lib/android/exec.js

/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
*/

/**
 * Execute a cordova command.  It is up to the native side whether this action
 * is synchronous or asynchronous.  The native side can return:
 *      Synchronous: PluginResult object as a JSON string
 *      Asynchronous: Empty string ""
 * If async, the native side will cordova.callbackSuccess or cordova.callbackError,
 * depending upon the result of the action.
 *
 * @param {Function} success    The success callback
 * @param {Function} fail       The fail callback
 * @param {String} service      The name of the service to use
 * @param {String} action       Action to be run in cordova
 * @param {String[]} [args]     Zero or more arguments to pass to the method
 */
var cordova = require('cordova'),
    nativeApiProvider = require('cordova/android/nativeapiprovider'),
    utils = require('cordova/utils'),
    base64 = require('cordova/base64'),
    jsToNativeModes = {
        PROMPT: 0,
        JS_OBJECT: 1,
        // This mode is currently for benchmarking purposes only. It must be enabled
        // on the native side through the ENABLE_LOCATION_CHANGE_EXEC_MODE
        // constant within CordovaWebViewClient.java before it will work.
        LOCATION_CHANGE: 2
    },
    nativeToJsModes = {
        // Polls for messages using the JS->Native bridge.
        POLLING: 0,
        // For LOAD_URL to be viable, it would need to have a work-around for
        // the bug where the soft-keyboard gets dismissed when a message is sent.
        LOAD_URL: 1,
        // For the ONLINE_EVENT to be viable, it would need to intercept all event
        // listeners (both through addEventListener and window.ononline) as well
        // as set the navigator property itself.
        ONLINE_EVENT: 2,
        // Uses reflection to access private APIs of the WebView that can send JS
        // to be executed.
        // Requires Android 3.2.4 or above.
        PRIVATE_API: 3
    },
    jsToNativeBridgeMode,  // Set lazily.
    nativeToJsBridgeMode = nativeToJsModes.ONLINE_EVENT,
    pollEnabled = false,
    messagesFromNative = [];

function androidExec(success, fail, service, action, args) {
    // Set default bridge modes if they have not already been set.
    // By default, we use the failsafe, since addJavascriptInterface breaks too often
    if (jsToNativeBridgeMode === undefined) {
        androidExec.setJsToNativeBridgeMode(jsToNativeModes.JS_OBJECT);
    }

    // Process any ArrayBuffers in the args into a string.
    for (var i = 0; i < args.length; i++) {
        if (utils.typeName(args[i]) == 'ArrayBuffer') {
            args[i] = base64.fromArrayBuffer(args[i]);
        }
    }

    var callbackId = service + cordova.callbackId++,
        argsJson = JSON.stringify(args);

    if (success || fail) {
        cordova.callbacks[callbackId] = {success:success, fail:fail};
    }

    if (jsToNativeBridgeMode == jsToNativeModes.LOCATION_CHANGE) {
        window.location = 'http://cdv_exec/' + service + '#' + action + '#' + callbackId + '#' + argsJson;
    } else {
        var messages = nativeApiProvider.get().exec(service, action, callbackId, argsJson);
        // If argsJson was received by Java as null, try again with the PROMPT bridge mode.
        // This happens in rare circumstances, such as when certain Unicode characters are passed over the bridge on a Galaxy S2.  See CB-2666.
        if (jsToNativeBridgeMode == jsToNativeModes.JS_OBJECT && messages === "@Null arguments.") {
            androidExec.setJsToNativeBridgeMode(jsToNativeModes.PROMPT);
            androidExec(success, fail, service, action, args);
            androidExec.setJsToNativeBridgeMode(jsToNativeModes.JS_OBJECT);
            return;
        } else {
            androidExec.processMessages(messages);
        }
    }
}

function pollOnceFromOnlineEvent() {
    pollOnce(true);
}

function pollOnce(opt_fromOnlineEvent) {
    var msg = nativeApiProvider.get().retrieveJsMessages(!!opt_fromOnlineEvent);
    androidExec.processMessages(msg);
}

function pollingTimerFunc() {
    if (pollEnabled) {
        pollOnce();
        setTimeout(pollingTimerFunc, 50);
    }
}

function hookOnlineApis() {
    function proxyEvent(e) {
        cordova.fireWindowEvent(e.type);
    }
    // The network module takes care of firing online and offline events.
    // It currently fires them only on document though, so we bridge them
    // to window here (while first listening for exec()-releated online/offline
    // events).
    window.addEventListener('online', pollOnceFromOnlineEvent, false);
    window.addEventListener('offline', pollOnceFromOnlineEvent, false);
    cordova.addWindowEventHandler('online');
    cordova.addWindowEventHandler('offline');
    document.addEventListener('online', proxyEvent, false);
    document.addEventListener('offline', proxyEvent, false);
}

