = $action;
    }
}


/**
 * Simple form with just one select field that gets submitted automatically.
 * If JS not enabled small go button is printed too.
 *
 * @copyright 2009 Petr Skoda
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class single_select implements renderable {
    /**
     * Target url - includes hidden fields
     * @var moodle_url
     */
    var $url;
    /**
     * Name of the select element.
     * @var string
     */
    var $name;
    /**
     * @var array $options associative array value=>label ex.:
     *              array(1=>'One, 2=>Two)
     *              it is also possible to specify optgroup as complex label array ex.:
     *                array(array('Odd'=>array(1=>'One', 3=>'Three)), array('Even'=>array(2=>'Two')))
     *                array(1=>'One', '--1uniquekey'=>array('More'=>array(2=>'Two', 3=>'Three')))
     */
    var $options;
    /**
     * Selected option
     * @var string
     */
    var $selected;
    /**
     * Nothing selected
     * @var array
     */
    var $nothing;
    /**
     * Extra select field attributes
     * @var array
     */
    var $attributes = array();
    /**
     * Button label
     * @var string
     */
    var $label = '';
    /**
     * Form submit method
     * @var string post or get
     */
    var $method = 'get';
    /**
     * Wrapping div class
     * @var string
     * */
    var $class = 'singleselect';
    /**
     * True if button disabled, false if normal
     * @var boolean
     */
    var $disabled = false;
    /**
     * Button tooltip
     * @var string
     */
    var $tooltip = null;
    /**
     * Form id
     * @var string
     */
    var $formid = null;
    /**
     * List of attached actions
     * @var array of component_action
     */
    var $helpicon = null;
    /**
     * Constructor
     * @param moodle_url $url form action target, includes hidden fields
     * @param string $name name of selection field - the changing parameter in url
     * @param array $options list of options
     * @param string $selected selected element
     * @param array $nothing
     */
    public function __construct(moodle_url $url, $name, array $options, $selected='', $nothing=array(''=>'choosedots')) {
        $this->url      = $url;
        $this->name     = $name;
        $this->options  = $options;
        $this->selected = $selected;
        $this->nothing  = $nothing;
    }

    /**
     * Shortcut for adding a JS confirm dialog when the button is clicked.
     * The message must be a yes/no question.
     * @param string $message The yes/no confirmation question. If "Yes" is clicked, the original action will occur.
     * @return void
     */
    public function add_confirm_action($confirmmessage) {
        $this->add_action(new component_action('submit', 'M.util.show_confirm_dialog', array('message' => $confirmmessage)));
    }

    /**
     * Add action to the button.
     * @param component_action $action
     * @return void
     */
    public function add_action(component_action $action) {
        $this->actions[] = $action;
    }
}


/**
 * Data structure describing html link with special action attached.
 * @copyright 2010 Petr Skoda
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class action_link implements renderable {
    /**
     * Href url
     * @var moodle_url
     */
    var $url;
    /**
     * Link text
     * @var string HTML fragment
     */
    var $text;
    /**
     * HTML attributes
     * @var array
     */
    var $attributes;
    /**
     * List of actions attached to link
     * @var array of component_action
     */
    var $actions;

    /**
     * Constructor
     * @param string|moodle_url $url
     * @param string $text HTML fragment
     * @param component_action $action
     * @param array $attributes associative array of html link attributes + disabled
     */
    public function __construct(moodle_url $url, $text, component_action $action=null, array $attributes=null) {
        $this->url       = clone($url);
        $this->text      = $text;
        if ($action) {
            $this->add_action($action);
        }
    }

    /**
     * Add action to the link.
     * @param component_action $action
     * @return void
     */
    public function add_action(component_action $action) {
        $this->actions[] = $action;
    }
}


// ==== HTML writer and helper classes, will be probably moved elsewhere ======

/**
 * Simple html output class
 * @copyright 2009 Tim Hunt, 2010 Petr Skoda
 */
class html_writer {
    /**
     * Outputs a tag with attributes and contents
     * @param string $tagname The name of tag ('a', 'img', 'span' etc.)
     * @param array $attributes The tag attributes (array('src' => $url, 'class' => 'class1') etc.)
     * @param string $contents What goes between the opening and closing tags
     * @return string HTML fragment
     */
    public static function tag($tagname, array $attributes = null, $contents) {
        return self::start_tag($tagname, $attributes) . $contents . self::end_tag($tagname);
    }

    /**
     * Outputs an opening tag with attributes
     * @param string $tagname The name of tag ('a', 'img', 'span' etc.)
     * @param array $attributes The tag attributes (array('src' => $url, 'class' => 'class1') etc.)
     * @return string HTML fragment
     */
    public static function start_tag($tagname, array $attributes = null) {
        return '<' . $tagname . self::attributes($attributes) . '>';
    }

    /**
     * Outputs a closing tag
     * @param string $tagname The name of tag ('a', 'img', 'span' etc.)
     * @return string HTML fragment
     */
    public static function end_tag($tagname) {
        return '</' . $tagname . '>';
    }

    /**
     * Outputs an empty tag with attributes
     * @param string $tagname The name of tag ('input', 'img', 'br' etc.)
     * @param array $attributes The tag attributes (array('src' => $url, 'class' => 'class1') etc.)
     * @return string HTML fragment
     */
    public static function empty_tag($tagname, array $attributes = null) {
        return '<' . $tagname . self::attributes($attributes) . ' />';
    }

    /**
     * Outputs a HTML attribute and value
     * @param string $name The name of the attribute ('src', 'href', 'class' etc.)
     * @param string $value The value of the attribute. The value will be escaped with {@link s()}
     * @return string HTML fragment
     */
    public static function attribute($name, $value) {
        if (is_array($value)) {
            debugging("Passed an array for the HTML attribute $name", DEBUG_DEVELOPER);
        }
        if ($value instanceof moodle_url) {
            return ' ' . $name . '="' . $value->out() . '"';
        }

        // special case, we do not want these in output
        if ($value === null) {
            return '';
        }

        // no sloppy trimming here!
        return ' ' . $name . '="' . s($value) . '"';
    }

    /**
     * Outputs a list of HTML attributes and values
     * @param array $attributes The tag attributes (array('src' => $url, 'class' => 'class1') etc.)
     *       The values will be escaped with {@link s()}
     * @return string HTML fragment
     */
    public static function attributes(array $attributes = null) {
        $attributes = (array)$attributes;
        $output = '';
        foreach ($attributes as $name => $value) {
            $output .= self::attribute($name, $value);
        }
        return $output;
    }

    /**
     * Generates random html element id.
     * @param string $base
     * @return string
     */
    public static function random_id($base='random') {
        return uniqid($base);
    }

    /**
     * Generates a simple html link
     * @param string|moodle_url $url
     * @param string $text link txt
     * @param array $attributes extra html attributes
     * @return string HTML fragment
     */
    public static function link($url, $text, array $attributes = null) {
        $attributes = (array)$attributes;
        $attributes['href']  = $url;
        return self::tag('a', $attributes, $text);
    }

    /**
     * generates a simple checkbox with optional label
     * @param string $name
     * @param string $value
     * @param bool $checked
     * @param string $label
     * @param array $attributes
     * @return string html fragment
     */
    public static function checkbox($name, $value, $checked = true, $label = '', array $attributes = null) {
        $attributes = (array)$attributes;
        $output = '';

        if ($label !== '' and !is_null($label)) {
            if (empty($attributes['id'])) {
                $attributes['id'] = self::random_id('checkbox_');
            }
        }
        $attributes['type']    = 'checkbox';
        $attributes['value']   = $value;
        $attributes['name']    = $name;
        $attributes['checked'] = $checked ? 'selected' : null;

