import { Injectable } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { AuditLogService } from '../audit/audit-log.service';
import { SiteSettings } from '../../generated/prisma';
import { UpdateSiteSettingsDto } from './dto/update-site-settings.dto';

const SINGLETON_ID = 'singleton';

function emptyToNull(value: string | undefined): string | null {
  return value === '' ? null : (value ?? null);
}

@Injectable()
export class SiteSettingsService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly auditLog: AuditLogService,
  ) {}

  // Find-or-create rather than a migration-time seed row: keeps the
  // singleton pattern self-contained in this service instead of coupling it
  // to seed.ts/migration ordering.
  async get(): Promise<SiteSettings> {
    const existing = await this.prisma.siteSettings.findUnique({
      where: { id: SINGLETON_ID },
    });
    if (existing) {
      return existing;
    }
    return this.prisma.siteSettings.create({ data: { id: SINGLETON_ID } });
  }

  async update(
    dto: UpdateSiteSettingsDto,
    actingUserId: string,
  ): Promise<SiteSettings> {
    const before = await this.get();
    const settings = await this.prisma.siteSettings.update({
      where: { id: SINGLETON_ID },
      data: {
        youtubeUrl:
          dto.youtubeUrl !== undefined
            ? emptyToNull(dto.youtubeUrl)
            : undefined,
        instagramUrl:
          dto.instagramUrl !== undefined
            ? emptyToNull(dto.instagramUrl)
            : undefined,
        tiktokUrl:
          dto.tiktokUrl !== undefined ? emptyToNull(dto.tiktokUrl) : undefined,
      },
    });
    await this.auditLog.record({
      entityType: 'SiteSettings',
      entityId: SINGLETON_ID,
      action: 'UPDATE',
      userId: actingUserId,
      beforeData: before,
      afterData: settings,
    });
    return settings;
  }
}