import {
  Injectable,
  CanActivate,
  ExecutionContext,
  UnauthorizedException,
} from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { JwtService } from '@nestjs/jwt';
import { ConfigService } from '@nestjs/config';
import { Request } from 'express';

export const IS_PUBLIC_KEY = 'isPublic';

@Injectable()
export class AdminAuthGuard implements CanActivate {
  private jwtSecret: string;

  constructor(
    private reflector: Reflector,
    private jwtService: JwtService,
    private config: ConfigService,
  ) {
    this.jwtSecret = this.config.get<string>('ADMIN_JWT_SECRET', 'admin-jwt-secret')!;
  }

  async canActivate(context: ExecutionContext): Promise<boolean> {
    const request = context.switchToHttp().getRequest<Request>();
    const url = request.url || '';

    // Skip auth for public support endpoints
    if (url.includes('/public/support')) {
      return true;
    }

    const isPublic = this.reflector.getAllAndOverride<boolean>(IS_PUBLIC_KEY, [
      context.getHandler(),
      context.getClass(),
    ]);
    if (isPublic) return true;

    const token = this.extractToken(request);
    if (!token) throw new UnauthorizedException();

    try {
      const payload = await this.jwtService.verifyAsync(token, {
        secret: this.jwtSecret,
      });
      (request as any)['admin'] = payload;
    } catch {
      throw new UnauthorizedException();
    }

    return true;
  }

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