localForage-IDBonly-toolkitport.js

const {Cc, Ci, Cu, Cr} = require("chrome");
Cu.importGlobalProperties(["indexedDB"]);
const {Promise} = Cu.import("resource://gre/modules/Promise.jsm", {});

/*!
    localForage -- Offline Storage, Improved
    Version 1.2.2
    https://mozilla.github.io/localForage
    (c) 2013-2015 Mozilla, Apache License 2.0
*/
module.exports = (function() {

    "use strict";

    // Some code originally from async_storage.js in
    // [Gaia](https://github.com/mozilla-b2g/gaia).
    // Originally found in https://github.com/mozilla-b2g/gaia/blob/e8f624e4cc9ea945727278039b3bc9bcb9f8667a/shared/js/async_storage.js

    // Open the IndexedDB database (automatically creates one if one didn't
    // previously exist), using any options set in the config.
    function _initStorage(options) {
        var self = this;
        var dbInfo = {
            db: null
        };
        if (options) {
            for (var i in options) {
                dbInfo[i] = options[i];
            }
        }

        return new Promise(function(resolve, reject) {
            var openreq = indexedDB.open(dbInfo.name, dbInfo.version);
            openreq.onerror = function() {
                reject(openreq.error);
            };
            openreq.onupgradeneeded = function() {
                // First time setup: create an empty object store
                openreq.result.createObjectStore(dbInfo.storeName);
            };
            openreq.onsuccess = function() {
                dbInfo.db = openreq.result;
                self._dbInfo = dbInfo;
                resolve();
            };
        });
    }

    function getItem(key, callback) {
        var self = this;

        // Cast the key to a string, as that's all we can set as a key.
        if (typeof key !== 'string') {
            window.console.warn(key +
                                ' used as a key, but it is not a string.');
            key = String(key);
        }

        var promise = new Promise(function(resolve, reject) {
            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var store = dbInfo.db.transaction(dbInfo.storeName, 'readonly')
                    .objectStore(dbInfo.storeName);
                var req = store.get(key);

                req.onsuccess = function() {
                    var value = req.result;
                    if (value === undefined) {
                        value = null;
                    }

                    resolve(value);
                };

                req.onerror = function() {
                    reject(req.error);
                };
            })["catch"](reject);
        });

        executeDeferedCallback(promise, callback);
        return promise;
    }

    // Iterate over all items stored in database.
    function iterate(iterator, callback) {
        var self = this;

        var promise = new Promise(function(resolve, reject) {
            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var store = dbInfo.db.transaction(dbInfo.storeName, 'readonly')
                                     .objectStore(dbInfo.storeName);

                var req = store.openCursor();
                var iterationNumber = 1;

                req.onsuccess = function() {
                    var cursor = req.result;

                    if (cursor) {
                        var result = iterator(cursor.value, cursor.key, iterationNumber++);

                        if (result !== void(0)) {
                            resolve(result);
                        } else {
                            cursor["continue"]();
                        }
                    } else {
                        resolve();
                    }
                };

                req.onerror = function() {
                    reject(req.error);
                };
            })["catch"](reject);
        });

        executeDeferedCallback(promise, callback);

        return promise;
    }

    function setItem(key, value, callback) {
        var self = this;

        // Cast the key to a string, as that's all we can set as a key.
        if (typeof key !== 'string') {
            window.console.warn(key +
                                ' used as a key, but it is not a string.');
            key = String(key);
        }

        var promise = new Promise(function(resolve, reject) {
            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var transaction = dbInfo.db.transaction(dbInfo.storeName, 'readwrite');
                var store = transaction.objectStore(dbInfo.storeName);

                // The reason we don't _save_ null is because IE 10 does
                // not support saving the `null` type in IndexedDB. How
                // ironic, given the bug below!
                // See: https://github.com/mozilla/localForage/issues/161
                if (value === null) {
                    value = undefined;
                }

                var req = store.put(value, key);
                transaction.oncomplete = function() {
                    // Cast to undefined so the value passed to
                    // callback/promise is the same as what one would get out
                    // of `getItem()` later. This leads to some weirdness
                    // (setItem('foo', undefined) will return `null`), but
                    // it's not my fault localStorage is our baseline and that
                    // it's weird.
                    if (value === undefined) {
                        value = null;
                    }

                    resolve(value);
                };
                transaction.onabort = transaction.onerror = function() {
                    reject(req.error);
                };
            })["catch"](reject);
        });

        executeDeferedCallback(promise, callback);
        return promise;
    }

    function removeItem(key, callback) {
        var self = this;

        // Cast the key to a string, as that's all we can set as a key.
        if (typeof key !== 'string') {
            window.console.warn(key +
                                ' used as a key, but it is not a string.');
            key = String(key);
        }

        var promise = new Promise(function(resolve, reject) {
            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var transaction = dbInfo.db.transaction(dbInfo.storeName, 'readwrite');
                var store = transaction.objectStore(dbInfo.storeName);

                // We use a Grunt task to make this safe for IE and some
                // versions of Android (including those used by Cordova).
                // Normally IE won't like `.delete()` and will insist on
                // using `['delete']()`, but we have a build step that
                // fixes this for us now.
                var req = store["delete"](key);
                transaction.oncomplete = function() {
                    resolve();
                };

                transaction.onerror = function() {
                    reject(req.error);
                };

