const dcrf = require('dcrf-client');

const client = dcrf.connect('wss://example.com', {
  /**
   * Options to pass along to ReconnectingWebsocket
   *
   * See https://github.com/pladaria/reconnecting-websocket#available-options for more info
   */
  websocket: {
    WebSocket?: any; // WebSocket constructor, if none provided, defaults to global WebSocket
    maxReconnectionDelay?: number; // max delay in ms between reconnections
    minReconnectionDelay?: number; // min delay in ms between reconnections
    reconnectionDelayGrowFactor?: number; // how fast the reconnection delay grows
    minUptime?: number; // min time in ms to consider connection as stable
    connectionTimeout?: number; // retry connect if not connected after this time, in ms
    maxRetries?: number; // maximum number of retries
    maxEnqueuedMessages?: number; // maximum number of messages to buffer until reconnection
    startClosed?: boolean; // start websocket in CLOSED state, call `.reconnect()` to connect
    debug?: boolean; // enables debug output
  },

  /**
   * Name of serializer field is used to identify objects in subscription event payloads.
   *
   * Default: 'pk'
   */
  pkField: 'id',

  /**
   * Whether to ensure subscription delete event payloads store the primary key of the object
   * in the configured `pkField`, instead of the default 'pk'.
   *
   * Because subscription delete payloads aren't run through the configured serializer (as the
   * objects do not exist), the DCRF backend must pick a field to store the primary key of the
   * object in the payload. DCRF chooses 'pk' for this field. If `pkField` is *not* 'pk' (and is
   * instead, say, 'id'), then subscription update payloads will return `{id: 123}`, but delete
   * payloads will return `{pk: 123}`.
   *
   * To address the potential inconsistencies between subscription update and delete payloads,
   * setting this option to true (default) will cause dcrf-client to replace the 'pk' field with
   * the configured `pkField` setting.
   *
   * Default: true
   */
  ensurePkFieldInDeleteEvents: true,

  /**
   * Customizes the format of a multiplexed message to be sent to the server.
   *
   * In almost all circumstances, the default behaviour is usually desired.
   *
   * The default behaviour is reproduced here.
   */
  buildMultiplexedMessage(stream: string, payload: object): object {
    return {stream, payload};
  },

  /**
   * Customizes the selector (a pattern matching an object) for the response to an API request
   *
   * In almost all circumstances, the default behaviour is usually desired.
   *
   * The default behaviour is reproduced here.
   */
  buildRequestResponseSelector(stream: string, requestId: string): object {
    return {
      stream,
      payload: {request_id: requestId},
    };
  },

  /**
   * Customizes the selector (a pattern matching an object) matching a subscription update event for
   * an object.
   *
   * In almost all circumstances, the default behaviour is usually desired.
   *
   * The default behaviour is reproduced here.
   */
  buildSubscribeUpdateSelector(stream: string, pk: number, requestId: string): object {
    return {
      stream,
      payload: {
        action: 'update',
        data: {[this.pkField]: pk},
        request_id: requestId,
      },
    };
  },

  /**
   * Customizes the selector (a pattern matching an object) matching a subscription delete event for
   * an object.
   *
   * In almost all circumstances, the default behaviour is usually desired.
   *
   * The default behaviour is reproduced here.
   */
  buildSubscribeDeleteSelector(stream: string, pk: number, requestId: string): object {
    return {
      stream,
      payload: {
        action: 'delete',
        data: {pk},
        request_id: requestId,
      },
    };
  },

  /**
   * Customizes the payload sent to begin subscriptions
   *
   * In almost all circumstances, the default behaviour is usually desired.
   *
   * The default behaviour is reproduced here.
   */
  buildSubscribePayload(pk: number, requestId: string): object {
    return {
      action: 'subscribe_instance',
      request_id: requestId,
      pk,  // NOTE: the subscribe_instance action REQUIRES the literal argument `pk`.
           //       this argument is NOT the same as the ID field of the model.
    };
  },

  preprocessPayload: (stream, payload, requestId) => {
    // Modify payload any way you see fit, before it's sent over the wire
    // For instance, add a custom authentication token:
    payload.token = '123';
    // Be sure not to return anything if you modify payload

    // Or, you can overwrite the payload by returning a new object:
    return {'this': 'is my new payload'};
  },

  preprocessMessage: (message) => {
    // The "message" is the final value which will be serialized and sent over the wire.
    // It includes the stream and the payload.

    // Modify the message any way you see fit, before its sent over the wire.
    message.token = 'abc';
    // Don't return anything if you modify message

    // Or, you can overwrite the the message by returning a new object:
    return {stream: 'creek', payload: 'craycrayload'};
  },
});