import _ from 'lodash'
import chokidar from 'chokidar'
import fs from 'fs-extra'
import hash from 'hash-sum'
import pify from 'pify'
import webpack from 'webpack'
import PostCompilePlugin from 'post-compile-webpack-plugin'
import serialize from 'serialize-javascript'
import { createBundleRenderer } from 'vue-server-renderer'
import { join, resolve, basename, dirname } from 'path'
import Tapable from 'tapable'
import { isUrl, r, wp } from './utils'
import clientWebpackConfig from './webpack/client.config.js'
import serverWebpackConfig from './webpack/server.config.js'
import defaults from './defaults'

const debug = require('debug')('nuxt:build')
debug.color = 2 // Force green color

const remove = pify(fs.remove)
const readFile = pify(fs.readFile)
const utimes = pify(fs.utimes)
const writeFile = pify(fs.writeFile)
const mkdirp = pify(fs.mkdirp)
const glob = pify(require('glob'))

export default class Builder extends Tapable {
  constructor (nuxt) {
    super()
    this.nuxt = nuxt
    this.options = nuxt.options

    // Add extra loaders only if they are not already provided
    let extraDefaults = {}
    if (this.options.build && !Array.isArray(this.options.build.loaders)) {
      extraDefaults.loaders = defaultsLoaders
    }
    if (this.options.build && !Array.isArray(this.options.build.postcss)) {
      extraDefaults.postcss = defaultsPostcss
    }
    this.options.build = _.defaultsDeep(this.options.build, extraDefaults)
    /* istanbul ignore if */
    if (this.options.dev && isUrl(this.options.build.publicPath)) {
      this.options.build.publicPath = defaults.publicPath.publicPath
    }

    // Stats
    this.webpackStats = {
      chunks: false,
      children: false,
      modules: false,
      colors: true
    }

    this._buildStatus = STATUS.INITIAL
  }

  ready () {
    if (this.options.dev) {
      // Don't await for builder in dev (faster startup)
      this.build().catch(err => {
        // eslint-disable-next-line no-console
        console.error(err)
        process.exit(1)
      })
      return Promise.resolve(this)
    } else {
      return this.production()
    }
  }

  async build () {
    // Avoid calling this method multiple times
    if (this._buildStatus === STATUS.BUILD_DONE) {
      return this
    }
    // If building
    if (this._buildStatus === STATUS.BUILDING) {
      return new Promise((resolve) => {
        setTimeout(() => {
          resolve(this.build())
        }, 300)
      })
    }
    this._buildStatus = STATUS.BUILDING
    // Check if pages dir exists and warn if not
    this._nuxtPages = typeof this.options.build.createRoutes !== 'function'

    if (this._nuxtPages) {
      if (!fs.existsSync(join(this.options.srcDir, 'pages'))) {
        if (fs.existsSync(join(this.options.srcDir, '..', 'pages'))) {
          console.error('> No `pages` directory found. Did you mean to run `nuxt` in the parent (`../`) directory?') // eslint-disable-line no-console
        } else {
          console.error('> Couldn\'t find a `pages` directory. Please create one under the project root') // eslint-disable-line no-console
        }
        process.exit(1)
      }
    }
    debug(`App root: ${this.options.srcDir}`)
    debug(`Generating ${this.options.buildDir} files...`)

    // Create .nuxt/, .nuxt/components and .nuxt/dist folders
    await remove(r(this.options.buildDir))
    await mkdirp(r(this.options.buildDir, 'components'))
    if (!this.options.dev) {
      await mkdirp(r(this.options.buildDir, 'dist'))
    }
    // Generate routes and interpret the template files
    await this.generateRoutesAndFiles()
    // Generate .nuxt/dist/ files
    await this.buildFiles()
    // Flag to set that building is done
    this._buildStatus = STATUS.BUILD_DONE
    return this
  }

  production () {
    // Production, create server-renderer
    const serverConfig = this.getWebpackServerConfig()
    const bundlePath = join(serverConfig.output.path, 'server-bundle.json')
    const manifestPath = join(serverConfig.output.path, 'client-manifest.json')
    if (fs.existsSync(bundlePath) && fs.existsSync(manifestPath)) {
      const bundle = fs.readFileSync(bundlePath, 'utf8')
      const manifest = fs.readFileSync(manifestPath, 'utf8')
      this.createRenderer(JSON.parse(bundle), JSON.parse(manifest))
      this.addAppTemplate()
    }
    return this
  }

