import loaderUtils from 'loader-utils'
import path from 'path'
import fs from 'fs'
import md5 from 'md5'
import * as config from './config'
import * as legacy from './legacy'
import {
  parseFragment
}
from './parser'
import {
  getNameByPath,
  getRequireString,
  stringifyLoaders
}
from './util'
import vueLoader from 'weex-vue-loader'
const loaderPath = __dirname
const defaultLoaders = {
  none: '',
  main: path.resolve(loaderPath, 'loader.js'),
  extract: path.resolve(loaderPath, 'extract.js'),
  template: path.resolve(loaderPath, 'template.js'),
  style: path.resolve(loaderPath, 'style.js'),
  script: path.resolve(loaderPath, 'script.js'),
  json: path.resolve(loaderPath, 'json.js'),
  babel: loadBabelModule('babel-loader')
}

function loadBabelModule(moduleName) {
  try {
    const filePath = require.resolve(moduleName)
    return filePath.slice(0, filePath.lastIndexOf(moduleName) + moduleName.length)
  }
  catch (e) {
    return moduleName
  }
}

function getLoaderString(type, config) {
  config = config || {}
  let customLoader
  let loaders
  if (config.lang && config.customLang[config.lang]) {
    customLoader = config.customLang[config.lang]
  }
  if (type === 'main') {
    loaders = [{
      name: defaultLoaders.main
    }]
    return stringifyLoaders(loaders)
  }
  if (type === 'element') {
    loaders = [{
      name: defaultLoaders.main,
      query: {
        element: config.source ? undefined : true
      }
    }]
    if (!config.source) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          index: config.name,
          type: 'elements'
        }
      })
    }
    return stringifyLoaders(loaders)
  }
  if (type === 'template') {
    loaders = [{
      name: defaultLoaders.json
    }, {
      name: defaultLoaders.template
    }]
    if (customLoader) {
      loaders = loaders.concat(customLoader)
    }
    if (!config.source) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          type: 'template'
        }
      })
    }
    if (config.element) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          index: config.elementName,
          type: 'elements'
        }
      })
    }
    return stringifyLoaders(loaders)
  }
  if (type === 'style') {
    loaders = [{
      name: defaultLoaders.json
    }, {
      name: defaultLoaders.style
    }]
    if (customLoader) {
      loaders = loaders.concat(customLoader)
    }
    if (!config.source) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          index: 0,
          type: 'styles'
        }
      })
    }
    if (config.element) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          index: config.elementName,
          type: 'elements'
        }
      })
    }
    return stringifyLoaders(loaders)
  }
  if (type === 'script') {
    loaders = [{
      name: defaultLoaders.script
    }]
    if (customLoader) {
      loaders = loaders.concat(customLoader)
    }
    else {
      loaders.push({
        name: defaultLoaders.babel,
        query: {
          presets: [loadBabelModule('babel-preset-es2015')],
          plugins: [loadBabelModule('babel-plugin-transform-runtime')],
          comments: 'false'
        }
      })
    }
    if (!config.source) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          index: 0,
          type: 'scripts'
        }
      })
    }
    if (config.element) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          index: config.elementName,
          type: 'elements'
        }
      })
    }
    return stringifyLoaders(loaders)
  }
  if (type === 'config') {
    loaders = [{
      name: defaultLoaders.json
    }]
    if (!config.source) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          type: 'config'
        }
      })
    }
    return stringifyLoaders(loaders)
  }
  if (type === 'data') {
    loaders = [{
      name: defaultLoaders.json
    }]
    if (!config.source) {
      loaders.push({
        name: defaultLoaders.extract,
        query: {
          type: 'data'
        }
      })
    }
    return stringifyLoaders(loaders)
  }
}

