path: root/lib/ephy-node-db.c

/* 
 *  Copyright (C) 2002 Jorn Baayen <jorn@nl.linux.org>
 *  Copyright (C) 2003 Marco Pesenti Gritti
 *  Copyright (C) 2003 Christian Persch
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 *  $Id$
 */

#include "config.h"

#include "ephy-node-db.h"
#include "ephy-file-helpers.h"
#include "ephy-debug.h"

#include <libxml/xmlreader.h>
#include <libxml/xmlwriter.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>

static void ephy_node_db_class_init (EphyNodeDbClass *klass);
static void ephy_node_db_init (EphyNodeDb *node);
static void ephy_node_db_finalize (GObject *object);

/* FIXME I want to find a better way to deal with "root" nodes */
#define RESERVED_IDS 30

enum
{
    PROP_0,
    PROP_NAME,
    PROP_IMMUTABLE,
};

#define EPHY_NODE_DB_GET_PRIVATE(object)(G_TYPE_INSTANCE_GET_PRIVATE ((object), EPHY_TYPE_NODE_DB, EphyNodeDbPrivate))

struct _EphyNodeDbPrivate
{
    char *name;
    gboolean immutable;

    guint id_factory;

    GPtrArray *id_to_node;
};

static GHashTable *ephy_node_databases = NULL;

static GObjectClass *parent_class = NULL;

GType
ephy_node_db_get_type (void)
{
    static GType type = 0;

    if (G_UNLIKELY (type == 0))
    {
        static const GTypeInfo our_info =
        {
            sizeof (EphyNodeDbClass),
            NULL,
            NULL,
            (GClassInitFunc) ephy_node_db_class_init,
            NULL,
            NULL,
            sizeof (EphyNodeDb),
            0,
            (GInstanceInitFunc) ephy_node_db_init
        };

        type = g_type_register_static (G_TYPE_OBJECT,
                           "EphyNodeDb",
                           &our_info, 0);
    }

    return type;
}

static void
ephy_node_db_set_name (EphyNodeDb *db, const char *name)
{
    db->priv->name = g_strdup (name);

    if (ephy_node_databases == NULL)
    {
        ephy_node_databases = g_hash_table_new (g_str_hash, g_str_equal);
    }

    g_hash_table_insert (ephy_node_databases, db->priv->name, db);
}

static void
ephy_node_db_get_property (GObject *object,
                           guint prop_id,
                           GValue *value,
                           GParamSpec *pspec)
{
    EphyNodeDb *db;

    db = EPHY_NODE_DB (object);

    switch (prop_id)
    {
        case PROP_NAME:
            g_value_set_string (value, db->priv->name);
            break;
        case PROP_IMMUTABLE:
            g_value_set_boolean (value, ephy_node_db_is_immutable (db));
            break;
    }
}

static void
ephy_node_db_set_property (GObject *object,
                           guint prop_id,
                           const GValue *value,
                           GParamSpec *pspec)
{
    EphyNodeDb *db;

    db = EPHY_NODE_DB (object);

    switch (prop_id)
    {
        case PROP_NAME:
            ephy_node_db_set_name (db, g_value_get_string (value));
            break;
        case PROP_IMMUTABLE:
            ephy_node_db_set_immutable (db, g_value_get_boolean (value));
            break;
    }
}

static void
ephy_node_db_class_init (EphyNodeDbClass *klass)
{
    GObjectClass *object_class = G_OBJECT_CLASS (klass);

    parent_class = g_type_class_peek_parent (klass);

    object_class->finalize = ephy_node_db_finalize;
        object_class->set_property = ephy_node_db_set_property;
        object_class->get_property = ephy_node_db_get_property;

    g_object_class_install_property (object_class,
                                         PROP_NAME,
                                         g_param_spec_string  ("name",
                                                               "Name",
                                                               "Name",
                                                               NULL,
                                                               G_PARAM_READWRITE));

    g_object_class_install_property (object_class,
                                         PROP_IMMUTABLE,
                                         g_param_spec_boolean  ("immutable",
                                "Immutable",
                                "Immutable",
                                FALSE,
                                G_PARAM_READWRITE));

    g_type_class_add_private (object_class, sizeof (EphyNodeDbPrivate));
}

static void
ephy_node_db_init (EphyNodeDb *db)
{
    db->priv = EPHY_NODE_DB_GET_PRIVATE (db);

