import {
  Injectable,
  CanActivate,
  ExecutionContext,
  UnauthorizedException,
} from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { ConfigService } from '@nestjs/config';
import { SKIP_API_TOKEN_KEY } from '../decorators/skip-api-token.decorator';
import { IS_PUBLIC_KEY } from '../decorators/public.decorator';

@Injectable()
export class ApiTokenGuard implements CanActivate {
  constructor(
    private reflector: Reflector,
    private configService: ConfigService,
  ) {}

  canActivate(context: ExecutionContext): boolean {
    // Check if API token validation is enabled
    const isEnabled = this.configService.get('API_TOKEN_ENABLED') === 'true';
    if (!isEnabled) {
      return true;
    }

    // Check if route is marked to skip API token validation
    const skipApiToken = this.reflector.getAllAndOverride<boolean>(
      SKIP_API_TOKEN_KEY,
      [context.getHandler(), context.getClass()],
    );

    if (skipApiToken) {
      return true;
    }

    // Check if route is marked as public (optional - you can remove this if you want public routes to still require API token)
    const isPublic = this.reflector.getAllAndOverride<boolean>(IS_PUBLIC_KEY, [
      context.getHandler(),
      context.getClass(),
    ]);

    if (isPublic) {
      return true;
    }

    const request = context.switchToHttp().getRequest();
    const token = request.headers['x-api-token'];

    if (!token) {
      throw new UnauthorizedException(
        'API token is required. Please provide x-api-token header.',
      );
    }

    const validToken = this.configService.get('API_SECRET_TOKEN');

    if (!validToken) {
      throw new UnauthorizedException('API token is not configured on server.');
    }

    if (token !== validToken) {
      throw new UnauthorizedException('Invalid API token.');
    }

    return true;
  }
}