path: root/e-util/e-rule-context.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * 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/>
 *
 *
 * Authors:
 *      Not Zed <notzed@lostzed.mmc.com.au>
 *      Jeffrey Stedfast <fejj@ximian.com>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#include <glib/gstdio.h>

#include <gtk/gtk.h>

#include <glib/gi18n.h>

#include <libedataserver/libedataserver.h>

#include "e-alert-dialog.h"
#include "e-filter-code.h"
#include "e-filter-color.h"
#include "e-filter-datespec.h"
#include "e-filter-file.h"
#include "e-filter-input.h"
#include "e-filter-int.h"
#include "e-filter-option.h"
#include "e-filter-rule.h"
#include "e-rule-context.h"
#include "e-xml-utils.h"

#define E_RULE_CONTEXT_GET_PRIVATE(obj) \
    (G_TYPE_INSTANCE_GET_PRIVATE \
    ((obj), E_TYPE_RULE_CONTEXT, ERuleContextPrivate))

struct _ERuleContextPrivate {
    gint frozen;
};

enum {
    RULE_ADDED,
    RULE_REMOVED,
    CHANGED,
    LAST_SIGNAL
};

static guint signals[LAST_SIGNAL];

struct _revert_data {
    GHashTable *rules;
    gint rank;
};

G_DEFINE_TYPE (
    ERuleContext,
    e_rule_context,
    G_TYPE_OBJECT)

static void
rule_context_set_error (ERuleContext *context,
                        gchar *error)
{
    g_free (context->error);
    context->error = error;
}

static void
new_rule_response (GtkWidget *dialog,
                   gint button,
                   ERuleContext *context)
{
    if (button == GTK_RESPONSE_OK) {
        EFilterRule *rule = g_object_get_data ((GObject *) dialog, "rule");
        gchar *user = g_object_get_data ((GObject *) dialog, "path");
        EAlert *alert = NULL;

        if (!e_filter_rule_validate (rule, &alert)) {
            e_alert_run_dialog (GTK_WINDOW (dialog), alert);
            g_object_unref (alert);
            return;
        }

        if (e_rule_context_find_rule (context, rule->name, rule->source)) {
            e_alert_run_dialog_for_args ((GtkWindow *) dialog,
                             "filter:bad-name-notunique",
                             rule->name, NULL);

            return;
        }

        g_object_ref (rule);
        e_rule_context_add_rule (context, rule);
        if (user)
            e_rule_context_save (context, user);
    }

    gtk_widget_destroy (dialog);
}

static void
revert_rule_remove (gpointer key,
                    EFilterRule *rule,
                    ERuleContext *context)
{
    e_rule_context_remove_rule (context, rule);
    g_object_unref (rule);
}

static void
revert_source_remove (gpointer key,
                      struct _revert_data *rest_data,
                      ERuleContext *context)
{
    g_hash_table_foreach (
        rest_data->rules, (GHFunc) revert_rule_remove, context);
    g_hash_table_destroy (rest_data->rules);
    g_free (rest_data);
}

static guint
source_hashf (const gchar *a)
{
    return (a != NULL) ? g_str_hash (a) : 0;
}

static gint
source_eqf (const gchar *a,
            const gchar *b)
{
    return (g_strcmp0 (a, b) == 0);
}

static void
free_part_set (struct _part_set_map *map)
{
    g_free (map->name);
    g_free (map);
}

static void
free_rule_set (struct _rule_set_map *map)
{
    g_free (map->name);
    g_free (map);
}

static void
rule_context_finalize (GObject *obj)
{
    ERuleContext *context =(ERuleContext *) obj;

    g_list_foreach (context->rule_set_list, (GFunc) free_rule_set, NULL);
    g_list_free (context->rule_set_list);
    g_hash_table_destroy (context->rule_set_map);

    g_list_foreach (context->part_set_list, (GFunc) free_part_set, NULL);
    g_list_free (context->part_set_list);
    g_hash_table_destroy (context->part_set_map);

    g_free (context->error);

    g_list_foreach (context->parts, (GFunc) g_object_unref, NULL);
    g_list_free (context->parts);

    g_list_foreach (context->rules, (GFunc) g_object_unref, NULL);
    g_list_free (context->rules);