                // The request will be aborted if we've exceeded our storage
                // space. In this case, we will reject with a specific
                // "QuotaExceededError".
                transaction.onabort = function(event) {
                    var error = event.target.error;
                    if (error === 'QuotaExceededError') {
                        reject(error);
                    }
                };
            })["catch"](reject);
        });

        executeDeferedCallback(promise, callback);
        return promise;
    }

    function clear(callback) {
        var self = this;

        var promise = new Promise(function(resolve, reject) {
            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var transaction = dbInfo.db.transaction(dbInfo.storeName, 'readwrite');
                var store = transaction.objectStore(dbInfo.storeName);
                var req = store.clear();

                transaction.oncomplete = function() {
                    resolve();
                };

                transaction.onabort = transaction.onerror = function() {
                    reject(req.error);
                };
            })["catch"](reject);
        });

        executeDeferedCallback(promise, callback);
        return promise;
    }

    function length(callback) {
        var self = this;

        var promise = new Promise(function(resolve, reject) {
            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var store = dbInfo.db.transaction(dbInfo.storeName, 'readonly')
                              .objectStore(dbInfo.storeName);
                var req = store.count();

                req.onsuccess = function() {
                    resolve(req.result);
                };

                req.onerror = function() {
                    reject(req.error);
                };
            })["catch"](reject);
        });

        executeCallback(promise, callback);
        return promise;
    }

    function key(n, callback) {
        var self = this;

        var promise = new Promise(function(resolve, reject) {
            if (n < 0) {
                resolve(null);

                return;
            }

            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var store = dbInfo.db.transaction(dbInfo.storeName, 'readonly')
                              .objectStore(dbInfo.storeName);

                var advanced = false;
                var req = store.openCursor();
                req.onsuccess = function() {
                    var cursor = req.result;
                    if (!cursor) {
                        // this means there weren't enough keys
                        resolve(null);

                        return;
                    }

                    if (n === 0) {
                        // We have the first key, return it if that's what they
                        // wanted.
                        resolve(cursor.key);
                    } else {
                        if (!advanced) {
                            // Otherwise, ask the cursor to skip ahead n
                            // records.
                            advanced = true;
                            cursor.advance(n);
                        } else {
                            // When we get here, we've got the nth key.
                            resolve(cursor.key);
                        }
                    }
                };

                req.onerror = function() {
                    reject(req.error);
                };
            })["catch"](reject);
        });

        executeCallback(promise, callback);
        return promise;
    }

    function keys(callback) {
        var self = this;

        var promise = new Promise(function(resolve, reject) {
            self.ready().then(function() {
                var dbInfo = self._dbInfo;
                var store = dbInfo.db.transaction(dbInfo.storeName, 'readonly')
                              .objectStore(dbInfo.storeName);

                var req = store.openCursor();
                var keys = [];

                req.onsuccess = function() {
                    var cursor = req.result;

                    if (!cursor) {
                        resolve(keys);
                        return;
                    }

                    keys.push(cursor.key);
                    cursor["continue"]();
                };

                req.onerror = function() {
                    reject(req.error);
                };
            })["catch"](reject);
        });

        executeCallback(promise, callback);
        return promise;
    }

    function executeCallback(promise, callback) {
        if (callback) {
            promise.then(function(result) {
                callback(null, result);
            }, function(error) {
                callback(error);
            });
        }
    }

    function executeDeferedCallback(promise, callback) {
        if (callback) {
            promise.then(function(result) {
                deferCallback(callback, result);
            }, function(error) {
                callback(error);
            });
        }
    }

    // Under Chrome the callback is called before the changes (save, clear)
    // are actually made. So we use a defer function which wait that the
    // call stack to be empty.
    // For more info : https://github.com/mozilla/localForage/issues/175
    // Pull request : https://github.com/mozilla/localForage/pull/178
    function deferCallback(callback, result) {
        if (callback) {
            return setTimeout(function() {
                return callback(null, result);
            }, 0);
        }
    }

    var asyncStorage = {
        _driver: 'asyncStorage',
        _initStorage: _initStorage,
        iterate: iterate,
        getItem: getItem,
        setItem: setItem,
        removeItem: removeItem,
        clear: clear,
        length: length,
        key: key,
        keys: keys
    };

    // Create an object to interface similarly to localForage.
    // We don't need the full-blown object, since we are only
    // ever going to use the idb driver.
    function localForageShim() {
    }
    localForageShim.prototype = {
        _ready: null,
        _dbInfo: null,
        _driver: 'asyncStorage',
        _initStorage: _initStorage,
        iterate: iterate,
        getItem: getItem,
        setItem: setItem,
        removeItem: removeItem,
        clear: clear,
        length: length,
        key: key,
        keys: keys
    };
    localForageShim.prototype.ready = function() {
      var ready;;
      if (!this._ready) {
          ready = this._initStorage({
            name: "devtools-async-storage",
            version: 1,
            storeName: "key-values",
          });
      console.log("Here", ready,  this._initStorage);
      }
      return this._ready;
    };

    return new localForageShim();
})();