  addAppTemplate () {
    let templatePath = resolve(this.options.buildDir, 'dist', 'index.html')
    if (fs.existsSync(templatePath)) {
      this.appTemplate = _.template(fs.readFileSync(templatePath, 'utf8'), {
        interpolate: /{{([\s\S]+?)}}/g
      })
    }
  }

  async generateRoutesAndFiles () {
    debug('Generating files...')
    // -- Templates --
    let templatesFiles = [
      'App.vue',
      'client.js',
      'index.js',
      'middleware.js',
      'router.js',
      'server.js',
      'utils.js',
      'components/nuxt-error.vue',
      'components/nuxt-loading.vue',
      'components/nuxt-child.js',
      'components/nuxt-link.js',
      'components/nuxt.vue'
    ]
    const templateVars = {
      options: this.options,
      uniqBy: _.uniqBy,
      isDev: this.options.dev,
      router: {
        mode: this.options.router.mode,
        base: this.options.router.base,
        middleware: this.options.router.middleware,
        linkActiveClass: this.options.router.linkActiveClass,
        linkExactActiveClass: this.options.router.linkExactActiveClass,
        scrollBehavior: this.options.router.scrollBehavior
      },
      env: this.options.env,
      head: this.options.head,
      middleware: fs.existsSync(join(this.options.srcDir, 'middleware')),
      store: this.options.store || fs.existsSync(join(this.options.srcDir, 'store')),
      css: this.options.css,
      plugins: this.options.plugins.map((p, i) => {
        if (typeof p === 'string') p = { src: p }
        p.src = r(this.options.srcDir, p.src)
        return { src: p.src, ssr: (p.ssr !== false), name: `plugin${i}` }
      }),
      appPath: './App.vue',
      layouts: Object.assign({}, this.options.layouts),
      loading: (typeof this.options.loading === 'string' ? r(this.options.srcDir, this.options.loading) : this.options.loading),
      transition: this.options.transition,
      components: {
        ErrorPage: this.options.ErrorPage ? r(this.options.ErrorPage) : null
      }
    }

    // -- Layouts --
    if (fs.existsSync(resolve(this.options.srcDir, 'layouts'))) {
      const layoutsFiles = await glob('layouts/*.vue', { cwd: this.options.srcDir })
      layoutsFiles.forEach((file) => {
        let name = file.split('/').slice(-1)[0].replace('.vue', '')
        if (name === 'error') return
        templateVars.layouts[name] = r(this.options.srcDir, file)
      })
      if (layoutsFiles.includes('layouts/error.vue')) {
        templateVars.components.ErrorPage = r(this.options.srcDir, 'layouts/error.vue')
      }
    }
    // If no default layout, create its folder and add the default folder
    if (!templateVars.layouts.default) {
      await mkdirp(r(this.options.buildDir, 'layouts'))
      templatesFiles.push('layouts/default.vue')
      templateVars.layouts.default = r(__dirname, 'app', 'layouts', 'default.vue')
    }

    // -- Routes --
    debug('Generating routes...')
    // If user defined a custom method to create routes
    if (this._nuxtPages) {
      // Use nuxt.js createRoutes bases on pages/
      const files = await glob('pages/**/*.vue', { cwd: this.options.srcDir })
      templateVars.router.routes = this.createRoutes(files, this.options.srcDir)
    } else {
      templateVars.router.routes = this.options.build.createRoutes(this.options.srcDir)
    }
    // router.extendRoutes method
    if (typeof this.options.router.extendRoutes === 'function') {
      // let the user extend the routes
      this.options.router.extendRoutes(this, templateVars.router.routes || [], r)
    }
    // Routes for generate command
    this.routes = this.flatRoutes(templateVars.router.routes || [])

    // -- Store --
    // Add store if needed
    if (this.options.store) {
      templatesFiles.push('store.js')
    }