    /* id to node */
    db->priv->id_to_node = g_ptr_array_new ();

    /* id factory */
    db->priv->id_factory = RESERVED_IDS;
}

static void
ephy_node_db_finalize (GObject *object)
{
    EphyNodeDb *db = EPHY_NODE_DB (object);

    g_hash_table_remove (ephy_node_databases, db->priv->name);
    if (g_hash_table_size (ephy_node_databases) == 0)
    {
        g_hash_table_destroy (ephy_node_databases);
    }

    g_ptr_array_free (db->priv->id_to_node, TRUE);

    g_free (db->priv->name);

    G_OBJECT_CLASS (parent_class)->finalize (object);
}

/**
 * ephy_node_db_get_by_name:
 * @name: the name of the desired #EphyNodeDb
 *
 * Returns the #EphyNodeDb named @name, or %NULL if no such database exists.
 *
 * Return value: an #EphyNodeDb
 **/
EphyNodeDb *
ephy_node_db_get_by_name (const char *name)
{
    EphyNodeDb *ret;

    ret = g_hash_table_lookup (ephy_node_databases, name);

    return ret;
}

/**
 * ephy_node_db_new:
 * @name: the name of the new #EphyNodeDb
 *
 * Creates and returns a new #EphyNodeDb, named @name.
 *
 * Return value: the new #EphyNodeDb
 **/
EphyNodeDb *
ephy_node_db_new (const char *name)
{
    EphyNodeDb *db;

    db = EPHY_NODE_DB (g_object_new (EPHY_TYPE_NODE_DB,
                     "name", name,
                         NULL));

    g_return_val_if_fail (db->priv != NULL, NULL);

    return db;
}

static inline EphyNode *
node_from_id_real (EphyNodeDb *db, guint id)
{
    EphyNode *ret = NULL;

    if (id < db->priv->id_to_node->len)
        ret = g_ptr_array_index (db->priv->id_to_node, id);;

    return ret;
}

/**
 * ephy_node_db_get_name:
 * @db: an #EphyNodeDb
 *
 * Return value: the name of @db
 **/
const char *
ephy_node_db_get_name (EphyNodeDb *db)
{
    return db->priv->name;
}

/**
 * ephy_node_db_is_immutable:
 * @db: an #EphyNodeDb
 *
 * Return value: %TRUE if @db is immutable
 **/
gboolean
ephy_node_db_is_immutable (EphyNodeDb *db)
{
    return db->priv->immutable;
}

/**
 * ephy_node_db_set_immutable:
 * @db: an #EphyNodeDb
 * @immutable: %TRUE to make @db immutable
 *
 * If @immutable is %TRUE, sets @db immutable (read-only). Otherwise, sets @db
 * to be read-write.
 **/
void
ephy_node_db_set_immutable (EphyNodeDb *db, gboolean immutable)
{
    db->priv->immutable = immutable;

    g_object_notify (G_OBJECT (db), "immutable");
}

/**
 * ephy_node_db_get_node_from_id:
 * @db: an #EphyNodeDb
 * @id: an id specifying an #EphyNode in @db
 *
 * Returns the #EphyNode with id @id from @db, or %NULL if no such id exists.
 *
 * Return value: an #EphyNode
 **/
EphyNode *
ephy_node_db_get_node_from_id (EphyNodeDb *db, guint id)
{
    EphyNode *ret = NULL;

    ret = node_from_id_real (db, id);

    return ret;
}

guint
_ephy_node_db_new_id (EphyNodeDb *db)
{
    guint ret;

    while (node_from_id_real (db, db->priv->id_factory) != NULL)
    {
        db->priv->id_factory++;
    }

    ret = db->priv->id_factory;

    return ret;
}

void
_ephy_node_db_add_id (EphyNodeDb *db,
              guint id,
              EphyNode *node)
{
    /* resize array if needed */
    if (id >= db->priv->id_to_node->len)
        g_ptr_array_set_size (db->priv->id_to_node, id + 1);

    g_ptr_array_index (db->priv->id_to_node, id) = node;
}

void
_ephy_node_db_remove_id (EphyNodeDb *db,
             guint id)
{
    g_ptr_array_index (db->priv->id_to_node, id) = NULL;

