path: root/e-util/e-plugin-ui.c

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the program; if not, see <http://www.gnu.org/licenses/>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 */

#include "e-plugin-ui.h"

#include "e-util.h"
#include "e-ui-manager.h"

#include <string.h>

#define E_PLUGIN_UI_HOOK_GET_PRIVATE(obj) \
    (G_TYPE_INSTANCE_GET_PRIVATE \
    ((obj), E_TYPE_PLUGIN_UI_HOOK, EPluginUIHookPrivate))

#define E_PLUGIN_UI_DEFAULT_FUNC    "e_plugin_ui_init"
#define E_PLUGIN_UI_HOOK_CLASS_ID   "org.gnome.evolution.ui:1.0"

struct _EPluginUIHookPrivate {

    /* Table of GtkUIManager ID's to UI definitions.
     *
     * For example:
     *
     *     <hook class="org.gnome.evolution.ui:1.0">
     *       <ui-manager id="org.gnome.evolution.foo">
     *               ... UI definition ...
     *       </ui-manager>
     *     </hook>
     *
     * Results in:
     *
     *     g_hash_table_insert (
     *             ui_definitions,
     *             "org.gnome.evolution.foo",
     *             "... UI definition ...");
     *
     * See http://library.gnome.org/devel/gtk/unstable/GtkUIManager.html
     * for more information about UI definitions.  Note: the <ui> tag is
     * optional.
     */
    GHashTable *ui_definitions;

    /* Table of GtkUIManager ID's to callback function names.
     *
     * This stores the optional "callback" attribute in the <ui-manager>
     * element.  If not specified, it defaults to "e_plugin_ui_init".
     *
     * This is useful when extending the UI of multiple GtkUIManager IDs
     * from a single plugin.
     *
     * For example:
     *
     *     <hook class="org.gnome.evolution.ui:1.0">
     *       <ui-manager id="org.gnome.evolution.foo" callback="init_foo">
     *         ...
     *       </ui-manager>
     *       <ui-manager id="org.gnome.evolution.bar" callback="init_bar">
     *         ...
     *       </ui-manager>
     *     </hook>
     *
     * Results in:
     *
     *     g_hash_table_insert (
     *             callbacks, "org.gnome.evolution.foo", "init_foo");
     *
     *     g_hash_table_insert (
     *             callbacks, "org.gnome.evolution.bar", "init_bar");
     */
    GHashTable *callbacks;

    /* The registry is the heart of EPluginUI.  It tracks GtkUIManager
     * instances, GtkUIManager IDs, and UI merge IDs as a hash table of
     * hash tables:
     *
     *     GtkUIManager instance -> GtkUIManager ID -> UI Merge ID
     *
     * A GtkUIManager instance and ID form a unique key for looking up
     * UI merge IDs.  The reason both are needed is because the same
     * GtkUIManager instance can be registered under multiple IDs.
     *
     * This is done primarily to support shell views, which share a
     * common GtkUIManager instance for a particular shell window.
     * Each shell view registers the same GtkUIManager instance under
     * a unique ID:
     *
     *     "org.gnome.evolution.mail"      }
     *     "org.gnome.evolution.contacts"  }  aliases for a common
     *     "org.gnome.evolution.calendar"  }  GtkUIManager instance
     *     "org.gnome.evolution.memos"     }
     *     "org.gnome.evolution.tasks"     }
     *
     * Note: The shell window also registers the same GtkUIManager
     *       instance as "org.gnome.evolution.shell".
     *
     * This way, plugins that extend a shell view's UI will follow the
     * merging and unmerging of the shell view automatically.
     *
     * The presence or absence of GtkUIManager IDs in the registry is
     * significant.  Presence of a (instance, ID) pair indicates that
     * UI manager is active, absence indicates inactive.  Furthermore,
     * a non-zero merge ID for an active UI manager indicates the
     * plugin is enabled.  Zero indicates disabled.
     *
     * Here's a quick scenario to illustrate:
     *
     * Suppose we have a plugin that extends the mail shell view UI.
     * Its EPlugin definition file has this section:
     *
     *     <hook class="org.gnome.evolution.ui:1.0">
     *       <ui-manager id="org.gnome.evolution.mail">
     *               ... UI definition ...
     *       </ui-manager>
     *     </hook>
     *
     * The plugin is enabled and the active shell view is "mail".
     * Let "ManagerA" denote the common GtkUIManager instance for
     * this shell window.  Here's what happens to the registry as
     * the user performs various actions;
     *
     *     - Initial State                            Merge ID
     *                                                   V
     *       { "ManagerA", { "org.gnome.evolution.mail", 3 } }
     *
     *     - User Disables the Plugin
     *
     *       { "ManagerA", { "org.gnome.evolution.mail", 0 } }
     *
     *     - User Enables the Plugin
     *
     *       { "ManagerA", { "org.gnome.evolution.mail", 4 } }
     *
     *     - User Switches to Calendar View
     *
     *       { "ManagerA", { } }
     *
     *     - User Disables the Plugin
     *
     *       { "ManagerA", { } }
     *
     *     - User Switches to Mail View
     *
     *       { "ManagerA", { "org.gnome.evolution.mail", 0 } }
     *
     *     - User Enables the Plugin
     *
     *       { "ManagerA", { "org.gnome.evolution.mail", 5 } }
     */
    GHashTable *registry;
};