        $output .= self::empty_tag('input', $attributes);

        if ($label !== '' and !is_null($label)) {
            $output .= self::tag('label', array('for'=>$attributes['id']), $label);
        }

        return $output;
    }

    /**
     * Generates a simple select form field
     * @param array $options associative array value=>label ex.:
     *                array(1=>'One, 2=>Two)
     *              it is also possible to specify optgroup as complex label array ex.:
     *                array(array('Odd'=>array(1=>'One', 3=>'Three)), array('Even'=>array(2=>'Two')))
     *                array(1=>'One', '--1uniquekey'=>array('More'=>array(2=>'Two', 3=>'Three')))
     * @param string $name name of select element
     * @param string|array $selected value or arary of values depending on multiple attribute
     * @param array|bool $nothing, add nothing selected option, or false of not added
     * @param array $attributes - html select element attributes
     * @return string HRML fragment
     */
    public static function select(array $options, $name, $selected = '', $nothing = array(''=>'choosedots'), array $attributes = null) {
        $attributes = (array)$attributes;
        if (is_array($nothing)) {
            foreach ($nothing as $k=>$v) {
                if ($v === 'choose' or $v === 'choosedots') {
                    $nothing[$k] = get_string('choosedots');
                }
            }
            $options = $nothing + $options; // keep keys, do not override

        } else if (is_string($nothing) and $nothing !== '') {
            // BC
            $options = array(''=>$nothing) + $options;
        }

        // we may accept more values if multiple attribute specified
        $selected = (array)$selected;
        foreach ($selected as $k=>$v) {
            $selected[$k] = (string)$v;
        }

        if (!isset($attributes['id'])) {
            $id = 'menu'.$name;
            // name may contaion [], which would make an invalid id. e.g. numeric question type editing form, assignment quickgrading
            $id = str_replace('[', '', $id);
            $id = str_replace(']', '', $id);
            $attributes['id'] = $id;
        }

        if (!isset($attributes['class'])) {
            $class = 'menu'.$name;
            // name may contaion [], which would make an invalid class. e.g. numeric question type editing form, assignment quickgrading
            $class = str_replace('[', '', $class);
            $class = str_replace(']', '', $class);
            $attributes['class'] = $class;
        }
        $attributes['class'] = 'select ' . $attributes['class']; /// Add 'select' selector always

        $attributes['name'] = $name;

        $output = '';
        foreach ($options as $value=>$label) {
            if (is_array($label)) {
                // ignore key, it just has to be unique
                $output .= self::select_optgroup(key($label), current($label), $selected);
            } else {
                $output .= self::select_option($label, $value, $selected);
            }
        }
        return self::tag('select', $attributes, $output);
    }

    private static function select_option($label, $value, array $selected) {
        $attributes = array();
        $value = (string)$value;
        if (in_array($value, $selected, true)) {
            $attributes['selected'] = 'selected';
        }
        $attributes['value'] = $value;
        return self::tag('option', $attributes, $label);
    }

    private static function select_optgroup($groupname, $options, array $selected) {
        if (empty($options)) {
            return '';
        }
        $attributes = array('label'=>$groupname);
        $output = '';
        foreach ($options as $value=>$label) {
            $output .= self::select_option($label, $value, $selected);
        }
        return self::tag('optgroup', $attributes, $output);
    }

    /**
     * Returns hidden input fields created from url parameters.
     * @param moodle_url $url
     * @param array $exclude list of excluded parameters
     * @return string HTML fragment
     */
    public static function input_hidden_params(moodle_url $url, array $exclude = null) {
        $exclude = (array)$exclude;
        $params = $url->params();
        foreach ($exclude as $key) {
            unset($params[$key]);
        }

        $output = '';
        foreach ($params as $key => $value) {
            $attributes = array('type'=>'hidden', 'name'=>$key, 'value'=>$value);
            $output .= self::empty_tag('input', $attributes)."\n";
        }
        return $output;
    }

    /**
     * Generate a script tag containing the the specified code.
     *
     * @param string $js the JavaScript code
	 * @param moodle_url|string optional url of the external script, $code ignored if specified
     * @return string HTML, the code wrapped in <script> tags.
     */
    public static function script($jscode, $url=null) {
        if ($jscode) {
            $attributes = array('type'=>'text/javascript');
            return self::tag('script', $attributes, "\n//<![CDATA[\n$jscode\n//]]>\n") . "\n";

        } else if ($url) {
            $attributes = array('type'=>'text/javascript', 'src'=>$url);
            return self::tag('script', $attributes, '') . "\n";

        } else {
            return '';
        }
    }
}

// ==== JS writer and helper classes, will be probably moved elsewhere ======

/**
 * Simple javascript output class
 * @copyright 2010 Petr Skoda
 */
class js_writer {
    /**
     * Returns javascript code calling the function
     * @param string $function function name, can be complex lin Y.Event.purgeElement
     * @param array $arguments parameters
     * @param int $delay execution delay in seconds
     * @return string JS code fragment
     */
    public function function_call($function, array $arguments = null, $delay=0) {
        if ($arguments) {
            $arguments = array_map('json_encode', $arguments);
            $arguments = implode(', ', $arguments);
        } else {
            $arguments = '';
        }
        $js = "$function($arguments);";

        if ($delay) {
            $delay = $delay * 1000; // in miliseconds
            $js = "setTimeout(function() { $js }, $delay);";
        }
        return $js . "\n";
    }

    /**
     * Special function which adds Y as first argument of fucntion call.
     * @param string $function
     * @param array $extraarguments
     * @return string
     */
    public function function_call_with_Y($function, array $extraarguments = null) {
        if ($extraarguments) {
            $extraarguments = array_map('json_encode', $extraarguments);
            $arguments = 'Y, ' . implode(', ', $extraarguments);
        } else {
            $arguments = 'Y';
        }
        return "$function($arguments);\n";
    }

    /**
     * Returns JavaScript code to initialise a new object
     * @param string|null $var If it is null then no var is assigned the new object
     * @param string $class
     * @param array $arguments
     * @param array $requirements
     * @param int $delay
     * @return string
     */
    public function object_init($var, $class, array $arguments = null, array $requirements = null, $delay=0) {
        if (is_array($arguments)) {
            $arguments = array_map('json_encode', $arguments);
            $arguments = implode(', ', $arguments);
        }

        if ($var === null) {
            $js = "new $class(Y, $arguments);";
        } else if (strpos($var, '.')!==false) {
            $js = "$var = new $class(Y, $arguments);";
        } else {
            $js = "var $var = new $class(Y, $arguments);";
        }

        if ($delay) {
            $delay = $delay * 1000; // in miliseconds
            $js = "setTimeout(function() { $js }, $delay);";
        }

        if (count($requirements) > 0) {
            $requirements = implode("', '", $requirements);
            $js = "Y.use('$requirements', function(Y){ $js });";
        }
        return $js."\n";
    }

    /**
     * Returns code setting value to variable
     * @param string $name
     * @param mixed $value json serialised value
     * @param bool $usevar add var definition, ignored for nested properties
     * @return string JS code fragment
     */
    public function set_variable($name, $value, $usevar=true) {
        $output = '';

        if ($usevar) {
            if (strpos($name, '.')) {
                $output .= '';
            } else {
                $output .= 'var ';
            }
        }

        $output .= "$name = ".json_encode($value).";";

        return $output;
    }

    /**
     * Writes event handler attaching code
     * @param mixed $selector standard YUI selector for elemnts, may be array or string, element id is in the form "#idvalue"
     * @param string $event A valid DOM event (click, mousedown, change etc.)
     * @param string $function The name of the function to call
     * @param array  $arguments An optional array of argument parameters to pass to the function
     * @return string JS code fragment
     */
    public function event_handler($selector, $event, $function, array $arguments = null) {
        $selector = json_encode($selector);
        $output = "Y.on('$event', $function, $selector, null";
        if (!empty($arguments)) {
            $output .= ', ' . json_encode($arguments);
        }
        return $output . ");\n";
    }
}


// ===============================================================================================
// TODO: Following components will be refactored soon

