import * as Sequelize from 'sequelize'
// TODO: import from ES6 when retry typing file will include errorFilter function
import * as retry from 'async/retry'

import { database as db } from '../initializers/database'
import { logger } from './logger'

function commitTransaction (t: Sequelize.Transaction, callback: (err: Error) => void) {
  return t.commit().asCallback(callback)
}

function rollbackTransaction (err: Error, t: Sequelize.Transaction, callback: (err: Error) => void) {
  // Try to rollback transaction
  if (t) {
    // Do not catch err, report the original one
    t.rollback().asCallback(function () {
      return callback(err)
    })
  } else {
    return callback(err)
  }
}

type RetryTransactionWrapperOptions = { errorMessage: string, arguments?: any[] }
function retryTransactionWrapper (functionToRetry: Function, options: RetryTransactionWrapperOptions, finalCallback: Function) {
  const args = options.arguments ? options.arguments : []

  transactionRetryer(
    function (callback) {
      return functionToRetry.apply(this, args.concat([ callback ]))
    },
    function (err) {
      if (err) {
        logger.error(options.errorMessage, { error: err })
      }

      // Do not return the error, continue the process
      return finalCallback(null)
    }
  )
}

function transactionRetryer (func: Function, callback: (err: Error) => void) {
  retry({
    times: 5,

    errorFilter: function (err) {
      const willRetry = (err.name === 'SequelizeDatabaseError')
      logger.debug('Maybe retrying the transaction function.', { willRetry })
      return willRetry
    }
  }, func, callback)
}

function startSerializableTransaction (callback: (err: Error, t: Sequelize.Transaction) => void) {
  db.sequelize.transaction(/* { isolationLevel: 'SERIALIZABLE' } */).asCallback(function (err, t) {
    // We force to return only two parameters
    return callback(err, t)
  })
}

// ---------------------------------------------------------------------------

export {
  commitTransaction,
  retryTransactionWrapper,
  rollbackTransaction,
  startSerializableTransaction,
  transactionRetryer
}