path: root/widgets/table/e-tree-model.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * e-tree-model.c: a Tree Model
 *
 * Author:
 *   Chris Toshok (toshok@ximian.com)
 *
 * Adapted from the gtree code and ETableModel.
 *
 * (C) 2000 Ximian, Inc.
 */
#include <config.h>

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>

#include <gnome-xml/parser.h>
#include <gnome-xml/xmlmemory.h>

#include <gtk/gtksignal.h>
#include <stdlib.h>
#include "gal/util/e-util.h"
#include "gal/util/e-xml-utils.h"
#include "e-tree-model.h"

#define ETM_CLASS(e) ((ETreeModelClass *)((GtkObject *)e)->klass)

#define PARENT_TYPE E_TABLE_MODEL_TYPE

#define TREEPATH_CHUNK_AREA_SIZE (30 * sizeof (ETreePath))

static ETableModel *e_tree_model_parent_class;

struct ETreeModelPriv {
    GMemChunk  *node_chunk;
    ETreePath  *root;
    gboolean    root_visible;
    GArray     *row_array; /* used in the mapping between ETable and our tree */
    GHashTable *expanded_state; /* used for loading/saving expanded state */
    GString    *sort_group; /* for caching the last sort group info */
    gboolean    expanded_default; /* whether nodes are created expanded or collapsed by default */
    gboolean   frozen;  /* has there been a pre-change event on us? */
};

struct ETreePath {
    gboolean             expanded;
    gboolean             expanded_set;
    guint                visible_descendents;
    char                *save_id;
    ETreePathCompareFunc compare;
    gpointer             node_data;

    /* parent/child/sibling pointers */
    ETreePath           *parent;
    ETreePath           *next_sibling;
    ETreePath           *prev_sibling;
    ETreePath           *first_child;
    ETreePath           *last_child;
    guint32              num_children;
};

enum {
    NODE_CHANGED,
    NODE_INSERTED,
    NODE_REMOVED,
    NODE_COLLAPSED,
    NODE_EXPANDED,
    LAST_SIGNAL
};

static guint e_tree_model_signals [LAST_SIGNAL] = {0, };

static void add_visible_descendents_to_array (ETreeModel *etm, ETreePath *node, int *row, int *count);


/* ETreePath functions */

static int
e_tree_path_depth (ETreePath *path)
{
    int depth = 0;
    while (path) {
        depth ++;
        path = path->parent;
    }
    return depth;
}

static void
e_tree_path_insert (ETreePath *parent, int position, ETreePath *child)
{
    g_return_if_fail (position <= parent->num_children || position == -1);

    child->parent = parent;

    if (parent->first_child == NULL)
        parent->first_child = child;

    if (position == -1 || position == parent->num_children) {
        child->prev_sibling = parent->last_child;
        if (parent->last_child)
            parent->last_child->next_sibling = child;
        parent->last_child = child;
    }
    else {
        ETreePath *c;
        for (c = parent->first_child; c; c = c->next_sibling) {
            if (position == 0) {
                child->next_sibling = c;
                child->prev_sibling = c->prev_sibling;

                if (child->next_sibling)
                    child->next_sibling->prev_sibling = child;
                if (child->prev_sibling)
                    child->prev_sibling->next_sibling = child;

                if (parent->first_child == c)
                    parent->first_child = child;
                break;
            }
            position --;
        }
    }

    parent->num_children++;
}

static void
e_tree_path_unlink (ETreePath *path)
{
    ETreePath *parent = path->parent;

    /* unlink first/last child if applicable */
    if (parent) {
        if (path == parent->first_child)
            parent->first_child = path->next_sibling;
        if (path == parent->last_child)
            parent->last_child = path->prev_sibling;

        parent->num_children --;
    }

    /* unlink prev/next sibling links */
    if (path->next_sibling)
        path->next_sibling->prev_sibling = path->prev_sibling;
    if (path->prev_sibling)
        path->prev_sibling->next_sibling = path->next_sibling;

    path->parent = NULL;
    path->next_sibling = NULL;
    path->prev_sibling = NULL;
}

void
e_tree_model_node_traverse (ETreeModel *model, ETreePath *path, ETreePathFunc func, gpointer data)
{
    ETreePath *child;

    g_return_if_fail (path);

    child = path->first_child;

    while (child) {
        ETreePath *next_child = child->next_sibling;
        e_tree_model_node_traverse (model, child, func, data);
        if (func (model, child, data) == TRUE)
            return;

        child = next_child;
    }
}



void
e_tree_model_freeze(ETreeModel *etm)
{
    ETreeModelPriv *priv = etm->priv;

    priv->frozen = TRUE;
}

void
e_tree_model_thaw(ETreeModel *etm)
{
    ETreeModelPriv *priv = etm->priv;

    priv->frozen = FALSE;
    e_table_model_changed(E_TABLE_MODEL(etm));
}


/* virtual methods */

static void
etree_destroy (GtkObject *object)
{
    ETreeModel *etree = E_TREE_MODEL (object);
    ETreeModelPriv *priv = etree->priv;

