const Flume = require('flumedb')
const Reduce = require('flumeview-reduce')
const FlumeLog = require('flumelog-offset')
const { pull, drain } = require('pull-stream')
const codec = require('flumecodec')

const db = Flume(FlumeLog('.test.db', { codec: codec.json }))
  .use('entries', Reduce(1, entriesReducer, null, null, []))
  .use('accounts', Reduce(1, accountReducer, null, null, {}))

const onDone = () => console.log('DONE')

module.exports = ledgerStore

function ledgerStore (state, emitter) {
  state.accounts = {}
  state.entries = []

  pull(
    db.accounts.stream(),
    drain(acctState => {
      state.accounts = acctState
      emitter.emit(state.events.RENDER)
  }, onDone))

  pull(
    db.entries.stream(),
    drain(entryState => {
      state.entries = entryState
      emitter.emit.RENDER
  }, onDone))

  function onLoad () {
    emitter.on('accounts', onEvent)
    emitter.on('entries', onEvent)
  }

  function onEvent (data) {
    db.append(data, (err, seq) => {
      if (err) throw err
      emitter.emit(state.events.RENDER)
    })
  }

  emitter.on('DOMContentLoaded', onLoad)

}

function entriesReducer (acc, item) {
  if (item.type !== 'entries') return acc
  acc.push(item)

  return acc
}

function accountReducer (acc, item) { // TODO account for account creation of existing account
  if (item.type === 'entries') {
    const { msg } = item
    acc[msg.debit].debit += msg.amount
    acc[msg.credit].credit += msg.amount

    return acc
  }
  if (item.type !== 'accounts') return acc

  const { msg } = item

  if (!acc[msg.name]) {
    acc[msg.name] = msg

    return acc
  }

  Object.assign(acc[msg.name], msg)
  return acc
}