/*
 * Copyright 2025 Commonwealth Scientific and Industrial Research
 * Organisation (CSIRO) ABN 41 687 119 230.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import type { OperationOutcomeIssue, QuestionnaireResponse } from 'fhir/r4';
import type {
  CustomContextResultParameter,
  OutputParameters,
  ResponseParameter
} from '../interfaces';
import { Base64 } from 'js-base64';

/**
 * Create output parameters as a response to be returned to the renderer. If they are issues, return with an issues parameter.
 * Encodes context results as a base64 JSON attachment for downstream use.
 */
export function createOutputParameters(
  questionnaireResponse: QuestionnaireResponse,
  issues: OperationOutcomeIssue[],
  contextResult: Record<string, any>
): OutputParameters {
  const responseParameter: ResponseParameter = {
    name: 'response',
    resource: questionnaireResponse
  };

  const customContextResultParameter: CustomContextResultParameter = {
    name: 'contextResult-custom',
    valueAttachment: {
      contentType: 'application/json',
      data: Base64.encode(JSON.stringify(contextResult))
    }
  };

  // No issues to report
  if (issues.length === 0) {
    return {
      resourceType: 'Parameters',
      parameter: [responseParameter, customContextResultParameter]
    };
  }

  // There are issues, so include issues parameter
  return {
    resourceType: 'Parameters',
    parameter: [
      responseParameter,
      {
        name: 'issues',
        resource: {
          resourceType: 'OperationOutcome',
          issue: issues
        }
      },
      customContextResultParameter
    ]
  };
}