SolutionsUtils.js

/*
 * GPII Solutions Utils - Independent helper functions and utilities for working with
 * solutions and their schemas.
 *
 * Copyright 2019 Raising the Floor - US
 *
 * Licensed under the New BSD license. You may not use this file except in
 * compliance with this License.
 *
 * The research leading to these results has received funding from the European Union's
 * Seventh Framework Programme (FP7/2007-2013)
 * under grant agreement no. 289016.
 *
 * You may obtain a copy of the License at
 * https://github.com/GPII/universal/blob/master/LICENSE.txt
 */
"use strict";
var fluid = require("infusion");
var gpii  = fluid.registerNamespace("gpii");

fluid.registerNamespace("gpii.universal.solutionsRegistry");

/**
 * This function will take a schema from a supported setting in the solutions
 * registry and return metadata on it's default value, including the type of
 * the default value. The function will always return a block of json in order
 * to avoid any ambiguities for a situation where the default value is perhaps
 * `null`. A key `hasDefault` will be `true` or `false` to communicate this.
 * If the schema does have a default value, then the properties `type` and
 * `default` can also be included. Note that there may not always be a `type`
 * that can be included, the inclusion of this in the return if optional and
 * will be included if a `type` is declared.
 *
 * This is NOT meant to be an exhaustive coverage of all the possible ways
 * default values can be set for any JSON Schema. We merely want to cover the
 * cases in use in the solutions registry, focussing on single primitive values,
 * and situations where we next one level deep due to a requirement of having a
 * `properties` entry in the schema.
 *
 * @param {Object} schema - Schema to search for a default value. This is what
 * would be in the solutions registry under `supportedSettings` and a
 * configuration. An example from the Windows Mouse Keys MaxSpeed setting is:
 * ```json
 * {
 *     "title": "Mouse keys speed",
 *     "description": "Speed of mouse keys",
 *     "type": "number",
 *     "multipleOf": 10,
 *     "default": 80
 * }
 * ```
 * @return {Object} Always returns a json block. For the example above the
 * return value would be:
 * ```json
 * {
 *     "hasDefault": true,
 *     "type": "number",
 *     "default": 80
 * }
 * ```
 * If a default value cannot be detected the return payload will be:
 * ```json
 * {
 *     "hasDefault": false
 * }
 * ```
 */
gpii.universal.solutionsRegistry.findDefaultValue = function (schema) {
    var togo;

    // 1. The most simple, and hopefull case is that there is a top level
    //    default value.
    if (schema["default"] !== undefined) {
        togo = {
            hasDefault: true,
            default: schema["default"]
        };
        if (schema.type) {
            togo.type = schema.type;
        }
    }
    // 2. Sometimes we have a properties structure that can be interogated, example:
    // "properties": {
    //    "path": { "type":  "string"},
    //     "value": {
    //         "type": "string",
    //         "default": "%SystemRoot%\\Web\\Wallpaper\\Windows\\img0.jpg"
    //     }
    // }
    else if (schema.properties && schema.properties.value && schema.properties.value["default"] !== undefined) {
        togo = {
            hasDefault: true,
            default: schema.properties.value["default"]
        };
        if (schema.properties.value.type) {
            togo.type = schema.properties.value.type;
        }
    }
    // We cannot find a default value for our simplified usage of json schema...
    else {
        togo = {
            hasDefault: false
        };
    }

    return togo;
};