import { Injectable, OnModuleInit, OnModuleDestroy, Logger } from '@nestjs/common';
import { PrismaClient } from '@prisma/client';

/**
 * Tenant subdomain -> organizationId lookup.
 *
 * Uses its own raw PrismaClient (NOT the RLS proxy) so it can query the
 * `organizations` table before any tenant context exists. The lookup runs
 * inside the TenantHeaderGuard, which executes BEFORE the
 * TenantContextInterceptor sets the GUC, so the RLS proxy wouldn't have
 * a tx to route to.
 *
 * `organizations` is intentionally NOT under RLS (see prisma.service.ts
 * docstring) so a raw client can read it without side effects.
 *
 * Results are cached in-memory for 60s to avoid hitting the DB on every
 * request. That's acceptable because org subdomains rarely change.
 */
@Injectable()
export class TenantLookupService implements OnModuleInit, OnModuleDestroy {
  private readonly logger = new Logger(TenantLookupService.name);
  private readonly prisma = new PrismaClient();
  private readonly cache = new Map<string, { orgId: string; expiresAt: number }>();
  private readonly ttlMs = 60_000;

  async onModuleInit() {
    await this.prisma.$connect();
    this.logger.log('TenantLookupService connected');
  }

  async onModuleDestroy() {
    await this.prisma.$disconnect();
  }

  async getOrgIdBySubdomain(subdomain: string): Promise<string | null> {
    const key = subdomain.toLowerCase().trim();
    const cached = this.cache.get(key);
    if (cached && cached.expiresAt > Date.now()) {
      return cached.orgId;
    }
    const org = await this.prisma.organization.findFirst({
      where: { subdomain: key },
      select: { id: true },
    });
    if (!org) return null;
    this.cache.set(key, { orgId: org.id, expiresAt: Date.now() + this.ttlMs });
    return org.id;
  }
}