    /* XXX lots of stuff to free here */
    g_array_free (priv->row_array, TRUE);
    g_hash_table_destroy (priv->expanded_state);

    g_string_free(priv->sort_group, TRUE);

    g_free (priv);

    GTK_OBJECT_CLASS (e_tree_model_parent_class)->destroy (object);
}

static ETreePath*
etree_get_root (ETreeModel *etm)
{
    ETreeModelPriv *priv = etm->priv;
    return priv->root;
}

static ETreePath*
etree_get_parent (ETreeModel *etm, ETreePath *path)
{
    g_return_val_if_fail (path, NULL);
    
    return path->parent;
}

static ETreePath*
etree_get_next (ETreeModel *etm, ETreePath *node)
{
    g_return_val_if_fail (node, NULL);

    return node->next_sibling;
}

static ETreePath*
etree_get_prev (ETreeModel *etm, ETreePath *node)
{
    g_return_val_if_fail (node, NULL);

    return node->prev_sibling;
}

static ETreePath*
etree_get_first_child (ETreeModel *etm, ETreePath *node)
{
    g_return_val_if_fail (node, NULL);

    return node->first_child;
}

static ETreePath*
etree_get_last_child (ETreeModel *etm, ETreePath *node)
{
    g_return_val_if_fail (node, NULL);

    return node->last_child;
}

static guint
etree_get_children (ETreeModel *etm, ETreePath* node, ETreePath ***paths)
{
    guint n_children;

    g_return_val_if_fail (node, 0);

    n_children = node->num_children;

    if (paths) {
        ETreePath *p;
        int i = 0;
        (*paths) = g_malloc (sizeof (ETreePath*) * n_children);
        for (p = node->first_child; p; p = p->next_sibling) {
            (*paths)[i++] = p;
        }
    }

    return n_children;
}

static gboolean
etree_is_expanded (ETreeModel *etm, ETreePath* node)
{
    g_return_val_if_fail (node, FALSE);
    
    return node->expanded;
}

static gboolean
etree_is_visible (ETreeModel *etm, ETreePath* node)
{
    g_return_val_if_fail (node, FALSE);

    for (node = node->parent; node; node = node->parent) {
        if (!node->expanded)
            return FALSE;
    }

    return TRUE;
}

static void
etree_set_expanded (ETreeModel *etm, ETreePath* node, gboolean expanded)
{
    ETreeModelPriv *priv = etm->priv;
    ETreePath *child;
    int row;

    g_return_if_fail (node);

    node->expanded_set = TRUE;

    if (node->expanded == expanded)
        return;

    if (expanded) {
        gboolean allow_expand = TRUE;
        e_tree_model_node_expanded (etm, node, &allow_expand);
        if (!allow_expand)
            return;
    }

    node->expanded = expanded;
    if (node->save_id) {
        g_hash_table_insert (priv->expanded_state, node->save_id, (gpointer)expanded);
    }

    /* if the node wasn't visible at present */
    if ((row = e_tree_model_row_of_node (etm, node)) == -1) {
        if (!expanded) {
            e_tree_model_node_collapsed (etm, node);
        }
        return;
    }
        
    row++;

    if (expanded) {
        ETreePath *parent;

        if (e_tree_model_node_is_visible (etm, node)) {
            node->visible_descendents = 0;
            for (child = node->first_child; child;
                 child = child->next_sibling) {
                add_visible_descendents_to_array (etm, child, &row, &node->visible_descendents);
            }
        }
        /* now iterate back up the tree, adding to our
           ancestors' visible descendents */

        for (parent = node->parent; parent; parent = parent->parent) {
            parent->visible_descendents += node->visible_descendents;
        }
    }
    else {
        int i;
        ETreePath *parent;

        if (e_tree_model_node_is_visible (etm, node)) {
            for (i = 0; i < node->visible_descendents; i ++) {
                priv->row_array = g_array_remove_index (priv->row_array, row);
                e_table_model_row_deleted (E_TABLE_MODEL (etm), row);
            }
        }
        /* now iterate back up the tree, subtracting from our
           ancestors' visible descendents */

        for (parent = node->parent; parent; parent = parent->parent) {
            parent->visible_descendents -= node->visible_descendents;
        }

        node->visible_descendents = 0;

        e_tree_model_node_collapsed (etm, node);
    }
}

void
e_tree_model_set_expanded_default (ETreeModel *etree,
                   gboolean expanded)
{
    ETreeModelPriv *priv = etree->priv;

    priv->expanded_default = expanded;
}

/* fairly naive implementation */
static void
etree_set_expanded_recurse (ETreeModel *etm, ETreePath* node, gboolean expanded)
{
    ETreePath *child;

    e_tree_model_node_set_expanded (etm, node, expanded);

    for (child = node->first_child; child; child = child->next_sibling)
        e_tree_model_node_set_expanded_recurse (etm, child, expanded);
}

