const _ = require('lodash/fp')
const pgp = require('pg-promise')()

const db = require('../db')
const E = require('../error')

const cashInLow = require('./cash-in-low')

module.exports = { atomic }

function atomic(machineTx) {
  const TransactionMode = pgp.txMode.TransactionMode
  const isolationLevel = pgp.txMode.isolationLevel
  const mode = new TransactionMode({ tiLevel: isolationLevel.serializable })
  function transaction(t) {
    const sql = 'select * from cash_in_txs where id=$1'
    const sql2 = 'select * from bills where cash_in_txs_id=$1'

    return t.oneOrNone(sql, [machineTx.id]).then(row => {
      if (row && row.tx_version >= machineTx.txVersion)
        throw new E.StaleTxError({ txId: machineTx.id })

      return t.any(sql2, [machineTx.id]).then(billRows => {
        const dbTx = cashInLow.toObj(row)

        return preProcess(dbTx, machineTx)
          .then(preProcessedTx => cashInLow.upsert(t, dbTx, preProcessedTx))
          .then(r => {
            return insertNewBills(t, billRows, machineTx).then(newBills =>
              _.set('newBills', newBills, r),
            )
          })
      })
    })
  }
  return db.tx({ mode }, transaction)
}

function insertNewBills(t, billRows, machineTx) {
  const bills = pullNewBills(billRows, machineTx)
  if (_.isEmpty(bills)) return Promise.resolve([])

  const dbBills = _.map(cashInLow.massage, bills)
  const billsByDestination = _.countBy(_.get(['destination_unit']), dbBills)

  const columns = [
    'id',
    'fiat',
    'fiat_code',
    'crypto_code',
    'cash_in_fee',
    'cash_in_txs_id',
    'device_time',
    'destination_unit',
  ]
  const sql = pgp.helpers.insert(dbBills, columns, 'bills')
  const deviceID = machineTx.deviceId
  const sql2 = `update devices set recycler1 = recycler1 + $2, recycler2 = recycler2 + $3, recycler3 = recycler3 + $4, recycler4 = recycler4 + $5, recycler5 = recycler5 + $6, recycler6 = recycler6 + $7
  where device_id = $1`

  return t
    .none(sql2, [
      deviceID,
      _.defaultTo(0, billsByDestination.recycler1),
      _.defaultTo(0, billsByDestination.recycler2),
      _.defaultTo(0, billsByDestination.recycler3),
      _.defaultTo(0, billsByDestination.recycler4),
      _.defaultTo(0, billsByDestination.recycler5),
      _.defaultTo(0, billsByDestination.recycler6),
    ])
    .then(() => {
      return t.none(sql)
    })
    .then(() => bills)
}

function pullNewBills(billRows, machineTx) {
  if (_.isEmpty(machineTx.bills)) return []

  const toBill = _.mapKeys(_.camelCase)
  const bills = _.map(toBill, billRows)

  return _.differenceBy(_.get('id'), machineTx.bills, bills)
}

function preProcess(dbTx, machineTx) {
  // Note: The way this works is if we're clear to send,
  // we mark the transaction as sendPending.
  //
  // If another process is trying to also mark this as sendPending
  // that means that it saw the tx as sendPending=false.
  // But if that's true, then it must be serialized before this
  // (otherwise it would see sendPending=true), and therefore we can't
  // be seeing sendPending=false (a pre-condition of clearToSend()).
  // Therefore, one of the conflicting transactions will error,
  // which is what we want.
  return new Promise(resolve => {
    if (!dbTx) return resolve(machineTx)

    if (cashInLow.isClearToSend(dbTx, machineTx)) {
      return resolve(_.set('sendPending', true, machineTx))
    }

    return resolve(machineTx)
  })
}