'use strict'

import fs from 'fs-extra'
import pify from 'pify'
import _ from 'lodash'
import { resolve, join, dirname, sep } from 'path'
import { isUrl, promisifyRoute, waitFor } from './utils'
import { minify } from 'html-minifier'
const debug = require('debug')('nuxt:generate')
const copy = pify(fs.copy)
const remove = pify(fs.remove)
const writeFile = pify(fs.writeFile)
const mkdirp = pify(fs.mkdirp)

const defaults = {
  dir: 'dist',
  routes: [],
  interval: 0,
  minify: {
    collapseBooleanAttributes: true,
    collapseWhitespace: true,
    decodeEntities: true,
    minifyCSS: true,
    minifyJS: true,
    processConditionalComments: true,
    removeAttributeQuotes: false,
    removeComments: false,
    removeEmptyAttributes: true,
    removeOptionalTags: true,
    removeRedundantAttributes: true,
    removeScriptTypeAttributes: false,
    removeStyleLinkTypeAttributes: false,
    removeTagWhitespace: false,
    sortAttributes: true,
    sortClassName: true,
    trimCustomFragments: true,
    useShortDoctype: true
  }
}

export default async function () {
  const s = Date.now()
  let errors = []
  /*
  ** Set variables
  */
  this.options.generate = _.defaultsDeep(this.options.generate, defaults)
  var srcStaticPath = resolve(this.srcDir, 'static')
  var srcBuiltPath = resolve(this.dir, '.nuxt', 'dist')
  var distPath = resolve(this.dir, this.options.generate.dir)
  var distNuxtPath = join(distPath, (isUrl(this.options.build.publicPath) ? '' : this.options.build.publicPath))
  /*
  ** Launch build process
  */
  await this.build()
  /*
  ** Clean destination folder
  */
  try {
    await remove(distPath)
    debug('Destination folder cleaned')
  } catch (e) {}
  /*
  ** Copy static and built files
  */
  if (fs.existsSync(srcStaticPath)) {
    await copy(srcStaticPath, distPath)
  }
  await copy(srcBuiltPath, distNuxtPath)
  debug('Static & build files copied')
  if (this.options.router.mode !== 'hash') {
    // Resolve config.generate.routes promises before generating the routes
    try {
      var generateRoutes = await promisifyRoute(this.options.generate.routes || [])
    } catch (e) {
      console.error('Could not resolve routes') // eslint-disable-line no-console
      console.error(e) // eslint-disable-line no-console
      process.exit(1)
      throw e // eslint-disable-line no-unreachable
    }
    /*
    ** Generate html files from routes
    */
    generateRoutes.forEach((route) => {
      if (this.routes.indexOf(route) < 0) {
        this.routes.push(route)
      }
    })
  }
  /*
  ** Generate only index.html for router.mode = 'hash'
  */
  let routes = (this.options.router.mode === 'hash') ? ['/'] : this.routes
  while (routes.length) {
    let n = 0
    await Promise.all(routes.splice(0, 500).map(async (route) => {
      await waitFor(n++ * this.options.generate.interval)
      let html
      try {
        const res = await this.renderRoute(route, { _generate: true })
        html = res.html
        if (res.error) {
          errors.push({ type: 'handled', route, error: res.error })
        }
      } catch (err) {
        /* istanbul ignore next */
        errors.push({ type: 'unhandled', route, error: err })
      }
      if (this.options.generate.minify) {
        try {
          html = minify(html, this.options.generate.minify)
        } catch (err) /* istanbul ignore next */ {
          const minifyErr = new Error(`HTML minification failed. Make sure the route generates valid HTML. Failed HTML:\n ${html}`)
          errors.push({ type: 'unhandled', route, error: minifyErr })
        }
      }
      let path = join(route, sep, 'index.html') // /about -> /about/index.html
      debug('Generate file: ' + path)
      path = join(distPath, path)
      // Make sure the sub folders are created
      await mkdirp(dirname(path))
      await writeFile(path, html, 'utf8')
    }))
  }
  // Add .nojekyll file to let Github Pages add the _nuxt/ folder
  // https://help.github.com/articles/files-that-start-with-an-underscore-are-missing/
  const nojekyllPath = resolve(distPath, '.nojekyll')
  writeFile(nojekyllPath, '')
  const duration = Math.round((Date.now() - s) / 100) / 10
  debug(`HTML Files generated in ${duration}s`)

  if (errors.length) {
    const report = errors.map(({ type, route, error }) => {
      /* istanbul ignore if */
      if (type === 'unhandled') {
        return `Route: '${route}'\n${error.stack}`
      } else {
        return `Route: '${route}' thrown an error: \n` + JSON.stringify(error)
      }
    })
    console.error('==== Error report ==== \n' + report.join('\n\n')) // eslint-disable-line no-console
  }
}