/**
 * Base class for classes representing HTML elements, like html_select.
 *
 * Handles the id and class attributes.
 *
 * @copyright 2009 Tim Hunt
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_component {
    /**
     * @var string value to use for the id attribute of this HTML tag.
     */
    public $id = null;
    /**
     * @var string $alt value to use for the alt attribute of this HTML tag.
     */
    public $alt = null;
    /**
     * @var string $style value to use for the style attribute of this HTML tag.
     */
    public $style = null;
    /**
     * @var array class names to add to this HTML element.
     */
    public $classes = array();
    /**
     * @var string $title The title attributes applicable to any XHTML element
     */
    public $title = null;
    /**
     * An optional array of component_action objects handling the action part of this component.
     * @var array $actions
     */
    protected $actions = array();

    /**
     * Compoment constructor.
     * @param array $options image attributes such as title, id, alt, style, class
     */
    public function __construct(array $options = null) {
        // not implemented in this class because we want to set only public properties of this component
        renderer_base::apply_component_options($this, $options);
    }

    /**
     * Ensure some class names are an array.
     * @param mixed $classes either an array of class names or a space-separated
     *      string containing class names.
     * @return array the class names as an array.
     */
    public static function clean_classes($classes) {
        if (empty($classes)) {
            return array();
        } else if (is_array($classes)) {
            return $classes;
        } else {
            return explode(' ', trim($classes));
        }
    }

    /**
     * Set the class name array.
     * @param mixed $classes either an array of class names or a space-separated
     *      string containing class names.
     * @return void
     */
    public function set_classes($classes) {
        $this->classes = self::clean_classes($classes);
    }

    /**
     * Add a class name to the class names array.
     * @param string $class the new class name to add.
     * @return void
     */
    public function add_class($class) {
        $this->classes[] = $class;
    }

    /**
     * Add a whole lot of class names to the class names array.
     * @param mixed $classes either an array of class names or a space-separated
     *      string containing class names.
     * @return void
     */
    public function add_classes($classes) {
        $this->classes = array_merge($this->classes, self::clean_classes($classes));
    }

    /**
     * Get the class names as a string.
     * @return string the class names as a space-separated string. Ready to be put in the class="" attribute.
     */
    public function get_classes_string() {
        return implode(' ', $this->classes);
    }

    /**
     * Perform any cleanup or final processing that should be done before an
     * instance of this class is output. This method is supposed to be called
     * only from renderers.
     *
     * @param renderer_base $output output renderer
     * @param moodle_page $page
     * @param string $target rendering target
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        $this->classes = array_unique(self::clean_classes($this->classes));
    }

    /**
     * This checks developer do not try to assign a property directly
     * if we have a setter for it. Otherwise, the property is set as expected.
     * @param string $name The name of the variable to set
     * @param mixed $value The value to assign to the variable
     * @return void
     */
    public function __set($name, $value) {
        if ($name == 'class') {
            debugging('this way of setting css class has been deprecated. use set_classes() method instead.');
            $this->set_classes($value);
        } else {
            $this->{$name} = $value;
        }
    }

    /**
     * Adds a JS action to this component.
     * Note: the JS function you write must have only two arguments: (string)event and (object|array)args
     * If you want to add an instantiated component_action (or one of its subclasses), give the object as the only parameter
     *
     * @param mixed  $event a DOM event (click, mouseover etc.) or a component_action object
     * @param string $jsfunction The name of the JS function to call. required if argument 1 is a string (event)
     * @param array  $jsfunctionargs An optional array of JS arguments to pass to the function
     */
    public function add_action($event, $jsfunction=null, $jsfunctionargs=array()) {
        if (empty($this->id)) {
            $this->generate_id();
        }

        if ($event instanceof component_action) {
            $this->actions[] = $event;
        } else {
            if (empty($jsfunction)) {
                throw new coding_exception('html_component::add_action requires a JS function argument if the first argument is a string event');
            }
            $this->actions[] = new component_action($event, $jsfunction, $jsfunctionargs);
        }
    }

    /**
     * Internal method for generating a unique ID for the purpose of event handlers.
     */
    protected function generate_id() {
        $this->id = uniqid(get_class($this));
    }

    /**
     * Returns the array of component_actions.
     * @return array Component actions
     */
    public function get_actions() {
        return $this->actions;
    }

    /**
     * Shortcut for adding a JS confirm dialog when the component is clicked.
     * The message must be a yes/no question.
     * @param string $message The yes/no confirmation question. If "Yes" is clicked, the original action will occur.
     * @param string $callback The name of a JS function whose scope will be set to the simpleDialog object and have this
     *    function's arguments set as this.args.
     * @return void
     */
    public function add_confirm_action($message, $callback=null) {
        $this->add_action(new component_action('click', 'M.util.show_confirm_dialog', array('message' => $message, 'callback' => $callback)));
    }

    /**
     * Returns true if this component has an action of the requested type (component_action by default).
     * @param string $class The class of the action we are looking for
     * @return boolean True if action is found
     */
    public function has_action($class='component_action') {
        foreach ($this->actions as $action) {
            if (get_class($action) == $class) {
                return true;
            }
        }
        return false;
    }
}


class labelled_html_component extends html_component {
    /**
     * @var mixed $label The label for that component. String or html_label object
     */
    public $label;

    /**
     * Compoment constructor.
     * @param array $options image attributes such as title, id, alt, style, class
     */
    public function __construct(array $options = null) {
        parent::__construct($options);
    }

    /**
     * Adds a descriptive label to the component.
     *
     * This can be used in two ways:
     *
     * <pre>
     * $component->set_label($elementlabel, $elementid);
     * // OR
     * $label = new html_label();
     * $label->for = $elementid;
     * $label->text = $elementlabel;
     * $component->set_label($label);
     * </pre>
     *
     * Use the second form when you need to add additional HTML attributes
     * to the label and/or JS actions.
     *
     * @param mixed $text Either the text of the label or a html_label object
     * @param text  $for The value of the "for" attribute (the associated element's id)
     * @return void
     */
    public function set_label($text, $for=null) {
        if ($text instanceof html_label) {
            $this->label = $text;
        } else if (!empty($text)) {
            $this->label = new html_label();
            $this->label->for = $for;
            if (empty($for)) {
                if (empty($this->id)) {
                    $this->generate_id();
                }
                $this->label->for = $this->id;
            }
            $this->label->text = $text;
        }
    }
}

/// Components representing HTML elements

/**
 * This class represents a label element
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_label extends html_component {
    /**
     * @var string $text The text to display in the label
     */
    public $text;
    /**
     * @var string $for The name of the form field this label is associated with
     */
    public $for;

    /**
     * @see html_component::prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        if (empty($this->text)) {
            throw new coding_exception('html_label must have a $text value.');
        }
        parent::prepare($output, $page, $target);
    }
}