    G_OBJECT_CLASS (e_rule_context_parent_class)->finalize (obj);
}

static gint
rule_context_load (ERuleContext *context,
                   const gchar *system,
                   const gchar *user)
{
    xmlNodePtr set, rule, root;
    xmlDocPtr systemdoc, userdoc;
    struct _part_set_map *part_map;
    struct _rule_set_map *rule_map;

    rule_context_set_error (context, NULL);

    systemdoc = e_xml_parse_file (system);
    if (systemdoc == NULL) {
        gchar * err_msg;

        err_msg = g_strdup_printf (
            "Unable to load system rules '%s': %s",
            system, g_strerror (errno));
        g_warning ("%s: %s", G_STRFUNC, err_msg);
        rule_context_set_error (context, err_msg);
        /* no need to free err_msg here */
        return -1;
    }

    root = xmlDocGetRootElement (systemdoc);
    if (root == NULL || strcmp ((gchar *) root->name, "filterdescription")) {
        gchar * err_msg;

        err_msg = g_strdup_printf (
            "Unable to load system rules '%s': "
            "Invalid format", system);
        g_warning ("%s: %s", G_STRFUNC, err_msg);
        rule_context_set_error (context, err_msg);
        /* no need to free err_msg here */
        xmlFreeDoc (systemdoc);
        return -1;
    }
    /* doesn't matter if this doens't exist */
    userdoc = NULL;
    if (g_file_test (user, G_FILE_TEST_IS_REGULAR))
        userdoc = e_xml_parse_file (user);

    /* now parse structure */
    /* get rule parts */
    set = root->children;
    while (set) {
        part_map = g_hash_table_lookup (context->part_set_map, set->name);
        if (part_map) {
            rule = set->children;
            while (rule) {
                if (!strcmp ((gchar *) rule->name, "part")) {
                    EFilterPart *part =
                        E_FILTER_PART (g_object_new (
                        part_map->type, NULL, NULL));

                    if (e_filter_part_xml_create (part, rule, context) == 0) {
                        part_map->append (context, part);
                    } else {
                        g_object_unref (part);
                        g_warning ("Cannot load filter part");
                    }
                }
                rule = rule->next;
            }
        } else if ((rule_map = g_hash_table_lookup (
                context->rule_set_map, set->name))) {
            rule = set->children;
            while (rule) {
                if (!strcmp ((gchar *) rule->name, "rule")) {
                    EFilterRule *part =
                        E_FILTER_RULE (g_object_new (
                        rule_map->type, NULL, NULL));

                    if (e_filter_rule_xml_decode (part, rule, context) == 0) {
                        part->system = TRUE;
                        rule_map->append (context, part);
                    } else {
                        g_object_unref (part);
                        g_warning ("Cannot load filter part");
                    }
                }
                rule = rule->next;
            }
        }
        set = set->next;
    }

    /* now load actual rules */
    if (userdoc) {
        root = xmlDocGetRootElement (userdoc);
        set = root ? root->children : NULL;
        while (set) {
            rule_map = g_hash_table_lookup (context->rule_set_map, set->name);
            if (rule_map) {
                rule = set->children;
                while (rule) {
                    if (!strcmp ((gchar *) rule->name, "rule")) {
                        EFilterRule *part =
                            E_FILTER_RULE (g_object_new (
                            rule_map->type, NULL, NULL));