    /* reset id factory so we use the freed node id */
    db->priv->id_factory = RESERVED_IDS;
}

/**
 * ephy_node_db_load_from_file:
 * @db: a new #EphyNodeDb
 * @xml_file: the filename from which @db will be populated
 * @xml_root: the root element in @xml_file
 * @xml_version: the required version attribute in the @xml_root
 *
 * Populates @db with data from @xml_file. The node database will be populated
 * with everything inside of the @xml_root tag from @xml_file. If @xml_version
 * is different from the version attribute of the @xml_root element, this
 * function will fail.
 *
 * The data will most probably have been stored using
 * ephy_node_db_write_to_xml_safe().
 *
 * Return value: %TRUE if successful
 **/
gboolean
ephy_node_db_load_from_file (EphyNodeDb *db,
                 const char *xml_file,
                 const xmlChar *xml_root,
                 const xmlChar *xml_version)
{
    xmlTextReaderPtr reader;
    gboolean success = TRUE;
    gboolean was_immutable;
    int ret;

    LOG ("ephy_node_db_load_from_file %s", xml_file)

    START_PROFILER ("loading node db")

    if (g_file_test (xml_file, G_FILE_TEST_EXISTS) == FALSE)
    {
        return FALSE;
    }

    reader = xmlNewTextReaderFilename (xml_file);
    if (reader == NULL)
    {
        return FALSE;
    }

    was_immutable = db->priv->immutable;
    db->priv->immutable = FALSE;

    ret = xmlTextReaderRead (reader);
    while (ret == 1)
    {
        const xmlChar *name;
        xmlReaderTypes type;
        gboolean skip = FALSE;

        name = xmlTextReaderConstName (reader);
        type = xmlTextReaderNodeType (reader);

        if (xmlStrEqual (name, "node")
            && type == XML_READER_TYPE_ELEMENT)
        {
            xmlNodePtr subtree;

            /* grow the subtree and load the node from it */
            subtree = xmlTextReaderExpand (reader);

            if (subtree != NULL)
            {
                ephy_node_new_from_xml (db, subtree);
            }           
                
            skip = TRUE;
        }
        else if (xmlStrEqual (name, xml_root)
             && type == XML_READER_TYPE_ELEMENT)
        {
            xmlChar *version;

            /* check version info */
            version = xmlTextReaderGetAttribute (reader, "version");
            if (xmlStrEqual (version, xml_version) == FALSE)
            {
                success = FALSE;
                xmlFree (version);

                break;
            }

            xmlFree (version);
        }

        /* next one, please */
        ret = skip ? xmlTextReaderNext (reader)
               : xmlTextReaderRead (reader);
    }

    xmlFreeTextReader (reader);

    db->priv->immutable = was_immutable;

    STOP_PROFILER ("loading node db")

    return (success && ret == 0);
}

static int
ephy_node_db_write_to_xml_valist (EphyNodeDb *db,
                  const xmlChar *filename,
                  const xmlChar *root,
                  const xmlChar *version,
                  const xmlChar *comment,
                  EphyNode *first_node,
                  va_list argptr)
{
    xmlTextWriterPtr writer;
    EphyNode *node;
    int ret;

    LOG ("Saving node db to %s", filename)

    START_PROFILER ("Saving node db")

