/**
 * Subscription manager module.
 *
 * @internal
 */

import { PubNubEventType, SubscribeRequestParameters as SubscribeRequestParameters } from '../endpoints/subscribe';
import { messageFingerprint, referenceSubscribeTimetoken, subscriptionTimetokenFromReference } from '../utils';
import { Payload, ResultCallback, Status, StatusCallback, StatusEvent } from '../types/api';
import { PrivateClientConfiguration } from '../interfaces/configuration';
import { HeartbeatRequest } from '../endpoints/presence/heartbeat';
import { ReconnectionManager } from './reconnection_manager';
import * as Subscription from '../types/api/subscription';
import StatusCategory from '../constants/categories';
import { DedupingManager } from './deduping_manager';
import * as Presence from '../types/api/presence';
import { PubNubCore } from '../pubnub-common';

/**
 * Subscription loop manager.
 *
 * @internal
 */
export class SubscriptionManager {
  /**
   * Connection availability check manager.
   */
  private readonly reconnectionManager: ReconnectionManager;

  /**
   * Real-time events deduplication manager.
   */
  private readonly dedupingManager: DedupingManager;

  /**
   * Map between channel / group name and `state` associated with `uuid` there.
   */
  readonly presenceState: Record<string, Payload>;

  /**
   * List of channel groups for which heartbeat calls should be performed.
   */
  private readonly heartbeatChannelGroups: Record<string, Record<string, unknown>>;

  /**
   * List of channels for which heartbeat calls should be performed.
   */
  private readonly heartbeatChannels: Record<string, Record<string, unknown>>;

  /**
   * List of channel groups for which real-time presence change events should be observed.
   */
  private readonly presenceChannelGroups: Record<string, Record<string, unknown>>;

  /**
   * List of channels for which real-time presence change events should be observed.
   */
  private readonly presenceChannels: Record<string, Record<string, unknown>>;

  /**
   * New list of channel groups to which manager will try to subscribe,
   */
  private pendingChannelGroupSubscriptions: Set<string>;

  /**
   * New list of channels to which manager will try to subscribe,
   */
  private pendingChannelSubscriptions: Set<string>;

  /**
   * List of channel groups for which real-time events should be observed.
   */
  private readonly channelGroups: Record<string, Record<string, unknown>>;

  /**
   * List of channels for which real-time events should be observed.
   */
  private readonly channels: Record<string, Record<string, unknown>>;

  /**
   * High-precision timetoken of the moment when a new high-precision timetoken has been used for subscription
   * loop.
   */
  private referenceTimetoken?: string | null;

  /**
   * Timetoken, which is used by the current subscription loop.
   */
  private currentTimetoken: string;

  /**
   * Timetoken which has been used with previous subscription loop.
   */
  private lastTimetoken: string;

  /**
   * User-provided timetoken or timetoken for catch up.
   */
  private storedTimetoken: string | null;

  /**
   * Timetoken's region.
   */
  private region?: number | null;

  private heartbeatTimer: number | null;

  /**
   * Whether subscription status change has been announced or not.
   */
  private subscriptionStatusAnnounced: boolean;

  /**
   * Whether PubNub client is online right now.
   */
  private isOnline: boolean;

  /**
   * Whether user code in event handlers requested disconnection or not.
   *
   * Won't continue subscription loop if user requested disconnection/unsubscribe from all in response to received
   * event.
   */
  private disconnectedWhileHandledEvent: boolean = false;

  /**
   * Active subscription request abort method.
   *
   * **Note:** Reference updated with each subscribe call.
   */
  private _subscribeAbort?: {
    /**
     * Request abort caller.
     */
    (): void;

