ama-team / voxengine-scenario-framework

var SDK = require('@ama-team/voxengine-sdk')

var Slf4j = SDK.Logger.Slf4j

var CancellationToken = SDK.Concurrent.CancellationToken

var Future = SDK.Concurrent.Future

var Branch = require('./Transition/Branch').Branch

var IllegalStateError = require('../Error').IllegalStateError

var statusFactory = function (id, successful) {

  var terminal = typeof successful === 'boolean'

  return {

    id: id,

    terminal: terminal,

    successful: terminal ? successful : null

  }

}

/**

 * @enum

 * @readonly

 */

var Status = {

  Idle: statusFactory('Idle'),

  Executing: statusFactory('Executing'),

  Aborting: statusFactory('Aborting'),

  /**

   * Transition has completed successfully

   */

  Executed: statusFactory('Executed', true),

  /**

   * Transition has been aborted successfully

   */

  Aborted: statusFactory('Aborted', true),

  /**

   * Transition has failed and thrown an error during normal execution

   */

  ExecutionFailure: statusFactory('ExecutionFailure', false),

  /**

   * Transition has been aborted and encountered an error during abort

   */

  AbortFailure: statusFactory('AbortFailure', false),

  /**

   * Transition has ended with error triggered by framework

   */

  Tripped: statusFactory('Tripped', false)

}

/**

 * @typedef {object} Transition~Options

 *

 * @property {TState} [origin]

 * @property {TState} target

 * @property {THints} hints

 * @property {LoggerOptions} [logger]

 * @property {IExecutor} executor

 */

/**

 * Represents transition from one state to another

 *

 * @param {Transition~Options} options

 *

 * @class

 */

function Transition (options) {

  var self = this

  if (!options || !options.target) {

    throw new IllegalStateError('Target state not provided')

  }

  var loggerName = 'ama-team.vsf.execution.transition'

  var origin = options.origin

  var target = options.target

  var originId = (origin && origin.id) || null

  var hints = options.hints

  options.logger = options.logger || {}

  options.logger.mdc = options.logger.mdc || {}

  options.logger.mdc['origin'] = originId

  options.logger.mdc['target'] = target.id

  var logger = Slf4j.factory(options.logger, loggerName)

  var token = new CancellationToken()

  var completion = new Future()

  var status = Status.Idle

  var launchedAt = null

  /**

   * @param {Transition.Status} next

   */

  function setStatus (next) {

    logger.trace('Changing status from {} to {}', status.id, next.id)

    status = next

  }

  function executionOptions (name) {

    return {

      name: name,

      handler: target[name],

      logger: options.logger,

      executor: options.executor

    }

  }

  /**

   * Returns function that will generate ITransitionResult from provided

   * value.

   *

   * @param {Status} status

   * @return {Function}

   */

  function factory (status) {

    return function (value) {

      return {

        value: value,

        status: status,

        duration: (new Date()).getTime() - launchedAt.getTime()

      }

    }

  }

  /**

   * Completes transition with provided result, if

   *

   * @param {TTransitionResult} result

   * @param {Status} [requiredStatus]

   */

  function complete (result, requiredStatus) {

    if (requiredStatus && status !== requiredStatus) {

      return

    }

    setStatus(result.status)

    logger.debug('Transition has ended with status {} and value {} in {} ms',

      status.id, result.value, result.duration)

    completion.resolve(result)

  }

  function run () {

    if (status !== Status.Idle) {

      throw new IllegalStateError('Tried to run ' + self + ' twice')

    }

    logger.debug('Running transition')

    launchedAt = new Date()

    setStatus(Status.Executing)

    var opts = executionOptions('transition')

    var execution = new Branch(opts)

    execution

      .run(originId, hints, token)

      .then(factory(Status.Executed), factory(Status.ExecutionFailure))

      .then(function (result) {

        var level = result.status.successful ? 'debug' : 'warn'

        var term = result.status.successful ? 'success' : 'error'

        logger[level]('Transition run has finished with {}: {}', term,

          result.value)

        complete(result, Status.Executing)

      })

    return completion

  }

  function abort () {

    if (status !== Status.Executing) {

      throw new IllegalStateError('Tried to abort ' + self)

    }

    setStatus(Status.Aborting)

    var options = executionOptions('abort')

    var execution = new Branch(options)

    execution

      .run(originId, hints)

      .then(factory(Status.Aborted), factory(Status.AbortFailure))

      .then(function (result) {

        var level = result.status.successful ? 'debug' : 'warn'

        var term = result.status.successful ? 'success' : 'error'

        logger[level]('Transition abort has finished with {}: {}', term,

          result.value)

        complete(result, Status.Aborting)

      })

    return completion

  }

  this.run = run

  this.abort = abort

  this.getStatus = function () {

    return status

  }

  this.toString = function () {

    return 'Transition ' + originId + ' -> ' + target.id +

      ' (' + status.id + ')'

  }

  /**

   * @return {TTransitionDetails}

   */

  this.toDetails = function () {

    return {

      origin: originId,

      target: target.id,

      hints: hints

    }

  }

  /**

   * @return {int}

   */

  this.getLaunchedAt = function () { return launchedAt }

  /**

   * @return {TState}

   */

  this.getTarget = function () { return target }

  this.getOrigin = function () { return origin }

  this.getHints = function () { return hints }

  this.getCompletion = function () { return completion }

}

Transition.Status = Status

module.exports = {

  Transition: Transition

}