define([
    "jquery",
    "underscore",
    "utils",
    "settings",
    "extensions/button-sync",
    "extensions/button-publish",
    "extensions/button-share",
    "extensions/button-stat",
    "extensions/document-selector",
    "extensions/document-title",
    "extensions/manage-publication",
    "extensions/manage-synchronization",
    "extensions/working-indicator",
    "extensions/notifications",
    "extensions/markdown-extra",
    "extensions/toc",
    "extensions/math-jax",
    "extensions/email-converter",
    "extensions/scroll-link",
    "lib/bootstrap"
], function($, _, utils, settings) {

    var extensionMgr = {};

    // Create a list of extensions
    var extensionList = _.chain(arguments).map(function(argument) {
        return _.isObject(argument) && argument.extensionId && argument;
    }).compact().value();

    // Return every named callbacks implemented in extensions
    function getExtensionCallbackList(hookName) {
        return _.chain(extensionList).map(function(extension) {
            return extension.config.enabled && extension[hookName];
        }).compact().value();
    }

    // Return a function that calls every callbacks from extensions
    function createHook(hookName) {
        var callbackList = getExtensionCallbackList(hookName);
        return function() {
            logger.debug(hookName, arguments);
            var callbackArguments = arguments;
            _.each(callbackList, function(callback) {
                callback.apply(null, callbackArguments);
            });
        };
    }

    // Add a Hook to the extensionMgr
    function addHook(hookName) {
        extensionMgr[hookName] = createHook(hookName);
    }

    // Set extension config
    extensionSettings = settings.extensionSettings || {};
    _.each(extensionList, function(extension) {
        extension.config = _.extend({}, extension.defaultConfig, extensionSettings[extension.extensionId]);
        extension.config.enabled = !extension.optional || extension.config.enabled === undefined || extension.config.enabled === true;
    });

    // Load/Save extension config from/to settings
    extensionMgr["onLoadSettings"] = function() {
        logger.debug("onLoadSettings");
        _.each(extensionList, function(extension) {
            utils.setInputChecked("#input-enable-extension-" + extension.extensionId, extension.config.enabled);
            var onLoadSettingsCallback = extension.onLoadSettings;
            onLoadSettingsCallback && onLoadSettingsCallback();
        });
    };
    extensionMgr["onSaveSettings"] = function(newExtensionSettings, event) {
        logger.debug("onSaveSettings");
        _.each(extensionList, function(extension) {
            var newExtensionConfig = _.extend({}, extension.defaultConfig);
            newExtensionConfig.enabled = utils.getInputChecked("#input-enable-extension-" + extension.extensionId);
            var onSaveSettingsCallback = extension.onSaveSettings;
            onSaveSettingsCallback && onSaveSettingsCallback(newExtensionConfig, event);
            newExtensionSettings[extension.extensionId] = newExtensionConfig;
        });
    };

    addHook("onReady");
    addHook("onMessage");
    addHook("onError");
    addHook("onOfflineChanged");
    addHook("onAsyncRunning");

    // To access modules that are loaded after extensions
    addHook("onFileMgrCreated");
    addHook("onSynchronizerCreated");
    addHook("onPublisherCreated");
    addHook("onExtensionMgrCreated");

    // Operations on files
    addHook("onFileCreated");
    addHook("onFileDeleted");
    addHook("onFileSelected");
    addHook("onContentChanged");
    addHook("onTitleChanged");

    // Sync events
    addHook("onSyncRunning");
    addHook("onSyncSuccess");
    addHook("onSyncImportSuccess");
    addHook("onSyncExportSuccess");
    addHook("onSyncRemoved");

    // Publish events
    addHook("onPublishRunning");
    addHook("onPublishSuccess");
    addHook("onNewPublishSuccess");
    addHook("onPublishRemoved");

    // Operations on Layout
    addHook("onLayoutConfigure");
    addHook("onLayoutCreated");

    // Operations on PageDown
    addHook("onEditorConfigure");

    var onPreviewFinished = createHook("onPreviewFinished");
    var onAsyncPreviewCallbackList = getExtensionCallbackList("onAsyncPreview");
    extensionMgr["onAsyncPreview"] = function() {
        logger.debug("onAsyncPreview");
        // Call onPreviewFinished callbacks when all async preview are finished
        var counter = 0;
        function tryFinished() {
            if(counter === onAsyncPreviewCallbackList.length) {
                onPreviewFinished();
            }
        }
        _.each(onAsyncPreviewCallbackList, function(asyncPreviewCallback) {
            asyncPreviewCallback(function() {
                counter++;
                tryFinished();
            });
        });
        tryFinished();
    };

    var accordionTmpl = [
        '<div class="accordion-group">',
        '   <div class="accordion-heading">',
        '       <label class="checkbox pull-right">',
        '           <input id="input-enable-extension-<%= extensionId %>" type="checkbox" <% if(!optional) { %> disabled <% } %>> enabled',
        '       </label>',
        '       <a id="accordion-toggle-test" data-toggle="collapse" data-parent="#accordion-extensions" class="accordion-toggle" href="#collapse-<%= extensionId %>">',
        '           <%= extensionName %>',
        '       </a>',
        '   </div>',
        '   <div id="collapse-<%= extensionId %>" class="accordion-body collapse">',
        '       <div class="accordion-inner"><%= settingsBloc %></div>',
        '   </div>',
        '</div>'
    ].join("");

    function createSettings(extension) {
        $("#accordion-extensions").append($(_.template(accordionTmpl, {
            extensionId: extension.extensionId,
            extensionName: extension.extensionName,
            optional: extension.optional,
            settingsBloc: extension.settingsBloc
        })));
    }

    $(function() {
        // Create accordion in settings dialog
        _.chain(extensionList).sortBy(function(extension) {
            return extension.extensionName.toLowerCase();
        }).each(createSettings);

        // Create extension buttons
        logger.debug("onCreateButton");
        var onCreateButtonCallbackList = getExtensionCallbackList("onCreateButton");
        _.each(onCreateButtonCallbackList, function(callback) {
            $("#extension-buttons").append($('<div class="btn-group">').append(callback()));
        });

    });

    // For extensions that need to call other extensions
    extensionMgr.onExtensionMgrCreated(extensionMgr);
    return extensionMgr;
});