/* Dia -- an diagram creation/manipulation program
 * Copyright (C) 1998 Alexander Larsson
 *
 * 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.
 */
#include <config.h>

/* so we get fdopen declared even when compiling with -ansi */
#define _POSIX_C_SOURCE 200809L
#define _DEFAULT_SOURCE 1 /* to get the prototype for fchmod() */
#include <stdlib.h>
#include <sys/types.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <glib.h>
#include <glib/gstdio.h> /* g_access() and friends */
#include <errno.h>

#ifndef W_OK
#define W_OK 2
#endif

#include "intl.h"

#include <libxml/tree.h>
#include <libxml/parser.h>
#include <libxml/xmlmemory.h>
#include "dia_xml_libxml.h"
#include "dia_xml.h"

#include "load_save.h"
#include "group.h"
#include "diagramdata.h"
#include "object.h"
#include "message.h"
#include "preferences.h"
#include "dia-page-layout.h"
#include "autosave.h"
#include "display.h"
#include "dia-layer.h"

#ifdef G_OS_WIN32
#include <io.h>
#endif

static void read_connections(GList *objects, xmlNodePtr layer_node,
			     GHashTable *objects_hash);
static void GHFuncUnknownObjects(gpointer key,
				 gpointer value,
				 gpointer user_data);
static GList *read_objects(xmlNodePtr objects,
			   GHashTable *objects_hash,
			   DiaContext *ctx,
			   DiaObject  *parent,
			   GHashTable *unknown_objects_hash);
static void hash_free_string(gpointer       key,
			     gpointer       value,
			     gpointer       user_data);
static xmlNodePtr find_node_named (xmlNodePtr p, const char *name);
static gboolean diagram_data_load(const gchar *filename, DiagramData *data,
				  DiaContext *ctx, void* user_data);
static gboolean write_objects(GList *objects, xmlNodePtr objects_node,
			      GHashTable *objects_hash, int *obj_nr,
			      const char *filename, DiaContext *ctx);
static gboolean write_connections(GList *objects, xmlNodePtr layer_node,
				  GHashTable *objects_hash);
static xmlDocPtr diagram_data_write_doc(DiagramData *data, const char *filename, DiaContext *ctx);
static int diagram_data_raw_save(DiagramData *data, const char *filename, DiaContext *ctx);
static gboolean diagram_data_save(DiagramData *data, DiaContext *ctx, const char *filename);


static void
GHFuncUnknownObjects (gpointer key,
                      gpointer value,
                      gpointer user_data)
{
  GString *s = (GString *) user_data;

  g_string_append (s, "\n");
  g_string_append (s, (char*) key);

  g_free (key);
}


/**
 * read_objects:
 * @objects: node to read from
 * @objects_hash: object id -> object of read objects
 * @ctx: the current #DiaContent
 * @parent: the parent #DiaObject
 * @unknown_objects_hash: objects with unknown type
 *
 * Recursive function to read objects from a specific level in the xml.
 *
 * Nowadays there are quite a few of them :
 * - Layers : a diagram may have different layers, but this function does *not*
 *   add the created objects to them as it does not know on which nesting level it
 *   is called. So the topmost caller must add the returned objects to the layer.
 * - Groups : groups in itself can have an arbitrary nesting level including other
 *   groups or objects or both of them. A group not containing any objects is by
 *   definition useless. So it is not created. This is to avoid trouble with some older
 *   diagrams which happen to be saved with empty groups.
 * - Parents : if the parent relations would have been there from the beginning of
 *   Dias file format they probably would have been added as nesting level
 *   themselves. But to maintain forward compatibility (allow to let older versions
 *   of Dia to see as much as possible) they were added all on the same level and
 *   the parent child relation is reconstructed from additional attributes.
 *
 * Since: dawn-of-time
 */
static GList *
read_objects (xmlNodePtr objects,
              GHashTable *objects_hash,
              DiaContext *ctx,
              DiaObject  *parent,
              GHashTable *unknown_objects_hash)
{
  GList *list;
  DiaObjectType *type;
  DiaObject *obj;
  ObjectNode obj_node;
  char *typestr;
  char *versionstr;
  char *id;
  int version;
  xmlNodePtr child_node;