    // Resolve template files
    const customTemplateFiles = this.options.build.templates.map(t => t.dst || basename(t.src || t))

    templatesFiles = templatesFiles.map(file => {
      // Skip if custom file was already provided in build.templates[]
      if (customTemplateFiles.indexOf(file) !== -1) {
        return
      }
      // Allow override templates using a file with same name in ${srcDir}/app
      const customPath = r(this.options.srcDir, 'app', file)
      const customFileExists = fs.existsSync(customPath)

      return {
        src: customFileExists ? customPath : r(__dirname, 'app', file),
        dst: file,
        custom: customFileExists
      }
    }).filter(i => !!i)

    // -- Custom templates --
    // Add custom template files
    templatesFiles = templatesFiles.concat(this.options.build.templates.map(t => {
      return Object.assign({
        src: r(this.options.srcDir, t.src || t),
        dst: t.dst || basename(t.src || t),
        custom: true
      }, t)
    }))

    // Interpret and move template files to .nuxt/
    return Promise.all(templatesFiles.map(async ({ src, dst, options, custom }) => {
      // Add template to watchers
      this.options.build.watch.push(src)
      // Render template to dst
      const fileContent = await readFile(src, 'utf8')
      const template = _.template(fileContent, {
        imports: {
          serialize,
          hash,
          r,
          wp
        }
      })
      const content = template(Object.assign({}, templateVars, {
        options: options || {},
        custom,
        src,
        dst
      }))
      const path = r(this.options.buildDir, dst)
      // Ensure parent dir exits
      await mkdirp(dirname(path))
      // Write file
      await writeFile(path, content, 'utf8')
      // Fix webpack loop (https://github.com/webpack/watchpack/issues/25#issuecomment-287789288)
      const dateFS = Date.now() / 1000 - 30
      return utimes(path, dateFS, dateFS)
    }))
  }

  async buildFiles () {
    if (this.options.dev) {
      debug('Adding webpack middleware...')
      this.createWebpackMiddleware()
      this.webpackWatchAndUpdate()
      this.watchFiles()
    } else {
      debug('Building files...')
      await this.webpackRunClient()
      await this.webpackRunServer()
      this.addAppTemplate()
    }
  }

  createRoutes (files, srcDir) {
    let routes = []
    files.forEach((file) => {
      let keys = file.replace(/^pages/, '').replace(/\.vue$/, '').replace(/\/{2,}/g, '/').split('/').slice(1)
      let route = { name: '', path: '', component: r(srcDir, file) }
      let parent = routes
      keys.forEach((key, i) => {
        route.name = route.name ? route.name + '-' + key.replace('_', '') : key.replace('_', '')
        route.name += (key === '_') ? 'all' : ''
        let child = _.find(parent, { name: route.name })
        if (child) {
          if (!child.children) {
            child.children = []
          }
          parent = child.children
          route.path = ''
        } else {
          if (key === 'index' && (i + 1) === keys.length) {
            route.path += (i > 0 ? '' : '/')
          } else {
            route.path += '/' + (key === '_' ? '*' : key.replace('_', ':'))
            if (key !== '_' && key.indexOf('_') !== -1) {
              route.path += '?'
            }
          }
        }
      })
      // Order Routes path
      parent.push(route)
      parent.sort((a, b) => {
        if (!a.path.length || a.path === '/') {
          return -1
        }
        if (!b.path.length || b.path === '/') {
          return 1
        }
        let res = 0
        let _a = a.path.split('/')
        let _b = b.path.split('/')
        for (let i = 0; i < _a.length; i++) {
          if (res !== 0) {
            break
          }
          let y = (_a[i].indexOf('*') > -1) ? 2 : (_a[i].indexOf(':') > -1 ? 1 : 0)
          let z = (_b[i].indexOf('*') > -1) ? 2 : (_b[i].indexOf(':') > -1 ? 1 : 0)
          res = y - z
          if (i === _b.length - 1 && res === 0) {
            res = 1
          }
        }
        return res === 0 ? -1 : res
      })
    })
    return this.cleanChildrenRoutes(routes)
  }

