import {
  CanActivate,
  ExecutionContext,
  ForbiddenException,
  Injectable,
} from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { ROLES_KEY } from '../decorators/roles.decorators';
import { Roles } from '.prisma/client';



interface RequestWithUser extends Request {
  // TODO: Create an actual user model based on OAuth signin
  user: any;
}

@Injectable()
export class RolesGuard implements CanActivate {
  constructor(private reflector: Reflector) { }

  /**
  * @swagger
  * @function canActivate
  * @description
  * Authorization guard that checks whether the current user has one of the required roles
  * to access a specific route handler. It uses metadata defined by the `@Roles()` decorator
  * and verifies the user's role accordingly.
  *
  * If no roles are specified for the route, access is granted by default.
  * If the user is not authenticated or does not have a required role, access is denied.
  *
  * @param {ExecutionContext} ctx - The current execution context, which provides access
  * to route metadata and the HTTP request.
  *
  * @returns {boolean} - Returns `true` if access is allowed, otherwise throws a `ForbiddenException`
  * or returns `false` if the user is not authenticated.
  */
  canActivate(ctx: ExecutionContext): boolean {
    const requiredRoles = this.reflector.getAllAndOverride<Roles[]>(
      ROLES_KEY,
      [ctx.getHandler(), ctx.getClass()],
    );
    //for "deny-by-default" when role is wrong or unavailable
    if (!requiredRoles || requiredRoles.length === 0) {
      return true;
    }
    const request = ctx.switchToHttp().getRequest<RequestWithUser>();
    const user = request.user;

    if (!user) {
      return false;
    }
    if (!requiredRoles.includes(user.role)) {
      throw new ForbiddenException(
        `The role ${user.role} is not authorized to access this resource.`,
      );
    }
    return true;
  }
}