import { Injectable, UnauthorizedException } from '@nestjs/common';
import { AsyncLocalStorage } from 'async_hooks';
import { RequestContext } from './request-context.type';

@Injectable()
/**
 * RequestContext holds per-request metadata including:
 * - HTTP request
 * - Auth payload (decoded JWT, optional)
 * - Prisma transaction client (optional)
 * - Correlation ID and other future cross-cutting concerns
 */
export class RequestContextService {
  private readonly als = new AsyncLocalStorage<RequestContext>();

  run(context: RequestContext, fn: () => void) {
    this.als.run(context, fn);
  }

  get(): RequestContext {
    const store = this.als.getStore();
    if (!store) {
      throw new Error('RequestContext not initialized');
    }
    return store;
  }

  set<K extends keyof RequestContext>(key: K, value: RequestContext[K]) {
    this.get()[key] = value;
  }

  // Helpers
  get user() {
    const user = this.get().user;
    if (!user) throw new UnauthorizedException();
    return user;
  }

  get tx() {
    return this.get().tx;
  }

  set tx(tx) {
    this.set('tx', tx);
  }

  get isTransaction(): boolean {
    return !!this.get().tx;
  }

  get orgId(): string {
    return this.orgId
  }

  set orgId(id: string) {
    this.set('orgId', id)
  }
}