import {get} from './ajax'
import {callHook} from '../init/lifecycle'
import {getParentPath, stringifyQuery} from '../router/util'
import {noop} from '../util/core'
import {getAndActive} from '../event/sidebar'

function loadNested(path, qs, file, next, vm, first) {
  path = first ? path : path.replace(/\/$/, '')
  path = getParentPath(path)

  if (!path) {
    return
  }

  get(
    vm.router.getFile(path + file) + qs,
    false,
    vm.config.requestHeaders
  ).then(next, _ => loadNested(path, qs, file, next, vm))
}

export function fetchMixin(proto) {
  let last

  const abort = () => last && last.abort && last.abort()
  const request = (url, hasbar, requestHeaders) => {
    abort()
    last = get(url, true, requestHeaders)
    return last
  }

  const get404Path = (path, config) => {
    const {notFoundPage, ext} = config
    const defaultPath = '_404' + (ext || '.md')
    let key
    let path404

    switch (typeof notFoundPage) {
      case 'boolean':
        path404 = defaultPath
        break
      case 'string':
        path404 = notFoundPage
        break

      case 'object':
        key = Object.keys(notFoundPage)
          .sort((a, b) => b.length - a.length)
          .find(key => path.match(new RegExp('^' + key)))

        path404 = (key && notFoundPage[key]) || defaultPath
        break

      default:
        break
    }

    return path404
  }

  proto._loadSideAndNav = function (path, qs, loadSidebar, cb) {
    return () => {
      if (!loadSidebar) {
        return cb()
      }

      const fn = result => {
        this._renderSidebar(result)
        cb()
      }

      // Load sidebar
      loadNested(path, qs, loadSidebar, fn, this, true)
    }
  }

  proto._fetch = function (cb = noop) {
    const {path, query} = this.route
    const qs = stringifyQuery(query, ['id'])
    const {loadNavbar, requestHeaders, loadSidebar} = this.config
    // Abort last request

    const file = this.router.getFile(path)
    const req = request(file + qs, true, requestHeaders)

    // Current page is html
    this.isHTML = /\.html$/g.test(file)

    // Load main content
    req.then(
      (text, opt) =>
        this._renderMain(
          text,
          opt,
          this._loadSideAndNav(path, qs, loadSidebar, cb)
        ),
      _ => {
        this._fetchFallbackPage(file, qs, cb) || this._fetch404(file, qs, cb)
      }
    )

    // Load nav
    loadNavbar &&
      loadNested(
        path,
        qs,
        loadNavbar,
        text => this._renderNav(text),
        this,
        true
      )
  }

  proto._fetchCover = function () {
    const {coverpage, requestHeaders} = this.config
    const query = this.route.query
    const root = getParentPath(this.route.path)

    if (coverpage) {
      let path = null
      const routePath = this.route.path
      if (typeof coverpage === 'string') {
        if (routePath === '/') {
          path = coverpage
        }
      } else if (Array.isArray(coverpage)) {
        path = coverpage.indexOf(routePath) > -1 && '_coverpage'
      } else {
        const cover = coverpage[routePath]
        path = cover === true ? '_coverpage' : cover
      }

      const coverOnly = Boolean(path) && this.config.onlyCover
      if (path) {
        path = this.router.getFile(root + path)
        this.coverIsHTML = /\.html$/g.test(path)
        get(path + stringifyQuery(query, ['id']), false, requestHeaders).then(
          text => this._renderCover(text, coverOnly)
        )
      } else {
        this._renderCover(null, coverOnly)
      }
      return coverOnly
    }
  }

  proto.$fetch = function (cb = noop) {
    const done = () => {
      callHook(this, 'doneEach')
      cb()
    }

    const onlyCover = this._fetchCover()

    if (onlyCover) {
      done()
    } else {
      this._fetch(() => {
        this.$resetEvents()
        done()
      })
    }
  }

  proto._fetchFallbackPage = function (path, qs, cb = noop) {
    const {requestHeaders, fallbackLanguages, loadSidebar} = this.config

    if (!fallbackLanguages) {
      return false
    }

    const local = path.split('/')[1]

    if (fallbackLanguages.indexOf(local) === -1) {
      return false
    }
    const newPath = path.replace(new RegExp(`^/${local}`), '')
    const req = request(newPath + qs, true, requestHeaders)

    req.then(
      (text, opt) =>
        this._renderMain(
          text,
          opt,
          this._loadSideAndNav(path, qs, loadSidebar, cb)
        ),
      () => this._fetch404(path, qs, cb)
    )

    return true
  }
  /**
   * Load the 404 page
   * @param path
   * @param qs
   * @param cb
   * @returns {*}
   * @private
   */
  proto._fetch404 = function (path, qs, cb = noop) {
    const {loadSidebar, requestHeaders, notFoundPage} = this.config

    const fnLoadSideAndNav = this._loadSideAndNav(path, qs, loadSidebar, cb)
    if (notFoundPage) {
      const path404 = get404Path(path, this.config)

      request(this.router.getFile(path404), true, requestHeaders).then(
        (text, opt) => this._renderMain(text, opt, fnLoadSideAndNav),
        () => this._renderMain(null, {}, fnLoadSideAndNav)
      )
      return true
    }

    this._renderMain(null, {}, fnLoadSideAndNav)
    return false
  }
}

export function initFetch(vm) {
  const {loadSidebar} = vm.config

  // Server-Side Rendering
  if (vm.rendered) {
    const activeEl = getAndActive(vm.router, '.sidebar-nav', true, true)
    if (loadSidebar && activeEl) {
      activeEl.parentNode.innerHTML += window.__SUB_SIDEBAR__
    }
    vm._bindEventOnRendered(activeEl)
    vm.$resetEvents()
    callHook(vm, 'doneEach')
    callHook(vm, 'ready')
  } else {
    vm.$fetch(_ => callHook(vm, 'ready'))
  }
}