Use indexeddb cache for blobs

www/common/media-tag.js

@@ -1,8 +1,5 @@
-(function(name, definition) {
-    if (typeof module !== 'undefined') { module.exports = definition(); }
-    else if (typeof define === 'function' && typeof define.amd === 'object') { define(definition); }
-    else  { this[name] = definition(); }
-}('MediaTag', function() {
+(function (window) {
+var factory = function (Cache) {
     var cache;
     var cypherChunkLength = 131088;
 
@@ -133,6 +130,12 @@
             cb = function () {};
         };
 
+        var _src = src.replace(/(\/)*$/, ''); // Remove trailing slashes
+        var idx = _src.lastIndexOf('/');
+        var cacheKey = _src.slice(idx+1);
+        if (!/^[a-f0-9]{48}$/.test(cacheKey)) { cacheKey = undefined; }
+
+        var fetch = function () {
             var xhr = new XMLHttpRequest();
             xhr.open('GET', src, true);
             xhr.responseType = 'arraybuffer';
@@ -143,12 +146,30 @@
                 if (/^4/.test('' + this.status)) { return void cb("XHR_ERROR " + this.status); }
 
                 var arrayBuffer = xhr.response;
-            if (arrayBuffer) { cb(null, new Uint8Array(arrayBuffer)); }
+                if (arrayBuffer) {
+                    var u8 = new Uint8Array(arrayBuffer);
+                    if (cacheKey) {
+                        return void Cache.setBlobCache(cacheKey, u8, function (err) {
+                            cb(null, u8);
+                        });
+                    }
+                    cb(null, u8);
+                }
             };
 
             xhr.send(null);
         };
 
+        if (!cacheKey) { return void fetch(); }
+
+        Cache.getBlobCache(cacheKey, function (err, u8) {
+            if (err || !u8) { return void fetch(); }
+            console.error('using cache', cacheKey);
+            cb(null, u8);
+        });
+
+    };
+
     // Decryption tools
     var Decrypt = {
         // Create a nonce
@@ -469,4 +490,19 @@
     };
 
     return init;
-}));
+};
+
+    if (typeof(module) !== 'undefined' && module.exports) {
+        module.exports = factory(
+            require("./outer/cache-store.js")
+        );
+    } else if ((typeof(define) !== 'undefined' && define !== null) && (define.amd !== null)) {
+        define([
+            '/common/outer/cache-store.js',
+        ], function (Cache) {
+            return factory(Cache);
+        });
+    } else {
+        // unsupported initialization
+    }
+}(typeof(window) !== 'undefined'? window : {}));

www/common/outer/cache-store.js

@@ -8,6 +8,28 @@ define([
         name: "cp_cache"
     });
 
+    S.getBlobCache = function (id, cb) {
+        cb = Util.once(Util.mkAsync(cb || function () {}));
+        cache.getItem(id, function (err, obj) {
+            if (err || !obj || !obj.c) {
+                return void cb(err || 'EINVAL');
+            }
+            cb(null, obj.c);
+            obj.t = +new Date();
+            cache.setItem(id, obj);
+        });
+    };
+    S.setBlobCache = function (id, u8, cb) {
+        cb = Util.once(Util.mkAsync(cb || function () {}));
+        if (!u8) { return void cb('EINVAL'); }
+        cache.setItem(id, {
+            c: u8,
+            t: (+new Date()) // 't' represent the "lastAccess" of this cache (get or set)
+        }, function (err) {
+            cb(err);
+        });
+    };
+
     // id: channel ID or blob ID
     // returns array of messages
     S.getChannelCache = function (id, cb) {