/**
 * This class hold all the information required to describe a <select> menu that
 * will be printed by {@link core_renderer::select()}. (Or by an overridden
 * version of that method in a subclass.)
 *
 * This component can also hold enough metadata to be used as a popup form. It just
 * needs a bit more setting up than for a simple menu. See the shortcut methods for
 * developer-friendly usage.
 *
 * All the fields that are not set by the constructor have sensible defaults, so
 * you only need to set the properties where you want non-default behaviour.
 *
 * @copyright 2009 Tim Hunt
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_select extends labelled_html_component {
    /**
     * The html_select object parses an array of options into component objects
     * @see nested attribute
     * @var mixed $options the choices to show in the menu. An array $value => $display, of html_select_option or of html_select_optgroup objects.
     */
    public $options;
    /**
     * @var string $name the name of this form control. That is, the name of the GET/POST
     * variable that will be set if this select is submitted as part of a form.
     */
    public $name;
    /**
     * @var string $selectedvalue the option to select initially. Should match one
     * of the $options array keys. Default none.
     */
    public $selectedvalue;
    /**
     * Defaults to get_string('choosedots').
     * Set this to '' if you do not want a 'nothing is selected' option.
     * This is ignored if the rendertype is 'radio' or 'checkbox'
     * @var string The label for the 'nothing is selected' option.
     */
    public $nothinglabel = null;
    /**
     * @var string The value returned by the 'nothing is selected' option. Defaults to 0.
     */
    public $nothingvalue = 0;
    /**
     * @var boolean set this to true if you want the control to appear disabled.
     */
    public $disabled = false;
    /**
     * @var integer if non-zero, sets the tabindex attribute on the <select> element. Default 0.
     */
    public $tabindex = 0;
    /**
     * @var mixed Defaults to false, which means display the select as a dropdown menu.
     * If true, display this select as a list box whose size is chosen automatically.
     * If an integer, display as list box of that size.
     */
    public $listbox = false;
    /**
     * @var integer if you are using $listbox === true to get an automatically
     * sized list box, the size of the list box will be the number of options,
     * or this number, whichever is smaller.
     */
    public $maxautosize = 10;
    /**
     * @var boolean if true, allow multiple selection. Only used if $listbox is true, or if
     *      the select is to be output as checkboxes.
     */
    public $multiple = false;
    /**
     * Another way to use nested menu is to prefix optgroup labels with -- and end the optgroup with --
     * Leave this setting to false if you are using the latter method.
     * @var boolean $nested if true, uses $options' keys as option headings (optgroup)
     */
    public $nested = false;
    /**
     * @var html_form $form An optional html_form component
     */
    public $form;
    /**
     * @var help_icon $array help icon params
     */
    public $helpicon;
    /**
     * @var boolean $rendertype How the select element should be rendered: menu or radio (checkbox is just radio + multiple)
     */
    public $rendertype = 'menu';

    /**
     * @see html_component::prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        global $CFG;

        // name may contain [], which would make an invalid id. e.g. numeric question type editing form, assignment quickgrading
        if (empty($this->id)) {
            $this->id = 'menu' . str_replace(array('[', ']'), '', $this->name);
        }

        if (empty($this->classes)) {
            $this->set_classes(array('menu' . str_replace(array('[', ']'), '', $this->name)));
        }

        if (is_null($this->nothinglabel)) {
            $this->nothinglabel = get_string('choosedots');
        }

        if (!empty($this->label) && !($this->label instanceof html_label)) {
            $label = new html_label();
            $label->text = $this->label;
            $label->for = $this->name;
            $this->label = $label;
        }

        $this->add_class('select');

        $this->initialise_options();
        parent::prepare($output, $page, $target);
    }

    /**
     * This is a shortcut for making a simple select menu. It lets you specify
     * the options, name and selected option in one line of code.
     * @param array $options used to initialise {@link $options}.
     * @param string $name used to initialise {@link $name}.
     * @param string $selected  used to initialise {@link $selected}.
     * @param string $nothinglabel The label for the 'nothing is selected' option. Defaults to "Choose..."
     * @return html_select A html_select object with the three common fields initialised.
     */
    public static function make($options, $name, $selected = '', $nothinglabel='choosedots') {
        $menu = new html_select();
        $menu->options = $options;
        $menu->name = $name;
        $menu->selectedvalue = $selected;
        return $menu;
    }

    /**
     * This is a shortcut for making a yes/no select menu.
     * @param string $name used to initialise {@link $name}.
     * @param string $selected  used to initialise {@link $selected}.
     * @return html_select A menu initialised with yes/no options.
     */
    public static function make_yes_no($name, $selected) {
        return self::make(array(0 => get_string('no'), 1 => get_string('yes')), $name, $selected);
    }

    /**
     * This is a shortcut for making an hour selector menu.
     * @param string $type The type of selector (years, months, days, hours, minutes)
     * @param string $name fieldname
     * @param int $currenttime A default timestamp in GMT
     * @param int $step minute spacing
     * @return html_select A menu initialised with hour options.
     */
    public static function make_time_selector($type, $name, $currenttime=0, $step=5) {

        if (!$currenttime) {
            $currenttime = time();
        }
        $currentdate = usergetdate($currenttime);
        $userdatetype = $type;

        switch ($type) {
            case 'years':
                for ($i=1970; $i<=2020; $i++) {
                    $timeunits[$i] = $i;
                }
                $userdatetype = 'year';
                break;
            case 'months':
                for ($i=1; $i<=12; $i++) {
                    $timeunits[$i] = userdate(gmmktime(12,0,0,$i,15,2000), "%B");
                }
                $userdatetype = 'month';
                $currentdate['month'] = $currentdate['mon'];
                break;
            case 'days':
                for ($i=1; $i<=31; $i++) {
                    $timeunits[$i] = $i;
                }
                $userdatetype = 'mday';
                break;
            case 'hours':
                for ($i=0; $i<=23; $i++) {
                    $timeunits[$i] = sprintf("%02d",$i);
                }
                break;
            case 'minutes':
                if ($step != 1) {
                    $currentdate['minutes'] = ceil($currentdate['minutes']/$step)*$step;
                }

                for ($i=0; $i<=59; $i+=$step) {
                    $timeunits[$i] = sprintf("%02d",$i);
                }
                break;
            default:
                throw new coding_exception("Time type $type is not supported by html_select::make_time_selector().");
        }

        $timerselector = self::make($timeunits, $name, $currentdate[$userdatetype]);
        $timerselector->label = new html_label();

        $timerselector->label->text = get_string(substr($type, 0, -1), 'form');
        $timerselector->label->for = "menu$timerselector->name";
        $timerselector->label->add_class('accesshide');
        $timerselector->nothinglabel = '';

        return $timerselector;
    }

    /**
     * Given an associative array of type => fieldname and an optional timestamp,
     * returns an array of html_select components representing date/time selectors.
     * @param array $selectors Arrays of type => fieldname. Selectors will be returned in the order of the types given
     * @param int $currenttime A UNIX timestamp
     * @param int $step minute spacing
     * @return array Instantiated date/time selectors
     */
    public static function make_time_selectors($selectors, $currenttime=0, $step=5) {
        $selects = array();
        foreach ($selectors as $type => $name) {
            $selects[] = html_select::make_time_selector($type, $name, $currenttime, $step);
        }
        return $selects;
    }

    /**
     * This is a shortcut for making a select popup form.
     * @param mixed $baseurl The target URL, string or moodle_url
     * @param string $name The variable which this select's options are changing in the URL
     * @param array $options A list of value-label pairs for the popup list
     * @param string $formid id for the control. Must be unique on the page. Used in the HTML.
     * @param string $selected The option that is initially selected
     * @return html_select A menu initialised as a popup form.
     */
    public static function make_popup_form($baseurl, $name, $options, $formid, $selected=null) {
        global $CFG;

        $selectedurl = null;

        if (!($baseurl instanceof moodle_url)) {
            $baseurl = new moodle_url($baseurl);
        }

        if (!empty($selected)) {
            $selectedurl = $baseurl->out(false, array($name => $selected));
        }

        // Replace real value by formatted URLs
        foreach ($options as $value => $label) {
            $options[$baseurl->out(false, array($name => $value))] = $label;
            unset($options[$value]);
        }

        $select = self::make($options, 'jump', $selectedurl);

        $select->form = new html_form();
        $select->form->id = $formid;
        $select->form->method = 'get';
        $select->form->jssubmitaction = true;
        $select->form->add_class('popupform');
        $select->form->url = new moodle_url('/course/jumpto.php', array('sesskey' => sesskey()));
        $select->form->button->text = get_string('go');

        $select->id = $formid . '_jump';

        $select->add_action('change', 'submit_form_by_id', array('id' => $formid, 'selectid' => $select->id));

        return $select;
    }

    /**
     * Override the URLs of the default popup_form, which only supports one base URL
     * @param array $options value=>label pairs representing select options
     * @return void
     */
    public function override_option_values($options) {
        // TODO: this is ugly hack because components shoudl never touch global $PAGE with the exception in prepare(),
        //       in any case this methods needs to be revisited because it does not make much sense to use the same $menu in
        //       html_select::make_popup_form() and then again in this method!
        global $PAGE; //TODO: remove