                        if (e_filter_rule_xml_decode (part, rule, context) == 0) {
                            rule_map->append (context, part);
                        } else {
                            g_object_unref (part);
                            g_warning ("Cannot load filter part");
                        }
                    }
                    rule = rule->next;
                }
            }
            set = set->next;
        }
    }

    xmlFreeDoc (userdoc);
    xmlFreeDoc (systemdoc);

    return 0;
}

static gint
rule_context_save (ERuleContext *context,
                   const gchar *user)
{
    xmlDocPtr doc;
    xmlNodePtr root, rules, work;
    GList *l;
    EFilterRule *rule;
    struct _rule_set_map *map;
    gint ret;

    doc = xmlNewDoc ((xmlChar *)"1.0");
    /* FIXME: set character encoding to UTF-8? */
    root = xmlNewDocNode (doc, NULL, (xmlChar *)"filteroptions", NULL);
    xmlDocSetRootElement (doc, root);
    l = context->rule_set_list;
    while (l) {
        map = l->data;
        rules = xmlNewDocNode (doc, NULL, (xmlChar *) map->name, NULL);
        xmlAddChild (root, rules);
        rule = NULL;
        while ((rule = map->next (context, rule, NULL))) {
            if (!rule->system) {
                work = e_filter_rule_xml_encode (rule);
                xmlAddChild (rules, work);
            }
        }
        l = g_list_next (l);
    }

    ret = e_xml_save_file (user, doc);

    xmlFreeDoc (doc);

    return ret;
}

static gint
rule_context_revert (ERuleContext *context,
                     const gchar *user)
{
    xmlNodePtr set, rule;
    /*struct _part_set_map *part_map;*/
    struct _rule_set_map *rule_map;
    struct _revert_data *rest_data;
    GHashTable *source_hash;
    xmlDocPtr userdoc;
    EFilterRule *frule;

    rule_context_set_error (context, NULL);

    userdoc = e_xml_parse_file (user);
    if (userdoc == NULL)
        /* clear out anythign we have? */
        return 0;

    source_hash = g_hash_table_new (
        (GHashFunc) source_hashf,
        (GCompareFunc) source_eqf);

    /* setup stuff we have now */
    /* Note that we assume there is only 1 set of rules in a given rule context,
     * although other parts of the code dont assume this */
    frule = NULL;
    while ((frule = e_rule_context_next_rule (context, frule, NULL))) {
        rest_data = g_hash_table_lookup (source_hash, frule->source);
        if (rest_data == NULL) {
            rest_data = g_malloc0 (sizeof (*rest_data));
            rest_data->rules = g_hash_table_new (g_str_hash, g_str_equal);
            g_hash_table_insert (source_hash, frule->source, rest_data);
        }
        g_hash_table_insert (rest_data->rules, frule->name, frule);
    }

    /* make what we have, match what we load */
    set = xmlDocGetRootElement (userdoc);
    set = set ? set->children : NULL;
    while (set) {
        rule_map = g_hash_table_lookup (context->rule_set_map, set->name);
        if (rule_map) {
            rule = set->children;
            while (rule) {
                if (!strcmp ((gchar *) rule->name, "rule")) {
                    EFilterRule *part =
                        E_FILTER_RULE (g_object_new (
                        rule_map->type, NULL, NULL));

                    if (e_filter_rule_xml_decode (part, rule, context) == 0) {
                        /* Use the revert data to keep
                         * track of the right rank of
                         * this rule part. */
                        rest_data = g_hash_table_lookup (source_hash, part->source);
                        if (rest_data == NULL) {
                            rest_data = g_malloc0 (sizeof (*rest_data));
                            rest_data->rules = g_hash_table_new (
                                g_str_hash,
                                g_str_equal);
                            g_hash_table_insert (
                                source_hash,
                                part->source,
                                rest_data);
                        }
                        frule = g_hash_table_lookup (
                            rest_data->rules,
                            part->name);
                        if (frule) {
                            if (context->priv->frozen == 0 &&
                                !e_filter_rule_eq (frule, part))
                                e_filter_rule_copy (frule, part);

                            g_object_unref (part);
                            e_rule_context_rank_rule (
                                context, frule,
                                frule->source,
                                rest_data->rank);
                            g_hash_table_remove (rest_data->rules, frule->name);
                        } else {
                            e_rule_context_add_rule (context, part);
                            e_rule_context_rank_rule (
                                context,
                                part,
                                part->source,
                                rest_data->rank);
                        }
                        rest_data->rank++;
                    } else {
                        g_object_unref (part);
                        g_warning ("Cannot load filter part");
                    }
                }
                rule = rule->next;
            }
        }
        set = set->next;
    }

    xmlFreeDoc (userdoc);