static ETreePath *
etree_node_at_row (ETreeModel *etree, int row)
{
    ETreeModelPriv *priv = etree->priv;

    g_return_val_if_fail (row < priv->row_array->len, NULL);

    return g_array_index (priv->row_array, ETreePath*, row);
}


/* ETable analogs */
static void*
etree_value_at (ETreeModel *etm, ETreePath* node, int col)
{
    /* shouldn't be called */
    g_assert (0);
    return NULL;
}

static GdkPixbuf*
etree_icon_at (ETreeModel *etm, ETreePath* node)
{
    /* shouldn't be called */
    g_assert (0);
    return NULL;
}

static void
etree_set_value_at (ETreeModel *etm, ETreePath* node, int col, const void *val)
{
    /* shouldn't be called */
    g_assert (0);
}

static gboolean
etree_is_editable (ETreeModel *etm, ETreePath* node, int col)
{
    /* shouldn't be called */
    g_assert(0);
    return FALSE;
}


/* ETable virtual functions we map */
static int
etable_row_count (ETableModel *etm)
{
    ETreeModel *tree = E_TREE_MODEL (etm);
    ETreeModelPriv *priv = tree->priv;
    return priv->row_array->len;
}

static void *
etable_value_at (ETableModel *etm, int col, int row)
{
    ETreeModel *etree = E_TREE_MODEL(etm);
    ETreeModelClass *et_class = ETM_CLASS(etm);
    ETreePath* node = e_tree_model_node_at_row (etree, row);

    g_return_val_if_fail (node, NULL);

    if (col == -1)
        return node;
    else if (col == -2)
        return etm;
    else
        return et_class->value_at (etree, node, col);
}

static void
etable_set_value_at (ETableModel *etm, int col, int row, const void *val)
{
    ETreeModel *etree = E_TREE_MODEL(etm);
    ETreeModelClass *et_class = ETM_CLASS(etm);
    ETreePath* node = e_tree_model_node_at_row (etree, row);

    g_return_if_fail (node);

    et_class->set_value_at (etree, node, col, val);
}

static gboolean
etable_is_cell_editable (ETableModel *etm, int col, int row)
{
    ETreeModel *etree = E_TREE_MODEL(etm);
    ETreeModelClass *et_class = ETM_CLASS(etm);
    ETreePath* node = e_tree_model_node_at_row (etree, row);

    g_return_val_if_fail (node, FALSE);

    return et_class->is_editable (etree, node, col);
}

static void
build_sort_group(GString *out, ETreePath *node)
{
    if (node->parent) {
        build_sort_group(out, node->parent);
    }
    g_string_sprintfa(out, "/%p", node);
}

static const char *
etable_row_sort_group(ETableModel *etm, int row)
{
    ETreeModel *etree = E_TREE_MODEL(etm);
    ETreeModelPriv *priv = etree->priv;
    ETreePath* node = e_tree_model_node_at_row (etree, row);

    g_return_val_if_fail (node, "");

    g_string_truncate(priv->sort_group, 0);
    if (node)
        build_sort_group(priv->sort_group, node);

    return priv->sort_group->str;
}

static gboolean
etable_has_sort_group(ETableModel *etm)
{
    /* could optimise for the flat &/or unexpanded tree case */
    return TRUE;
}


static void
e_tree_model_class_init (GtkObjectClass *klass)
{
    ETableModelClass *table_class = (ETableModelClass *) klass;
    ETreeModelClass *tree_class = (ETreeModelClass *) klass;

    e_tree_model_parent_class = gtk_type_class (PARENT_TYPE);
    
    klass->destroy = etree_destroy;

    e_tree_model_signals [NODE_CHANGED] =
        gtk_signal_new ("node_changed",
                GTK_RUN_LAST,
                klass->type,
                GTK_SIGNAL_OFFSET (ETreeModelClass, node_changed),
                gtk_marshal_NONE__POINTER,
                GTK_TYPE_NONE, 1, GTK_TYPE_POINTER);

    e_tree_model_signals [NODE_INSERTED] =
        gtk_signal_new ("node_inserted",
                GTK_RUN_LAST,
                klass->type,
                GTK_SIGNAL_OFFSET (ETreeModelClass, node_inserted),
                gtk_marshal_NONE__POINTER_POINTER,
                GTK_TYPE_NONE, 2, GTK_TYPE_POINTER, GTK_TYPE_POINTER);

    e_tree_model_signals [NODE_REMOVED] =
        gtk_signal_new ("node_removed",
                GTK_RUN_LAST,
                klass->type,
                GTK_SIGNAL_OFFSET (ETreeModelClass, node_removed),
                gtk_marshal_NONE__POINTER_POINTER,
                GTK_TYPE_NONE, 2, GTK_TYPE_POINTER, GTK_TYPE_POINTER);