    /**
     * Abort controller owner identifier.
     */
    identifier: string;
  } | null;

  constructor(
    private readonly configuration: PrivateClientConfiguration,
    private readonly emitEvent: (
      cursor: Subscription.SubscriptionCursor,
      event: Subscription.SubscriptionResponse['messages'][0],
    ) => void,
    private readonly emitStatus: (status: Status | StatusEvent) => void,
    private readonly subscribeCall: (
      parameters: Omit<SubscribeRequestParameters, 'crypto' | 'timeout' | 'keySet' | 'getFileUrl'> & {
        onDemand: boolean;
      },
      callback: ResultCallback<Subscription.SubscriptionResponse>,
    ) => void,
    private readonly heartbeatCall: (
      parameters: Presence.PresenceHeartbeatParameters,
      callback: StatusCallback,
    ) => void,
    private readonly leaveCall: (parameters: Presence.PresenceLeaveParameters, callback: StatusCallback) => void,
    time: typeof PubNubCore.prototype.time,
  ) {
    configuration.logger().trace('SubscriptionManager', 'Create manager.');

    this.reconnectionManager = new ReconnectionManager(time);
    this.dedupingManager = new DedupingManager(this.configuration);
    this.heartbeatChannelGroups = {};
    this.heartbeatChannels = {};
    this.presenceChannelGroups = {};
    this.presenceChannels = {};
    this.heartbeatTimer = null;
    this.presenceState = {};
    this.pendingChannelGroupSubscriptions = new Set();
    this.pendingChannelSubscriptions = new Set();
    this.channelGroups = {};
    this.channels = {};

    this.currentTimetoken = '0';
    this.lastTimetoken = '0';
    this.storedTimetoken = null;
    this.referenceTimetoken = null;

    this.subscriptionStatusAnnounced = false;
    this.isOnline = true;
  }

  // region Information
  /**
   * Subscription-based current timetoken.
   *
   * @returns Timetoken based on current timetoken plus diff between current and loop start time.
   */
  get subscriptionTimetoken(): string | undefined {
    return subscriptionTimetokenFromReference(this.currentTimetoken, this.referenceTimetoken ?? '0');
  }

  get subscribedChannels(): string[] {
    return Object.keys(this.channels);
  }

  get subscribedChannelGroups(): string[] {
    return Object.keys(this.channelGroups);
  }

  get abort() {
    return this._subscribeAbort;
  }

  set abort(call: typeof this._subscribeAbort) {
    this._subscribeAbort = call;
  }
  // endregion

  // region Subscription

  public disconnect() {
    // Potentially called during received events handling.
    // Mark to prevent subscription loop continuation in subscribe response handler.
    this.disconnectedWhileHandledEvent = true;

    this.stopSubscribeLoop();
    this.stopHeartbeatTimer();
    this.reconnectionManager.stopPolling();
  }

  /**
   * Restart subscription loop with current state.
   *
   * @param forUnsubscribe - Whether restarting subscription loop as part of channels list change on
   * unsubscribe or not.
   */
  public reconnect(forUnsubscribe: boolean = false) {
    this.startSubscribeLoop(forUnsubscribe);

    // Starting heartbeat loop for provided channels and groups.
    if (!forUnsubscribe && !this.configuration.useSmartHeartbeat) this.startHeartbeatTimer();
  }

  /**
   * Update channels and groups used in subscription loop.
   *
   * @param parameters - Subscribe configuration parameters.
   */
  public subscribe(parameters: Subscription.SubscribeParameters) {
    const { channels, channelGroups, timetoken, withPresence = false, withHeartbeats = false } = parameters;

    if (timetoken) {
      this.lastTimetoken = this.currentTimetoken;
      this.currentTimetoken = `${timetoken}`;
    }

    if (this.currentTimetoken !== '0') {
      this.storedTimetoken = this.currentTimetoken;
      this.currentTimetoken = '0';
    }

    channels?.forEach((channel) => {
      this.pendingChannelSubscriptions.add(channel);
      this.channels[channel] = {};

      if (withPresence) this.presenceChannels[channel] = {};
      if (withHeartbeats || this.configuration.getHeartbeatInterval()) this.heartbeatChannels[channel] = {};
    });

    channelGroups?.forEach((group) => {
      this.pendingChannelGroupSubscriptions.add(group);
      this.channelGroups[group] = {};

      if (withPresence) this.presenceChannelGroups[group] = {};
      if (withHeartbeats || this.configuration.getHeartbeatInterval()) this.heartbeatChannelGroups[group] = {};
    });

    this.subscriptionStatusAnnounced = false;
    this.reconnect();
  }

  public unsubscribe(parameters: Presence.PresenceLeaveParameters, isOffline: boolean = false) {
    let { channels, channelGroups } = parameters;

    const actualChannelGroups: Set<string> = new Set();
    const actualChannels: Set<string> = new Set();