    /* remove any we still have that weren't in the file */
    g_hash_table_foreach (source_hash, (GHFunc) revert_source_remove, context);
    g_hash_table_destroy (source_hash);

    return 0;
}

static EFilterElement *
rule_context_new_element (ERuleContext *context,
                          const gchar *type)
{
    if (!strcmp (type, "string")) {
        return (EFilterElement *) e_filter_input_new ();
    } else if (!strcmp (type, "address")) {
        /* FIXME: temporary ... need real address type */
        return (EFilterElement *) e_filter_input_new_type_name (type);
    } else if (!strcmp (type, "code")) {
        return (EFilterElement *) e_filter_code_new (FALSE);
    } else if (!strcmp (type, "rawcode")) {
        return (EFilterElement *) e_filter_code_new (TRUE);
    } else if (!strcmp (type, "colour")) {
        return (EFilterElement *) e_filter_color_new ();
    } else if (!strcmp (type, "optionlist")) {
        return (EFilterElement *) e_filter_option_new ();
    } else if (!strcmp (type, "datespec")) {
        return (EFilterElement *) e_filter_datespec_new ();
    } else if (!strcmp (type, "command")) {
        return (EFilterElement *) e_filter_file_new_type_name (type);
    } else if (!strcmp (type, "file")) {
        return (EFilterElement *) e_filter_file_new_type_name (type);
    } else if (!strcmp (type, "integer")) {
        return (EFilterElement *) e_filter_int_new ();
    } else if (!strcmp (type, "regex")) {
        return (EFilterElement *) e_filter_input_new_type_name (type);
    } else if (!strcmp (type, "completedpercent")) {
        return (EFilterElement *) e_filter_int_new_type (
            "completedpercent", 0,100);
    } else {
        g_warning ("Unknown filter type '%s'", type);
        return NULL;
    }
}

static void
e_rule_context_class_init (ERuleContextClass *class)
{
    GObjectClass *object_class;

    g_type_class_add_private (class, sizeof (ERuleContextPrivate));

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

    class->load = rule_context_load;
    class->save = rule_context_save;
    class->revert = rule_context_revert;
    class->new_element = rule_context_new_element;

    signals[RULE_ADDED] = g_signal_new (
        "rule-added",
        E_TYPE_RULE_CONTEXT,
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (ERuleContextClass, rule_added),
        NULL,
        NULL,
        g_cclosure_marshal_VOID__POINTER,
        G_TYPE_NONE, 1,
        G_TYPE_POINTER);

    signals[RULE_REMOVED] = g_signal_new (
        "rule-removed",
        E_TYPE_RULE_CONTEXT,
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (ERuleContextClass, rule_removed),
        NULL,
        NULL,
        g_cclosure_marshal_VOID__POINTER,
        G_TYPE_NONE, 1,
        G_TYPE_POINTER);

    signals[CHANGED] = g_signal_new (
        "changed",
        E_TYPE_RULE_CONTEXT,
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (ERuleContextClass, changed),
        NULL,
        NULL,
        g_cclosure_marshal_VOID__VOID,
        G_TYPE_NONE, 0);
}

static void
e_rule_context_init (ERuleContext *context)
{
    context->priv = E_RULE_CONTEXT_GET_PRIVATE (context);

    context->part_set_map = g_hash_table_new (g_str_hash, g_str_equal);
    context->rule_set_map = g_hash_table_new (g_str_hash, g_str_equal);

    context->flags = E_RULE_CONTEXT_GROUPING;
}

/**
 * e_rule_context_new:
 *
 * Create a new ERuleContext object.
 *
 * Return value: A new #ERuleContext object.
 **/
ERuleContext *
e_rule_context_new (void)
{
    return g_object_new (E_TYPE_RULE_CONTEXT, NULL);
}