    e_tree_model_signals [NODE_COLLAPSED] =
        gtk_signal_new ("node_collapsed",
                GTK_RUN_LAST,
                klass->type,
                GTK_SIGNAL_OFFSET (ETreeModelClass, node_collapsed),
                gtk_marshal_NONE__POINTER,
                GTK_TYPE_NONE, 1, GTK_TYPE_POINTER);

    e_tree_model_signals [NODE_EXPANDED] =
        gtk_signal_new ("node_expanded",
                GTK_RUN_LAST,
                klass->type,
                GTK_SIGNAL_OFFSET (ETreeModelClass, node_expanded),
                gtk_marshal_NONE__POINTER_POINTER,
                GTK_TYPE_NONE, 2, GTK_TYPE_POINTER, GTK_TYPE_POINTER);

    gtk_object_class_add_signals (klass, e_tree_model_signals, LAST_SIGNAL);

    table_class->row_count        = etable_row_count;
    table_class->value_at         = etable_value_at;
    table_class->set_value_at     = etable_set_value_at;
    table_class->is_cell_editable = etable_is_cell_editable;
#if 0
    /* XX need to pass these through */
    table_class->duplicate_value  = etable_duplicate_value;
    table_class->free_value       = etable_free_value;
    table_class->initialize_value = etable_initialize_value;
    table_class->value_is_empty   = etable_value_is_empty;
    table_class->value_to_string  = etable_value_to_string;
    table_class->thaw             = etable_thaw;
#endif

    table_class->row_sort_group   = etable_row_sort_group;
    table_class->has_sort_group   = etable_has_sort_group;

    tree_class->get_root          = etree_get_root;
    tree_class->get_prev          = etree_get_prev;
    tree_class->get_next          = etree_get_next;
    tree_class->get_first_child   = etree_get_first_child;
    tree_class->get_last_child    = etree_get_last_child;
    tree_class->get_parent        = etree_get_parent;

    tree_class->value_at          = etree_value_at;
    tree_class->icon_at           = etree_icon_at;
    tree_class->set_value_at      = etree_set_value_at;
    tree_class->is_editable       = etree_is_editable;

    tree_class->get_children      = etree_get_children;
    tree_class->is_expanded       = etree_is_expanded;
    tree_class->is_visible        = etree_is_visible;
    tree_class->set_expanded      = etree_set_expanded;
    tree_class->set_expanded_recurse = etree_set_expanded_recurse;
    tree_class->node_at_row       = etree_node_at_row;
}

static void
e_tree_init (GtkObject *object)
{
    ETreeModel *etree = (ETreeModel *)object;
    e_tree_model_construct (etree);
}

E_MAKE_TYPE(e_tree_model, "ETreeModel", ETreeModel, e_tree_model_class_init, e_tree_init, PARENT_TYPE)


/* signals */
void
e_tree_model_node_changed  (ETreeModel *tree_model, ETreePath *node)
{
    int row;
    g_return_if_fail (tree_model != NULL);
    g_return_if_fail (E_IS_TREE_MODEL (tree_model));
    
    row = e_tree_model_row_of_node (tree_model, node);
    if (row != -1)
        e_table_model_row_changed (E_TABLE_MODEL (tree_model), row);

    gtk_signal_emit (GTK_OBJECT (tree_model),
             e_tree_model_signals [NODE_CHANGED]);
}

void
e_tree_model_node_inserted (ETreeModel *tree_model,
                ETreePath *parent_node,
                ETreePath *inserted_node)
{
    int row;
    g_return_if_fail (tree_model != NULL);
    g_return_if_fail (E_IS_TREE_MODEL (tree_model));

    row = e_tree_model_row_of_node (tree_model, inserted_node);
    if (row != -1)
        e_table_model_row_inserted (E_TABLE_MODEL (tree_model), row);
    
    gtk_signal_emit (GTK_OBJECT (tree_model),
             e_tree_model_signals [NODE_INSERTED],
             parent_node, inserted_node);
}

void
e_tree_model_node_removed  (ETreeModel *tree_model, ETreePath *parent_node, ETreePath *removed_node)
{
    int row;

    g_return_if_fail (tree_model != NULL);
    g_return_if_fail (E_IS_TREE_MODEL (tree_model));

    row = e_tree_model_row_of_node (tree_model, removed_node);
    if (row != -1)
        e_table_model_row_deleted (E_TABLE_MODEL (tree_model), row);
    
    gtk_signal_emit (GTK_OBJECT (tree_model),
             e_tree_model_signals [NODE_REMOVED],
             parent_node, removed_node);
}

void
e_tree_model_node_collapsed (ETreeModel *tree_model, ETreePath *node)
{
    g_return_if_fail (tree_model != NULL);
    g_return_if_fail (E_IS_TREE_MODEL (tree_model));
    
    gtk_signal_emit (GTK_OBJECT (tree_model),
             e_tree_model_signals [NODE_COLLAPSED],
             node);
}

void
e_tree_model_node_expanded  (ETreeModel *tree_model, ETreePath *node, gboolean *allow_expand)
{
    g_return_if_fail (tree_model != NULL);
    g_return_if_fail (E_IS_TREE_MODEL (tree_model));
    
