import {
  CanActivate,
  ExecutionContext,
  Injectable,
  UnauthorizedException,
} from "@nestjs/common";
import { JwtService } from "@nestjs/jwt";
import { Request } from "express";
import { RoleEnum } from "src/Types&Enums/role.enum";

/**
 * Verifies a Bearer JWT and restricts access to `super_admin` role only.
 * Use this guard on all endpoints that should be reachable only by the
 * super-admin panel.
 */
@Injectable()
export class SuperAdminGuard implements CanActivate {
  constructor(private readonly jwtService: JwtService) {}

  async canActivate(context: ExecutionContext): Promise<boolean> {
    const request = context.switchToHttp().getRequest<Request>();
    const token = this.extractTokenFromHeader(request);
    if (!token) {
      throw new UnauthorizedException("Token not found");
    }

    let payload: any;
    try {
      payload = await this.jwtService.verifyAsync(token, {
        secret: `${process.env.JWT_SECRET}`,
      });
    } catch {
      throw new UnauthorizedException("Invalid or expired token");
    }

    if (payload?.role !== RoleEnum.SUPER_ADMIN) {
      throw new UnauthorizedException("Super-admin access required");
    }

    (request as any).user = payload;
    (request as any).identity = payload;
    return true;
  }

  private extractTokenFromHeader(request: Request): string | undefined {
    const [type, token] = request.headers.authorization?.split(" ") ?? [];
    return type === "Bearer" ? token : undefined;
  }
}