WIP serviceworker storage prototype

src/jio.storage/serviceworkerstorage.js

+/**
+ * JIO Service Worker Storage Type = "serviceworker".
+ * Servieworker "filesystem" storage.
+ */
+/*global Blob, jIO, RSVP, navigator MessageChannel*/
+/*jslint indent: 2 nomen: true maxerr: 3*/
+
+(function (jIO, RSVP, navigator) {
+  "use strict";
+
+  // no need to validate attachment name, because serviceworker.js will throw
+  function restrictDocumentId(id) {
+    if (id.indexOf("/") > -1) {
+      throw new jIO.util.jIOError("id should be a name, not a path)", 400);
+    }
+    return id;
+  }
+
+  // validate browser support, serviceworker registration must be done in gadget
+  function validateConnection() {
+    if ("serviceWorker" in navigator === false) {
+      throw new jIO.util.jIOError("Serviceworker not available in browser", 503);
+    }
+  }
+
+  // This wraps the message posting/response in a promise, which will resolve if
+  // the response doesn't contain an error, and reject with the error if it does.
+  // Alternatively, onmessage handle and controller.postMessage() could be used
+  function sendMessage(message) {
+    return new RSVP.Promise(function (resolve, reject, notify) {
+      var messageChannel = new MessageChannel();
+      messageChannel.port1.onmessage = function (event) {
+        if (event.data.error) {
+          reject(event.data.error);
+        } else {
+          resolve(event.data.data);
+        }
+      };
+
+      // This sends the message data as well as transferring
+      // messageChannel.port2 to the service worker. The service worker can then
+      // use the transferred port to reply via postMessage(), which will in turn
+      // trigger the onmessage handler on messageChannel.port1.
+      // See https://html.spec.whatwg.org/multipage/workers.html
+      return navigator.serviceWorker.controller
+        .postMessage(message, [messageChannel.port2]);
+    });
+  }
+
+  /**
+   * The JIO Serviceworker Storage extension
+   *
+   * @class ServiceWorkerStorage
+   * @constructor
+   */
+  function ServiceWorkerStorage () {}
+
+  ServiceWorkerStorage.prototype.post = function () {
+    throw new jIO.util.jIOError("Storage requires 'put' to create new cache",
+                                400);
+  };
+
+  ServiceWorkerStorage.prototype.get = function (id) {
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "get",
+          id: restrictDocumentId(id)
+        });
+      })
+      .push(undefined, function (error) {
+        if (error.status === 404) {
+          throw new jIO.util.jIOError(error.message, 404);
+        }
+        throw error;
+      });
+  };
+
+  ServiceWorkerStorage.prototype.put = function (id) {
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "get",
+          id: restrictDocumentId(id)
+        });
+      })
+      .push(undefined, function (error) {
+        if (error.status === 404) {
+          return new RSVP.Queue()
+            .push(function () {
+              return sendMessage({
+                command: "put",
+                id: id
+              });
+            });
+          }
+          throw error;
+      });
+  };
+
+  ServiceWorkerStorage.prototype.remove = function (id) {
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "allAttachments",
+          id: restrictDocumentId(id)
+        });
+      })
+      .push(function (attachment_dict) {
+        var url_list = [],
+          url;
+        for (url in attachment_dict) {
+          if (attachment_dict.hasOwnProperty(url)) {
+            url_list.append(sendMessage({
+              command: "removeAttachment",
+              id: url
+            }));
+          }
+        }
+        return RSVP.all(url_list);
+      })
+      .push(function () {
+        return sendMessage({
+          command: "remove",
+          id: restrictDocumentId(id)
+        });
+      });
+  };
+
+  ServiceWorkerStorage.prototype.removeAttachment = function (id, url) {
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "removeAttachment",
+          id: restrictDocumentId(id),
+          name: url
+        });
+      });
+  };
+
+  ServiceWorkerStorage.prototype.getAttachment = function (id, url) {
+
+    // NOTE: alternatively get could also be run "official" way via
+    // an ajax request, which the serviceworker would catch via fetch listener!
+    // for a filesystem equivalent however, we don't assume fetching resources
+    // from the network, so all methods will go through sendMessage
+
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "getAttachment",
+          id: restrictDocumentId(id),
+          name: url
+        });
+      })
+      .push(function (my_blob_response) {
+        return my_blob_response;
+      });
+  };
+
+  ServiceWorkerStorage.prototype.putAttachment = function (id, name, param) {
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "putAttachment",
+          id: id,
+          name: name,
+          content: param
+        });
+      });
+  };
+
+  ServiceWorkerStorage.prototype.allAttachments = function (id) {
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "allAttachments",
+          id: restrictDocumentId(id)
+        });
+      });
+  };
+
+  ServiceWorkerStorage.prototype.hasCapacity = function (name) {
+    return (name === "list");
+  };
+
+  // returns a list of all caches ~ folders
+  ServiceWorkerStorage.prototype.allDocs = function (options) {
+    var context = this;
+
+    if (options === undefined) {
+      options = {};
+    }
+
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        if (context.hasCapacity("list")) {
+          return context.buildQuery(options);
+        }
+      })
+      .push(function (result) {
+        return result;
+      });
+  };
+
+  ServiceWorkerStorage.prototype.buildQuery = function (options) {
+    return new RSVP.Queue()
+      .push(function () {
+        return validateConnection();
+      })
+      .push(function () {
+        return sendMessage({
+          command: "allDocs",
+          options: options
+        });
+      });
+  };
+
+  jIO.addStorage("serviceworker", ServiceWorkerStorage);
+
+}(jIO, RSVP, navigator, MessageChannel));