/**
 * @module sparkslift
 * @description Easily integrate GameSparks with GameLift.
 * @version 1.1.0
 */

require('sha')
require('GameLiftCredentials')

// This library will always perform actions only against GameLift.
var SERVICE = 'gamelift'

// The default request method the actions will be performed.
// GameLift uses 'POST' as the default one for every and each action.
var DEFAULT_REQUEST_METHOD = 'POST'

function hmac (key, keyEncoding, string) {
  var shaObj = new JSSHA('SHA-256', 'TEXT')
  shaObj.setHMACKey(key, keyEncoding)
  shaObj.update(string)

  return shaObj.getHMAC('HEX')
}

function hash (string) {
  return Spark.getDigester().sha256Hex(string)
}

/**
 * The AWS object
 * @param {Object} options All the options needed to perform AWS requests.
 * @param {string} options.region Region of the fleet corresponding to GameLift.
 * @param {string} options.action The action to perform the request. Ie. CreateGameSession, SearchGameSessions.
 * @param {string[]} [options.headers] Request headers given in object format {"key": "value"}
 * @param {Object[]} [options.params] Request parameters given in object format {"key": "value"}
 * @param {Object} [options.payload] Request payload given in object format {"key": "value"}
 * @param {Object} [options.local] Information needed to perform requests to GameLiftLocal
 * @param {string} options.local.address The address (IP, domain, etc.) where GameLiftLocal is running at.
 * @param {number} options.local.port The port GameLiftLocal is listening to.
 * @returns {Object} response The response object of the performed request.
 **/
var AWS = function (options) {
  this.options = options
  this.region = options.region
  this.params = options.params || {}
  this.headers = options.headers || {}
  this.payload = options.payload || {}
  this.payload = JSON.stringify(this.payload)

  var local = options.local || {}
  var date = new Date()

  this.key = GAMELIFT_CREDENTIALS.key
  this.secret = GAMELIFT_CREDENTIALS.secret

  this.headers.Host = getHost(options.region) // Must be present in headers
  this.headers['X-Amz-Date'] = this.awsDateTimeFormat(date)
  this.headers['Content-Type'] = 'application/x-amz-json-1.1'
  this.headers['X-Amz-Target'] = 'GameLift.' + options.action

  var requestHeaders = JSON.parse(JSON.stringify(this.headers))
  requestHeaders.Authorization = this.getAuthHeader(date)

  var requestURL = getRequestURL({
    region: options.region,
    canonicalQueryString: this.getCanonicalQueryString(),
    hasParameters: Object.keys(this.params).length > 0,
    local: local
  })
  var response = Spark.getHttp(requestURL)
    .setHeaders(requestHeaders)
    .postString(this.payload)

  if (response === null) {
    return {
      status: 0,
      json: {}
    }
  }

  return {
    status: response.getResponseCode(),
    json: response.getResponseJson()
  }
}

/**
 * Get the endpoint to issue GameLift requests
 * @param {Object} options
 * @param {string} options.region
 * @param {Object} [options.local]
 */
function getEndpoint (options) {
  if (options.local.address) {
    var port = options.local.port || '8080'

    return 'http://' + options.local.address + ':' + port
  }

  return 'https://' + getHost(options.region)
}

/**
 * Get the host of which requests will be performed against.
 * @param {string} region
 */
function getHost (region) {
  return SERVICE + '.' + region + '.amazonaws.com'
}

/**
 * Get the correct request URL depending on the target environment: local or production.
 * @param {Object} options The parameters of the function
 * @param {string} options.region The region of the GameLift's fleet
 * @param {string} options.canonicalQueryString The canonical query string to mount the request URL
 * @param {boolean} options.hasParameters If parameters are sending alongside the request, needed to prepare the endpoint.
 * @param {Object} [options.local] - the local object, containing information to make the request ping against GameLiftLocal
 * @returns {string}
 */
function getRequestURL (options) {
  var endpoint = getEndpoint({
    local: options.local,
    region: options.region
  })

  if (options.hasParameters) {
    endpoint = +'?' + options.canonicalQueryString
  }

  return endpoint
}

AWS.prototype.getCanonicalHeaders = function () {
  var h = this.headers
  return Object.keys(h)
    .sort()
    .map(function (name) {
      return name.toLowerCase().trim() + ':' + h[name].toString().trim() + '\n'
    })
    .join('')
}

AWS.prototype.getCanonicalQueryString = function () {
  var p = this.params
  return Object.keys(p)
    .sort()
    .map(function (key) {
      return encodeURIComponent(key) + '=' + encodeURIComponent(p[key])
    })
    .join('&')
}

AWS.prototype.getAuthHeader = function (date) {
  return (
    'AWS4-HMAC-SHA256 Credential=' +
    this.key +
    '/' +
    this.getAwsCredentialScope(date) +
    ', SignedHeaders=' +
    this.getAwsSignedHeaders() +
    ', Signature=' +
    this.getAwsCredentialSignature(date)
  )
}

AWS.prototype.getAwsCredentialSignature = function (date) {
  return hmac(
    this.getAwsCredentialSignatureKey(date),
    'HEX',
    this.getAwsCredentialSignatureValue(date)
  )
}

AWS.prototype.getAwsCredentialSignatureKey = function (date) {
  var h1 = hmac('AWS4' + this.secret, 'TEXT', this.awsDateTimeFormatShort(date))
  var h2 = hmac(h1, 'HEX', this.region)
  var h3 = hmac(h2, 'HEX', SERVICE)
  return hmac(h3, 'HEX', 'aws4_request')
}

AWS.prototype.getAwsCredentialSignatureValue = function (date) {
  return [
    'AWS4-HMAC-SHA256',
    this.awsDateTimeFormat(date),
    this.getAwsCredentialScope(date),
    hash(this.getCanonicalRequest())
  ].join('\n')
}

AWS.prototype.getCanonicalRequest = function () {
  return [
    DEFAULT_REQUEST_METHOD,
    '/',
    this.getCanonicalQueryString(),
    this.getCanonicalHeaders(),
    this.getAwsSignedHeaders(),
    hash(this.payload)
  ].join('\n')
}

AWS.prototype.getAwsSignedHeaders = function () {
  return Object.keys(this.headers)
    .sort()
    .map(function (name) {
      return name.toLowerCase().trim()
    })
    .join(';')
}

AWS.prototype.getAwsCredentialScope = function (date) {
  return [
    this.awsDateTimeFormatShort(date),
    this.region,
    SERVICE,
    'aws4_request'
  ].join('/')
}

AWS.prototype.awsDateTimeFormat = function (date) {
  return date.toISOString().replace(/[:-]|\.\d{3}/g, '')
}

AWS.prototype.awsDateTimeFormatShort = function (date) {
  return this.awsDateTimeFormat(date).substring(0, 8)
}