import { CanActivate, ExecutionContext, Injectable, UnauthorizedException } from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { AppLogger } from '../../logger';
import { GuardMetadata } from '../enums';
import { DecodedToken } from '../dto';
import { AuthenticationGuardService } from './services';

@Injectable()
export class AuthenticationGuard implements CanActivate {
  private readonly TAG: string = `${this.constructor.name}`;

  constructor(private readonly authenticationGuardService: AuthenticationGuardService,
              private readonly reflector: Reflector) {
    AppLogger.log('Init', this.TAG);
  }

  async canActivate(
    context: ExecutionContext,
  ): Promise<boolean> {
    const request: any = context.switchToHttp().getRequest();
    if (request && request.headers && request.headers.authorization) {
      const cleanJwt: string = request.headers.authorization.substring(7, request.headers.authorization.length);
      const serviceAccountOnly: boolean = this.reflector.get(GuardMetadata.SERVICE_ACCOUNT_ONLY, context.getHandler());
      const decodedToken: DecodedToken = await this.validateRequest(cleanJwt, serviceAccountOnly);
      if (!decodedToken) {
        throw new UnauthorizedException();
      }
      request.token = decodedToken;
      return true;
    }
    throw new UnauthorizedException();
  }

  async validateRequest(token: string, serviceAccountOnly: boolean): Promise<DecodedToken> {
    try {
      const decodedToken: DecodedToken = await this.authenticationGuardService.verify(token, serviceAccountOnly);
      if (!decodedToken) {
        throw new UnauthorizedException();
      }
      return decodedToken;
    } catch (e) {
      AppLogger.error(e, this.TAG);
      throw new UnauthorizedException();
    }
  }

}