G_DEFINE_TYPE (
    EPluginUIHook,
    e_plugin_ui_hook,
    E_TYPE_PLUGIN_HOOK)

static void
plugin_ui_hook_unregister_manager (EPluginUIHook *hook,
                                   GtkUIManager *ui_manager)
{
    GHashTable *registry;

    /* Note: Manager may already be finalized. */
    registry = hook->priv->registry;
    g_hash_table_remove (registry, ui_manager);
}

static void
plugin_ui_hook_register_manager (EPluginUIHook *hook,
                                 GtkUIManager *ui_manager,
                                 const gchar *id,
                                 gpointer user_data)
{
    EPlugin *plugin;
    EPluginUIInitFunc func;
    GHashTable *registry;
    GHashTable *hash_table;
    const gchar *func_name;

    plugin = ((EPluginHook *) hook)->plugin;

    hash_table = hook->priv->callbacks;
    func_name = g_hash_table_lookup (hash_table, id);

    if (func_name == NULL)
        func_name = E_PLUGIN_UI_DEFAULT_FUNC;

    func = e_plugin_get_symbol (plugin, func_name);

    if (func == NULL) {
        g_critical (
            "Plugin \"%s\" is missing a function named %s()",
            plugin->name, func_name);
        return;
    }

    /* Pass the manager and user_data to the plugin's callback function.
     * The plugin should install whatever GtkActions and GtkActionGroups
     * are neccessary to implement the actions in its UI definition. */
    if (!func (ui_manager, user_data))
        return;

    g_object_weak_ref (
        G_OBJECT (ui_manager), (GWeakNotify)
        plugin_ui_hook_unregister_manager, hook);

    registry = hook->priv->registry;
    hash_table = g_hash_table_lookup (registry, ui_manager);

    if (hash_table == NULL) {
        hash_table = g_hash_table_new_full (
            g_str_hash, g_str_equal,
            (GDestroyNotify) g_free,
            (GDestroyNotify) NULL);
        g_hash_table_insert (registry, ui_manager, hash_table);
    }
}

static guint
plugin_ui_hook_merge_ui (EPluginUIHook *hook,
                         GtkUIManager *ui_manager,
                         const gchar *id)
{
    GHashTable *hash_table;
    const gchar *ui_definition;
    guint merge_id;
    GError *error = NULL;

    hash_table = hook->priv->ui_definitions;
    ui_definition = g_hash_table_lookup (hash_table, id);
    g_return_val_if_fail (ui_definition != NULL, 0);

