import { join, dirname, parse, normalize } from 'node:path'
import { Worker, parentPort } from 'node:worker_threads'
import os from 'node:os'
import fs from 'iofs'

import { compileFiles } from './compile.js'
import { defaultCustomElement } from './utils.js'

const IS_WIN = process.platform === 'win32'
const PREFIX = IS_WIN ? 'pages\\' : 'pages/'
// 4核(或4线程)以上的CPU, 才开启多线程编译。且线程开销太高, 开太多线程效率反而不高。
const CPU_CORES = os.cpus().length > 5 ? 6 : os.cpus().length
const THREADS_NUM = CPU_CORES > 3 ? CPU_CORES - 1 : 0
const __filename = normalize(import.meta.url.slice(IS_WIN ? 8 : 7))
const __dirname = dirname(__filename)
const WORKER_POOL = new Set() // 线程池
const JOBS_QUEUE = [] // 任务队列

function readFile(file) {
  return (file && fs.cat(file)?.toString()) || ''
}

function doJob() {
  while (JOBS_QUEUE.length && WORKER_POOL.size) {
    let job = JOBS_QUEUE.shift()
    let worker = WORKER_POOL.values().next().value

    WORKER_POOL.delete(worker)

    worker.once('message', _ => {
      if (JOBS_QUEUE.length) {
        WORKER_POOL.add(worker)
        doJob()
      } else {
        worker.terminate()
      }
    })

    worker.postMessage(job)
  }
}

export default function compile(root = '', dist = '', conf = {}, verbose) {
  //
  const SOURCE_DIR = join(root, 'src')
  const PUBLIC_DIR = join(root, 'public')
  const DEPLOY_PATH = conf.base || '' // 部署目录, 默认是根目录部署
  const PAGES_KEYS = Object.keys(conf.pages)
  const IS_MPA = PAGES_KEYS.length > 1
  const PAGES_PREFIX = PAGES_KEYS.map(it =>
    IS_WIN ? `${PREFIX + it}\\` : `${PREFIX + it}/`
  )
  const INJECT_SCSS = readFile(conf.inject?.scss)
  const LEGACY_MODE = !!conf.legacy
  const {
    ABS_CONFIG_FILEPATH,
    compileOptions = {},
    define = {},
    plugin = []
  } = conf
  const { isCustomElement = defaultCustomElement } = compileOptions

  conf.inject = conf.inject || { scss: '' }

  let timeStart = Date.now()
  let template = fs.cat(join(process.cwd(), 'index.html')).toString()
  let list = new Map()
  let options = {
    IS_MPA,
    SOURCE_DIR,
    DEPLOY_PATH,
    INJECT_SCSS,
    LEGACY_MODE,
    ABS_CONFIG_FILEPATH,
    define
  }

  fs.ls(SOURCE_DIR, true).forEach(path => {
    if (fs.isdir(path)) {
      return
    }

    let name = path.slice(SOURCE_DIR.length + 1)
    let it = {
      name,
      ext: parse(name).ext
    }
    if (it.ext) {
      if (IS_MPA && it.name.startsWith(PREFIX)) {
        if (PAGES_PREFIX.some(it => it.startsWith(it.name))) {
          list.set(path, it)
        }
        return
      }

      if (path === conf.inject.scss) {
        return
      }
      list.set(path, it)
    }
  })

  // 创建线程池
  if (THREADS_NUM > 0 && (IS_MPA || list.size > THREADS_NUM * 10)) {
    // 页面数过少时, 线程数量不能比页面数多
    let max = Math.min(THREADS_NUM, PAGES_KEYS.length)

    for (let i = 0; i < max; i++) {
      WORKER_POOL.add(
        new Worker(join(__dirname, './thread.js'), {
          workerData: {
            options,
            verbose,
            dist,
            imports: conf.imports
          }
        })
      )
    }
  } else {
    options.isCustomElement = isCustomElement
  }

  // 优先处理静态目录, 之后的源码目录中, 以便如果有产生相同的文件名, 则覆盖静态目录中的文件
  if (fs.isdir(PUBLIC_DIR)) {
    console.log('\n正在处理静态资源 ...')
    fs.ls(PUBLIC_DIR, true).forEach(it => {
      let ext = parse(it).ext

      if (ext && fs.isfile(it)) {
        let name = it.slice(PUBLIC_DIR.length + 1)
        verbose && console.log('  复制 %s ...', name)
        fs.cp(it, join(dist, name))
      }
    })
  }

  if (IS_MPA) {
    for (let currentPage of PAGES_KEYS) {
      let page = conf.pages[currentPage]
      let dir = dirname(page.entry)
      let files = new Map()
      let chunk = new Map()

      fs.ls(dir, true).forEach(path => {
        if (fs.isdir(path)) {
          return
        }

        let name = path.slice(dir.length + 1)
        let ext = parse(name).ext

        if (ext === '') {
          return
        }

        list.delete(path)
        files.set(path, { name, ext })
      })

      if (THREADS_NUM > 0) {
        chunk.set(currentPage, { page, files })
        JOBS_QUEUE.push(chunk)
        doJob()
      } else {
        console.log(`正在生成 ${currentPage}.html ...`)
        compileFiles(currentPage, page, files, options, {
          verbose,
          dist,
          imports: conf.imports
        })
      }
    }

    // 公共依赖
    if (THREADS_NUM > 0) {
      let chunk = new Map()
      chunk.set('', { page: null, files: list })

      JOBS_QUEUE.push(chunk)
      doJob()
    } else {
      console.log('\n正在解析公共依赖 ...')
      compileFiles('', null, list, options, {
        verbose,
        dist,
        imports: conf.imports
      })
    }
  } else {
    // 每个线程处理的文件数
    let chunkSize = Math.ceil(list.size / THREADS_NUM)
    let currentPage = PAGES_KEYS[0]
    let page = conf.pages[currentPage]

    console.log(`正在生成 ${currentPage}.html ...`)

    if (THREADS_NUM > 0 && list.size > THREADS_NUM * 10) {
      list = [...list]
      for (let i = 0; i < THREADS_NUM; i++) {
        let start = i * chunkSize
        let end = start + chunkSize
        let chunk = new Map()

        chunk.set(currentPage, { page, files: list.slice(start, end) })

        JOBS_QUEUE.push(chunk)
        doJob()
      }
    } else {
      options.plugin = plugin
      options.isCustomElement = isCustomElement
      compileFiles(currentPage, page, list, options, {
        verbose,
        dist,
        imports: conf.imports
      })
    }
  }

  process.on('exit', _ => {
    console.log('\n页面处理完成, 耗时 %ss\n', (Date.now() - timeStart) / 1000)
  })
}