  list = NULL;

  obj_node = objects->xmlChildrenNode;

  while (obj_node != NULL) {
    if (xmlIsBlankNode (obj_node)) {
      obj_node = obj_node->next;
      continue;
    }

    if (!obj_node) break;

    if (xmlStrcmp(obj_node->name, (const xmlChar *)"object")==0) {
      typestr = (char *) xmlGetProp(obj_node, (const xmlChar *)"type");
      versionstr = (char *) xmlGetProp(obj_node, (const xmlChar *)"version");
      id = (char *) xmlGetProp(obj_node, (const xmlChar *)"id");

      version = 0;
      if (versionstr != NULL) {
        version = atoi (versionstr);
        dia_clear_xml_string (&versionstr);
      }

      type = object_get_type ((char *) typestr);

      if (!type) {
        if (g_utf8_validate (typestr, -1, NULL) &&
            g_hash_table_lookup (unknown_objects_hash, typestr) == NULL) {
          g_hash_table_insert (unknown_objects_hash, g_strdup (typestr), 0);
        }
      } else {
        obj = type->ops->load (obj_node, version, ctx);
        list = g_list_append (list, obj);

        if (parent) {
          obj->parent = parent;
          parent->children = g_list_append (parent->children, obj);
        }

        g_hash_table_insert (objects_hash, g_strdup ((char *) id), obj);

        child_node = obj_node->children;

        while (child_node) {
          if (xmlStrcmp (child_node->name, (const xmlChar *) "children") == 0) {
            GList *children_read = read_objects (child_node,
                                                 objects_hash,
                                                 ctx,
                                                 obj,
                                                 unknown_objects_hash);
            list = g_list_concat (list, children_read);
            break;
          }
          child_node = child_node->next;
        }
      }

      dia_clear_xml_string (&typestr);
      dia_clear_xml_string (&id);
    } else if (xmlStrcmp (obj_node->name, (const xmlChar *) "group") == 0 &&
               obj_node->children) {
      /* don't create empty groups */
      GList *inner_objects = read_objects (obj_node,
                                           objects_hash,
                                           ctx,
                                           NULL,
                                           unknown_objects_hash);

      if (inner_objects) {
        obj = group_create (inner_objects);
        object_load_props (obj, obj_node, ctx);
        list = g_list_append (list, obj);
      }
    } else {
      /* silently ignore other nodes */
    }

    obj_node = obj_node->next;
  }

  return list;
}


static void
read_connections(GList *objects, xmlNodePtr layer_node,
		 GHashTable *objects_hash)
{
  ObjectNode obj_node;
  GList *list;
  xmlNodePtr connections;
  xmlNodePtr connection;
  char *handlestr;
  char *tostr;
  char *connstr;
  int handle, conn;
  DiaObject *to;

  list = objects;
  obj_node = layer_node->xmlChildrenNode;
  while ((list != NULL) && (obj_node != NULL)) {
    DiaObject *obj = (DiaObject *) list->data;

    /* the obj and there node must stay in sync to properly setup connections */
    while (obj_node && (xmlIsBlankNode(obj_node) || XML_COMMENT_NODE == obj_node->type))
      obj_node = obj_node->next;
    if (!obj_node) break;

    if IS_GROUP(obj) {
      read_connections(group_objects(obj), obj_node, objects_hash);
    } else {
      gboolean broken = FALSE;
      /* an invalid bounding box is a good sign for some need of corrections */
      gboolean wants_update = obj->bounding_box.right >= obj->bounding_box.left
                           || obj->bounding_box.top >= obj->bounding_box.bottom;
      connections = obj_node->xmlChildrenNode;
      while ((connections!=NULL) &&
	     (xmlStrcmp(connections->name, (const xmlChar *)"connections")!=0))
	connections = connections->next;
      if (connections != NULL) {
	connection = connections->xmlChildrenNode;
	while (connection != NULL) {
	  char *donestr;
          if (xmlIsBlankNode(connection)) {
            connection = connection->next;
            continue;
          }
	  handlestr = (char * )xmlGetProp(connection, (const xmlChar *)"handle");
	  tostr = (char *) xmlGetProp(connection, (const xmlChar *)"to");
 	  connstr = (char *) xmlGetProp(connection, (const xmlChar *)"connection");

