import tv4 from 'tv4';
import Parse from 'parse/node';
import { Subscription } from './Subscription';
import { Client } from './Client';
import { ParseWebSocketServer } from './ParseWebSocketServer';
import logger from '../logger';
import RequestSchema from './RequestSchema';
import { matchesQuery, queryHash } from './QueryTools';
import { ParsePubSub } from './ParsePubSub';
import { SessionTokenCache } from './SessionTokenCache';
import _ from 'lodash';

class ParseLiveQueryServer {
  clientId: number;
  clients: Object;
  // className -> (queryHash -> subscription)
  subscriptions: Object;
  parseWebSocketServer: Object;
  keyPairs : any;
  // The subscriber we use to get object update from publisher
  subscriber: Object;

  constructor(server: any, config: any) {
    this.clientId = 0;
    this.clients = new Map();
    this.subscriptions = new Map();

    config = config || {};

    // Store keys, convert obj to map
    const keyPairs = config.keyPairs || {};
    this.keyPairs = new Map();
    for (const key of Object.keys(keyPairs)) {
      this.keyPairs.set(key, keyPairs[key]);
    }
    logger.verbose('Support key pairs', this.keyPairs);

    // Initialize Parse
    Parse.Object.disableSingleInstance();

    const serverURL = config.serverURL || Parse.serverURL;
    Parse.serverURL = serverURL;
    const appId = config.appId || Parse.applicationId;
    const javascriptKey = Parse.javaScriptKey;
    const masterKey = config.masterKey || Parse.masterKey;
    Parse.initialize(appId, javascriptKey, masterKey);

    // Initialize websocket server
    this.parseWebSocketServer = new ParseWebSocketServer(
      server,
      (parseWebsocket) => this._onConnect(parseWebsocket),
      config.websocketTimeout
    );

    // Initialize subscriber
    this.subscriber = ParsePubSub.createSubscriber(config);
    this.subscriber.subscribe(Parse.applicationId + 'afterSave');
    this.subscriber.subscribe(Parse.applicationId + 'afterDelete');
    // Register message handler for subscriber. When publisher get messages, it will publish message
    // to the subscribers and the handler will be called.
    this.subscriber.on('message', (channel, messageStr) => {
      logger.verbose('Subscribe messsage %j', messageStr);
      let message;
      try {
        message = JSON.parse(messageStr);
      } catch(e) {
        logger.error('unable to parse message', messageStr, e);
        return;
      }
      this._inflateParseObject(message);
      if (channel === Parse.applicationId + 'afterSave') {
        this._onAfterSave(message);
      } else if (channel === Parse.applicationId + 'afterDelete') {
        this._onAfterDelete(message);
      } else {
        logger.error('Get message %s from unknown channel %j', message, channel);
      }
    });

    // Initialize sessionToken cache
    this.sessionTokenCache = new SessionTokenCache(config.cacheTimeout);
  }

  // Message is the JSON object from publisher. Message.currentParseObject is the ParseObject JSON after changes.
  // Message.originalParseObject is the original ParseObject JSON.
  _inflateParseObject(message: any): void {
    // Inflate merged object
    const currentParseObject = message.currentParseObject;
    let className = currentParseObject.className;
    let parseObject = new Parse.Object(className);
    parseObject._finishFetch(currentParseObject);
    message.currentParseObject = parseObject;
    // Inflate original object
    const originalParseObject = message.originalParseObject;
    if (originalParseObject) {
      className = originalParseObject.className;
      parseObject = new Parse.Object(className);
      parseObject._finishFetch(originalParseObject);
      message.originalParseObject = parseObject;
    }
  }

  // Message is the JSON object from publisher after inflated. Message.currentParseObject is the ParseObject after changes.
  // Message.originalParseObject is the original ParseObject.
  _onAfterDelete(message: any): void {
    logger.verbose(Parse.applicationId + 'afterDelete is triggered');

    const deletedParseObject = message.currentParseObject.toJSON();
    const className = deletedParseObject.className;
    logger.verbose('ClassName: %j | ObjectId: %s', className, deletedParseObject.id);
    logger.verbose('Current client number : %d', this.clients.size);

    const classSubscriptions = this.subscriptions.get(className);
    if (typeof classSubscriptions === 'undefined') {
      logger.debug('Can not find subscriptions under this class ' + className);
      return;
    }
    for (const subscription of classSubscriptions.values()) {
      const isSubscriptionMatched = this._matchesSubscription(deletedParseObject, subscription);
      if (!isSubscriptionMatched) {
        continue;
      }
      for (const [clientId, requestIds] of _.entries(subscription.clientRequestIds)) {
        const client = this.clients.get(clientId);
        if (typeof client === 'undefined') {
          continue;
        }
        for (const requestId of requestIds) {
          const acl = message.currentParseObject.getACL();
          // Check ACL
          this._matchesACL(acl, client, requestId).then((isMatched) => {
            if (!isMatched) {
              return null;
            }
            client.pushDelete(requestId, deletedParseObject);
          }, (error) => {
            logger.error('Matching ACL error : ', error);
          });
        }
      }
    }
  }