        $originalcount = count($options);
        $this->initialise_options();
        $newcount = count($this->options);
        $first = true;

        reset($options);

        foreach ($this->options as $optkey => $optgroup) {
            if ($optgroup instanceof html_select_optgroup) {
                foreach ($optgroup->options as $key => $option) {
                    next($options);
                    $this->options[$optkey]->options[$key]->value = key($options);

                    $optionurl = new moodle_url(key($options));

                    if ($optionurl->compare($PAGE->url, URL_MATCH_PARAMS)) {
                        $this->options[$optkey]->options[$key]->selected = 'selected';
                    }
                }
                next($options);
            } else if ($optgroup instanceof html_select_option && !($first && $originalcount < $newcount)) {
                $this->options[$optkey]->value = key($options);
                $optionurl = new moodle_url(key($options));

                if ($optionurl->compare($PAGE->url, URL_MATCH_PARAMS)) {
                    $this->options[$optkey]->selected = 'selected';
                }
                next($options);
            }
            $first = false;
        }
    }

    /**
     * Adds a help icon next to the select menu.
     *
     * <pre>
     * $select->set_help_icon($page, $text, $component);
     * </pre>
     *
     * @param string $helppage Either the keyword that defines a help page or a help_icon object
     * @param text  $text The text of the help icon
     * @param component $component
     * @param boolean $linktext Whether or not to show text next to the icon
     * @return void
     */
    public function set_help_icon($helppage='', $text='', $component='moodle') {
        if ($helppage) {
            $this->helpicon = array('helppage'=>$helppage, 'text'=>$text, 'component'=>$component);
        } else {
            $this->helpicon = null;
        }
    }

    /**
     * Parses the $options array and instantiates html_select_option objects in
     * the place of the original value => label pairs. This is useful for when you
     * need to setup extra html attributes and actions on individual options before
     * the component is sent to the renderer
     * @return void;
     */
    public function initialise_options() {
        // If options are already instantiated objects, stop here
        $firstoption = reset($this->options);
        if ($firstoption instanceof html_select_option || $firstoption instanceof html_select_optgroup) {
            return;
        }

        if ($this->rendertype == 'radio' && $this->multiple) {
            $this->rendertype = 'checkbox';
        }

        // If nested is on, or if radio/checkbox rendertype is set, remove the default Choose option
        if ($this->nested || $this->rendertype == 'radio' || $this->rendertype == 'checkbox') {
            $this->nothinglabel = '';
        }

        $options = $this->options;

        $this->options = array();

        if ($this->nested && $this->rendertype != 'menu') {
            throw new coding_exception('html_select cannot render nested options as radio buttons or checkboxes.');
        } else if ($this->nested) {
            foreach ($options as $section => $values) {
                $optgroup = new html_select_optgroup();
                $optgroup->text = $section;

                foreach ($values as $value => $display) {
                    $option = new html_select_option();
                    $option->value = s($value);
                    $option->text = $display;
                    if ($display === '') {
                        $option->text = $value;
                    }

                    if ((string) $value == (string) $this->selectedvalue ||
                            (is_array($this->selectedvalue) && in_array($value, $this->selectedvalue))) {
                        $option->selected = 'selected';
                    }

                    $optgroup->options[] = $option;
                }

                $this->options[] = $optgroup;
            }
        } else {
            $inoptgroup = false;
            $optgroup = false;

            foreach ($options as $value => $display) {
                if ($display == '--') { /// we are ending previous optgroup
                    // $this->options[] = $optgroup;
                    $inoptgroup = false;
                    continue;
                } else if (substr($display,0,2) == '--') { /// we are starting a new optgroup
                    if (!empty($optgroup->options)) {
                        $this->options[] = $optgroup;
                    }

                    $optgroup = new html_select_optgroup();
                    $optgroup->text = substr($display,2); // stripping the --

                    $inoptgroup = true; /// everything following will be in an optgroup
                    continue;

                } else {
                    // Add $nothing option if there are not optgroups
                    if ($this->nothinglabel && empty($this->options[0]) && !$inoptgroup) {
                        $nothingoption = new html_select_option();
                        $nothingoption->value = 0;
                        if (!empty($this->nothingvalue)) {
                            $nothingoption->value = $this->nothingvalue;
                        }
                        $nothingoption->text = $this->nothinglabel;
                        $this->options = array($nothingoption) + $this->options;
                    }

                    $option = new html_select_option();
                    $option->text = $display;

                    if ($display === '') {
                        $option->text = $value;
                    }

                    if ((string) $value == (string) $this->selectedvalue ||
                            (is_array($this->selectedvalue) && in_array($value, $this->selectedvalue))) {
                        $option->selected = 'selected';
                    }

                    $option->value = s($value);

                    if ($inoptgroup) {
                        $optgroup->options[] = $option;
                    } else {
                        $this->options[] = $option;
                    }
                }
            }

            if ($optgroup) {
                $this->options[] = $optgroup;
            }
        }
    }
}


/**
 * This class represents a select option element
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_select_option extends labelled_html_component {
    /**
     * @var string $value The value of this option (will be sent with form)
     */
    public $value;
    /**
     * @var string $text The display value of the option
     */
    public $text;
    /**
     * @var boolean $selected Whether or not this option is selected
     */
    public $selected = false;
    /**
     * @var boolean $disabled Whether or not this option is disabled
     */
    public $disabled = false;

    public function __construct() {
        $this->label = new html_label();
    }

    /**
     * @see html_component::prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        if (empty($this->text) && (string)$this->text!=='0') {
            throw new coding_exception('html_select_option requires a $text value.');
        }

        if (empty($this->label->text)) {
            $this->set_label($this->text);
        } else if (!($this->label instanceof html_label)) {
            $this->set_label($this->label);
        }
        if (empty($this->id)) {
            $this->generate_id();
        }

        parent::prepare($output, $page, $target);
    }
}


/**
 * This class represents a select optgroup element
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_select_optgroup extends html_component {
    /**
     * @var string $text The display value of the optgroup
     */
    public $text;
    /**
     * @var array $options An array of html_select_option objects
     */
    public $options = array();

    public function prepare(renderer_base $output, moodle_page $page, $target) {
        if (empty($this->text)) {
            throw new coding_exception('html_select_optgroup requires a $text value.');
        }
        if (empty($this->options)) {
            throw new coding_exception('html_select_optgroup requires at least one html_select_option object');
        }
        parent::prepare($output, $page, $target);
    }
}


