import { Injectable, NotFoundException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { Attachment } from './entity/attachment.entity';
import { CreateAttachmentDto } from './dto/create_attachment.dto';
import { UpdateAttachmentDto } from './dto/update_attachment.dto';
import { AuthRequest } from '../middleware/jwtMiddleware';

@Injectable()
export class AttachmentService {
  constructor(
    @InjectRepository(Attachment)
    private readonly attachmentRepository: Repository<Attachment>,
  ) {}

  async create(data: CreateAttachmentDto, user: AuthRequest['user']): Promise<Attachment> {
    const attachment = this.attachmentRepository.create({
      ...data,
      ownerId: user.sub,
    });
    return await this.attachmentRepository.save(attachment);
  }

  async findAll(
    page = 1,
    limit = 10,
  ): Promise<{
    docs: Attachment[];
    totalDocs: number;
    limit: number;
    page: number;
    totalPages: number;
    hasNextPage: boolean;
    hasPrevPage: boolean;
    nextPage: number | null;
    prevPage: number | null;
  }> {
    try {
      const skip = (page - 1) * limit;
      const [docs, totalDocs] = await this.attachmentRepository.findAndCount({
        skip,
        take: limit,
      });
      const totalPages = Math.ceil(totalDocs / limit);
      return {
        docs,
        totalDocs,
        limit,
        page,
        totalPages,
        hasNextPage: page < totalPages,
        hasPrevPage: page > 1,
        nextPage: page < totalPages ? page + 1 : null,
        prevPage: page > 1 ? page - 1 : null,
      };
    } catch (error) {
      throw new Error(`Failed to fetch attachments: ${error.message}`);
    }
  }

  async findById(id: string): Promise<Attachment | null> {
    try {
      const attachment = await this.attachmentRepository.findOne({ where: { id } });
      if (!attachment) {
        throw new NotFoundException(`Attachment with ID "${id}" not found`);
      }
      return attachment;
    } catch (error) {
      throw new Error(`Failed to find attachment: ${error.message}`);
    }
  }

  async update(id: string, data: UpdateAttachmentDto): Promise<Attachment | null> {
    try {
      await this.attachmentRepository.update({ id }, { ...data, updatedAt: new Date() });
      const updatedAttachment = await this.attachmentRepository.findOne({ where: { id } });
      if (!updatedAttachment) {
        throw new NotFoundException(`Attachment with ID "${id}" not found`);
      }
      return updatedAttachment;
    } catch (error) {
      throw new Error(`Failed to update attachment: ${error.message}`);
    }
  }

  async remove(id: string): Promise<void> {
    try {
      const result = await this.attachmentRepository.delete({ id });
      if (result.affected === 0) {
        throw new NotFoundException(`Attachment with ID "${id}" not found`);
      }
    } catch (error) {
      throw new Error(`Failed to delete attachment: ${error.message}`);
    }
  }
}