  cleanChildrenRoutes (routes, isChild = false) {
    let start = -1
    let routesIndex = []
    routes.forEach((route) => {
      if (/-index$/.test(route.name) || route.name === 'index') {
        // Save indexOf 'index' key in name
        let res = route.name.split('-')
        let s = res.indexOf('index')
        start = (start === -1 || s < start) ? s : start
        routesIndex.push(res)
      }
    })
    routes.forEach((route) => {
      route.path = (isChild) ? route.path.replace('/', '') : route.path
      if (route.path.indexOf('?') > -1) {
        let names = route.name.split('-')
        let paths = route.path.split('/')
        if (!isChild) {
          paths.shift()
        } // clean first / for parents
        routesIndex.forEach((r) => {
          let i = r.indexOf('index') - start //  children names
          if (i < paths.length) {
            for (let a = 0; a <= i; a++) {
              if (a === i) {
                paths[a] = paths[a].replace('?', '')
              }
              if (a < i && names[a] !== r[a]) {
                break
              }
            }
          }
        })
        route.path = (isChild ? '' : '/') + paths.join('/')
      }
      route.name = route.name.replace(/-index$/, '')
      if (route.children) {
        if (route.children.find((child) => child.path === '')) {
          delete route.name
        }
        route.children = this.cleanChildrenRoutes(route.children, true)
      }
    })
    return routes
  }

  flatRoutes (router, path = '', routes = []) {
    router.forEach((r) => {
      if (!r.path.includes(':') && !r.path.includes('*')) {
        if (r.children) {
          this.flatRoutes(r.children, path + r.path + '/', routes)
        } else {
          routes.push((r.path === '' && path[path.length - 1] === '/' ? path.slice(0, -1) : path) + r.path)
        }
      }
    })
    return routes
  }

  getWebpackClientConfig () {
    return clientWebpackConfig.call(this)
  }

  getWebpackServerConfig () {
    return serverWebpackConfig.call(this)
  }

  createWebpackMiddleware () {
    const clientConfig = this.getWebpackClientConfig()
    const host = process.env.HOST || process.env.npm_package_config_nuxt_host || 'localhost'
    const port = process.env.PORT || process.env.npm_package_config_nuxt_port || '3000'

    // setup on the fly compilation + hot-reload
    clientConfig.entry.app = _.flatten(['webpack-hot-middleware/client?reload=true', clientConfig.entry.app])
    clientConfig.plugins.push(
      new webpack.HotModuleReplacementPlugin(),
      new webpack.NoEmitOnErrorsPlugin(),
      new PostCompilePlugin(stats => {
        if (!stats.hasErrors() && !stats.hasWarnings()) {
          // We don't use os.host() here because browsers have special behaviour with localhost
          // For example chrome allows Geolocation api only to https or localhost origins
          let _host = host === '0.0.0.0' ? 'localhost' : host
          console.log(`> Open http://${_host}:${port}\n`) // eslint-disable-line no-console
        }
      })
    )
    const clientCompiler = webpack(clientConfig)
    this.clientCompiler = clientCompiler
    // Add the middleware to the instance context
    this.webpackDevMiddleware = pify(require('webpack-dev-middleware')(clientCompiler, {
      publicPath: clientConfig.output.publicPath,
      stats: this.webpackStats,
      quiet: true,
      noInfo: true,
      watchOptions: this.options.watchers.webpack
    }))
    this.webpackHotMiddleware = pify(require('webpack-hot-middleware')(clientCompiler, {
      log: () => {
      }
    }))
    clientCompiler.plugin('done', () => {
      const fs = this.webpackDevMiddleware.fileSystem
      const filePath = join(clientConfig.output.path, 'index.html')
      if (fs.existsSync(filePath)) {
        const template = fs.readFileSync(filePath, 'utf-8')
        this.appTemplate = _.template(template, {
          interpolate: /{{([\s\S]+?)}}/g
        })
      }
      this.watchHandler()
    })
  }

  webpackWatchAndUpdate () {
    const MFS = require('memory-fs') // <- dependencies of webpack
    const serverFS = new MFS()
    const clientFS = this.clientCompiler.outputFileSystem
    const serverConfig = this.getWebpackServerConfig()
    const serverCompiler = webpack(serverConfig)
    const bundlePath = join(serverConfig.output.path, 'server-bundle.json')
    const manifestPath = join(serverConfig.output.path, 'client-manifest.json')
    serverCompiler.outputFileSystem = serverFS
    const watchHandler = (err) => {
      if (err) throw err
      const bundleExists = serverFS.existsSync(bundlePath)
      const manifestExists = clientFS.existsSync(manifestPath)
      if (bundleExists && manifestExists) {
        const bundle = serverFS.readFileSync(bundlePath, 'utf8')
        const manifest = clientFS.readFileSync(manifestPath, 'utf8')
        this.createRenderer(JSON.parse(bundle), JSON.parse(manifest))
      }
    }
    this.watchHandler = watchHandler
    this.webpackServerWatcher = serverCompiler.watch(this.options.watchers.webpack, watchHandler)
  }