    gtk_signal_emit (GTK_OBJECT (tree_model),
             e_tree_model_signals [NODE_EXPANDED],
             node, allow_expand);
}



void
e_tree_model_construct (ETreeModel *etree)
{
    ETreeModelPriv *priv = g_new0 (ETreeModelPriv, 1);

    etree->priv = priv;

    priv->node_chunk = g_mem_chunk_create (ETreePath, TREEPATH_CHUNK_AREA_SIZE, G_ALLOC_AND_FREE);
    priv->root = NULL;
    priv->root_visible = TRUE;
    priv->row_array = g_array_new (FALSE, FALSE, sizeof(ETreePath*));
    priv->expanded_state = g_hash_table_new (g_str_hash, g_str_equal);
    priv->sort_group = g_string_new("");
}

ETreeModel *
e_tree_model_new ()
{
    ETreeModel *et;

    et = gtk_type_new (e_tree_model_get_type ());

    return et;
}

ETreePath *
e_tree_model_get_root (ETreeModel *etree)
{
    return ETM_CLASS(etree)->get_root(etree);
}

ETreePath *
e_tree_model_node_at_row (ETreeModel *etree, int row)
{
    return ETM_CLASS(etree)->node_at_row (etree, row);
}

GdkPixbuf *
e_tree_model_icon_of_node (ETreeModel *etree, ETreePath *path)
{
    return ETM_CLASS(etree)->icon_at (etree, path);
}

int
e_tree_model_row_of_node (ETreeModel *etree, ETreePath *node)
{
    ETreeModelPriv *priv = etree->priv;
    int i;

    for (i = 0; i < priv->row_array->len; i ++)
        if (g_array_index (priv->row_array, ETreePath*, i) == node)
            return i;

    return -1;
}

void
e_tree_model_root_node_set_visible (ETreeModel *etm, gboolean visible)
{
    ETreeModelPriv *priv = etm->priv;

    if (visible != priv->root_visible) {
        priv->root_visible = visible;
        if (priv->root) {
            if (visible) {
                priv->row_array = g_array_insert_val (priv->row_array, 0, priv->root);
            }
            else {
                ETreePath *root_path = e_tree_model_get_root (etm);
                e_tree_model_node_set_expanded (etm, root_path, TRUE);
                priv->row_array = g_array_remove_index (priv->row_array, 0);
            }
            
            e_table_model_changed (E_TABLE_MODEL (etm));
        }
    }
}

gboolean
e_tree_model_root_node_is_visible (ETreeModel *etm)
{
    ETreeModelPriv *priv = etm->priv;
    return priv->root_visible;
}

ETreePath *
e_tree_model_node_get_first_child (ETreeModel *etree, ETreePath *node)
{
    return ETM_CLASS(etree)->get_first_child(etree, node);
}

ETreePath *
e_tree_model_node_get_last_child (ETreeModel *etree, ETreePath *node)
{
    return ETM_CLASS(etree)->get_last_child(etree, node);
}


ETreePath *
e_tree_model_node_get_next (ETreeModel *etree, ETreePath *node)
{
    return ETM_CLASS(etree)->get_next(etree, node);
}

ETreePath *
e_tree_model_node_get_prev (ETreeModel *etree, ETreePath *node)
{
    return ETM_CLASS(etree)->get_prev(etree, node);
}

guint
e_tree_model_node_depth (ETreeModel *etree, ETreePath *path)
{
    return e_tree_path_depth (path) - 1;
}

ETreePath *
e_tree_model_node_get_parent (ETreeModel *etree, ETreePath *path)
{
    return ETM_CLASS(etree)->get_parent(etree, path);
}

gboolean
e_tree_model_node_is_root (ETreeModel *etree, ETreePath *path)
{
    return (e_tree_model_node_depth (etree, path) == 0);
}

gboolean
e_tree_model_node_is_expandable (ETreeModel *etree, ETreePath *path)
{
    return (e_tree_model_node_get_children (etree, path, NULL) > 0);
}

gboolean
e_tree_model_node_is_expanded (ETreeModel *etree, ETreePath *path)
{
    return ETM_CLASS(etree)->is_expanded (etree, path);
}

gboolean
e_tree_model_node_is_visible (ETreeModel *etree, ETreePath *path)
{
    return ETM_CLASS(etree)->is_visible (etree, path);
}

void
e_tree_model_node_set_expanded (ETreeModel *etree, ETreePath *path, gboolean expanded)
{
    ETM_CLASS(etree)->set_expanded (etree, path, expanded);
}

void
e_tree_model_node_set_expanded_recurse (ETreeModel *etree, ETreePath *path, gboolean expanded)
{
    ETM_CLASS(etree)->set_expanded_recurse (etree, path, expanded);
}

guint
e_tree_model_node_get_children (ETreeModel *etree, ETreePath *path, ETreePath ***paths)
{
    return ETM_CLASS(etree)->get_children (etree, path, paths);
}

