const nest = require('depnest')
const { h } = require('mutant')
const isString = require('lodash/isString')
const More = require('hypermore')
const morphdom = require('morphdom')
const Debounce = require('obv-debounce')

exports.gives = nest('app.page.home')

exports.needs = nest({
  'history.sync.push': 'first',
  'keys.sync.id': 'first',
  'translations.sync.strings': 'first',
  'state.obs.threads': 'first',
  'app.html.threadCard': 'first',
  'unread.sync.isUnread': 'first'
})

function toRecpGroup(msg) {
  //cannocialize
  return Array.isArray(msg.value.content.repcs) &&
    msg.value.content.recps.map(function (e) {
    return (isString(e) ? e : e.link)
  }).sort().map(function (id) {
    return id.substring(0, 10)
  }).join(',')
}

exports.create = (api) => {
  return nest('app.page.home', function (location) {
    // location here can expected to be: { page: 'home'}
    var strings = api.translations.sync.strings()


    // function filterForThread (thread) {
    //   if(thread.value.private)
    //     return {private: toRecpGroup(thread)}
    //   else if(thread.value.content.channel)
    //     return {channel: thread.value.content.channel}
    // }

    // function filter (rule, thread) {
    //   if(!thread.value) return false
    //   if(!rule) return true
    //   if(rule.channel) {
    //     return rule.channel == thread.value.content.channel
    //   }
    //   else if(rule.group)
    //     return rule.group == thread.value.content.group
    //   else if(rule.private)
    //     return rule.private == toRecpGroup(thread)
    //   else return true
    // }

    var morePlease = false
    var threadsObs = api.state.obs.threads()

    // DUCT TAPE: debounce the observable so it doesn't
    // update the dom more than 1/second
    threadsObs(function () {
      if(morePlease) threadsObs.more()
    })
    threadsObsDebounced = Debounce(threadsObs, 1000)
    threadsObsDebounced(function () {
      morePlease = false
    })
    threadsObsDebounced.more = function () {
      morePlease = true
      requestIdleCallback(threadsObs.more)
    }

    var container = h('div.container', [])
    var threadsHtmlObs = More(
      threadsObsDebounced,
      function render (threads) {

        function latestUpdate(thread) {
          var m = thread.timestamp
          if(!thread.replies) return m

          for(var i = 0; i < thread.replies.length; i++)
            m = Math.max(thread.replies[i].timestamp, m)
          return m
        }

        function roots (r) {
          return Object.keys(r || {}).map(function (k) {
            return threads.roots[r[k]]
          }).filter(function (e) {
            return e && e.value
          })
        }

        var groupedThreads =
        roots(threads.private)
        .concat(roots(threads.channels))
        .concat(roots(threads.groups))
        .filter(function (thread) {
          return thread.value.content.recps || thread.value.content.channel
        })
        .map(function (thread) {
          var unread = 0
          if(api.unread.sync.isUnread(thread))
            unread ++
          ;(thread.replies || []).forEach(function (msg) {
            if(api.unread.sync.isUnread(msg)) unread ++
          })
          thread.unread = unread
          return thread
        })
        .sort(function (a, b) {
          return (
            (latestUpdate(b) - latestUpdate(a))
          )
        })

        morphdom(container,
          // LEGACY: some of these containers could be removed
          // but they are here to be compatible with the old MCSS.
          h('div.container', [
            //private section
            h('section.updates -directMessage', [
              h('div.threads',
                groupedThreads.map(thread => {
                  const channel = thread.value.content.channel
                  const onClick = channel
                    ? (ev) => api.history.sync.push({ channel })
                    : null // threadCard will install default onClick

                  return api.app.html.threadCard(thread, { onClick })
                })
              )
            ])
         ])
       )
      return container
      }
    )
    return h('Page -home', {title: strings.home}, [
      threadsHtmlObs,
      h('button', {'ev-click': threadsHtmlObs.more}, [strings.showMore])
    ])
  })
}