import { Injectable, BadRequestException, NotFoundException } from '@nestjs/common';
import { TenantService } from '../../database/tenant.service';

const ALLOWED_MIMES = [
  'application/pdf',
  'image/jpeg',
  'image/png',
  'image/webp',
  'image/gif',
  'application/vnd.ms-excel',
  'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
];

const MAX_FILE_SIZE = 10 * 1024 * 1024; // 10MB

@Injectable()
export class AttachmentsService {
  constructor(private tenant: TenantService) {}

  async upload(journalEntryId: string, file: Express.Multer.File, userId: string) {
    if (!file) {
      throw new BadRequestException('No file provided');
    }
    if (file.size > MAX_FILE_SIZE) {
      throw new BadRequestException('File size exceeds 10MB limit');
    }
    if (!ALLOWED_MIMES.includes(file.mimetype)) {
      throw new BadRequestException(
        `File type "${file.mimetype}" not allowed. Allowed: PDF, JPEG, PNG, WebP, GIF, XLS, XLSX`,
      );
    }

    // Verify journal entry exists
    const jeRows = await this.tenant.query(
      `SELECT id FROM journal_entries WHERE id = $1`,
      [journalEntryId],
    );
    if (!jeRows.length) {
      throw new NotFoundException('Journal entry not found');
    }

    const rows = await this.tenant.query(
      `INSERT INTO attachments (journal_entry_id, filename, mime_type, file_size, file_data, uploaded_by)
       VALUES ($1, $2, $3, $4, $5, $6)
       RETURNING id, filename, mime_type, file_size, created_at`,
      [journalEntryId, file.originalname, file.mimetype, file.size, file.buffer, userId],
    );
    return rows[0];
  }

  async findByJournalEntry(journalEntryId: string) {
    return this.tenant.query(
      `SELECT id, journal_entry_id, filename, mime_type, file_size, created_at
       FROM attachments
       WHERE journal_entry_id = $1
       ORDER BY created_at`,
      [journalEntryId],
    );
  }

  async download(id: string) {
    const rows = await this.tenant.query(
      `SELECT filename, mime_type, file_data FROM attachments WHERE id = $1`,
      [id],
    );
    if (!rows.length) throw new NotFoundException('Attachment not found');
    return rows[0];
  }

  async delete(id: string) {
    const result = await this.tenant.query(
      `DELETE FROM attachments WHERE id = $1 RETURNING id`,
      [id],
    );
    if (!result.length) throw new NotFoundException('Attachment not found');
    return { deleted: true };
  }
}