function loader(source) {
  this.cacheable && this.cacheable()
    // Support *.vue files.
    // If file extname is vue then go to `weex-vue-loader`.
  if (path.extname(this.resourcePath).match(/\.vue/)) {
    return vueLoader.call(this, source)
  }
  const options = this.options.weex || {}
  const customLang = options.lang || {}
  const loaderQuery = loaderUtils.getOptions(this) || {}
  const resourceQuery = this.resourceQuery && loaderUtils.parseQuery(this.resourceQuery) || {}
  const resourcePath = this.resourcePath
  const isElement = loaderQuery.element
  const isEntry = resourceQuery.entry
  const filename = path.relative('.', resourcePath)
  const name = isEntry ? md5(fs.readFileSync(filename)) : (resourceQuery.name || getNameByPath(resourcePath))
  let output = ''
  const frag = parseFragment(source)
  const elementNames = []
  if (frag.element.length) {
    for (let i = 0; i < frag.element.length; i++) {
      const element = frag.element[i]
      if (!element.name) {
        this.emitError('Element block need a name attribute')
        return ''
      }
      elementNames.push(element.name)
      let src = resourcePath
      if (element.src) {
        src = element.src
      }
      output += getRequireString(this, getLoaderString('element', {
        customLang,
        name: element.name,
        source: element.src
      }), `${src}?name=${element.name}`)
    }
  }
  if (frag.deps.length) {
    for (const dep of frag.deps) {
      const filepath = path.resolve(path.dirname(resourcePath), `${dep}.we`)
      if (elementNames.indexOf(dep) < 0 && fs.existsSync(filepath)) {
        output += getRequireString(this, getLoaderString('none'), `./${dep}.we`)
      }
    }
  }
  if (!frag.template.length) {
    this.emitError('Template block is required')
    return ''
  }
  else {
    const template = frag.template[0]
    let src = resourcePath
    if (template.src) {
      src = template.src
    }
    output += 'var __weex_template__ = ' + getRequireString(this, getLoaderString('template', {
      customLang,
      lang: template.lang,
      element: isElement,
      elementName: isElement ? name : undefined,
      source: template.src
    }), src)
  }
  if (frag.style.length) {
    const style = frag.style[0]
    let src = resourcePath
    if (style.src) {
      src = style.src
    }
    output += 'var __weex_style__ = ' + getRequireString(this, getLoaderString('style', {
      customLang,
      lang: style.lang,
      element: isElement,
      elementName: isElement ? name : undefined,
      source: style.src
    }), src)
  }
  if (frag.script.length) {
    const script = frag.script[0]
    let src = resourcePath
    if (script.src) {
      src = script.src
    }
    output += 'var __weex_script__ = ' + getRequireString(this, getLoaderString('script', {
      customLang,
      lang: script.lang,
      element: isElement,
      elementName: isElement ? name : undefined,
      source: script.src
    }), src)
  }
  if (isEntry && frag.data.length) {
    const data = frag.data[0]
    let src = resourcePath
    if (data.src) {
      src = data.src
    }
    output += 'var __weex_data__ = ' + getRequireString(this, getLoaderString('data', {
      source: data.src
    }), src)
  }
  if (isEntry && frag.config.length) {
    const config = frag.config[0]
    let src = resourcePath
    if (config.src) {
      src = config.src
    }
    output += 'var __weex_config__ = ' + getRequireString(this, getLoaderString('config', {
      source: config.src
    }), src)
  }
  output += `
__weex_define__('@weex-component/${name}', [], function(__weex_require__, __weex_exports__, __weex_module__) {
` + (frag.script.length > 0 ? `
    __weex_script__(__weex_module__, __weex_exports__, __weex_require__)
    if (__weex_exports__.__esModule && __weex_exports__.default) {
      __weex_module__.exports = __weex_exports__.default
    }
` : '') + `
    __weex_module__.exports.template = __weex_template__
` + (frag.style.length > 0 ? `
    __weex_module__.exports.style = __weex_style__
` : '') + `
})
`
  if (isEntry) {
    output += `
__weex_bootstrap__('@weex-component/${name}'` + (frag.config.length > 0 ? `,__weex_config__` : ',undefined') + (frag.data.length > 0 ? `,__weex_data__` : ',undefined') + `)`
  }
  return output
}
loader.setLogLevel = level => {
  config.logLevel = level
}
for (const key in legacy) {
  loader[key] = legacy[key]
}
module.exports = loader