    channels?.forEach((channel) => {
      if (channel in this.channels) {
        delete this.channels[channel];
        actualChannels.add(channel);

        if (channel in this.heartbeatChannels) delete this.heartbeatChannels[channel];
      }

      if (channel in this.presenceState) delete this.presenceState[channel];
      if (channel in this.presenceChannels) {
        delete this.presenceChannels[channel];
        actualChannels.add(channel);
      }
    });

    channelGroups?.forEach((group) => {
      if (group in this.channelGroups) {
        delete this.channelGroups[group];
        actualChannelGroups.add(group);

        if (group in this.heartbeatChannelGroups) delete this.heartbeatChannelGroups[group];
      }

      if (group in this.presenceState) delete this.presenceState[group];
      if (group in this.presenceChannelGroups) {
        delete this.presenceChannelGroups[group];
        actualChannelGroups.add(group);
      }
    });

    // There is no need to unsubscribe to empty list of data sources.
    if (actualChannels.size === 0 && actualChannelGroups.size === 0) return;

    const lastTimetoken = this.lastTimetoken;
    const currentTimetoken = this.currentTimetoken;

    if (
      Object.keys(this.channels).length === 0 &&
      Object.keys(this.presenceChannels).length === 0 &&
      Object.keys(this.channelGroups).length === 0 &&
      Object.keys(this.presenceChannelGroups).length === 0
    ) {
      this.lastTimetoken = '0';
      this.currentTimetoken = '0';
      this.referenceTimetoken = null;
      this.storedTimetoken = null;
      this.region = null;
      this.reconnectionManager.stopPolling();
    }

    this.reconnect(true);

    // Send leave request after long-poll connection closed and loop restarted (the same way as it happens in new
    // subscription flow).
    if (this.configuration.suppressLeaveEvents === false && !isOffline) {
      channelGroups = Array.from(actualChannelGroups);
      channels = Array.from(actualChannels);

      this.leaveCall({ channels, channelGroups }, (status) => {
        const { error, ...restOfStatus } = status;
        let errorMessage: string | undefined;

        if (error) {
          if (
            status.errorData &&
            typeof status.errorData === 'object' &&
            'message' in status.errorData &&
            typeof status.errorData.message === 'string'
          )
            errorMessage = status.errorData.message;
          else if ('message' in status && typeof status.message === 'string') errorMessage = status.message;
        }

        this.emitStatus({
          ...restOfStatus,
          error: errorMessage ?? false,
          affectedChannels: channels,
          affectedChannelGroups: channelGroups,
          currentTimetoken,
          lastTimetoken,
        } as StatusEvent);
      });
    }
  }

  public unsubscribeAll(isOffline: boolean = false) {
    this.disconnectedWhileHandledEvent = true;

    this.unsubscribe(
      {
        channels: this.subscribedChannels,
        channelGroups: this.subscribedChannelGroups,
      },
      isOffline,
    );
  }

  /**
   * Start next subscription loop.
   *
   * @param restartOnUnsubscribe - Whether restarting subscription loop as part of channels list change on
   * unsubscribe or not.
   *
   * @internal
   */
  private startSubscribeLoop(restartOnUnsubscribe: boolean = false) {
    this.disconnectedWhileHandledEvent = false;
    this.stopSubscribeLoop();

    const channelGroups = [...Object.keys(this.channelGroups)];
    const channels = [...Object.keys(this.channels)];

    Object.keys(this.presenceChannelGroups).forEach((group) => channelGroups.push(`${group}-pnpres`));
    Object.keys(this.presenceChannels).forEach((channel) => channels.push(`${channel}-pnpres`));

    // There is no need to start subscription loop for an empty list of data sources.
    if (channels.length === 0 && channelGroups.length === 0) return;

    this.subscribeCall(
      {
        channels,
        channelGroups,
        state: this.presenceState,
        heartbeat: this.configuration.getPresenceTimeout(),
        timetoken: this.currentTimetoken,
        ...(this.region !== null ? { region: this.region } : {}),
        ...(this.configuration.filterExpression ? { filterExpression: this.configuration.filterExpression } : {}),
        onDemand: !this.subscriptionStatusAnnounced || restartOnUnsubscribe,
      },
      (status, result) => {
        this.processSubscribeResponse(status, result);
      },
    );

    if (!restartOnUnsubscribe && this.configuration.useSmartHeartbeat) this.startHeartbeatTimer();
  }

  private stopSubscribeLoop() {
    if (this._subscribeAbort) {
      this._subscribeAbort();
      this._subscribeAbort = null;
    }
  }