guint
e_tree_model_node_num_visible_descendents (ETreeModel *etm, ETreePath *node)
{
    return node->visible_descendents;
}

gpointer
e_tree_model_node_get_data (ETreeModel *etm, ETreePath *node)
{
    g_return_val_if_fail (node, NULL);

    return node->node_data;
}

void
e_tree_model_node_set_data (ETreeModel *etm, ETreePath *node, gpointer node_data)
{
    g_return_if_fail (node);

    node->node_data = node_data;
}

ETreePath*
e_tree_model_node_insert (ETreeModel *tree_model,
              ETreePath *parent_path,
              int position,
              gpointer node_data)
{
    ETreeModelPriv *priv;
    ETreePath *new_path;

    priv = tree_model->priv;

    g_return_val_if_fail (parent_path != NULL || priv->root == NULL, NULL);

    priv = tree_model->priv;

    new_path = g_chunk_new0 (ETreePath, priv->node_chunk);

    new_path->expanded = FALSE;
    new_path->node_data = node_data;

    if (parent_path != NULL) {

        if (parent_path->first_child == NULL
            && !parent_path->expanded_set) {
            e_tree_model_node_set_expanded (tree_model,
                            parent_path,
                            priv->expanded_default);
        }

        e_tree_path_insert (parent_path, position, new_path);

        if (e_tree_model_node_is_visible (tree_model, new_path)) {
            int parent_row, child_offset = 0;
            ETreePath *n;

            /* we need to iterate back up to the root, incrementing the number of visible
               descendents */
            for (n = parent_path; n; n = n->parent) {
                n->visible_descendents ++;
            }
                
            /* determine if we are inserting at the end of this parent */
            if (position == -1 || position == parent_path->num_children) {
                position = e_tree_model_node_num_visible_descendents (tree_model, parent_path) - 1;
            } else {
                /* if we're not inserting at the end of the array, position is the child node we're
                   inserting at, not the absolute row position - need to count expanded nodes before it too */
                int i = position;

                n = e_tree_model_node_get_first_child(tree_model, parent_path);
                while (n != NULL && i > 0) {
                    child_offset += n->visible_descendents;
                    n = n->next_sibling;
                    i--;
                }
            }


            /* if the parent is the root, no need to search for its position since it aint there */
            if (parent_path->parent == NULL) {
                parent_row = -1;
            } else {
                parent_row = e_tree_model_row_of_node (tree_model, parent_path);
            }

            e_table_model_pre_change(E_TABLE_MODEL(tree_model));

            priv->row_array = g_array_insert_val (priv->row_array,
                                  parent_row + position + 1 + child_offset, new_path);

            /* only do this if we know a changed signal isn't coming later on */
            if (!priv->frozen)
                e_table_model_row_inserted (E_TABLE_MODEL(tree_model), parent_row + position + 1 + child_offset);
        }

        if (parent_path->compare)
            e_tree_model_node_sort (tree_model, parent_path);
    }
    else {
        priv->root = new_path;
        if (priv->root_visible) {
            priv->row_array = g_array_insert_val (priv->row_array, 0, priv->root);
            e_table_model_row_inserted (E_TABLE_MODEL (tree_model), 0);
        }
        else {
            /* need to mark the new node as expanded or
                           we'll never see it's children */
            new_path->expanded = TRUE;
            new_path->expanded_set = TRUE;
        }
    }

    return new_path;
}

ETreePath*
e_tree_model_node_insert_id (ETreeModel *tree_model,
                 ETreePath *parent_path,
                 int position,
                 gpointer node_data,
                 const char *save_id)
{
    ETreePath *path = e_tree_model_node_insert (tree_model, parent_path, position, node_data);

    e_tree_model_node_set_save_id (tree_model, path, save_id);

    return path;
}

              
ETreePath *
e_tree_model_node_insert_before (ETreeModel *etree,
                 ETreePath *parent,
                 ETreePath *sibling,
                 gpointer node_data)
{
    ETreePath *child;
    int position = 0;
    for (child = parent->first_child; child; child = child->next_sibling) {
        if (child == sibling)
            break;
        position ++;
    }
    return e_tree_model_node_insert (etree, parent, position, node_data);
}

/* just blows away child data, doesn't take into account unlinking/etc */
static void
child_free(ETreeModel *etree, ETreePath *node)
{
    ETreePath *child, *next;
    ETreeModelPriv *priv = etree->priv;

    child = node->first_child;
    while (child) {
        next = child->next_sibling;
        child_free(etree, child);
        child = next;
    }

    if (node->save_id) {
        g_hash_table_remove(priv->expanded_state, node->save_id);
        g_free(node->save_id);
    }
    g_chunk_free(node, priv->node_chunk);
}

gpointer
e_tree_model_node_remove (ETreeModel *etree, ETreePath *path)
{
    ETreeModelPriv *priv = etree->priv;
    ETreePath *parent = path->parent;
    gpointer ret = path->node_data;
    int row, visible = 0, base = 0;
    gboolean dochanged;

