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

export interface JwtPayload {
  sub: string; // user id
  openid: string;
}

@Injectable()
export class JwtAuthGuard implements CanActivate {
  constructor(private readonly jwtService: JwtService) {}

  async canActivate(context: ExecutionContext): Promise<boolean> {
    const request = context.switchToHttp().getRequest<Request>();
    const token = this.extractToken(request);

    if (!token) {
      throw new UnauthorizedException('未提供访问令牌');
    }

    try {
      const payload = await this.jwtService.verifyAsync<JwtPayload>(token);
      // 将用户信息挂载到 request 上
      (request as any).user = payload;
    } catch {
      throw new UnauthorizedException('访问令牌无效或已过期');
    }

    return true;
  }

  private extractToken(request: Request): string | null {
    const authorization = request.headers.authorization;
    if (!authorization) return null;

    const [type, token] = authorization.split(' ');
    return type === 'Bearer' ? token : null;
  }
}