  /**
   * Process subscribe REST API endpoint response.
   */
  private processSubscribeResponse(status: Status, result: Subscription.SubscriptionResponse | null) {
    if (status.error) {
      // Ignore aborted request.
      if (
        (typeof status.errorData === 'object' &&
          'name' in status.errorData &&
          status.errorData.name === 'AbortError') ||
        status.category === StatusCategory.PNCancelledCategory
      )
        return;

      if (status.category === StatusCategory.PNTimeoutCategory) {
        this.startSubscribeLoop();
      } else if (
        status.category === StatusCategory.PNNetworkIssuesCategory ||
        status.category === StatusCategory.PNMalformedResponseCategory
      ) {
        this.disconnect();

        if (status.error && this.configuration.autoNetworkDetection && this.isOnline) {
          this.isOnline = false;
          this.emitStatus({ category: StatusCategory.PNNetworkDownCategory });
        }

        this.reconnectionManager.onReconnect(() => {
          if (this.configuration.autoNetworkDetection && !this.isOnline) {
            this.isOnline = true;
            this.emitStatus({ category: StatusCategory.PNNetworkUpCategory });
          }

          this.reconnect();
          this.subscriptionStatusAnnounced = true;

          const reconnectedAnnounce = {
            category: StatusCategory.PNReconnectedCategory,
            operation: status.operation,
            lastTimetoken: this.lastTimetoken,
            currentTimetoken: this.currentTimetoken,
          };
          this.emitStatus(reconnectedAnnounce);
        });

        this.reconnectionManager.startPolling();
        this.emitStatus({ ...status, category: StatusCategory.PNNetworkIssuesCategory });
      } else if (status.category === StatusCategory.PNBadRequestCategory) {
        this.stopHeartbeatTimer();
        this.emitStatus(status);
      } else this.emitStatus(status);

      return;
    }
    this.referenceTimetoken = referenceSubscribeTimetoken(result!.cursor.timetoken, this.storedTimetoken);
    if (this.storedTimetoken) {
      this.currentTimetoken = this.storedTimetoken;
      this.storedTimetoken = null;
    } else {
      this.lastTimetoken = this.currentTimetoken;
      this.currentTimetoken = result!.cursor.timetoken;
    }

    if (!this.subscriptionStatusAnnounced) {
      const connected: StatusEvent = {
        category: StatusCategory.PNConnectedCategory,
        operation: status.operation,
        affectedChannels: Array.from(this.pendingChannelSubscriptions),
        subscribedChannels: this.subscribedChannels,
        affectedChannelGroups: Array.from(this.pendingChannelGroupSubscriptions),
        lastTimetoken: this.lastTimetoken,
        currentTimetoken: this.currentTimetoken,
      };

      this.subscriptionStatusAnnounced = true;
      this.emitStatus(connected);

      // Clear pending channels and groups.
      this.pendingChannelGroupSubscriptions.clear();
      this.pendingChannelSubscriptions.clear();
    }

    const { messages } = result!;
    const { requestMessageCountThreshold, dedupeOnSubscribe } = this.configuration;

    if (requestMessageCountThreshold && messages.length >= requestMessageCountThreshold) {
      this.emitStatus({
        category: StatusCategory.PNRequestMessageCountExceededCategory,
        operation: status.operation,
      });
    }

    try {
      const cursor: Subscription.SubscriptionCursor = {
        timetoken: this.currentTimetoken,
        region: this.region ? this.region : undefined,
      };

      this.configuration.logger().debug('SubscriptionManager', () => {
        const hashedEvents = messages.map((event) => ({
          type: event.type,
          data: { ...event.data, pn_mfp: event.pn_mfp },
        }));
        return { messageType: 'object', message: hashedEvents, details: 'Received events:' };
      });