  // Message is the JSON object from publisher after inflated. Message.currentParseObject is the ParseObject after changes.
  // Message.originalParseObject is the original ParseObject.
  _onAfterSave(message: any): void {
    logger.verbose(Parse.applicationId + 'afterSave is triggered');

    let originalParseObject = null;
    if (message.originalParseObject) {
      originalParseObject = message.originalParseObject.toJSON();
    }
    const currentParseObject = message.currentParseObject.toJSON();
    const className = currentParseObject.className;
    logger.verbose('ClassName: %s | ObjectId: %s', className, currentParseObject.id);
    logger.verbose('Current client number : %d', this.clients.size);

    const classSubscriptions = this.subscriptions.get(className);
    if (typeof classSubscriptions === 'undefined') {
      logger.debug('Can not find subscriptions under this class ' + className);
      return;
    }
    for (const subscription of classSubscriptions.values()) {
      const isOriginalSubscriptionMatched = this._matchesSubscription(originalParseObject, subscription);
      const isCurrentSubscriptionMatched = this._matchesSubscription(currentParseObject, subscription);
      for (const [clientId, requestIds] of _.entries(subscription.clientRequestIds)) {
        const client = this.clients.get(clientId);
        if (typeof client === 'undefined') {
          continue;
        }
        for (const requestId of requestIds) {
          // Set orignal ParseObject ACL checking promise, if the object does not match
          // subscription, we do not need to check ACL
          let originalACLCheckingPromise;
          if (!isOriginalSubscriptionMatched) {
            originalACLCheckingPromise = Parse.Promise.as(false);
          } else {
            let originalACL;
            if (message.originalParseObject) {
              originalACL = message.originalParseObject.getACL();
            }
            originalACLCheckingPromise = this._matchesACL(originalACL, client, requestId);
          }
          // Set current ParseObject ACL checking promise, if the object does not match
          // subscription, we do not need to check ACL
          let currentACLCheckingPromise;
          if (!isCurrentSubscriptionMatched) {
            currentACLCheckingPromise = Parse.Promise.as(false);
          } else {
            const currentACL = message.currentParseObject.getACL();
            currentACLCheckingPromise = this._matchesACL(currentACL, client, requestId);
          }

          Parse.Promise.when(
            originalACLCheckingPromise,
            currentACLCheckingPromise
          ).then((isOriginalMatched, isCurrentMatched) => {
            logger.verbose('Original %j | Current %j | Match: %s, %s, %s, %s | Query: %s',
              originalParseObject,
              currentParseObject,
              isOriginalSubscriptionMatched,
              isCurrentSubscriptionMatched,
              isOriginalMatched,
              isCurrentMatched,
              subscription.hash
            );

            // Decide event type
            let type;
            if (isOriginalMatched && isCurrentMatched) {
              type = 'Update';
            } else if (isOriginalMatched && !isCurrentMatched) {
              type = 'Leave';
            } else if (!isOriginalMatched && isCurrentMatched) {
              if (originalParseObject) {
                type = 'Enter';
              } else {
                type = 'Create';
              }
            } else {
              return null;
            }
            const functionName = 'push' + type;
            client[functionName](requestId, currentParseObject);
          }, (error) => {
            logger.error('Matching ACL error : ', error);
          });
        }
      }
    }
  }

  _onConnect(parseWebsocket: any): void {
    parseWebsocket.on('message', (request) => {
      if (typeof request === 'string') {
        try {
          request = JSON.parse(request);
        } catch(e) {
          logger.error('unable to parse request', request, e);
          return;
        }
      }
      logger.verbose('Request: %j', request);

      // Check whether this request is a valid request, return error directly if not
      if (!tv4.validate(request, RequestSchema['general']) || !tv4.validate(request, RequestSchema[request.op])) {
        Client.pushError(parseWebsocket, 1, tv4.error.message);
        logger.error('Connect message error %s', tv4.error.message);
        return;
      }

      switch(request.op) {
      case 'connect':
        this._handleConnect(parseWebsocket, request);
        break;
      case 'subscribe':
        this._handleSubscribe(parseWebsocket, request);
        break;
      case 'update':
        this._handleUpdateSubscription(parseWebsocket, request);
        break;
      case 'unsubscribe':
        this._handleUnsubscribe(parseWebsocket, request);
        break;
      default:
        Client.pushError(parseWebsocket, 3, 'Get unknown operation');
        logger.error('Get unknown operation', request.op);
      }
    });

    parseWebsocket.on('disconnect', () => {
      logger.info('Client disconnect: %d', parseWebsocket.clientId);
      const clientId = parseWebsocket.clientId;
      if (!this.clients.has(clientId)) {
        logger.error('Can not find client %d on disconnect', clientId);
        return;
      }

