import fs from 'node:fs'
import { spawn } from 'node:child_process'
import path from 'node:path'
import { defineConfig } from 'vite'
import { createRegenerationQueue } from './dev-reload.js'
import { contentDirectories, contentSources, generatedRoot } from './site.config.js'

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(generatedRoot, 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 === generatedRoot) {
      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(generatedRoot, file)
        if (fs.existsSync(source)) fs.copyFileSync(source, path.join(dist, file))
      }
    },
  }
}

function contentGenerator() {
  return {
    name: 'content-generator',
    configureServer(server) {
      const queue = createRegenerationQueue({
        generate: () => new Promise((resolve, reject) => {
          const child = spawn(process.execPath, ['generator.js', '--drafts'], { stdio: 'inherit' })
          child.once('error', reject)
          child.once('close', (code) => code === 0 ? resolve() : reject(new Error(`exit ${code ?? 'unknown'}`)))
        }),
        onSuccess: () => server.ws.send({ type: 'full-reload' }),
        onError: (error) => {
          console.error(`Content generation failed: ${error.message}`)
          server.ws.send({
            type: 'error',
            err: { message: `Content generation failed (${error.message}). Check the terminal for details.`, stack: '' },
          })
        },
      })
      const sources = new Set(contentSources.map((source) => path.resolve(source)))
      server.watcher.add([...sources])
      server.httpServer?.once('close', () => queue.close())
      server.watcher.on('all', (event, file) => {
        if (!['add', 'change', 'unlink'].includes(event)) return
        const isMarkdown =
          file.endsWith('.md') &&
          contentDirectories.some((dir) => file.startsWith(`${path.resolve(dir)}/`))
        if (!isMarkdown && !sources.has(file)) return
        queue.request()
      })
    },
  }
}

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