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JS/StateManager.js

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+////////////////////////////////////////////////////////////
+////   © Microsoft. All rights reserved.                ////
+////////////////////////////////////////////////////////////
+
+/// <reference path="Global.js"/>
+/// <reference path="Utilities.js"/>
+
+(function (AppNS) {
+
+    // Error strings for logging purposes
+    var invalidKeyError = "Invalid argument: The specified key is not a non-empty string.";
+    var invalidValueError = "Invalid argument: The specified value is not valid.";
+    var storeValueError = "Error storing value '{0}' for key '{1}': '{2}'";
+    var getValueError = "Error getting value for key '{0}': '{1}'";
+    var removeError = "Error removing key '{0}': '{1}'";
+
+    // Local scope objects
+    var emptyFunction = function () {};
+    var localSettings = Windows.Storage.ApplicationData.current.localSettings.values;
+
+    // Etw with default noop handlers
+    var etw = {
+        stateManagerStoreValueStart: emptyFunction,
+        stateManagerStoreValueEnd: emptyFunction,
+        stateManagerGetValueStart: emptyFunction,
+        stateManagerGetValueEnd: emptyFunction
+    };
+
+    function validateKey(key) {
+        /// <summary>
+        /// Check if the given key is a non-empty string
+        /// </summary>
+        return (typeof key === "string" && key !== "");
+    };
+
+    /// <summary>
+    /// Static methods for manipulating persisted states in key/value pairs
+    /// </summary>
+    WinJS.Namespace.defineWithParent(AppNS, "StateManager", {
+        storeValue: function (key, value) {
+            /// <summary>
+            /// Stores the given key/value pair
+            /// </summary>
+            /// <param name='key'>
+            /// The name of the key the value is associated with
+            /// </param>
+            /// <param name='value'>
+            /// The value to store
+            /// </param>
+            /// <returns>
+            /// true if successful; false otherwise.
+            /// </returns>
+            if (!validateKey(key)) {
+                throw new Error(invalidKeyError);
+            }
+
+            if (value === undefined || value === null) {
+                throw new Error(invalidValueError);
+            }
+
+            etw.stateManagerStoreValueStart(key);
+
+            var succeeded = false;
+
+            try {
+                var valueToStore = "";
+
+                if (typeof value === "object") {
+                    valueToStore = JSON.stringify(value);
+                } else {
+                    valueToStore = value.toString();
+                }
+
+                localSettings.insert(key, valueToStore);
+
+                succeeded = true;
+            } catch (error) {
+                window.console.log("StateManager.storeValue", storeValueError.format([value, key, error]));
+            }
+
+            etw.stateManagerStoreValueEnd(key);
+
+            return succeeded;
+        },
+
+        getValueAsString: function (key) {
+            /// <summary>
+            /// Retrieves the value for the given key
+            /// </summary>
+            /// <param name='key'>
+            /// The name of the key to retrieve the value
+            /// </param>
+            /// <returns>
+            /// The string value associated with the given key,
+            /// or null if the key is not found or error.
+            /// </returns>
+            if (!validateKey(key)) {
+                throw new Error(invalidKeyError);
+            }
+
+            etw.stateManagerGetValueStart(key);
+
+            var value = null;
+
+            try {
+                value = localSettings.lookup(key);
+            } catch (error) {
+                window.console.log("StateManager.getValueAsString", getValueError.format([key, error]));
+            }
+
+            etw.stateManagerGetValueEnd(key);
+
+            return value;
+        },
+
+        getValueAsObject: function (key) {
+            /// <summary>
+            /// Retrieves the value for the given key and returns it as a JSON object
+            /// </summary>
+            /// <param name='key'>
+            /// The name of the key to retrieve the value
+            /// </param>
+            /// <returns>
+            /// The JSON value associated with the given key,
+            /// or null if the key is not found or error.
+            /// </returns>
+            if (!validateKey(key)) {
+                throw new Error(invalidKeyError);
+            }
+
+            etw.stateManagerGetValueStart(key);
+
+            var value = null;
+
+            try {
+                value = JSON.parse(localSettings.lookup(key));
+            } catch (error) {
+                window.console.log("StateManager.getValueAsObject", getValueError.format([key, error]));
+            }
+
+            etw.stateManagerGetValueEnd(key);
+
+            return value;
+        },
+
+        remove: function (key) {
+            /// <summary>
+            /// Removes the given key from the store
+            /// </summary>
+            /// <param name='key'>
+            /// The name of the key to be removed
+            /// </param>
+            /// <returns>
+            /// true if the key is successfully removed or not present; false otherwise.
+            /// </returns>
+            if (!validateKey(key)) {
+                throw new Error(invalidKeyError);
+            }
+
+            var succeeded = false;
+
+            try {
+                localSettings.remove(key);
+                succeeded = true;
+            } catch (error) {
+                window.console.log("StateManager.remove", removeError.format([key, error]));
+            }
+
+            return succeeded;
+        },
+
+        clear: function () {
+            /// <summary>
+            /// Clear all settings
+            /// </summary>
+            localSettings.clear();
+        },
+
+        init: function (etwProvider) {
+            /// <summary>
+            /// Initializes state manager
+            /// </summary>
+            /// <param name='etwProvider'>
+            /// etwProvider is a reference to the ETW provider for logging events.
+            /// </param>
+            if (etwProvider) {
+                etw.stateManagerStoreValueStart = etwProvider.stateManagerStoreValueStart || etw.stateManagerStoreValueStart;
+                etw.stateManagerStoreValueEnd = etwProvider.stateManagerStoreValueEnd || etw.stateManagerStoreValueEnd;
+                etw.stateManagerGetValueStart = etwProvider.stateManagerGetValueStart || etw.stateManagerGetValueStart;
+                etw.stateManagerGetValueEnd = etwProvider.stateManagerGetValueEnd || etw.stateManagerGetValueEnd;
+            }
+        }
+    });
+})(Microsoft.Paint);