hookOnlineApis();

androidExec.jsToNativeModes = jsToNativeModes;
androidExec.nativeToJsModes = nativeToJsModes;

androidExec.setJsToNativeBridgeMode = function(mode) {
    if (mode == jsToNativeModes.JS_OBJECT && !window._cordovaNative) {
        console.log('Falling back on PROMPT mode since _cordovaNative is missing. Expected for Android 3.2 and lower only.');
        mode = jsToNativeModes.PROMPT;
    }
    nativeApiProvider.setPreferPrompt(mode == jsToNativeModes.PROMPT);
    jsToNativeBridgeMode = mode;
};

androidExec.setNativeToJsBridgeMode = function(mode) {
    if (mode == nativeToJsBridgeMode) {
        return;
    }
    if (nativeToJsBridgeMode == nativeToJsModes.POLLING) {
        pollEnabled = false;
    }

    nativeToJsBridgeMode = mode;
    // Tell the native side to switch modes.
    nativeApiProvider.get().setNativeToJsBridgeMode(mode);

    if (mode == nativeToJsModes.POLLING) {
        pollEnabled = true;
        setTimeout(pollingTimerFunc, 1);
    }
};

// Processes a single message, as encoded by NativeToJsMessageQueue.java.
function processMessage(message) {
    try {
        var firstChar = message.charAt(0);
        if (firstChar == 'J') {
            eval(message.slice(1));
        } else if (firstChar == 'S' || firstChar == 'F') {
            var success = firstChar == 'S';
            var keepCallback = message.charAt(1) == '1';
            var spaceIdx = message.indexOf(' ', 2);
            var status = +message.slice(2, spaceIdx);
            var nextSpaceIdx = message.indexOf(' ', spaceIdx + 1);
            var callbackId = message.slice(spaceIdx + 1, nextSpaceIdx);
            var payloadKind = message.charAt(nextSpaceIdx + 1);
            var payload;
            if (payloadKind == 's') {
                payload = message.slice(nextSpaceIdx + 2);
            } else if (payloadKind == 't') {
                payload = true;
            } else if (payloadKind == 'f') {
                payload = false;
            } else if (payloadKind == 'N') {
                payload = null;
            } else if (payloadKind == 'n') {
                payload = +message.slice(nextSpaceIdx + 2);
            } else if (payloadKind == 'A') {
                var data = message.slice(nextSpaceIdx + 2);
                var bytes = window.atob(data);
                var arraybuffer = new Uint8Array(bytes.length);
                for (var i = 0; i < bytes.length; i++) {
                    arraybuffer[i] = bytes.charCodeAt(i);
                }
                payload = arraybuffer.buffer;
            } else if (payloadKind == 'S') {
                payload = window.atob(message.slice(nextSpaceIdx + 2));
            } else {
                payload = JSON.parse(message.slice(nextSpaceIdx + 1));
            }
            cordova.callbackFromNative(callbackId, success, status, [payload], keepCallback);
        } else {
            console.log("processMessage failed: invalid message:" + message);
        }
    } catch (e) {
        console.log("processMessage failed: Message: " + message);
        console.log("processMessage failed: Error: " + e);
        console.log("processMessage failed: Stack: " + e.stack);
    }
}

// This is called from the NativeToJsMessageQueue.java.
androidExec.processMessages = function(messages) {
    if (messages) {
        messagesFromNative.push(messages);
        // Check for the reentrant case, and enqueue the message if that's the case.
        if (messagesFromNative.length > 1) {
            return;
        }
        while (messagesFromNative.length) {
            // Don't unshift until the end so that reentrancy can be detected.
            messages = messagesFromNative[0];
            // The Java side can send a * message to indicate that it
            // still has messages waiting to be retrieved.
            if (messages == '*') {
                messagesFromNative.shift();
                window.setTimeout(pollOnce, 0);
                return;
            }

            var spaceIdx = messages.indexOf(' ');
            var msgLen = +messages.slice(0, spaceIdx);
            var message = messages.substr(spaceIdx + 1, msgLen);
            messages = messages.slice(spaceIdx + msgLen + 1);
            processMessage(message);
            if (messages) {
                messagesFromNative[0] = messages;
            } else {
                messagesFromNative.shift();
            }
        }
    }
};

module.exports = androidExec;