'use strict';
/**
 * @module opcua.client
 */

import { EventEmitter } from '../eventemitter';
import { StatusCodes } from '../constants';
import { assert } from '../assert';

import * as subscription_service from '../service-subscription';
import * as read_service from '../service-read';

import { TimestampsToReturn } from '../generated/TimestampsToReturn';
import { AttributeIds } from '../constants';
import { ClientSubscription } from './ClientSubscription';

import { ModifyMonitoredItemsRequest } from '../generated/ModifyMonitoredItemsRequest';
import { MonitoringParameters, IMonitoringParameters } from '../generated/MonitoringParameters';
import { MonitoringMode } from '../generated/MonitoringMode';
import { MonitoredItemCreateResult } from '../generated/MonitoredItemCreateResult';

import { StatusCode, NodeId } from '../basic-types';
import { IReadValueId } from '../generated/ReadValueId';
import { ResponseCallback, ErrorCallback } from './client_base';
import { ISetMonitoringModeRequest, DataValue } from '../generated';
import { ExtensionObject } from '../basic-types/extension_object';
import { Variant } from '../variant/variant';
import { debugLog } from '../common/debug';

export interface MonitoredItemEvents {
  initialized: () => void;
  changed:
    | ((value: DataValue /* a value change */) => void)
    | ((value: Variant[] /* an event */) => void);
  terminated: () => void;
  err: (errorMessage: string) => void;
}

// import {MonitoredItemsModifyRequest} from '../generated/MonitoredItemsModifyRequest';
const MonitoredItemModifyRequest = subscription_service.MonitoredItemModifyRequest;

export class MonitoredItemBase extends EventEmitter<MonitoredItemEvents> {
  protected _itemToMonitor: read_service.ReadValueId;
  protected _monitoringParameters: MonitoringParameters;
  protected _subscription: ClientSubscription;
  protected _monitoringMode: MonitoringMode;
  protected _statusCode: StatusCode = StatusCodes.BadDataUnavailable;
  public result?: MonitoredItemCreateResult;
  public monitoredItemId?: number;
  public filterResult?: ExtensionObject;

  constructor(
    subscription: ClientSubscription,
    itemToMonitor: IReadValueId,
    monitoringParameters: IMonitoringParameters
  ) {
    super();
    // assert(subscription.constructor.name === "ClientSubscription");

    this._itemToMonitor = new read_service.ReadValueId(itemToMonitor);
    this._monitoringParameters = new MonitoringParameters(monitoringParameters);
    this._subscription = subscription;
    this._monitoringMode = subscription_service.MonitoringMode.Reporting;
    assert(!this._monitoringParameters.clientHandle, 'should not have a client handle yet');
  }

  public get monitoringParameters() {
    return this._monitoringParameters;
  }

  public get itemToMonitor() {
    return this._itemToMonitor;
  }

  public get nodeId(): NodeId {
    return this._itemToMonitor.nodeId;
  }

  public get monitoringMode() {
    return this._monitoringMode;
  }

  public get statusCode(): StatusCode {
    return this._statusCode;
  }

  public get subscription(): ClientSubscription {
    return this._subscription;
  }

  public _notify_value_change(value: DataValue) {
    /**
     * Notify the observers that the MonitoredItem value has changed on the server side.
     * @event changed
     * @param value
     */
    try {
      this.emit('changed', value);
    } catch (err) {
      console.log(
        "Exception raised inside the event handler called by ClientMonitoredItem.on('change')",
        err
      );
      console.log('Please verify the application using this node-opcua client');
    }
  }

  /**
   * @internal
   * @param eventFields
   * @private
   */
  public _notify_event(eventFields: Variant[]) {
    /**
     * Notify the observers that the MonitoredItem value has changed on the server side.
     * @event changed
     * @param value
     */
    try {
      this.emit('changed', eventFields);
    } catch (err) {
      debugLog(
        "Exception raised inside the event handler called by ClientMonitoredItem.on('change')",
        err
      );
      debugLog('Please verify the application using this node-opcua client');
    }
  }

  protected _prepare_for_monitoring(): subscription_service.MonitoredItemCreateRequest | Error {
    assert(this._subscription.subscriptionId !== 'pending');
    assert(!this._monitoringParameters.clientHandle, 'should not have a client handle yet');
    this._monitoringParameters.clientHandle = this._subscription.nextClientHandle();
    assert(
      this._monitoringParameters.clientHandle > 0 &&
        this._monitoringParameters.clientHandle !== null /* 4294967295*/
    );