    /* work out what range of visible rows to remove */
    if (parent) {
        if (e_tree_model_node_is_visible(etree, path)) {
            base = e_tree_model_row_of_node(etree, path);
            visible = path->visible_descendents + 1;
        }
    } else if (path == priv->root) {
        priv->root = NULL;
        if (priv->root_visible) {
            base = 0;
            visible = path->visible_descendents + 1;
        } else {
            base = 0;
            visible = path->visible_descendents;
        }
    } else {
        g_warning("Trying to remove invalid path %p", path);
        return NULL;
    }

    /* unlink this node - we only have to unlink the root node being removed,
       since the others are only references from this node */
    e_tree_path_unlink (path);

    /*printf("removing %d nodes from position %d\n", visible, base);*/

    if (visible > 0) {
        /* fix up the parent visible counts */
        for (; parent; parent = parent->parent) {
            parent->visible_descendents -= visible;
        }

        /* if we have a lot of nodes to remove, then we dont row_deleted each one */
        /* could probably be tuned, but this'll do, since its normally only when we
           remove the whole lot do we really care */
        dochanged = (visible > 1000) || (visible > (priv->row_array->len / 4));

        e_table_model_pre_change(E_TABLE_MODEL (etree));

        /* and physically remove them */
        if (visible == priv->row_array->len) {
            g_array_set_size(priv->row_array, 0);
        } else {
            memmove(&g_array_index(priv->row_array, ETreePath *, base),
                &g_array_index(priv->row_array, ETreePath *, base+visible),
                (priv->row_array->len - (base+visible)) * sizeof(ETreePath *));
            g_array_set_size(priv->row_array, priv->row_array->len - visible);
        }

        /* tell the system we've removed (these) nodes */
        if (!priv->frozen) {
            if (dochanged) {
                e_table_model_changed(E_TABLE_MODEL(etree));
            } else {
                for (row=visible-1;row>=0;row--) {
                    e_table_model_row_deleted(E_TABLE_MODEL(etree), row+base);
                }
            }
        }
    }

    child_free(etree, path);

    return ret;
}

static void
add_visible_descendents_to_array (ETreeModel *etm, ETreePath *node, int *row, int *count)
{
    ETreeModelPriv *priv = etm->priv;

    /* add a row for this node */
    e_table_model_pre_change(E_TABLE_MODEL (etm));
    priv->row_array = g_array_insert_val (priv->row_array, (*row), node);
    if (!priv->frozen)
        e_table_model_row_inserted (E_TABLE_MODEL (etm), (*row));
    (*row) ++;
    (*count) ++;

    /* then loop over its children, calling this routine for each
           of them */
    if (node->expanded) {
        ETreePath *child;
        for (child = node->first_child; child;
             child = child->next_sibling) {
            add_visible_descendents_to_array (etm, child, row, count);
        }
    }
}

static void
save_expanded_state_func (char *key, gboolean expanded, gpointer user_data)
{
    if (expanded) {
        xmlNode *root = (xmlNode*)user_data;
        xmlNode *node_root = xmlNewNode (NULL, (xmlChar*) "node");

        xmlAddChild (root, node_root);
        xmlNewChild (node_root, NULL, (xmlChar *) "id", (xmlChar*) key);
    }
}

gboolean
e_tree_model_save_expanded_state (ETreeModel *etm, const char *filename)
{
    xmlDoc *doc;
    xmlNode *root;
    int fd, rv;
    xmlChar *buf;
    int buf_size;
    ETreeModelPriv *priv = etm->priv;

    doc = xmlNewDoc ((xmlChar*) "1.0");
    root = xmlNewDocNode (doc, NULL,
                  (xmlChar *) "expanded_state",
                  NULL);
    xmlDocSetRootElement (doc, root);

    g_hash_table_foreach (priv->expanded_state,
                  (GHFunc)save_expanded_state_func,
                  root);

    fd = open (filename, O_CREAT | O_TRUNC | O_WRONLY, 0777);

    xmlDocDumpMemory (doc, &buf, &buf_size);

    if (buf == NULL) {
        g_error ("Failed to write %s: xmlBufferCreate() == NULL", filename);
        return FALSE;
    }

    rv = write (fd, buf, buf_size);
    xmlFree (buf);
    close (fd);

    if (0 > rv) {
        g_error ("Failed to write new %s: %d\n", filename, errno);
        unlink (filename);
        return FALSE;
    }

    return TRUE;
}

static char *
get_string_value (xmlNode *node,
          const char *name)
{
    xmlNode *p;
    xmlChar *xml_string;
    char *retval;

    p = e_xml_get_child_by_name (node, (xmlChar *) name);
    if (p == NULL)
        return NULL;

    p = e_xml_get_child_by_name (p, (xmlChar *) "text");
    if (p == NULL) /* there's no text between the tags, return the empty string */
        return g_strdup("");