    /* FIXME: do we want to turn compression on ? */
    writer = xmlNewTextWriterFilename (filename, 0);
    if (writer == NULL)
    {
        return -1;
    }

    ret = xmlTextWriterSetIndent (writer, 1);
    if (ret < 0) goto out;

    ret = xmlTextWriterSetIndentString (writer, "  ");
    if (ret < 0) goto out;

    ret = xmlTextWriterStartDocument (writer, "1.0", NULL, NULL);
    if (ret < 0) goto out;

    ret = xmlTextWriterStartElement (writer, root);
    if (ret < 0) goto out;

    ret = xmlTextWriterWriteAttribute (writer, "version", version);
    if (ret < 0) goto out;

    if (comment != NULL)
    {
        ret = xmlTextWriterWriteComment (writer, comment);
        if (ret < 0) goto out;
    }

    node = first_node;
    while (node != NULL)
    {
        GPtrArray *children;
        guint n_exceptions, i;
        GSList *exceptions = NULL;

        n_exceptions = va_arg (argptr, guint);
        for (i=0; i < n_exceptions; i++)
        {
            exceptions = g_slist_prepend (exceptions,
                              va_arg (argptr, EphyNode *));
        }

        children = ephy_node_get_children (node);
        for (i=0; i < children->len; i++)
        {
            EphyNode *kid;
        
            kid = g_ptr_array_index (children, i);
        
            if (g_slist_find (exceptions, kid) == NULL)
            {
                ret = ephy_node_write_to_xml (kid, writer);
                if (ret < 0) break;
            }
        }
        if (ret < 0) break;

        g_slist_free (exceptions);

        node = va_arg (argptr, EphyNode *);
    }
    if (ret < 0) goto out;

    ret = xmlTextWriterEndElement (writer); /* root */
    if (ret < 0) goto out;

    ret = xmlTextWriterEndDocument (writer);
    if (ret < 0) goto out;

out:
    xmlFreeTextWriter (writer);

    STOP_PROFILER ("Saving node db")

    return ret >= 0 ? 0 : -1;
}

/**
 * ephy_node_db_write_to_xml_safe:
 * @db: an #EphyNodeDb
 * @filename: the XML file in which @db's data will be stored
 * @root: the desired root element in @filename
 * @version: the version attribute to the @root element
 * @comment: a comment to place directly inside the @root element of @filename
 * @node: The first node of data to write
 * @Varargs: number of exceptions, list of their #EphyNodes, and more such
 *       sequences, followed by %NULL
 *
 * Writes @db's data to an XML file for storage. The data can be retrieved in
 * the future using ephy_node_db_load_from_file().
 *
 * The function arguments are straightforward until @node, at which point some
 * explanation is necessary.
 *
 * The variable argument list starts at @node, which is an #EphyNode containing
 * data to write to @filename. The next argument is an integer specifying the
 * number of <quote>exception</quote> nodes. After this integer, that number of
 * #EphyNode arguments should be given. Each of these <quote>exception</quote>
 * nodes determines which data out of @node will <emphasis>not</emphasis> be
 * written to @filename.
 *
 * To insert all of an #EphyNode's contents without exception, simply give the
 * integer %0 after @node.
 *
 * The remainder of this function's arguments will be groups of such #EphyNode -
 * integer - (list of #EphyNode<!-- -->s). Finally, the last argument must be
 * %NULL.
 *
 * Return value: %0 on success or a negative number on failure
 **/
int
ephy_node_db_write_to_xml_safe (EphyNodeDb *db,
                const xmlChar *filename,
                const xmlChar *root,
                const xmlChar *version,
                const xmlChar *comment,
                EphyNode *node, ...)
{
    va_list argptr;
    int ret = 0;
    char *tmp_file;

    tmp_file = g_strconcat (filename, ".tmp", NULL);

    va_start (argptr, node);
 
    ret = ephy_node_db_write_to_xml_valist
        (db, tmp_file, root, version, comment, node, argptr);

    va_end (argptr);

    if (ret < 0)
    {
        g_warning ("Failed to write XML data to %s", tmp_file);
        goto failed;
    }

    if (ephy_file_switch_temp_file (filename, tmp_file) == FALSE)
    {
        ret = -1;
    }

failed:
    g_free (tmp_file);

    return ret;
}