      // Delete client
      const client = this.clients.get(clientId);
      this.clients.delete(clientId);

      // Delete client from subscriptions
      for (const [requestId, subscriptionInfo] of _.entries(client.subscriptionInfos)) {
        const subscription = subscriptionInfo.subscription;
        subscription.deleteClientSubscription(clientId, requestId);

        // If there is no client which is subscribing this subscription, remove it from subscriptions
        const classSubscriptions = this.subscriptions.get(subscription.className);
        if (!subscription.hasSubscribingClient()) {
          classSubscriptions.delete(subscription.hash);
        }
        // If there is no subscriptions under this class, remove it from subscriptions
        if (classSubscriptions.size === 0) {
          this.subscriptions.delete(subscription.className);
        }
      }

      logger.verbose('Current clients %d', this.clients.size);
      logger.verbose('Current subscriptions %d', this.subscriptions.size);
    });
  }

  _matchesSubscription(parseObject: any, subscription: any): boolean {
    // Object is undefined or null, not match
    if (!parseObject) {
      return false;
    }
    return matchesQuery(parseObject, subscription.query);
  }

  _matchesACL(acl: any, client: any, requestId: number): any {
    // Return true directly if ACL isn't present, ACL is public read, or client has master key
    if (!acl || acl.getPublicReadAccess() || client.hasMasterKey) {
      return Parse.Promise.as(true);
    }
    // Check subscription sessionToken matches ACL first
    const subscriptionInfo = client.getSubscriptionInfo(requestId);
    if (typeof subscriptionInfo === 'undefined') {
      return Parse.Promise.as(false);
    }

    const subscriptionSessionToken = subscriptionInfo.sessionToken;
    return this.sessionTokenCache.getUserId(subscriptionSessionToken).then((userId) => {
      return acl.getReadAccess(userId);
    }).then((isSubscriptionSessionTokenMatched) => {
      if (isSubscriptionSessionTokenMatched) {
        return Parse.Promise.as(true);
      }

      // Check if the user has any roles that match the ACL
      return new Parse.Promise((resolve, reject) => {

        // Resolve false right away if the acl doesn't have any roles
        const acl_has_roles = Object.keys(acl.permissionsById).some(key => key.startsWith("role:"));
        if (!acl_has_roles) {
          return resolve(false);
        }

        this.sessionTokenCache.getUserId(subscriptionSessionToken)
          .then((userId) => {

            // Pass along a null if there is no user id
            if (!userId) {
              return Parse.Promise.as(null);
            }

            // Prepare a user object to query for roles
            // To eliminate a query for the user, create one locally with the id
            var user = new Parse.User();
            user.id = userId;
            return user;

          })
          .then((user) => {

            // Pass along an empty array (of roles) if no user
            if (!user) {
              return Parse.Promise.as([]);
            }

            // Then get the user's roles
            var rolesQuery = new Parse.Query(Parse.Role);
            rolesQuery.equalTo("users", user);
            return rolesQuery.find({useMasterKey:true});
          }).
          then((roles) => {

            // Finally, see if any of the user's roles allow them read access
            for (const role of roles) {
              if (acl.getRoleReadAccess(role)) {
                return resolve(true);
              }
            }
            resolve(false);
          })
          .catch((error) => {
            reject(error);
          });

      });
    }).then((isRoleMatched) => {

      if(isRoleMatched) {
        return Parse.Promise.as(true);
      }

      // Check client sessionToken matches ACL
      const clientSessionToken = client.sessionToken;
      return this.sessionTokenCache.getUserId(clientSessionToken).then((userId) => {
        return acl.getReadAccess(userId);
      });
    }).then((isMatched) => {
      return Parse.Promise.as(isMatched);
    }, () => {
      return Parse.Promise.as(false);
    });
  }

  _handleConnect(parseWebsocket: any, request: any): any {
    if (!this._validateKeys(request, this.keyPairs)) {
      Client.pushError(parseWebsocket, 4, 'Key in request is not valid');
      logger.error('Key in request is not valid');
      return;
    }
    const hasMasterKey = this._hasMasterKey(request, this.keyPairs);
    const client = new Client(this.clientId, parseWebsocket, hasMasterKey);
    parseWebsocket.clientId = this.clientId;
    this.clientId += 1;
    this.clients.set(parseWebsocket.clientId, client);
    logger.info('Create new client: %d', parseWebsocket.clientId);
    client.pushConnect();
  }

