import fs from 'node:fs'
import { spawn } from 'node:child_process'
import path from 'node:path'
import { defineConfig } from 'vite'

function generatedPages(directory) {
  const inputs = {}
  for (const entry of fs.readdirSync(directory, { withFileTypes: true })) {
    const filePath = path.join(directory, entry.name)
    if (entry.isDirectory()) Object.assign(inputs, generatedPages(filePath))
    else if (entry.name === 'index.html') {
      const relativePath = path.relative('.generated', filePath)
      const key = relativePath.endsWith('/index.html') ? relativePath.slice(0, -'/index.html'.length) : relativePath
      inputs[key] = path.resolve(filePath)
    } else if (entry.name === '404.html' && directory === '.generated') {
      inputs['404'] = path.resolve(filePath)
    }
  }
  return inputs
}

function copyGeneratedFiles() {
  const files = ['feed.xml', 'sitemap.xml']
  return {
    name: 'copy-generated-files',
    closeBundle() {
      const dist = path.resolve('dist')
      if (!fs.existsSync(dist)) return
      for (const file of files) {
        const source = path.resolve('.generated', file)
        if (fs.existsSync(source)) fs.copyFileSync(source, path.join(dist, file))
      }
    },
  }
}

function contentGenerator() {
  let timer
  let generator
  let rerun = false

  const generate = (server) => {
    if (generator) {
      rerun = true
      return
    }

    generator = spawn(process.execPath, ['generator.js', '--drafts'], { stdio: 'inherit' })
    generator.on('error', (error) => {
      console.error(`Content generation failed: ${error.message}`)
    })
    generator.on('close', (code) => {
      generator = undefined
      if (code === 0) server.ws.send({ type: 'full-reload' })
      if (rerun) {
        rerun = false
        generate(server)
      }
    })
  }

  return {
    name: 'content-generator',
    configureServer(server) {
      const sources = [
        path.resolve('notes'),
        path.resolve('posts'),
        path.resolve('README.md'),
        path.resolve('THIRD_PARTY_LICENSES.md'),
        path.resolve('external.json'),
        path.resolve('generator.js'),
        path.resolve('html.js'),
      ]
      server.watcher.add(sources)
      server.watcher.on('all', (event, file) => {
        if (!['add', 'change', 'unlink'].includes(event)) return
        const isMarkdown =
          file.endsWith('.md') &&
          (file.startsWith(`${path.resolve('notes')}/`) || file.startsWith(`${path.resolve('posts')}/`))
        const isExternal = file === path.resolve('external.json')
        const isStandaloneMarkdown =
          file === path.resolve('README.md') || file === path.resolve('THIRD_PARTY_LICENSES.md')
        const isGenerator = file === path.resolve('generator.js') || file === path.resolve('html.js')
        if (!isMarkdown && !isStandaloneMarkdown && !isExternal && !isGenerator) return
        clearTimeout(timer)
        timer = setTimeout(() => {
          generate(server)
        }, 100)
      })
    },
  }
}

export default defineConfig({
  plugins: [contentGenerator(), copyGeneratedFiles()],
  root: '.generated',
  publicDir: '../public',
  resolve: {
    alias: {
      '/src': path.resolve('src'),
    },
  },
  server: {
    watch: {
      ignored: ['**/.generated/**'],
    },
  },
  build: {
    outDir: path.resolve('dist'),
    emptyOutDir: true,
    rollupOptions: {
      input: generatedPages('.generated'),
    },
  },
})