    if (E_IS_UI_MANAGER (ui_manager))
        merge_id = e_ui_manager_add_ui_from_string (
            E_UI_MANAGER (ui_manager), ui_definition, &error);
    else
        merge_id = gtk_ui_manager_add_ui_from_string (
            ui_manager, ui_definition, -1, &error);

    if (error != NULL) {
        g_warning ("%s", error->message);
        g_error_free (error);
    }

    return merge_id;
}

static void
plugin_ui_enable_manager (EPluginUIHook *hook,
                          GtkUIManager *ui_manager,
                          const gchar *id)
{
    GHashTable *hash_table;
    GHashTable *ui_definitions;
    GList *keys;

    hash_table = hook->priv->registry;
    hash_table = g_hash_table_lookup (hash_table, ui_manager);

    if (hash_table == NULL)
        return;

    if (id != NULL)
        keys = g_list_prepend (NULL, (gpointer) id);
    else
        keys = g_hash_table_get_keys (hash_table);

    ui_definitions = hook->priv->ui_definitions;

    while (keys != NULL) {
        guint merge_id;
        gpointer data;

        id = keys->data;
        keys = g_list_delete_link (keys, keys);

        if (g_hash_table_lookup (ui_definitions, id) == NULL)
            continue;

        data = g_hash_table_lookup (hash_table, id);
        merge_id = GPOINTER_TO_UINT (data);

        if (merge_id > 0)
            continue;

        if (((EPluginHook *) hook)->plugin->enabled)
            merge_id = plugin_ui_hook_merge_ui (
                hook, ui_manager, id);

        /* Merge ID will be 0 on error, which is what we want. */
        data = GUINT_TO_POINTER (merge_id);
        g_hash_table_insert (hash_table, g_strdup (id), data);
    }
}

static void
plugin_ui_disable_manager (EPluginUIHook *hook,
                           GtkUIManager *ui_manager,
                           const gchar *id,
                           gboolean remove)
{
    GHashTable *hash_table;
    GHashTable *ui_definitions;
    GList *keys;

    hash_table = hook->priv->registry;
    hash_table = g_hash_table_lookup (hash_table, ui_manager);

    if (hash_table == NULL)
        return;

    if (id != NULL)
        keys = g_list_prepend (NULL, (gpointer) id);
    else
        keys = g_hash_table_get_keys (hash_table);

    ui_definitions = hook->priv->ui_definitions;

    while (keys != NULL) {
        guint merge_id;
        gpointer data;

        id = keys->data;
        keys = g_list_delete_link (keys, keys);

        if (g_hash_table_lookup (ui_definitions, id) == NULL)
            continue;

        data = g_hash_table_lookup (hash_table, id);
        merge_id = GPOINTER_TO_UINT (data);

        /* Merge ID could be 0 if the plugin is disabled. */
        if (merge_id > 0)
            gtk_ui_manager_remove_ui (ui_manager, merge_id);

        if (remove)
            g_hash_table_remove (hash_table, id);
        else
            g_hash_table_insert (hash_table, g_strdup (id), NULL);
    }
}

static void
plugin_ui_enable_hook (EPluginUIHook *hook)
{
    GHashTable *hash_table;
    GHashTableIter iter;
    gpointer key;

    /* Enable all GtkUIManagers for this hook. */

    hash_table = hook->priv->registry;
    g_hash_table_iter_init (&iter, hash_table);

    while (g_hash_table_iter_next (&iter, &key, NULL)) {
        GtkUIManager *ui_manager = key;
        plugin_ui_enable_manager (hook, ui_manager, NULL);
    }
}

static void
plugin_ui_disable_hook (EPluginUIHook *hook)
{
    GHashTable *hash_table;
    GHashTableIter iter;
    gpointer key;

