doneit-web/src/app/module/chat/data/repository/message/message-local-data-source.service.ts

import { Injectable } from '@angular/core';
import { liveQuery } from 'Dexie';
import { MessageEntity } from '../../../../../core/chat/entity/message';
import { DexieRepository } from 'src/app/infra/repository/dexie/dexie-repository.service';
import { Observable as  DexieObservable, PromiseExtended } from 'Dexie';
import { MessageTable, MessageTableSchema } from 'src/app/infra/database/dexie/instance/chat/schema/message';
import { chatDatabase } from 'src/app/infra/database/dexie/service';
import { IMessageLocalRepository } from 'src/app/core/chat/repository/message/message-local-repository';
import { BehaviorSubject, combineLatest, from, Observable } from 'rxjs';
import { filter, map } from 'rxjs/operators';
import { v4 as uuidv4 } from 'uuid'

@Injectable({
  providedIn: 'root'
})
export class MessageLocalDataSourceService extends DexieRepository<MessageTable, MessageEntity> implements IMessageLocalRepository  {

  private creatingSubject : BehaviorSubject<MessageTable> = new BehaviorSubject<MessageTable>(null);
  private lastTimestamp = 0;

  constructor() {
    super(chatDatabase.message, MessageTableSchema)

    this.setAllSenderToFalse();
    this.onCreatingHook()
  }

  private onCreatingHook() {
    chatDatabase.message.hook('creating', (primaryKey, obj, transaction) => {

      let now = Date.now();

      // If the current time is the same as the last, increment
      if (now <= this.lastTimestamp) {
        obj.$createAt = this.lastTimestamp + 1;
        this.lastTimestamp = this.lastTimestamp + 1;
      } else {
        this.lastTimestamp = now;
        obj.$createAt = now;
      }

      if(obj.id) {
        obj.$id = obj.id
      } else {
        obj.$id = 'Local-'+uuidv4()
      }

      this.creatingSubject.next(obj)
    });
  }

  onCreateObservable() {
    return this.creatingSubject.asObservable()
  }

  async setAllSenderToFalse() {
    try {
      await chatDatabase.transaction('rw', chatDatabase.message, async () => {
        // Perform the update operation within the transaction
        await chatDatabase.message.toCollection().modify({ sending: false });
      });
    } catch (error) {
      console.error('Error updating messages:', error);
    }
  }

  getItems(roomId: string): PromiseExtended<MessageEntity[]> {
    return chatDatabase.message.where('roomId').equals(roomId).sortBy('$id') as any
  }

  getItemsLive(roomId: string): DexieObservable<MessageEntity[]> {
    return liveQuery(() => chatDatabase.message.where('roomId').equals(roomId).sortBy('$id') as any)
  }

  async getOfflineMessages () {
    try {
      const allMessages = await chatDatabase.message
        .filter(msg => typeof msg.id !== 'string' && msg.sending == false)
        .toArray();

      return allMessages as MessageEntity[];
    } catch (error) {
      console.error('Error fetching messages:', error);
    }
  }



  getLastMessageForRooms(roomIds: string[]): Observable<any[]> {
    const observables = roomIds.map(roomId =>
      from (liveQuery(async() =>{
        const messages = await chatDatabase.message
          .where('roomId')
          .equals(roomId)
          .reverse()
          .sortBy('timestamp')

        return messages[0] || null; // Return the first item (latest message) or null if no message
      })).pipe(
        map((message) => ({ roomId, message: message || null })) // Attach roomId to the result
      )
    );

    return combineLatest(observables); // Combine all observables into one array of results
  }
}