var PullObv = require('pull-obv')
var threadReduce = require('ssb-reduce-stream')
var pull = require('pull-stream')
const Next = require('pull-next')

function isObject (o) {
  return 'object' === typeof o
}

exports.gives = {
  state: {obs: {threads: true}}
}

exports.needs = {
  message: {sync: {unbox: 'first'}},
  sbot: {pull: {log: 'first'}}
}

exports.create = function (api) {

  var initial
  try { initial = JSON.parse(localStorage.threadsState) }
  catch (_) { }

  var lastTimestamp = initial ? initial.last : Date.now()
  var firstTimestamp = initial ? initial.last : Date.now()

  function unbox () {
    return pull(
      pull.map(function (data) {
        lastTimestamp = data.timestamp
        if(isObject(data.value.content)) return data
        return api.message.sync.unbox(data)
      }),
      pull.filter(Boolean)
    )
  }

  var threadsObs = PullObv(
    threadReduce,
    pull(
      Next(function () {
        console.log('More', lastTimestamp)
        return api.sbot.pull.log({reverse: true, limit: 500, lt: lastTimestamp})
      }),
      pull.through(function (data) {
        console.log(data.timestamp)
        lastTimestamp = data.timestamp
      }),
      unbox()
    ),
    //value recovered from localStorage
    initial
  )

  threadsObs(function (threadsState) {
    if(threadsState.ended && threadsState.ended !== true)
      console.error('threadObs error:', threadsState.ended)
  })

  var timer
  //keep localStorage up to date
  threadsObs(function (threadsState) {
    console.log(threadsState)
    clearTimeout(timer)
    setTimeout(function () {
      threadsState.last = lastTimestamp
      localStorage.threadsState = JSON.stringify(threadsState)
    }, 1000)
  })

  //stream live messages. this *should* work.
  //there is no back pressure on new events
  //only a show more on the top (currently)

//  pull(
//    Next(function () {
//      return api.sbot.pull.log({reverse: true, limit: 500, gte: firstTimestamp})
//    }),
//    pull.drain(function (data) {
//      firstTimestamp = data.timestamp
//      threadsObs.set(threadReduce(threadsObs.value, data))
//    })
//  )

  return {state: {obs: {threads: function () {
    return threadsObs
  }}}}

}