  _hasMasterKey(request: any, validKeyPairs: any): boolean {
    if(!validKeyPairs || validKeyPairs.size == 0 ||
      !validKeyPairs.has("masterKey")) {
      return false;
    }
    if(!request || !request.hasOwnProperty("masterKey")) {
      return false;
    }
    return request.masterKey === validKeyPairs.get("masterKey");
  }

  _validateKeys(request: any, validKeyPairs: any): boolean {
    if (!validKeyPairs || validKeyPairs.size == 0) {
      return true;
    }
    let isValid = false;
    for (const [key, secret] of validKeyPairs) {
      if (!request[key] || request[key] !== secret) {
        continue;
      }
      isValid = true;
      break;
    }
    return isValid;
  }

  _handleSubscribe(parseWebsocket: any, request: any): any {
    // If we can not find this client, return error to client
    if (!parseWebsocket.hasOwnProperty('clientId')) {
      Client.pushError(parseWebsocket, 2, 'Can not find this client, make sure you connect to server before subscribing');
      logger.error('Can not find this client, make sure you connect to server before subscribing');
      return;
    }
    const client = this.clients.get(parseWebsocket.clientId);

    // Get subscription from subscriptions, create one if necessary
    const subscriptionHash = queryHash(request.query);
    // Add className to subscriptions if necessary
    const className = request.query.className;
    if (!this.subscriptions.has(className)) {
      this.subscriptions.set(className, new Map());
    }
    const classSubscriptions = this.subscriptions.get(className);
    let subscription;
    if (classSubscriptions.has(subscriptionHash)) {
      subscription = classSubscriptions.get(subscriptionHash);
    } else {
      subscription = new Subscription(className, request.query.where, subscriptionHash);
      classSubscriptions.set(subscriptionHash, subscription);
    }

    // Add subscriptionInfo to client
    const subscriptionInfo = {
      subscription: subscription
    };
    // Add selected fields and sessionToken for this subscription if necessary
    if (request.query.fields) {
      subscriptionInfo.fields = request.query.fields;
    }
    if (request.sessionToken) {
      subscriptionInfo.sessionToken = request.sessionToken;
    }
    client.addSubscriptionInfo(request.requestId, subscriptionInfo);

    // Add clientId to subscription
    subscription.addClientSubscription(parseWebsocket.clientId, request.requestId);

    client.pushSubscribe(request.requestId);

    logger.verbose('Create client %d new subscription: %d', parseWebsocket.clientId, request.requestId);
    logger.verbose('Current client number: %d', this.clients.size);
  }

  _handleUpdateSubscription(parseWebsocket: any, request: any): any {
    this._handleUnsubscribe(parseWebsocket, request, false);
    this._handleSubscribe(parseWebsocket, request);
  }

  _handleUnsubscribe(parseWebsocket: any, request: any, notifyClient: bool = true): any {
    // If we can not find this client, return error to client
    if (!parseWebsocket.hasOwnProperty('clientId')) {
      Client.pushError(parseWebsocket, 2, 'Can not find this client, make sure you connect to server before unsubscribing');
      logger.error('Can not find this client, make sure you connect to server before unsubscribing');
      return;
    }
    const requestId = request.requestId;
    const client = this.clients.get(parseWebsocket.clientId);
    if (typeof client === 'undefined') {
      Client.pushError(parseWebsocket, 2, 'Cannot find client with clientId '  + parseWebsocket.clientId +
        '. Make sure you connect to live query server before unsubscribing.');
      logger.error('Can not find this client ' + parseWebsocket.clientId);
      return;
    }

    const subscriptionInfo = client.getSubscriptionInfo(requestId);
    if (typeof subscriptionInfo === 'undefined') {
      Client.pushError(parseWebsocket, 2, 'Cannot find subscription with clientId '  + parseWebsocket.clientId +
        ' subscriptionId ' + requestId + '. Make sure you subscribe to live query server before unsubscribing.');
      logger.error('Can not find subscription with clientId ' + parseWebsocket.clientId +  ' subscriptionId ' + requestId);
      return;
    }

    // Remove subscription from client
    client.deleteSubscriptionInfo(requestId);
    // Remove client from subscription
    const subscription = subscriptionInfo.subscription;
    const className = subscription.className;
    subscription.deleteClientSubscription(parseWebsocket.clientId, requestId);
    // If there is no client which is subscribing this subscription, remove it from subscriptions
    const classSubscriptions = this.subscriptions.get(className);
    if (!subscription.hasSubscribingClient()) {
      classSubscriptions.delete(subscription.hash);
    }
    // If there is no subscriptions under this class, remove it from subscriptions
    if (classSubscriptions.size === 0) {
      this.subscriptions.delete(className);
    }

    if (!notifyClient) {
      return;
    }

    client.pushUnsubscribe(request.requestId);

    logger.verbose('Delete client: %d | subscription: %d', parseWebsocket.clientId, request.requestId);
  }
}

export {
  ParseLiveQueryServer
}