      messages.forEach((message) => {
        if (dedupeOnSubscribe && 'message' in message.data && 'timetoken' in message.data) {
          if (this.dedupingManager.isDuplicate(message.data)) {
            this.configuration.logger().warn('SubscriptionManager', () => ({
              messageType: 'object',
              message: message.data,
              details: 'Duplicate message detected (skipped):',
            }));

            return;
          }
          this.dedupingManager.addEntry(message.data);
        }

        this.emitEvent(cursor, message);
      });
    } catch (e) {
      const errorStatus: Status = {
        error: true,
        category: StatusCategory.PNUnknownCategory,
        errorData: e as Error,
        statusCode: 0,
      };
      this.emitStatus(errorStatus);
    }

    this.region = result!.cursor.region;
    if (!this.disconnectedWhileHandledEvent) this.startSubscribeLoop();
    else this.disconnectedWhileHandledEvent = false;
  }
  // endregion

  // region Presence
  /**
   * Update `uuid` state which should be sent with subscribe request.
   *
   * @param parameters - Channels and groups with state which should be associated to `uuid`.
   */
  public setState(parameters: { state: Payload; channels?: string[]; channelGroups?: string[] }) {
    const { state, channels, channelGroups } = parameters;
    channels?.forEach((channel) => channel in this.channels && (this.presenceState[channel] = state));
    channelGroups?.forEach((group) => group in this.channelGroups && (this.presenceState[group] = state));
  }

  /**
   * Manual presence management.
   *
   * @param parameters - Desired presence state for provided list of channels and groups.
   */
  public changePresence(parameters: { connected: boolean; channels?: string[]; channelGroups?: string[] }) {
    const { connected, channels, channelGroups } = parameters;

    if (connected) {
      channels?.forEach((channel) => (this.heartbeatChannels[channel] = {}));
      channelGroups?.forEach((group) => (this.heartbeatChannelGroups[group] = {}));
    } else {
      channels?.forEach((channel) => {
        if (channel in this.heartbeatChannels) delete this.heartbeatChannels[channel];
      });
      channelGroups?.forEach((group) => {
        if (group in this.heartbeatChannelGroups) delete this.heartbeatChannelGroups[group];
      });

      if (this.configuration.suppressLeaveEvents === false) {
        this.leaveCall({ channels, channelGroups }, (status) => this.emitStatus(status));
      }
    }

    this.reconnect();
  }

  private startHeartbeatTimer() {
    this.stopHeartbeatTimer();

    const heartbeatInterval = this.configuration.getHeartbeatInterval();
    if (!heartbeatInterval || heartbeatInterval === 0) return;

    // Sending immediate heartbeat only if not working as a smart heartbeat.
    if (!this.configuration.useSmartHeartbeat) this.sendHeartbeat();
    this.heartbeatTimer = setInterval(() => this.sendHeartbeat(), heartbeatInterval * 1000) as unknown as number;
  }

  /**
   * Stop heartbeat.
   *
   * Stop timer which trigger {@link HeartbeatRequest} sending with configured presence intervals.
   */
  private stopHeartbeatTimer() {
    if (!this.heartbeatTimer) return;

    clearInterval(this.heartbeatTimer);
    this.heartbeatTimer = null;
  }

  /**
   * Send heartbeat request.
   */
  private sendHeartbeat() {
    const heartbeatChannelGroups = Object.keys(this.heartbeatChannelGroups);
    const heartbeatChannels = Object.keys(this.heartbeatChannels);

    // There is no need to start heartbeat loop if there is no channels and groups to use.
    if (heartbeatChannels.length === 0 && heartbeatChannelGroups.length === 0) return;

    this.heartbeatCall(
      {
        channels: heartbeatChannels,
        channelGroups: heartbeatChannelGroups,
        heartbeat: this.configuration.getPresenceTimeout(),
        state: this.presenceState,
      },
      (status) => {
        if (status.error && this.configuration.announceFailedHeartbeats) this.emitStatus(status);
        if (status.error && this.configuration.autoNetworkDetection && this.isOnline) {
          this.isOnline = false;
          this.disconnect();
          this.emitStatus({ category: StatusCategory.PNNetworkDownCategory });
          this.reconnect();
        }

        if (!status.error && this.configuration.announceSuccessfulHeartbeats) this.emitStatus(status);
      },
    );
  }
  // endregion
}