    /* Disable all GtkUIManagers for this hook. */

    hash_table = hook->priv->registry;
    g_hash_table_iter_init (&iter, hash_table);

    while (g_hash_table_iter_next (&iter, &key, NULL)) {
        GtkUIManager *ui_manager = key;
        plugin_ui_disable_manager (hook, ui_manager, NULL, FALSE);
    }
}

static void
plugin_ui_hook_finalize (GObject *object)
{
    EPluginUIHookPrivate *priv;
    GHashTableIter iter;
    gpointer ui_manager;

    priv = E_PLUGIN_UI_HOOK_GET_PRIVATE (object);

    /* Remove weak reference callbacks to GtkUIManagers. */
    g_hash_table_iter_init (&iter, priv->registry);
    while (g_hash_table_iter_next (&iter, &ui_manager, NULL))
        g_object_weak_unref (
            G_OBJECT (ui_manager), (GWeakNotify)
            plugin_ui_hook_unregister_manager, object);

    g_hash_table_destroy (priv->ui_definitions);
    g_hash_table_destroy (priv->callbacks);
    g_hash_table_destroy (priv->registry);

    /* Chain up to parent's dispose() method. */
    G_OBJECT_CLASS (e_plugin_ui_hook_parent_class)->dispose (object);
}

static gint
plugin_ui_hook_construct (EPluginHook *hook,
                          EPlugin *plugin,
                          xmlNodePtr node)
{
    EPluginUIHookPrivate *priv;

    priv = E_PLUGIN_UI_HOOK_GET_PRIVATE (hook);

    /* XXX The EPlugin should be a property of EPluginHookClass.
     *     Then it could be passed directly to g_object_new() and
     *     we wouldn't have to chain up here. */

    /* Chain up to parent's construct() method. */
    E_PLUGIN_HOOK_CLASS (e_plugin_ui_hook_parent_class)->
        construct (hook, plugin, node);

    for (node = xmlFirstElementChild (node); node != NULL;
        node = xmlNextElementSibling (node)) {

        xmlNodePtr child;
        xmlBufferPtr buffer;
        GString *content;
        const gchar *temp;
        gchar *callback;
        gchar *id;

        if (strcmp ((gchar *) node->name, "ui-manager") != 0)
            continue;

        id = e_plugin_xml_prop (node, "id");
        if (id == NULL) {
            g_warning ("<ui-manager> requires 'id' property");
            continue;
        }

        callback = e_plugin_xml_prop (node, "callback");
        if (callback != NULL)
            g_hash_table_insert (
                priv->callbacks,
                g_strdup (id), callback);

        content = g_string_sized_new (1024);

        /* Extract the XML content below <ui-manager> */
        buffer = xmlBufferCreate ();
        for (child = node->children; child != NULL; child = child->next) {
            xmlNodeDump (buffer, node->doc, child, 2, 1);
            temp = (const gchar *) xmlBufferContent (buffer);
            g_string_append (content, temp);
        }

        g_hash_table_insert (
            priv->ui_definitions,
            id, g_string_free (content, FALSE));

        xmlBufferFree (buffer);
    }

    return 0;
}

static void
plugin_ui_hook_enable (EPluginHook *hook,
                       gint state)
{
    if (state)
        plugin_ui_enable_hook (E_PLUGIN_UI_HOOK (hook));
    else
        plugin_ui_disable_hook (E_PLUGIN_UI_HOOK (hook));
}

static void
e_plugin_ui_hook_class_init (EPluginUIHookClass *class)
{
    GObjectClass *object_class;
    EPluginHookClass *plugin_hook_class;

    g_type_class_add_private (class, sizeof (EPluginUIHookPrivate));

    object_class = G_OBJECT_CLASS (class);
    object_class->finalize = plugin_ui_hook_finalize;

    plugin_hook_class = E_PLUGIN_HOOK_CLASS (class);
    plugin_hook_class->id = E_PLUGIN_UI_HOOK_CLASS_ID;
    plugin_hook_class->construct = plugin_ui_hook_construct;
    plugin_hook_class->enable = plugin_ui_hook_enable;
}

