/**
 * Creates sentence cased string
 * @param string {string | undefined}
 * @returns {string}
 */
export function capitalize(string) {
  return `${string?.charAt(0).toUpperCase()}${string?.slice(1).toLowerCase()}`;
}

/**
 * Generate documentation snippet for one route
 * @typedef {import('../types.js').RouteMeta} RouteMeta
 *
 * @param routeMeta {RouteMeta} A route instance with its meta information
 * @param schemaName {string} Path to directory that will contain relevant schemas for the route
 * @param tagsToKeep {string[]} Tags / keywords that can be used for grouping routes
 * @returns {import('openapi-types').OpenAPIV3.PathItemObject}
 */
export function generateOpenAPIForRoute({route, description, tags}, schemaName, tagsToKeep) {
  /** @type {(name: string) => ({$ref: string})} */
  const schema = name => ({$ref: `./${schemaName}#/definitions/${name}`});

  /** @type {import('openapi-types').OpenAPIV3.ResponsesObject} */
  const responses = Object.fromEntries(
    route.instance.errorNames
      .map(RouteError => new RouteError())
      .map(error => [
        error.statusCode,
        {
          description:
            error.message ?? capitalize(error.name.replaceAll(/([A-Z][a-z])/g, ' $1').replace('SC ', '')),
          content: {
            'application/json': {
              schema: schema(error.name),
            },
          },
        },
      ]),
  );

  /** @type {import('openapi-types').OpenAPIV3.ParameterObject[]} */
  const parameters = Object.entries(route.instance.obligatoryParameters ?? {}).map(
    ([parameter, schemaDefinition]) => ({
      in: 'path',
      name: parameter,
      required: true,
      schema: schema(schemaDefinition),
    }),
  );

  /** @type {import('openapi-types').OpenAPIV3.OperationObject} */
  const operation = {
    summary: capitalize(description?.replace(/(Route to |Route for )/gim, '')),
    requestBody: {
      description: route.responseBodyDescription ?? undefined,
      content: {
        'application/json': {
          schema: schema(route.instance.requestBodyName),
        },
      },
    },
    parameters: [
      {
        name: 'X-StApps-Version',
        in: 'header',
        schema: {
          type: 'string',
          example: '2.0.0',
        },
        required: true,
      },
      ...parameters,
    ],
    responses: {
      200: {
        description: route.responseBodyDescription,
        content: {
          'application/json': {
            schema: schema(route.instance.responseBodyName),
          },
        },
      },
      ...responses,
    },
    tags: tags?.filter(value => tagsToKeep.includes(value)),
  };

  return {[route.instance.method.toLowerCase()]: operation};
}