import { resolve, join } from 'path'
import { createHash } from 'crypto'
import { existsSync } from 'fs'
import webpack from 'webpack'
import glob from 'glob-promise'
import WriteFilePlugin from 'write-file-webpack-plugin'
import FriendlyErrorsWebpackPlugin from 'friendly-errors-webpack-plugin'
import UnlinkFilePlugin from './plugins/unlink-file-plugin'
import WatchPagesPlugin from './plugins/watch-pages-plugin'
import WatchRemoveEventPlugin from './plugins/watch-remove-event-plugin'
import DynamicEntryPlugin from './plugins/dynamic-entry-plugin'
import DetachPlugin from './plugins/detach-plugin'
import JsonPagesPlugin from './plugins/json-pages-plugin'
import getConfig from '../config'

const documentPage = join('pages', '_document.js')
const defaultPages = [
  '_error.js',
  '_error-debug.js',
  '_document.js'
]

export default async function createCompiler (dir, { dev = false, quiet = false } = {}) {
  dir = resolve(dir)
  const config = getConfig(dir)

  const pages = await glob('pages/**/*.js', { cwd: dir })

  const entry = {
    'main.js': dev ? require.resolve('../../client/next-dev') : require.resolve('../../client/next')
  }

  const defaultEntries = dev
    ? [join(__dirname, '..', '..', 'client/webpack-hot-middleware-client')] : []
  for (const p of pages) {
    entry[join('bundles', p)] = defaultEntries.concat([`./${p}?entry`])
  }

  const nextPagesDir = join(__dirname, '..', '..', 'pages')
  const interpolateNames = new Map()

  for (const p of defaultPages) {
    const entryName = join('bundles', 'pages', p)
    const path = join(nextPagesDir, p)
    if (!entry[entryName]) {
      entry[entryName] = defaultEntries.concat([path + '?entry'])
    }
    interpolateNames.set(path, `dist/pages/${p}`)
  }

  const nextNodeModulesDir = join(__dirname, '..', '..', '..', 'node_modules')
  const minChunks = pages.filter((p) => p !== documentPage).length

  const plugins = [
    new webpack.LoaderOptionsPlugin({
      options: {
        context: dir,
        customInterpolateName (url, name, opts) {
          return interpolateNames.get(this.resourcePath) || url
        }
      }
    }),
    new WriteFilePlugin({
      exitOnErrors: false,
      log: false,
      // required not to cache removed files
      useHashIndex: false
    }),
    new webpack.optimize.CommonsChunkPlugin({
      name: 'commons',
      filename: 'commons.js',
      minChunks: Math.max(2, minChunks)
    }),
    new JsonPagesPlugin()
  ]

  if (dev) {
    plugins.push(
      new webpack.HotModuleReplacementPlugin(),
      new webpack.NoErrorsPlugin(),
      new DetachPlugin(),
      new DynamicEntryPlugin(),
      new UnlinkFilePlugin(),
      new WatchRemoveEventPlugin(),
      new WatchPagesPlugin(dir)
    )
    if (!quiet) {
      plugins.push(new FriendlyErrorsWebpackPlugin())
    }
  } else {
    plugins.push(
      new webpack.DefinePlugin({
        'process.env.NODE_ENV': JSON.stringify('production')
      }),
      new webpack.optimize.UglifyJsPlugin({
        compress: { warnings: false },
        sourceMap: false
      })
    )
  }

  const mainBabelOptions = {
    babelrc: true,
    cacheDirectory: true,
    sourceMaps: dev ? 'both' : false,
    presets: []
  }

  const hasBabelRc = existsSync(join(dir, '.babelrc'))
  if (hasBabelRc) {
    console.log('> Using .babelrc defined in your app root')
  } else {
    mainBabelOptions.presets.push(require.resolve('./babel/preset'))
  }

  const rules = (dev ? [{
    test: /\.js(\?[^?]*)?$/,
    loader: 'hot-self-accept-loader',
    include: [
      join(dir, 'pages'),
      nextPagesDir
    ]
  }, {
    test: /\.js(\?[^?]*)?$/,
    loader: 'react-hot-loader/webpack',
    exclude: /node_modules/
  }] : [])
  .concat([{
    test: /\.json$/,
    loader: 'json-loader'
  }, {
    test: /\.(js|json)(\?[^?]*)?$/,
    loader: 'emit-file-loader',
    include: [dir, nextPagesDir],
    exclude (str) {
      return /node_modules/.test(str) && str.indexOf(nextPagesDir) !== 0
    },
    options: {
      name: 'dist/[path][name].[ext]'
    }
  }, {
    loader: 'babel-loader',
    include: nextPagesDir,
    options: {
      babelrc: false,
      cacheDirectory: true,
      sourceMaps: dev ? 'both' : false,
      plugins: [
        [
          require.resolve('babel-plugin-module-resolver'),
          {
            alias: {
              'ansi-html': require.resolve('ansi-html'),
              'styled-jsx/style': require.resolve('styled-jsx/style')
            }
          }
        ]
      ]
    }
  }, {
    test: /\.js(\?[^?]*)?$/,
    loader: 'babel-loader',
    include: [dir, nextPagesDir],
    exclude (str) {
      return /node_modules/.test(str) && str.indexOf(nextPagesDir) !== 0
    },
    query: mainBabelOptions
  }])

  let webpackConfig = {
    context: dir,
    entry,
    output: {
      path: join(dir, '.next'),
      filename: '[name]',
      libraryTarget: 'commonjs2',
      publicPath: '/_webpack/',
      devtoolModuleFilenameTemplate ({ resourcePath }) {
        const hash = createHash('sha1')
        hash.update(Date.now() + '')
        const id = hash.digest('hex').slice(0, 7)

        // append hash id for cache busting
        return `webpack:///${resourcePath}?${id}`
      }
    },
    resolve: {
      modules: [
        nextNodeModulesDir,
        'node_modules'
      ].concat(
        (process.env.NODE_PATH || '')
        .split(process.platform === 'win32' ? ';' : ':')
        .filter((p) => !!p)
      )
    },
    resolveLoader: {
      modules: [
        nextNodeModulesDir,
        'node_modules',
        join(__dirname, 'loaders')
      ]
    },
    plugins,
    module: {
      rules
    },
    devtool: dev ? 'inline-source-map' : false,
    performance: { hints: false }
  }

  if (config.webpack) {
    console.log('> Using "webpack" config function defined in next.config.js.')
    webpackConfig = await config.webpack(webpackConfig, { dev })
  }
  return webpack(webpackConfig)
}