[Persistence] Move persistence sources

Move persistence sources into a deeper bundle in preparation for
splitting of persistence into two bundles - one specific to the
Couch adapter, and one for persistence caching generally. This
supports WTD-702, the WARP persistence adapter, which will not
use Couch for persistence but which will want to use the platform-
provided persistence cache.

platform/persistence/couch/src/CouchIndicator.js

@@ -0,0 +1,103 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        // Set of connection states; changing among these states will be
+        // reflected in the indicator's appearance.
+        // CONNECTED: Everything nominal, expect to be able to read/write.
+        // DISCONNECTED: HTTP failed; maybe misconfigured, disconnected.
+        // SEMICONNECTED: Connected to the database, but it reported an error.
+        // PENDING: Still trying to connect, and haven't failed yet.
+        var CONNECTED = {
+                text: "Connected",
+                glyphClass: "ok",
+                description: "Connected to the domain object database."
+            },
+            DISCONNECTED = {
+                text: "Disconnected",
+                glyphClass: "err",
+                description: "Unable to connect to the domain object database."
+            },
+            SEMICONNECTED = {
+                text: "Unavailable",
+                glyphClass: "caution",
+                description: "Database does not exist or is unavailable."
+            },
+            PENDING = {
+                text: "Checking connection..."
+            };
+
+        /**
+         * Indicator for the current CouchDB connection. Polls CouchDB
+         * at a regular interval (defined by bundle constants) to ensure
+         * that the database is available.
+         */
+        function CouchIndicator($http, $interval, PATH, INTERVAL) {
+            // Track the current connection state
+            var state = PENDING;
+
+            // Callback if the HTTP request to Couch fails
+            function handleError(err) {
+                state = DISCONNECTED;
+            }
+
+            // Callback if the HTTP request succeeds. CouchDB may
+            // report an error, so check for that.
+            function handleResponse(response) {
+                var data = response.data;
+                state = data.error ? SEMICONNECTED : CONNECTED;
+            }
+
+            // Try to connect to CouchDB, and update the indicator.
+            function updateIndicator() {
+                $http.get(PATH).then(handleResponse, handleError);
+            }
+
+            // Update the indicator initially, and start polling.
+            updateIndicator();
+            $interval(updateIndicator, INTERVAL);
+
+            return {
+                /**
+                 * Get the glyph (single character used as an icon)
+                 * to display in this indicator. This will return "D",
+                 * which should appear as a database icon.
+                 * @returns {string} the character of the database icon
+                 */
+                getGlyph: function () {
+                    return "D";
+                },
+                /**
+                 * Get the name of the CSS class to apply to the glyph.
+                 * This is used to color the glyph to match its
+                 * state (one of ok, caution or err)
+                 * @returns {string} the CSS class to apply to this glyph
+                 */
+                getGlyphClass: function () {
+                    return state.glyphClass;
+                },
+                /**
+                 * Get the text that should appear in the indicator.
+                 * @returns {string} brief summary of connection status
+                 */
+                getText: function () {
+                    return state.text;
+                },
+                /**
+                 * Get a longer-form description of the current connection
+                 * space, suitable for display in a tooltip
+                 * @returns {string} longer summary of connection status
+                 */
+                getDescription: function () {
+                    return state.description;
+                }
+            };
+
+        }
+
+        return CouchIndicator;
+    }
+);