import { copyFileSync, existsSync } from 'node:fs'
import { resolve } from 'node:path'
import { defineConfig, type Plugin } from 'vite'
import react from '@vitejs/plugin-react'
import { renderFallbackHtml } from './src/fallback/inject'

function fallbackPlugin(): Plugin {
  return {
    name: 'inject-fallback',
    transformIndexHtml: (html) => renderFallbackHtml(html),
  }
}

// chiptune3's chiptune3.worklet.js does `import libopenmptPromise from
// './libopenmpt.worklet.js'` — a plain relative import. Vite's `new URL(...,
// import.meta.url)` handling (used internally by chiptune3.js to load the
// worklet) copies chiptune3.worklet.js into the build output verbatim but
// does not follow that nested relative import, so libopenmpt.worklet.js is
// missing from `dist/` and AudioWorklet.addModule() fails at runtime
// ("Unable to load a worklet's module."). Copy the sibling file next to the
// emitted worklet chunk so the relative import resolves in prod too.
function chiptuneWorkletFix(): Plugin {
  let outDir = 'dist'
  let assetsDir = 'assets'
  return {
    name: 'chiptune3-worklet-fix',
    configResolved(config) {
      outDir = config.build.outDir
      assetsDir = config.build.assetsDir
    },
    closeBundle() {
      const src = resolve('node_modules/chiptune3/libopenmpt.worklet.js')
      if (!existsSync(src)) {
        throw new Error(
          'chiptuneWorkletFix: libopenmpt.worklet.js not found — chiptune3 layout changed?',
        )
      }
      const dest = resolve(outDir, assetsDir, 'libopenmpt.worklet.js')
      copyFileSync(src, dest)
    },
  }
}

export default defineConfig({
  plugins: [react(), fallbackPlugin(), chiptuneWorkletFix()],
  optimizeDeps: {
    // In dev, esbuild's dep pre-bundling copies chiptune3.js into
    // node_modules/.vite/deps/, which breaks its internal
    // `new URL('./chiptune3.worklet.js', import.meta.url)` (the worklet
    // sibling file isn't copied along). Excluding it keeps chiptune3
    // served straight from node_modules, where the relative lookup works.
    exclude: ['chiptune3'],
  },
  test: {
    exclude: ['node_modules', 'dist', 'e2e'],
  },
})