    // If attributeId is EventNotifier then monitoring parameters need a filter.
    // The filter must then either be DataChangeFilter, EventFilter or AggregateFilter.
    // todo can be done in another way?
    // todo implement AggregateFilter
    // todo support DataChangeFilter
    // todo support whereClause
    if (this._itemToMonitor.attributeId === AttributeIds.EventNotifier) {
      //
      // see OPCUA Spec 1.02 part 4 page 65 : 5.12.1.4 Filter
      // see                 part 4 page 130: 7.16.3 EventFilter
      //                     part 3 page 11 : 4.6 Event Model
      // To monitor for Events, the attributeId element of the ReadValueId structure is the
      // the id of the EventNotifierAttribute

      // OPC Unified Architecture 1.02, Part 4 5.12.1.2 Sampling interval page 64:
      // "A Client shall define a sampling interval of 0 if it subscribes for Events."
      // toDO

      // note : the EventFilter is used when monitoring Events.
      this._monitoringParameters.filter =
        this._monitoringParameters.filter || new subscription_service.EventFilter({});

      const filter: ExtensionObject = this._monitoringParameters.filter;
      if (!(filter instanceof subscription_service.EventFilter)) {
        return new Error(
          'Mismatch between attributeId and filter in monitoring parameters : ' +
            'An EventFilter object is required when itemToMonitor.attributeId== AttributeIds.EventNotifier'
        );
      }
    } else if (this._itemToMonitor.attributeId === AttributeIds.Value) {
      // the DataChangeFilter and the AggregateFilter are used when monitoring Variable Values
      // The Value Attribute is used when monitoring Variables. Variable values are monitored for a change
      // in value or a change in their status. The filters defined in this standard (see 7.16.2) and in Part 8 are
      // used to determine if the value change is large enough to cause a Notification to be generated for the
      // to do : check 'DataChangeFilter'  && 'AggregateFilter'
    } else {
      if (this._monitoringParameters.filter) {
        return new Error(
          'Mismatch between attributeId and filter in monitoring parameters : ' +
            'no filter expected when attributeId is not Value  or  EventNotifier'
        );
      }
    }
    return new subscription_service.MonitoredItemCreateRequest({
      itemToMonitor: this._itemToMonitor,
      monitoringMode: this._monitoringMode,
      requestedParameters: this._monitoringParameters,
    });
  }

  protected _after_create(monitoredItemResult: MonitoredItemCreateResult) {
    this._statusCode = monitoredItemResult.statusCode || (StatusCodes.Good);
    /* istanbul ignore else */
    if (monitoredItemResult.statusCode === StatusCodes.Good) {
      this.result = monitoredItemResult;
      this.monitoredItemId = monitoredItemResult.monitoredItemId;
      this._monitoringParameters.samplingInterval = monitoredItemResult.revisedSamplingInterval;
      this._monitoringParameters.queueSize = monitoredItemResult.revisedQueueSize;
      this.filterResult = monitoredItemResult.filterResult || undefined;

      this._subscription._add_monitored_item(this._monitoringParameters.clientHandle, this);
      /**
       * Notify the observers that the monitored item is now fully initialized.
       * @event initialized
       */
      this.emit('initialized');
    } else {
      /**
       * Notify the observers that the monitored item has failed to initialized.
       * @event err
       * @param statusCode {StatusCode}
       */
      const err = new Error(monitoredItemResult.statusCode.toString());
      this.emit('err', err.message);
      this.emit('terminated');
    }
  }