/**
 * Holds all the information required to render a <table> by
 * {@see core_renderer::table()} or by an overridden version of that
 * method in a subclass.
 *
 * Example of usage:
 * $t = new html_table();
 * ... // set various properties of the object $t as described below
 * echo $OUTPUT->table($t);
 *
 * @copyright 2009 David Mudrak <david.mudrak@gmail.com>
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_table extends labelled_html_component {
    /**
     * For more control over the rendering of the headers, an array of html_table_cell objects
     * can be passed instead of an array of strings.
     * @var array of headings. The n-th array item is used as a heading of the n-th column.
     *
     * Example of usage:
     * $t->head = array('Student', 'Grade');
     */
    public $head;
    /**
     * @var array can be used to make a heading span multiple columns
     *
     * Example of usage:
     * $t->headspan = array(2,1);
     *
     * In this example, {@see html_table:$data} is supposed to have three columns. For the first two columns,
     * the same heading is used. Therefore, {@see html_table::$head} should consist of two items.
     */
    public $headspan;
    /**
     * @var array of column alignments. The value is used as CSS 'text-align' property. Therefore, possible
     * values are 'left', 'right', 'center' and 'justify'. Specify 'right' or 'left' from the perspective
     * of a left-to-right (LTR) language. For RTL, the values are flipped automatically.
     *
     * Examples of usage:
     * $t->align = array(null, 'right');
     * or
     * $t->align[1] = 'right';
     *
     */
    public $align;
    /**
     * @var array of column sizes. The value is used as CSS 'size' property.
     *
     * Examples of usage:
     * $t->size = array('50%', '50%');
     * or
     * $t->size[1] = '120px';
     */
    public $size;
    /**
     * @var array of wrapping information. The only possible value is 'nowrap' that sets the
     * CSS property 'white-space' to the value 'nowrap' in the given column.
     *
     * Example of usage:
     * $t->wrap = array(null, 'nowrap');
     */
    public $wrap;
    /**
     * @var array of arrays or html_table_row objects containing the data. Alternatively, if you have
     * $head specified, the string 'hr' (for horizontal ruler) can be used
     * instead of an array of cells data resulting in a divider rendered.
     *
     * Example of usage with array of arrays:
     * $row1 = array('Harry Potter', '76 %');
     * $row2 = array('Hermione Granger', '100 %');
     * $t->data = array($row1, $row2);
     *
     * Example with array of html_table_row objects: (used for more fine-grained control)
     * $cell1 = new html_table_cell();
     * $cell1->text = 'Harry Potter';
     * $cell1->colspan = 2;
     * $row1 = new html_table_row();
     * $row1->cells[] = $cell1;
     * $cell2 = new html_table_cell();
     * $cell2->text = 'Hermione Granger';
     * $cell3 = new html_table_cell();
     * $cell3->text = '100 %';
     * $row2 = new html_table_row();
     * $row2->cells = array($cell2, $cell3);
     * $t->data = array($row1, $row2);
     */
    public $data;
    /**
     * @var string width of the table, percentage of the page preferred. Defaults to 80% of the page width.
     * @deprecated since Moodle 2.0. Styling should be in the CSS.
     */
    public $width = null;
    /**
     * @var string alignment the whole table. Can be 'right', 'left' or 'center' (default).
     * @deprecated since Moodle 2.0. Styling should be in the CSS.
     */
    public $tablealign = null;
    /**
     * @var int padding on each cell, in pixels
     * @deprecated since Moodle 2.0. Styling should be in the CSS.
     */
    public $cellpadding = null;
    /**
     * @var int spacing between cells, in pixels
     * @deprecated since Moodle 2.0. Styling should be in the CSS.
     */
    public $cellspacing = null;
    /**
     * @var array classes to add to particular rows, space-separated string.
     * Classes 'r0' or 'r1' are added automatically for every odd or even row,
     * respectively. Class 'lastrow' is added automatically for the last row
     * in the table.
     *
     * Example of usage:
     * $t->rowclasses[9] = 'tenth'
     */
    public $rowclasses;
    /**
     * @var array classes to add to every cell in a particular column,
     * space-separated string. Class 'cell' is added automatically by the renderer.
     * Classes 'c0' or 'c1' are added automatically for every odd or even column,
     * respectively. Class 'lastcol' is added automatically for all last cells
     * in a row.
     *
     * Example of usage:
     * $t->colclasses = array(null, 'grade');
     */
    public $colclasses;
    /**
     * @var string description of the contents for screen readers.
     */
    public $summary;
    /**
     * @var bool true causes the contents of the heading cells to be rotated 90 degrees.
     */
    public $rotateheaders = false;
    /**
     * @var array $headclasses Array of CSS classes to apply to the table's thead.
     */
    public $headclasses = array();
    /**
     * @var array $bodyclasses Array of CSS classes to apply to the table's tbody.
     */
    public $bodyclasses = array();
    /**
     * @var array $footclasses Array of CSS classes to apply to the table's tfoot.
     */
    public $footclasses = array();


    /**
     * @see html_component::prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        if (!empty($this->align)) {
            foreach ($this->align as $key => $aa) {
                if ($aa) {
                    $this->align[$key] = 'text-align:'. fix_align_rtl($aa) .';';  // Fix for RTL languages
                } else {
                    $this->align[$key] = null;
                }
            }
        }
        if (!empty($this->size)) {
            foreach ($this->size as $key => $ss) {
                if ($ss) {
                    $this->size[$key] = 'width:'. $ss .';';
                } else {
                    $this->size[$key] = null;
                }
            }
        }
        if (!empty($this->wrap)) {
            foreach ($this->wrap as $key => $ww) {
                if ($ww) {
                    $this->wrap[$key] = 'white-space:nowrap;';
                } else {
                    $this->wrap[$key] = '';
                }
            }
        }
        if (!empty($this->head)) {
            foreach ($this->head as $key => $val) {
                if (!isset($this->align[$key])) {
                    $this->align[$key] = null;
                }
                if (!isset($this->size[$key])) {
                    $this->size[$key] = null;
                }
                if (!isset($this->wrap[$key])) {
                    $this->wrap[$key] = null;
                }

            }
        }
        if (empty($this->classes)) { // must be done before align
            $this->set_classes(array('generaltable'));
        }
        if (!empty($this->tablealign)) {
            $this->add_class('boxalign' . $this->tablealign);
        }
        if (!empty($this->rotateheaders)) {
            $this->add_class('rotateheaders');
        } else {
            $this->rotateheaders = false; // Makes life easier later.
        }
        parent::prepare($output, $page, $target);
    }
    /**
     * @param string $name The name of the variable to set
     * @param mixed $value The value to assign to the variable
     * @return void
     */
    public function __set($name, $value) {
        if ($name == 'rowclass') {
            debugging('rowclass[] has been deprecated for html_table ' .
                      'and should be replaced with rowclasses[]. please fix the code.');
            $this->rowclasses = $value;
        } else {
            parent::__set($name, $value);
        }
    }
}


/**
 * Component representing a table row.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_table_row extends html_component {
    /**
     * @var array $cells Array of html_table_cell objects
     */
    public $cells = array();

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        parent::prepare($output, $page, $target);
    }

    /**
     * Shortcut method for creating a row with an array of cells. Converts cells to html_table_cell objects.
     * @param array $cells
     * @return html_table_row
     */
    public static function make($cells=array()) {
        $row = new html_table_row();
        foreach ($cells as $celltext) {
            if (!($celltext instanceof html_table_cell)) {
                $cell = new html_table_cell();
                $cell->text = $celltext;
                $row->cells[] = $cell;
            } else {
                $row->cells[] = $celltext;
            }
        }
        return $row;
    }
}


/**
 * Component representing a table cell.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_table_cell extends html_component {
    /**
     * @var string $text The contents of the cell
     */
    public $text;
    /**
     * @var string $abbr Abbreviated version of the contents of the cell
     */
    public $abbr = null;
    /**
     * @var int $colspan Number of columns this cell should span
     */
    public $colspan = null;
    /**
     * @var int $rowspan Number of rows this cell should span
     */
    public $rowspan = null;
    /**
     * @var string $scope Defines a way to associate header cells and data cells in a table
     */
    public $scope = null;
    /**
     * @var boolean $header Whether or not this cell is a header cell
     */
    public $header = null;

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        if ($this->header && empty($this->scope)) {
            $this->scope = 'col';
        }
        parent::prepare($output, $page, $target);
    }
}


/**
 * Component representing a XHTML link.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_link extends html_component {
    /**
     * URL can be simple text or a moodle_url object
     * @var mixed $url
     */
    public $url;

    /**
     * @var string $text The HTML text that will appear between the link tags
     */
    public $text = null;

    /**
     * @var boolean $disabled Whether or not this link is disabled (will be rendered as plain text)
     */
    public $disabled = false;

    /**
     * @var boolean $disableifcurrent Whether or not this link should be disabled if it the same as the current page
     */
    public $disableifcurrent = false;

    /**
     * New link constructor.
     *
     * @param moodle_url|string $url url of the image
     * @param array $options link attributes such as title, id, disabled, disableifcurrent, etc.
     */
    public function __construct($url = null, $text = null, array $options = null) {
        parent::__construct($options);

        if (is_null($url)) {
            // to be filled later

        } else if ($url instanceof moodle_url) {
            $this->url = clone($url);

        } else if (is_string($url)) {
            $this->url = new moodle_url($url);

        } else {
            throw new coding_style_exception('Image can be constructed only from moodle_url or string url.');
        }

