import {
  Injectable,
  BadRequestException,
  NotFoundException,
} from '@nestjs/common';
import * as QRCode from 'qrcode';
import { PrismaService } from '../prisma/prisma.service';

const ENTITY_TYPES = [
  'colonies',
  'apiaries',
  'queens',
  'honey-batches',
  'storage-containers',
  'bottling-batches',
] as const;
type EntityType = (typeof ENTITY_TYPES)[number];

function isEntityType(value: string): value is EntityType {
  return (ENTITY_TYPES as readonly string[]).includes(value);
}

@Injectable()
export class QrService {
  constructor(private readonly prisma: PrismaService) {}

  async generateSvg(entityType: string, id: string): Promise<string> {
    const url = await this.resolveUrl(entityType, id);
    return QRCode.toString(url, { type: 'svg', margin: 1, width: 256 });
  }

  async resolveUrl(entityType: string, id: string): Promise<string> {
    if (!isEntityType(entityType)) {
      throw new BadRequestException(
        `Unsupported QR entity type: ${entityType}`,
      );
    }

    const deepLink = await this.resolveDeepLink(entityType, id);
    if (!deepLink) {
      throw new NotFoundException('Object not found');
    }

    const frontendOrigin =
      process.env.FRONTEND_ORIGIN ?? 'http://localhost:3000';
    return `${frontendOrigin}${deepLink}`;
  }

  private async resolveDeepLink(
    entityType: EntityType,
    id: string,
  ): Promise<string | null> {
    switch (entityType) {
      case 'colonies': {
        const colony = await this.prisma.colony.findUnique({
          where: { id },
        });
        return colony ? `/inspections/new?colonyId=${id}` : null;
      }
      case 'apiaries': {
        const apiary = await this.prisma.apiary.findUnique({ where: { id } });
        return apiary ? `/apiaries/${id}` : null;
      }
      case 'queens': {
        const queen = await this.prisma.queen.findUnique({ where: { id } });
        return queen ? `/queens/${id}` : null;
      }
      case 'honey-batches': {
        const honeyBatch = await this.prisma.honeyBatch.findUnique({
          where: { id },
        });
        return honeyBatch ? `/honey-batches/${id}` : null;
      }
      case 'storage-containers': {
        const container = await this.prisma.storageContainer.findUnique({
          where: { id },
        });
        return container ? `/storage` : null;
      }
      case 'bottling-batches': {
        const bottlingBatch = await this.prisma.bottlingBatch.findUnique({
          where: { id },
          select: { lotNumber: true },
        });
        return bottlingBatch ? `/herkunft/${bottlingBatch.lotNumber}` : null;
      }
    }
  }
}