  public static _toolbox_monitor(
    subscription: ClientSubscription,
    timestampsToReturn: TimestampsToReturn,
    monitoredItems: MonitoredItemBase[],
    done: ErrorCallback
  ) {
    assert('function' === typeof done && typeof subscription.subscriptionId === 'number');
    const itemsToCreate: subscription_service.MonitoredItemCreateRequest[] = [];
    for (let i = 0; i < monitoredItems.length; i++) {
      const monitoredItem = monitoredItems[i];
      const itemToCreate = (<any>monitoredItem)._prepare_for_monitoring(done);
      if (
        typeof itemToCreate.error === 'string' ||
        itemToCreate.error instanceof String /* _.isString(itemToCreate.error)*/
      ) {
        return done(new Error(itemToCreate.error));
      }
      itemsToCreate.push(itemToCreate);
    }

    if (typeof subscription.subscriptionId === 'string') {
      // subscription either pending or terminated
      throw new Error(
        'subscription either pending or terminated - subscription.subscriptionId: ' +
          subscription.subscriptionId
      );
    }

    const createMonitorItemsRequest = new subscription_service.CreateMonitoredItemsRequest({
      subscriptionId: subscription.subscriptionId,
      timestampsToReturn: timestampsToReturn,
      itemsToCreate: itemsToCreate,
    });

    assert(subscription.session);
    subscription.session.createMonitoredItems(createMonitorItemsRequest, function (err, response) {
      /* istanbul ignore next */
      if (err || !response) {
        // xx console.log("ClientMonitoredItemBase#_toolbox_monitor:  ERROR in createMonitoredItems ".red, err.message);
        // xx  console.log("ClientMonitoredItemBase#_toolbox_monitor:  ERROR in createMonitoredItems ".red, err);
        // xx  console.log(createMonitorItemsRequest.toString());
      } else {
        assert(response instanceof subscription_service.CreateMonitoredItemsResponse);

        for (let i = 0; i < response.results.length; i++) {
          const monitoredItemResult = response.results[i];
          const monitoredItem = monitoredItems[i];
          monitoredItem._after_create(monitoredItemResult);
        }
      }
      done(err);
    });
  }
  public static _toolbox_modify(
    subscription: ClientSubscription,
    monitoredItems: MonitoredItemBase[],
    parameters: IMonitoringParameters,
    timestampsToReturn: TimestampsToReturn,
    callback: ResponseCallback<subscription_service.MonitoredItemModifyResult[]>
  ) {
    assert(callback === undefined || 'function' === typeof callback);

    const itemsToModify = monitoredItems.map(function (monitoredItem) {
      const monParams = new MonitoringParameters(parameters);
      monParams.clientHandle = monitoredItem.monitoringParameters.clientHandle;
      return new MonitoredItemModifyRequest({
        monitoredItemId: monitoredItem.monitoredItemId,
        requestedParameters: monParams,
      });
    });
    const modifyMonitoredItemsRequest = new ModifyMonitoredItemsRequest({
      subscriptionId: <number>subscription.subscriptionId,
      timestampsToReturn: timestampsToReturn,
      itemsToModify: itemsToModify,
    });

    subscription.session.modifyMonitoredItems(
      modifyMonitoredItemsRequest,
      function (err, response) {
        /* istanbul ignore next */
        if (err || !response) {
          return callback(err);
        }
        assert(response.results.length === monitoredItems.length);

        const res = response.results[0];

        /* istanbul ignore next */
        if (response.results.length === 1 && res.statusCode !== StatusCodes.Good) {
          return callback(new Error('Error' + res.statusCode.toString()));
        }
        callback(null, response.results);
      }
    );
  }
  public static _toolbox_setMonitoringMode(
    subscription: ClientSubscription,
    monitoredItems: MonitoredItemBase[],
    monitoringMode: MonitoringMode,
    callback: ResponseCallback<StatusCode[]>
  ) {
    const monitoredItemIds = monitoredItems.map(function (monitoredItem) {
      return monitoredItem.monitoredItemId;
    }) as number[];

    const setMonitoringModeRequest: ISetMonitoringModeRequest = {
      subscriptionId: <number>subscription.subscriptionId,
      monitoringMode: monitoringMode,
      monitoredItemIds: monitoredItemIds,
    };
    subscription.session.setMonitoringMode(setMonitoringModeRequest, (err, response) => {
      if (!err) {
        monitoredItems.forEach((monitoredItem) => {
          monitoredItem._monitoringMode = monitoringMode;
        });
      }
      if (callback) {
        callback(err, response?.results);
      }
    });
  }
}