static void
e_plugin_ui_hook_init (EPluginUIHook *hook)
{
    GHashTable *ui_definitions;
    GHashTable *callbacks;
    GHashTable *registry;

    ui_definitions = g_hash_table_new_full (
        g_str_hash, g_str_equal,
        (GDestroyNotify) g_free,
        (GDestroyNotify) g_free);

    callbacks = g_hash_table_new_full (
        g_str_hash, g_str_equal,
        (GDestroyNotify) g_free,
        (GDestroyNotify) g_free);

    registry = g_hash_table_new (g_direct_hash, g_direct_equal);

    hook->priv = E_PLUGIN_UI_HOOK_GET_PRIVATE (hook);
    hook->priv->ui_definitions = ui_definitions;
    hook->priv->callbacks = callbacks;
    hook->priv->registry = registry;
}

void
e_plugin_ui_register_manager (GtkUIManager *ui_manager,
                              const gchar *id,
                              gpointer user_data)
{
    GSList *plugin_list;

    g_return_if_fail (GTK_IS_UI_MANAGER (ui_manager));
    g_return_if_fail (id != NULL);

    /* Loop over all installed plugins. */
    plugin_list = e_plugin_list_plugins ();
    while (plugin_list != NULL) {
        EPlugin *plugin = plugin_list->data;
        GSList *iter;

        plugin_list = g_slist_remove (plugin_list, plugin);

        /* Look for hooks of type EPluginUIHook. */
        for (iter = plugin->hooks; iter != NULL; iter = iter->next) {
            EPluginUIHook *hook = iter->data;
            GHashTable *hash_table;

            if (!E_IS_PLUGIN_UI_HOOK (hook))
                continue;

            hash_table = hook->priv->ui_definitions;

            /* Check if the hook has a UI definition
             * for the GtkUIManager being registered. */
            if (g_hash_table_lookup (hash_table, id) == NULL)
                continue;

            /* Register the manager with the hook. */
            plugin_ui_hook_register_manager (
                hook, ui_manager, id, user_data);
        }

        g_object_unref (plugin);
    }
}

void
e_plugin_ui_enable_manager (GtkUIManager *ui_manager,
                            const gchar *id)
{
    GSList *plugin_list;

    g_return_if_fail (GTK_IS_UI_MANAGER (ui_manager));
    g_return_if_fail (id != NULL);

    /* Loop over all installed plugins. */
    plugin_list = e_plugin_list_plugins ();
    while (plugin_list != NULL) {
        EPlugin *plugin = plugin_list->data;
        GSList *iter;

        plugin_list = g_slist_remove (plugin_list, plugin);

        /* Look for hooks of type EPluginUIHook. */
        for (iter = plugin->hooks; iter != NULL; iter = iter->next) {
            EPluginUIHook *hook = iter->data;

            if (!E_IS_PLUGIN_UI_HOOK (hook))
                continue;

            plugin_ui_enable_manager (hook, ui_manager, id);
        }

        g_object_unref (plugin);
    }
}

void
e_plugin_ui_disable_manager (GtkUIManager *ui_manager,
                             const gchar *id)
{
    GSList *plugin_list;

    g_return_if_fail (GTK_IS_UI_MANAGER (ui_manager));
    g_return_if_fail (id != NULL);

    /* Loop over all installed plugins. */
    plugin_list = e_plugin_list_plugins ();
    while (plugin_list != NULL) {
        EPlugin *plugin = plugin_list->data;
        GSList *iter;

        plugin_list = g_slist_remove (plugin_list, plugin);

        /* Look for hooks of type EPluginUIHook. */
        for (iter = plugin->hooks; iter != NULL; iter = iter->next) {
            EPluginUIHook *hook = iter->data;

            if (!E_IS_PLUGIN_UI_HOOK (hook))
                continue;

            plugin_ui_disable_manager (hook, ui_manager, id, TRUE);
        }

        g_object_unref (plugin);
    }
}