void
e_rule_context_add_part_set (ERuleContext *context,
                             const gchar *setname,
                             GType part_type,
                             ERuleContextPartFunc append,
                             ERuleContextNextPartFunc next)
{
    struct _part_set_map *map;

    g_return_if_fail (E_IS_RULE_CONTEXT (context));
    g_return_if_fail (setname != NULL);
    g_return_if_fail (append != NULL);
    g_return_if_fail (next != NULL);

    map = g_hash_table_lookup (context->part_set_map, setname);
    if (map != NULL) {
        g_hash_table_remove (context->part_set_map, setname);
        context->part_set_list = g_list_remove (context->part_set_list, map);
        free_part_set (map);
        map = NULL;
    }

    map = g_malloc0 (sizeof (*map));
    map->type = part_type;
    map->append = append;
    map->next = next;
    map->name = g_strdup (setname);
    g_hash_table_insert (context->part_set_map, map->name, map);
    context->part_set_list = g_list_append (context->part_set_list, map);
}

void
e_rule_context_add_rule_set (ERuleContext *context,
                             const gchar *setname,
                             GType rule_type,
                             ERuleContextRuleFunc append,
                             ERuleContextNextRuleFunc next)
{
    struct _rule_set_map *map;

    g_return_if_fail (E_IS_RULE_CONTEXT (context));
    g_return_if_fail (setname != NULL);
    g_return_if_fail (append != NULL);
    g_return_if_fail (next != NULL);

    map = g_hash_table_lookup (context->rule_set_map, setname);
    if (map != NULL) {
        g_hash_table_remove (context->rule_set_map, setname);
        context->rule_set_list = g_list_remove (context->rule_set_list, map);
        free_rule_set (map);
        map = NULL;
    }

    map = g_malloc0 (sizeof (*map));
    map->type = rule_type;
    map->append = append;
    map->next = next;
    map->name = g_strdup (setname);
    g_hash_table_insert (context->rule_set_map, map->name, map);
    context->rule_set_list = g_list_append (context->rule_set_list, map);
}

/**
 * e_rule_context_load:
 * @context:
 * @system:
 * @user:
 *
 * Load a rule context from a system and user description file.
 *
 * Return value:
 **/
gint
e_rule_context_load (ERuleContext *context,
                     const gchar *system,
                     const gchar *user)
{
    ERuleContextClass *class;
    gint result;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), -1);
    g_return_val_if_fail (system != NULL, -1);
    g_return_val_if_fail (user != NULL, -1);

    class = E_RULE_CONTEXT_GET_CLASS (context);
    g_return_val_if_fail (class->load != NULL, -1);

    context->priv->frozen++;
    result = class->load (context, system, user);
    context->priv->frozen--;

    return result;
}

/**
 * e_rule_context_save:
 * @context:
 * @user:
 *
 * Save a rule context to disk.
 *
 * Return value:
 **/
gint
e_rule_context_save (ERuleContext *context,
                     const gchar *user)
{
    ERuleContextClass *class;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), -1);
    g_return_val_if_fail (user != NULL, -1);

    class = E_RULE_CONTEXT_GET_CLASS (context);
    g_return_val_if_fail (class->save != NULL, -1);

    return class->save (context, user);
}

/**
 * e_rule_context_revert:
 * @context:
 * @user:
 *
 * Reverts a rule context from a user description file.  Assumes the
 * system description file is unchanged from when it was loaded.
 *
 * Return value:
 **/
gint
e_rule_context_revert (ERuleContext *context,
                       const gchar *user)
{
    ERuleContextClass *class;

    g_return_val_if_fail (E_RULE_CONTEXT (context), 0);
    g_return_val_if_fail (user != NULL, 0);

    class = E_RULE_CONTEXT_GET_CLASS (context);
    g_return_val_if_fail (class->revert != NULL, 0);

    return class->revert (context, user);
}

EFilterPart *
e_rule_context_find_part (ERuleContext *context,
                          const gchar *name)
{
    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);
    g_return_val_if_fail (name != NULL, NULL);