    xml_string = xmlNodeListGetString (node->doc, p, 1);
    retval = g_strdup ((char *) xml_string);
    xmlFree (xml_string);

    return retval;
}

gboolean
e_tree_model_load_expanded_state (ETreeModel *etm, const char *filename)
{
    ETreeModelPriv *priv = etm->priv;
    xmlDoc *doc;
    xmlNode *root;
    xmlNode *child;

    doc = xmlParseFile (filename);
    if (!doc)
        return FALSE;

    root = xmlDocGetRootElement (doc);
    if (root == NULL || strcmp (root->name, "expanded_state")) {
        xmlFreeDoc (doc);
        return FALSE;
    }

    for (child = root->childs; child; child = child->next) {
        char *id;

        if (strcmp (child->name, "node")) {
            g_warning ("unknown node '%s' in %s", child->name, filename);
            continue;
        }

        id = get_string_value (child, "id");

        g_hash_table_insert (priv->expanded_state, id, (gpointer)TRUE);
    }

    xmlFreeDoc (doc);

    return TRUE;
}


void
e_tree_model_node_set_save_id (ETreeModel *etm, ETreePath *node, const char *id)
{
    char *key;
    gboolean expanded_state;
    ETreeModelPriv *priv;

    g_return_if_fail (E_TREE_MODEL (etm));
    g_return_if_fail (node);

    priv = etm->priv;

    if (g_hash_table_lookup_extended (priv->expanded_state,
                      id, (gpointer*)&key, (gpointer*)&expanded_state)) {

        e_tree_model_node_set_expanded (etm, node,
                        expanded_state);

        /* important that this comes after the e_tree_model_node_set_expanded */
        node->save_id = key;
    }
    else {
        node->save_id = g_strdup (id);

        g_hash_table_insert (priv->expanded_state, node->save_id, (gpointer)node->expanded);
    }
}



void
e_tree_model_node_set_compare_function (ETreeModel *tree_model,
                    ETreePath *node,
                    ETreePathCompareFunc compare)
{
    gboolean need_sort;

    g_return_if_fail (E_TREE_MODEL (tree_model));
    g_return_if_fail (node);

    need_sort = (compare != node->compare);

    node->compare = compare;

    if (need_sort)
        e_tree_model_node_sort (tree_model, node);
}

typedef struct {
    ETreeModel *model;
    ETreePath *path;
    ETreePathCompareFunc compare;
    gboolean was_expanded;
} ETreeSortInfo;

static gint
e_tree_model_node_compare (ETreeSortInfo *info1, ETreeSortInfo *info2)
{
    return info1->compare (info1->model, info1->path, info2->path);
}

void
e_tree_model_node_sort (ETreeModel *tree_model,
            ETreePath *node)
{
    int num_nodes = node->num_children;
    ETreeSortInfo *sort_info;
    int i;
    int child_index;
    gboolean node_expanded = e_tree_model_node_is_expanded (tree_model, node);
    ETreeModelPriv *priv = tree_model->priv;;

    g_return_if_fail (E_TREE_MODEL (tree_model));
    g_return_if_fail (node);

    g_return_if_fail (node->compare);

    if (num_nodes == 0)
        return;

    e_table_model_pre_change(E_TABLE_MODEL (tree_model));

    sort_info = g_new (ETreeSortInfo, num_nodes);

    child_index = e_tree_model_row_of_node (tree_model, node) + 1;

    /* collect our info and remove the children */
    for (i = 0; i < num_nodes; i ++) {
        sort_info[i].path = node->first_child;
        sort_info[i].was_expanded = e_tree_model_node_is_expanded (tree_model, sort_info[i].path);
        sort_info[i].model = tree_model;
        sort_info[i].compare = node->compare;

        e_tree_model_node_set_expanded(tree_model, sort_info[i].path, FALSE);
        if (node_expanded)
            priv->row_array = g_array_remove_index (priv->row_array, child_index);
        e_tree_path_unlink (sort_info[i].path);
    }

    /* sort things */
    qsort (sort_info, num_nodes, sizeof(ETreeSortInfo), (GCompareFunc)e_tree_model_node_compare);
    
    /* reinsert the children nodes into the tree in the sorted order */
    for (i = 0; i < num_nodes; i ++) {
        e_tree_path_insert (node, i, sort_info[i].path);
        if (node_expanded)
            priv->row_array = g_array_insert_val (priv->row_array, child_index + i,
                                  sort_info[i].path);
    }

    /* make another pass expanding the children as needed.  

       XXX this used to be in the loop above, but a recent change
       (either here or in the etable code) causes an assertion and
       a crash */
    for (i = 0; i < num_nodes; i ++) {
        e_tree_model_node_set_expanded (tree_model, sort_info[i].path, sort_info[i].was_expanded);
    }

    g_free (sort_info);

    if (!priv->frozen)
        e_table_model_changed (E_TABLE_MODEL (tree_model));
}