  webpackRunClient () {
    return new Promise((resolve, reject) => {
      const clientConfig = this.getWebpackClientConfig()
      const clientCompiler = webpack(clientConfig)
      clientCompiler.run((err, stats) => {
        if (err) return reject(err)
        console.log('[nuxt:build:client]\n', stats.toString(this.webpackStats)) // eslint-disable-line no-console
        if (stats.hasErrors()) {
          return reject(new Error('Webpack build exited with errors'))
        }
        resolve()
      })
    })
  }

  webpackRunServer () {
    return new Promise((resolve, reject) => {
      const serverConfig = this.getWebpackServerConfig()
      const serverCompiler = webpack(serverConfig)
      serverCompiler.run((err, stats) => {
        if (err) return reject(err)
        console.log('[nuxt:build:server]\n', stats.toString(this.webpackStats)) // eslint-disable-line no-console
        if (stats.hasErrors()) return reject(new Error('Webpack build exited with errors'))
        const bundlePath = join(serverConfig.output.path, 'server-bundle.json')
        const manifestPath = join(serverConfig.output.path, 'client-manifest.json')
        readFile(bundlePath, 'utf8')
          .then(bundle => {
            readFile(manifestPath, 'utf8')
              .then(manifest => {
                this.createRenderer(JSON.parse(bundle), JSON.parse(manifest))
                resolve()
              })
          })
      })
    })
  }

  createRenderer (bundle, manifest) {
    // Create bundle renderer to give a fresh context for every request
    this.renderer = createBundleRenderer(bundle, Object.assign({
      clientManifest: manifest,
      runInNewContext: false,
      basedir: this.options.rootDir
    }, this.options.build.ssr))
    this.renderToString = pify(this.renderer.renderToString)
    this.renderToStream = this.renderer.renderToStream
  }

  watchFiles () {
    const patterns = [
      r(this.options.srcDir, 'layouts'),
      r(this.options.srcDir, 'store'),
      r(this.options.srcDir, 'middleware'),
      r(this.options.srcDir, 'layouts/*.vue'),
      r(this.options.srcDir, 'layouts/**/*.vue')
    ]
    if (this._nuxtPages) {
      patterns.push(r(this.options.srcDir, 'pages'))
      patterns.push(r(this.options.srcDir, 'pages/*.vue'))
      patterns.push(r(this.options.srcDir, 'pages/**/*.vue'))
    }
    const options = Object.assign({}, this.options.watchers.chokidar, {
      ignoreInitial: true
    })
    /* istanbul ignore next */
    const refreshFiles = _.debounce(this.generateRoutesAndFiles, 200)
    // Watch for internals
    this.filesWatcher = chokidar.watch(patterns, options)
      .on('add', refreshFiles)
      .on('unlink', refreshFiles)
    // Watch for custom provided files
    this.customFilesWatcher = chokidar.watch(_.uniq(this.options.build.watch), options)
      .on('change', refreshFiles)
  }
}

const defaultsLoaders = [
  {
    test: /\.(png|jpe?g|gif|svg)$/,
    loader: 'url-loader',
    query: {
      limit: 1000, // 1KO
      name: 'img/[name].[hash:7].[ext]'
    }
  },
  {
    test: /\.(woff2?|eot|ttf|otf)(\?.*)?$/,
    loader: 'url-loader',
    query: {
      limit: 1000, // 1 KO
      name: 'fonts/[name].[hash:7].[ext]'
    }
  }
]

const defaultsPostcss = [
  require('autoprefixer')({
    browsers: ['last 3 versions']
  })
]

const STATUS = {
  INITIAL: 1,
  BUILD_DONE: 2,
  BUILDING: 3
}