        $this->text = $text;
    }

    /**
     * @see lib/html_component#prepare() Disables the link if it links to the current page.
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        // We can't accept an empty text value
        if ($this->text === '' or is_null($this->text)) { // 0 is valid value, do not use empty()
            throw new coding_exception('A html_link must have a descriptive text value!');
        }

        if (!($this->url instanceof moodle_url)) {
            $this->url = new moodle_url($this->url);
        }

        if ($this->disableifcurrent and $this->url->compare($page->url, URL_MATCH_PARAMS)) {
            $this->disabled = true;
        }

        parent::prepare($output, $page, $target);
    }

    /**
     * Shortcut for creating a link component.
     * @param mixed  $url String or moodle_url
     * @param string $text The text of the link
     * @return html_link The link component
     */
    public static function make($url, $text) {
        return new html_link($url, $text);
    }
}


/**
 * Component representing a XHTML button (input of type 'button').
 * The renderer will either output it as a button with an onclick event,
 * or as a form with hidden inputs.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_button extends labelled_html_component {
    /**
     * @var string $text
     */
    public $text;

    /**
     * @var boolean $disabled Whether or not this button is disabled
     */
    public $disabled = false;

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        $this->add_class('singlebutton');

        if (empty($this->text)) {
            $this->text = get_string('submit');
        }

        if ($this->disabled) {
            $this->disabled = 'disabled';
        }

        parent::prepare($output, $page, $target);
    }
}

/**
 * Component representing an image.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_image extends labelled_html_component {
    /**
     * @var string $src The path to the image being used
     */
    public $src;
    /**
     * @var int $width of image
     */
    public $width;
    /**
     * @var int $height of image
     */
    public $height;

    /**
     * New image constructor.
     *
     * @param moodle_url|string $url url of the image
     * @param array $options image attributes such as title, id, alt, widht, height
     */
    public function __construct($src = null, array $options = null) {
        parent::__construct($options);

        if (is_null($src)) {
            // to be filled later

        } else if ($src instanceof moodle_url) {
            $this->src = clone($src);

        } else if (is_string($src)) {
            $this->src = new moodle_url($src);

        } else {
            throw new coding_style_exception('Image can be constructed only from moodle_url or string url.');
        }
    }

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        if (empty($this->src)) {
            throw new coding_exception('html_image requires a $src value (moodle_url).');
        }

        // no general class here, use custom class instead or img element directly in css selectors
        parent::prepare($output, $page, $target);

        if ($this->alt === null) {
            // needs to be set for accessibility reasons
            $this->alt = '';
        }
    }
}


/**
 * Component representing a textarea.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_textarea extends html_component {
    /**
     * @param string $name Name to use for the textarea element.
     */
    public $name;
    /**
     * @param string $value Initial content to display in the textarea.
     */
    public $value;
    /**
     * @param int $rows Number of rows to display  (minimum of 10 when $height is non-null)
     */
    public $rows;
    /**
     * @param int $cols Number of columns to display (minimum of 65 when $width is non-null)
     */
    public $cols;
    /**
     * @param bool $usehtmleditor Enables the use of the htmleditor for this field.
     */
    public $usehtmleditor;

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        $this->add_class('form-textarea');

        if (empty($this->id)) {
            $this->id = "edit-$this->name";
        }

        if ($this->usehtmleditor) {
            editors_head_setup();
            $editor = get_preferred_texteditor(FORMAT_HTML);
            $editor->use_editor($this->id, array('legacy'=>true));
            $this->value = htmlspecialchars($value);
        }

        parent::prepare($output, $page, $target);
    }
}


/**
 * Component representing a simple form wrapper. Its purpose is mainly to enclose
 * a submit input with the appropriate action and hidden inputs.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_form extends html_component {
    /**
     * @var string $method post or get
     */
    public $method = 'post';
    /**
     * If a string is given, it will be converted to a moodle_url during prepare()
     * @var mixed $url A moodle_url including params or a string
     */
    public $url;
    /**
     * @var boolean $showbutton If true, the submit button will always be shown even if JavaScript is available
     */
    public $showbutton = false;
    /**
     * @var string $targetwindow The name of the target page to open the linked page in.
     */
    public $targetwindow = 'self';
    /**
     * @var html_button $button A submit button
     */
    public $button;
    /**
     * @var boolean $jssubmitaction If true, the submit button will be hidden when JS is enabled
     */
    public $jssubmitaction = false;
    /**
     * Constructor: sets up the other components in case they are needed
     * @return void
     */
    public function __construct(array $options = null) {
        parent::__construct($options);
        $this->button = new html_button();
        $this->button->text = get_string('go');
    }

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {

        if (empty($this->url)) {
            throw new coding_exception('A html_form must have a $url value (string or moodle_url).');
        }

        if (is_string($this->url)) {
            $this->url = new moodle_url($this->url);
        }

        if ($this->method == 'post') {
            // automatic CSRF protection
            $this->url->param('sesskey', sesskey());
        }

        parent::prepare($output, $page, $target);
    }
}


/**
 * Component representing a list.
 *
 * The advantage of using this object instead of a flat array is that you can load it
 * with metadata (CSS classes, event handlers etc.) which can be used by the renderers.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_list extends html_component {

    /**
     * @var array $items An array of html_list_item or html_list objects
     */
    public $items = array();

    /**
     * @var string $type The type of list (ordered|unordered), definition type not yet supported
     */
    public $type = 'unordered';

    /**
     * @var string $text An optional descriptive text for the list. Will be output as a list item before opening the new list
     */
    public $text = false;

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        parent::prepare($output, $page, $target);
    }

    /**
     * This function takes a nested array of data and maps it into this list's $items array
     * as proper html_list_item and html_list objects, with appropriate metadata.
     *
     * @param array $tree A nested array (array keys are ignored);
     * @param int $row Used in identifying the iteration level and in ul classes
     * @return void
     */
    public function load_data($tree, $level=0) {

        $this->add_class("list-$level");

        $i = 1;
        foreach ($tree as $key => $element) {
            if (is_array($element)) {
                $newhtmllist = new html_list();
                $newhtmllist->type = $this->type;
                $newhtmllist->load_data($element, $level + 1);
                $newhtmllist->text = $key;
                $this->items[] = $newhtmllist;
            } else {
                $listitem = new html_list_item();
                $listitem->value = $element;
                $listitem->add_class("list-item-$level-$i");
                $this->items[] = $listitem;
            }
            $i++;
        }
    }

    /**
     * Adds a html_list_item or html_list to this list.
     * If the param is a string, a html_list_item will be added.
     * @param mixed $item String, html_list or html_list_item object
     * @return void
     */
    public function add_item($item) {
        if ($item instanceof html_list_item || $item instanceof html_list) {
            $this->items[] = $item;
        } else {
            $listitem = new html_list_item();
            $listitem->value = $item;
            $this->items[] = $item;
        }
    }
}


/**
 * Component representing a list item.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_list_item extends html_component {
    /**
     * @var string $value The value of the list item
     */
    public $value;

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        parent::prepare($output, $page, $target);
    }
}


/**
 * Component representing a span element. It has no special attributes, so
 * it is very low-level and can be used for styling and JS actions.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class html_span extends html_component {
    /**
     * @var string $text The contents of the span
     */
    public $contents;
    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        parent::prepare($output, $page, $target);
    }
}

/// Complex components aggregating simpler components


/**
 * Component representing a paging bar.
 *
 * @copyright 2009 Nicolas Connault
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class moodle_paging_bar extends html_component {
    /**
     * @var int $maxdisplay The maximum number of pagelinks to display
     */
    public $maxdisplay = 18;
    /**
     * @var int $totalcount post or get
     */
    public $totalcount;
    /**
     * @var int $page The page you are currently viewing
     */
    public $page = 0;
    /**
     * @var int $perpage The number of entries that should be shown per page
     */
    public $perpage;
    /**
     * @var string $baseurl If this  is a string then it is the url which will be appended with $pagevar, an equals sign and the page number.
     *      If this is a moodle_url object then the pagevar param will be replaced by the page no, for each page.
     */
    public $baseurl;
    /**
     * @var string $pagevar This is the variable name that you use for the page number in your code (ie. 'tablepage', 'blogpage', etc)
     */
    public $pagevar = 'page';
    /**
     * @var html_link $previouslink A HTML link representing the "previous" page
     */
    public $previouslink = null;
    /**
     * @var html_link $nextlink A HTML link representing the "next" page
     */
    public $nextlink = null;
    /**
     * @var html_link $firstlink A HTML link representing the first page
     */
    public $firstlink = null;
    /**
     * @var html_link $lastlink A HTML link representing the last page
     */
    public $lastlink = null;
    /**
     * @var array $pagelinks An array of html_links. One of them is just a string: the current page
     */
    public $pagelinks = array();

