import { IChatRepository } from '../../../Domain/IRepository/IChatRepository';
import { GetChatsByPageQuery } from './GetChatsByPageQuery';
import { ShortChatDto } from '../../DTOs/ChatDto';
import { ChatMapper } from '../../DTOs/Mappers/ChatMapper';
import { logRequest, logError } from '../../Services/Logger';

export class GetChatsByPageQueryHandler {
  constructor(private readonly chatRepo: IChatRepository) {}

  async execute(query: GetChatsByPageQuery): Promise<{ chats: ShortChatDto[], totalCount: number }> {
    try {
      // Validate pagination parameters
      if (query.from < 0 || query.to < query.from) {
        throw new Error('Invalid pagination parameters');
      }

      const limit = query.to - query.from + 1;
      if (limit > 100) {
        throw new Error('Page size too large. Maximum 100 records per request');
      }

      logRequest('Get chats by page query started', undefined, undefined, {
        from: query.from,
        to: query.to,
        includeDeleted: query.includeDeleted || false
      });

      const result = query.includeDeleted
        ? await this.chatRepo.findByPageIncludingDeleted(query.from, query.to)
        : await this.chatRepo.findByPage(query.from, query.to);

      logRequest('Get chats by page query completed', undefined, undefined, {
        from: query.from,
        to: query.to,
        returned: result.chats.length,
        totalCount: result.totalCount,
        includeDeleted: query.includeDeleted || false
      });

      return {
        chats: ChatMapper.toShortDtoList(result.chats),
        totalCount: result.totalCount
      };
    } catch (error) {
      logError('GetChatsByPageQueryHandler error', error instanceof Error ? error : new Error(String(error)));
      
      // Re-throw validation errors as-is
      if (error instanceof Error && (error.message.includes('Invalid pagination') || error.message.includes('Page size'))) {
        throw error;
      }
      
      throw new Error('Failed to retrieve chats page');
    }
  }
}