import { ForbiddenException, Injectable, UnauthorizedException } from '@nestjs/common';
import { PassportStrategy } from '@nestjs/passport';
import { AdminRole } from '@prisma/client';
import type { Request } from 'express';
import { ExtractJwt, Strategy } from 'passport-jwt';
import { PrismaService } from '../../prisma/prisma.service';
import { customerJwtSecret } from './customer-auth.service';
import {
  ACT_AS_CUSTOMER_HEADER,
  CUSTOMER_TOKEN_TYPE,
  EXPERT_TOKEN_TYPE,
  type AppJwtPayload,
  type AuthenticatedCustomer,
} from './app-principal';
import { AppSessionService } from '../sessions/app-session.service';

export {
  ACT_AS_CUSTOMER_HEADER,
  CUSTOMER_TOKEN_TYPE,
  EXPERT_TOKEN_TYPE,
  isActingAsCustomer,
  type AuthenticatedCustomer,
} from './app-principal';

/** Kept for the existing imports; the payload now covers both principals. */
export type CustomerJwtPayload = AppJwtPayload;

/**
 * The app principal, kept entirely separate from JwtStrategy (which reads
 * AdminUser for the admin PANEL). The reference had the same split: `auth:api`
 * for admins and `auth('api-customer')` for the app.
 *
 * This strategy accepts TWO token types and resolves both to one shape:
 *
 *   typ 'customer'     -> the Customer row named by `sub`
 *   typ 'sales-expert' -> the AdminUser named by `sub`, plus their trading
 *                         Customer row, which becomes `id`
 *
 * Because `id` is always a Customer id, every route already written for a
 * customer works unchanged for an expert — which is exactly the reference's
 * behaviour, where an agent was a customer with extra screens.
 *
 * An expert's app token is NOT an admin-panel token: its `typ` is
 * 'sales-expert', while JwtStrategy requires the admin type, so it is refused
 * on every admin route.
 */
@Injectable()
export class CustomerJwtStrategy extends PassportStrategy(Strategy, 'customer-jwt') {
  constructor(
    private readonly prisma: PrismaService,
    private readonly sessions: AppSessionService,
  ) {
    super({
      jwtFromRequest: ExtractJwt.fromAuthHeaderAsBearerToken(),
      ignoreExpiration: false,
      secretOrKey: customerJwtSecret(),
      // Needed only to read the act-as header; the token itself is still the
      // only thing that establishes WHO is calling.
      passReqToCallback: true,
    });
  }

  async validate(req: Request, payload: AppJwtPayload): Promise<AuthenticatedCustomer> {
    // نشست باطل‌شده (خروج سراسری از IdP یا ابطال محلی). در حالت خاموشِ ردیابی،
    // بدون هیچ کوئری true برمی‌گردد ⇒ هزینه و رفتار دقیقاً مثل قبل.
    if (!(await this.sessions.isActive(payload?.jti))) {
      throw new UnauthorizedException();
    }

    if (payload?.typ === EXPERT_TOKEN_TYPE) {
      return this.validateExpert(payload, this.actAsHeader(req));
    }

    // A token that is not explicitly a customer token is refused, whatever
    // else it carries.
    if (payload?.typ !== CUSTOMER_TOKEN_TYPE) {
      throw new UnauthorizedException();
    }

    // Re-read on every request, so deactivating or archiving a customer takes
    // effect immediately instead of at token expiry.
    const customer = await this.prisma.customer.findUnique({
      where: { id: payload.sub },
      select: { id: true, mobile: true, isActive: true, isArchived: true },
    });

    if (!customer || !customer.isActive || customer.isArchived) {
      throw new UnauthorizedException();
    }

    return { id: customer.id, mobile: customer.mobile, type: CUSTOMER_TOKEN_TYPE };
  }

  /**
   * The act-as header, or null. Deliberately read ONLY for an expert token: on
   * a customer's token the header has no effect at all, rather than being an
   * error — a customer cannot grant themselves anything by sending it.
   */
  private actAsHeader(req: Request): string | null {
    const raw = (req?.headers as Record<string, unknown> | undefined)?.[ACT_AS_CUSTOMER_HEADER];
    const value = Array.isArray(raw) ? raw[0] : raw;
    return typeof value === 'string' && value.trim() ? value.trim() : null;
  }

  /**
   * A sales expert. `sub` is their AdminUser id, so the role and active flag
   * are re-checked on every request: demoting an expert or deactivating them
   * locks them out immediately rather than at token expiry.
   *
   * The trading Customer row is resolved here rather than stored in the token,
   * so a token issued before that row existed keeps working.
   *
   * ACTING AS A CUSTOMER («ورود به حساب مشتری», owner request 2026-10-12)
   *
   * With `actAs` set, the returned principal's `id` is that customer, so every
   * customer route — orders, me, ledger, report, favourites, documents — serves
   * the customer's own data with no change to any route. That is the whole
   * feature, and it is why this is the only place the behaviour lives.
   *
   * How this differs from the reference, which did the same thing by handing the
   * expert the customer's own `api_token` (ApiMobileController.php:197-201):
   *
   *   - no token is minted, so nothing durable leaks into a device's storage
   *     and ending the app session ends the impersonation;
   *   - ownership is re-checked on EVERY request, so moving a customer to
   *     another expert cuts access off at once instead of at token expiry;
   *   - `adminUserId` survives, so the real actor is auditable — in the
   *     reference the request was indistinguishable from the customer's own.
   */
  private async validateExpert(
    payload: AppJwtPayload,
    actAs: string | null,
  ): Promise<AuthenticatedCustomer> {
    const admin = await this.prisma.adminUser.findUnique({
      where: { id: payload.sub },
      select: {
        id: true,
        mobile: true,
        role: true,
        isActive: true,
        salesExpertProfile: {
          select: {
            tradingCustomerId: true,
            tradingCustomer: { select: { id: true, isActive: true, isArchived: true } },
          },
        },
      },
    });

    if (!admin || !admin.isActive || admin.role !== AdminRole.SALES_EXPERT) {
      throw new UnauthorizedException();
    }

    if (actAs) {
      // Scoped by referredByAgentId in the same query as the id, so another
      // expert's customer and a non-existent id are the same answer: no row,
      // 403. The lookup cannot be talked out of its scope.
      const customer = await this.prisma.customer.findFirst({
        where: {
          id: actAs,
          referredByAgentId: admin.id,
          isActive: true,
          isArchived: false,
        },
        select: { id: true, mobile: true },
      });

      if (!customer) {
        // Not 401: the expert's own session is perfectly valid, it is this
        // particular impersonation that is refused — so the app can clear the
        // act-as state instead of logging them out.
        throw new ForbiddenException('دسترسی به این مشتری مجاز نیست');
      }

      return {
        id: customer.id,
        mobile: customer.mobile,
        type: EXPERT_TOKEN_TYPE,
        adminUserId: admin.id,
        actingAsCustomerId: customer.id,
      };
    }

    const trading = admin.salesExpertProfile?.tradingCustomer;
    if (!trading || !trading.isActive || trading.isArchived) {
      // The account is created at sign-in; if it is missing or has been
      // deactivated, the session cannot act. Refused rather than silently
      // degraded, so an expert never places an order against nothing.
      throw new UnauthorizedException();
    }

    return {
      id: trading.id,
      mobile: admin.mobile,
      type: EXPERT_TOKEN_TYPE,
      adminUserId: admin.id,
    };
  }
}