    /**
     * @see lib/html_component#prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        if (!isset($this->totalcount) || is_null($this->totalcount)) {
            throw new coding_exception('moodle_paging_bar requires a totalcount value.');
        }
        if (!isset($this->page) || is_null($this->page)) {
            throw new coding_exception('moodle_paging_bar requires a page value.');
        }
        if (empty($this->perpage)) {
            throw new coding_exception('moodle_paging_bar requires a perpage value.');
        }
        if (empty($this->baseurl)) {
            throw new coding_exception('moodle_paging_bar requires a baseurl value.');
        }
        if (!($this->baseurl instanceof moodle_url)) {
            $this->baseurl = new moodle_url($this->baseurl);
        }

        if ($this->totalcount > $this->perpage) {
            $pagenum = $this->page - 1;

            if ($this->page > 0) {
                $this->previouslink = new html_link();
                $this->previouslink->add_class('previous');
                $this->previouslink->url = clone($this->baseurl);
                $this->previouslink->url->param($this->pagevar, $pagenum);
                $this->previouslink->text = get_string('previous');
            }

            if ($this->perpage > 0) {
                $lastpage = ceil($this->totalcount / $this->perpage);
            } else {
                $lastpage = 1;
            }

            if ($this->page > 15) {
                $startpage = $this->page - 10;

                $this->firstlink = new html_link();
                $this->firstlink->url = clone($this->baseurl);
                $this->firstlink->url->param($this->pagevar, 0);
                $this->firstlink->text = 1;
                $this->firstlink->add_class('first');
            } else {
                $startpage = 0;
            }

            $currpage = $startpage;
            $displaycount = $displaypage = 0;

            while ($displaycount < $this->maxdisplay and $currpage < $lastpage) {
                $displaypage = $currpage + 1;

                if ($this->page == $currpage) {
                    $this->pagelinks[] = $displaypage;
                } else {
                    $pagelink = new html_link();
                    $pagelink->url = clone($this->baseurl);
                    $pagelink->url->param($this->pagevar, $currpage);
                    $pagelink->text = $displaypage;
                    $this->pagelinks[] = $pagelink;
                }

                $displaycount++;
                $currpage++;
            }

            if ($currpage < $lastpage) {
                $lastpageactual = $lastpage - 1;
                $this->lastlink = new html_link();
                $this->lastlink->url = clone($this->baseurl);
                $this->lastlink->url->param($this->pagevar, $lastpageactual);
                $this->lastlink->text = $lastpage;
                $this->lastlink->add_class('last');
            }

            $pagenum = $this->page + 1;

            if ($pagenum != $displaypage) {
                $this->nextlink = new html_link();
                $this->nextlink->url = clone($this->baseurl);
                $this->nextlink->url->param($this->pagevar, $pagenum);
                $this->nextlink->text = get_string('next');
                $this->nextlink->add_class('next');
            }
        }
    }

    /**
     * Shortcut for initialising a moodle_paging_bar with only the required params.
     *
     * @param int $totalcount Thetotal number of entries available to be paged through
     * @param int $page The page you are currently viewing
     * @param int $perpage The number of entries that should be shown per page
     * @param mixed $baseurl If this  is a string then it is the url which will be appended with $pagevar, an equals sign and the page number.
     *                          If this is a moodle_url object then the pagevar param will be replaced by the page no, for each page.
     */
    public static function make($totalcount, $page, $perpage, $baseurl) {
        $pagingbar = new moodle_paging_bar();
        $pagingbar->totalcount = $totalcount;
        $pagingbar->page = $page;
        $pagingbar->perpage = $perpage;
        $pagingbar->baseurl = $baseurl;
        return $pagingbar;
    }
}


/**
 * This class represents how a block appears on a page.
 *
 * During output, each block instance is asked to return a block_contents object,
 * those are then passed to the $OUTPUT->block function for display.
 *
 * {@link $contents} should probably be generated using a moodle_block_..._renderer.
 *
 * Other block-like things that need to appear on the page, for example the
 * add new block UI, are also represented as block_contents objects.
 *
 * @copyright 2009 Tim Hunt
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class block_contents extends html_component {
    /** @var int used to set $skipid. */
    protected static $idcounter = 1;

    const NOT_HIDEABLE = 0;
    const VISIBLE = 1;
    const HIDDEN = 2;

    /**
     * @param integer $skipid All the blocks (or things that look like blocks)
     * printed on a page are given a unique number that can be used to construct
     * id="" attributes. This is set automatically be the {@link prepare()} method.
     * Do not try to set it manually.
     */
    public $skipid;

    /**
     * @var integer If this is the contents of a real block, this should be set to
     * the block_instance.id. Otherwise this should be set to 0.
     */
    public $blockinstanceid = 0;

    /**
     * @var integer if this is a real block instance, and there is a corresponding
     * block_position.id for the block on this page, this should be set to that id.
     * Otherwise it should be 0.
     */
    public $blockpositionid = 0;

    /**
     * @param array $attributes an array of attribute => value pairs that are put on the
     * outer div of this block. {@link $id} and {@link $classes} attributes should be set separately.
     */
    public $attributes = array();

    /**
     * @param string $title The title of this block. If this came from user input,
     * it should already have had format_string() processing done on it. This will
     * be output inside <h2> tags. Please do not cause invalid XHTML.
     */
    public $title = '';

    /**
     * @param string $content HTML for the content
     */
    public $content = '';

    /**
     * @param array $list an alternative to $content, it you want a list of things with optional icons.
     */
    public $footer = '';

    /**
     * Any small print that should appear under the block to explain to the
     * teacher about the block, for example 'This is a sticky block that was
     * added in the system context.'
     * @var string
     */
    public $annotation = '';

    /**
     * @var integer one of the constants NOT_HIDEABLE, VISIBLE, HIDDEN. Whether
     * the user can toggle whether this block is visible.
     */
    public $collapsible = self::NOT_HIDEABLE;

    /**
     * A (possibly empty) array of editing controls. Each element of this array
     * should be an array('url' => $url, 'icon' => $icon, 'caption' => $caption).
     * $icon is the icon name. Fed to $OUTPUT->pix_url.
     * @var array
     */
    public $controls = array();

    /**
     * @see html_component::prepare()
     * @return void
     */
    public function prepare(renderer_base $output, moodle_page $page, $target) {
        $this->skipid = self::$idcounter;
        self::$idcounter += 1;
        $this->add_class('sideblock');
        if (empty($this->blockinstanceid) || !strip_tags($this->title)) {
            $this->collapsible = self::NOT_HIDEABLE;
        }
        if ($this->collapsible == self::HIDDEN) {
            $this->add_class('hidden');
        }
        if (!empty($this->controls)) {
            $this->add_class('block_with_controls');
        }
        parent::prepare($output, $page, $target);
    }
}


/**
 * This class represents a target for where a block can go when it is being moved.
 *
 * This needs to be rendered as a form with the given hidden from fields, and
 * clicking anywhere in the form should submit it. The form action should be
 * $PAGE->url.
 *
 * @copyright 2009 Tim Hunt
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @since     Moodle 2.0
 */
class block_move_target extends html_component {
    /**
     * List of hidden form fields.
     * @var array
     */
    public $url = array();
    /**
     * List of hidden form fields.
     * @var array
     */
    public $text = '';
}