    return e_filter_part_find_list (context->parts, name);
}

EFilterPart *
e_rule_context_create_part (ERuleContext *context,
                            const gchar *name)
{
    EFilterPart *part;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);
    g_return_val_if_fail (name != NULL, NULL);

    part = e_rule_context_find_part (context, name);

    if (part == NULL)
        return NULL;

    return e_filter_part_clone (part);
}

EFilterPart *
e_rule_context_next_part (ERuleContext *context,
                          EFilterPart *last)
{
    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);

    return e_filter_part_next_list (context->parts, last);
}

EFilterRule *
e_rule_context_next_rule (ERuleContext *context,
                          EFilterRule *last,
                          const gchar *source)
{
    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);

    return e_filter_rule_next_list (context->rules, last, source);
}

EFilterRule *
e_rule_context_find_rule (ERuleContext *context,
                          const gchar *name,
                          const gchar *source)
{
    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);
    g_return_val_if_fail (name != NULL, NULL);

    return e_filter_rule_find_list (context->rules, name, source);
}

void
e_rule_context_add_part (ERuleContext *context,
                         EFilterPart *part)
{
    g_return_if_fail (E_IS_RULE_CONTEXT (context));
    g_return_if_fail (E_IS_FILTER_PART (part));

    context->parts = g_list_append (context->parts, part);
}

void
e_rule_context_add_rule (ERuleContext *context,
                         EFilterRule *rule)
{
    g_return_if_fail (E_IS_RULE_CONTEXT (context));
    g_return_if_fail (E_IS_FILTER_RULE (rule));

    context->rules = g_list_append (context->rules, rule);

    if (context->priv->frozen == 0) {
        g_signal_emit (context, signals[RULE_ADDED], 0, rule);
        g_signal_emit (context, signals[CHANGED], 0);
    }
}

/* Add a rule, with a gui, asking for confirmation first,
 * and optionally save to path. */
void
e_rule_context_add_rule_gui (ERuleContext *context,
                             EFilterRule *rule,
                             const gchar *title,
                             const gchar *path)
{
    GtkDialog *dialog;
    GtkWidget *widget;
    GtkWidget *content_area;

    g_return_if_fail (E_IS_RULE_CONTEXT (context));
    g_return_if_fail (E_IS_FILTER_RULE (rule));

    widget = e_filter_rule_get_widget (rule, context);
    gtk_widget_show (widget);

    dialog =(GtkDialog *) gtk_dialog_new ();
    gtk_dialog_add_buttons (
        dialog,
        GTK_STOCK_CANCEL, GTK_RESPONSE_CANCEL,
        GTK_STOCK_OK, GTK_RESPONSE_OK,
        NULL);

    gtk_window_set_title ((GtkWindow *) dialog, title);
    gtk_window_set_default_size ((GtkWindow *) dialog, 600, 400);
    gtk_window_set_resizable ((GtkWindow *) dialog, TRUE);

    content_area = gtk_dialog_get_content_area (dialog);
    gtk_box_pack_start (GTK_BOX (content_area), widget, TRUE, TRUE, 0);

    g_object_set_data_full ((GObject *) dialog, "rule", rule, g_object_unref);
    if (path)
        g_object_set_data_full ((GObject *) dialog, "path", g_strdup (path), g_free);

    g_signal_connect (
        dialog, "response",
        G_CALLBACK (new_rule_response), context);

    g_object_ref (context);

    g_object_set_data_full ((GObject *) dialog, "context", context, g_object_unref);

    gtk_widget_show ((GtkWidget *) dialog);
}

void
e_rule_context_remove_rule (ERuleContext *context,
                            EFilterRule *rule)
{
    g_return_if_fail (E_IS_RULE_CONTEXT (context));
    g_return_if_fail (E_IS_FILTER_RULE (rule));

    context->rules = g_list_remove (context->rules, rule);

    if (context->priv->frozen == 0) {
        g_signal_emit (context, signals[RULE_REMOVED], 0, rule);
        g_signal_emit (context, signals[CHANGED], 0);
    }
}

