const Flume = require('flumedb')
const Reduce = require('flumeview-reduce')
const FlumeLog = require('flumelog-memory')

function ledger (state, emitter) {
  state.accounts = {}
  state.transactions = []

  const db = Flume(FlumeLog())
    .use('transactions', Reduce(
      1,
      transactionReducer,
      null,
      null,
      state.transactions))
    .use('account', Reduce(
      1,
      accountReducer,
      null,
      null,
      state.accounts))

  state.db = db

  function transactionReducer (acc, item) {
    if (item.type !== 'transaction') return acc
    acc.push(item)
    return acc
  }

  function accountReducer (acc, item) {
    if (item.type !== 'accounts') return acc
    const {msg} = item
    switch (msg.type) {
      case 'TOGGLE':
        acc[msg.name].archived = !acc[msg.name].archived
        return acc
      default:
        acc[msg.name] = msg
        return acc
    }
  }

  function onLoad () {
    emitter.on('account', onEvent)
    emitter.on('transaction:add', onEvent)
  }

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

  emitter.on('DOMContentLoaded', onLoad)
}

module.exports = ledger