void
e_rule_context_rank_rule (ERuleContext *context,
                          EFilterRule *rule,
                          const gchar *source,
                          gint rank)
{
    GList *node;
    gint i = 0, index = 0;

    g_return_if_fail (E_IS_RULE_CONTEXT (context));
    g_return_if_fail (E_IS_FILTER_RULE (rule));

    if (e_rule_context_get_rank_rule (context, rule, source) == rank)
        return;

    context->rules = g_list_remove (context->rules, rule);
    node = context->rules;
    while (node) {
        EFilterRule *r = node->data;

        if (i == rank) {
            context->rules = g_list_insert (context->rules, rule, index);
            if (context->priv->frozen == 0)
                g_signal_emit (context, signals[CHANGED], 0);

            return;
        }

        index++;
        if (source == NULL || (r->source && strcmp (r->source, source) == 0))
            i++;

        node = node->next;
    }

    context->rules = g_list_append (context->rules, rule);
    if (context->priv->frozen == 0)
        g_signal_emit (context, signals[CHANGED], 0);
}

gint
e_rule_context_get_rank_rule (ERuleContext *context,
                              EFilterRule *rule,
                              const gchar *source)
{
    GList *node;
    gint i = 0;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), -1);
    g_return_val_if_fail (E_IS_FILTER_RULE (rule), -1);

    node = context->rules;
    while (node) {
        EFilterRule *r = node->data;

        if (r == rule)
            return i;

        if (source == NULL || (r->source && strcmp (r->source, source) == 0))
            i++;

        node = node->next;
    }

    return -1;
}

EFilterRule *
e_rule_context_find_rank_rule (ERuleContext *context,
                               gint rank,
                               const gchar *source)
{
    GList *node;
    gint i = 0;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);

    node = context->rules;
    while (node) {
        EFilterRule *r = node->data;

        if (source == NULL || (r->source && strcmp (r->source, source) == 0)) {
            if (rank == i)
                return r;
            i++;
        }

        node = node->next;
    }

    return NULL;
}

GList *
e_rule_context_rename_uri (ERuleContext *context,
                           const gchar *old_uri,
                           const gchar *new_uri,
                           GCompareFunc compare)
{
    ERuleContextClass *class;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);
    g_return_val_if_fail (old_uri != NULL, NULL);
    g_return_val_if_fail (new_uri != NULL, NULL);
    g_return_val_if_fail (compare != NULL, NULL);

    class = E_RULE_CONTEXT_GET_CLASS (context);

    /* This method is optional. */
    if (class->rename_uri == NULL)
        return NULL;

    return class->rename_uri (context, old_uri, new_uri, compare);
}

GList *
e_rule_context_delete_uri (ERuleContext *context,
                           const gchar *uri,
                           GCompareFunc compare)
{
    ERuleContextClass *class;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);
    g_return_val_if_fail (uri != NULL, NULL);
    g_return_val_if_fail (compare != NULL, NULL);

    class = E_RULE_CONTEXT_GET_CLASS (context);

    /* This method is optional. */
    if (class->delete_uri == NULL)
        return NULL;

    return class->delete_uri (context, uri, compare);
}

void
e_rule_context_free_uri_list (ERuleContext *context,
                              GList *uris)
{
    g_return_if_fail (E_IS_RULE_CONTEXT (context));

    /* TODO: should be virtual */

    g_list_foreach (uris, (GFunc) g_free, NULL);
    g_list_free (uris);
}

/**
 * e_rule_context_new_element:
 * @context:
 * @name:
 *
 * create a new filter element based on name.
 *
 * Return value:
 **/
EFilterElement *
e_rule_context_new_element (ERuleContext *context,
                            const gchar *name)
{
    ERuleContextClass *class;

    g_return_val_if_fail (E_IS_RULE_CONTEXT (context), NULL);
    g_return_val_if_fail (name != NULL, NULL);

    class = E_RULE_CONTEXT_GET_CLASS (context);
    g_return_val_if_fail (class->new_element != NULL, NULL);

    return class->new_element (context, name);
}