	  handle = atoi(handlestr);
	  conn = strtol(connstr, &donestr, 10);
	  if (*donestr != '\0') { /* Didn't convert it all -- use string */
	    conn = -1;
	  }

	  to = g_hash_table_lookup(objects_hash, tostr);

	  if (to == NULL) {
	    message_error(_("Error loading diagram.\n"
			    "Linked object not found in document."));
	    broken = TRUE;
	  } else if (handle < 0 || handle >= obj->num_handles) {
	    message_error(_("Error loading diagram.\n"
			    "Connection handle %d does not exist on '%s'."),
			    handle, to->type->name);
	    broken = TRUE;
	  } else {
	    if (conn >= 0 && conn < to->num_connections) {
	      object_connect(obj, obj->handles[handle],
			     to->connections[conn]);
	      /* force an update on the connection, helpful with (incomplete) generated files */
	      if (wants_update) {
#if 0
	        obj->ops->move_handle(obj, obj->handles[handle], &to->connections[conn]->pos,
				      to->connections[conn], HANDLE_MOVE_CONNECTED,0);
#endif
	      }
	    } else {
	      message_error(_("Error loading diagram.\n"
			      "Connection point %d does not exist on '%s'."),
			    conn, to->type->name);
	      broken = TRUE;
	    }
	  }

	  if (handlestr) xmlFree(handlestr);
	  if (tostr) xmlFree(tostr);
	  if (connstr) xmlFree(connstr);

	  connection = connection->next;
	}
        /* Fix positions of the connection object for (de)generated files.
         * Only done for the last point connected otherwise the intermediate posisitions
         * may screw the auto-routing algorithm.
         */
        if (!broken && obj && obj->ops->set_props && wants_update) {
	  /* called for it's side-effect of update_data */
	  obj->ops->move(obj,&obj->position);

	  for (handle = 0; handle < obj->num_handles; ++handle) {
	    if (obj->handles[handle]->connected_to)
	      obj->ops->move_handle(obj, obj->handles[handle], &obj->handles[handle]->pos,
				    obj->handles[handle]->connected_to, HANDLE_MOVE_CONNECTED,0);
	  }
	}
      }
    }

    /* Now set up parent relationships. */
    connections = obj_node->xmlChildrenNode;
    while ((connections!=NULL) &&
	   (xmlStrcmp(connections->name, (const xmlChar *)"childnode")!=0))
      connections = connections->next;
    if (connections != NULL) {
      tostr = (char *)xmlGetProp(connections, (const xmlChar *)"parent");
      if (tostr) {
	obj->parent = g_hash_table_lookup(objects_hash, tostr);
	if (obj->parent == NULL) {
	  message_error(_("Can't find parent %s of %s object\n"),
			tostr, obj->type->name);
	} else {
	  obj->parent->children = g_list_prepend(obj->parent->children, obj);
	}
      }
    }

    list = g_list_next(list);
    obj_node = obj_node->next;
  }
}


static void
hash_free_string (gpointer key,
                  gpointer value,
                  gpointer user_data)
{
  g_free (key);
}


static xmlNodePtr
find_node_named (xmlNodePtr p, const char *name)
{
  while (p && 0 != xmlStrcmp(p->name, (xmlChar *)name))
    p = p->next;
  return p;
}

static gboolean
_get_bool_prop (xmlNodePtr node, const char *name, gboolean preset)
{
  gboolean ret;
  xmlChar *val = xmlGetProp(node, (const xmlChar *)name);

  if (val) {
    ret = (strcmp((char *)val, "true")==0);
    xmlFree(val);
  } else {
    ret = preset;
  }
  return ret;
}


static gboolean
diagram_data_load (const char  *filename,
                   DiagramData *data,
                   DiaContext  *ctx,
                   void        *user_data)
{
  GHashTable *objects_hash;
  int fd;
  GList *list;
  xmlDocPtr doc;
  xmlNodePtr root;
  xmlNodePtr diagramdata;
  xmlNodePtr paperinfo, gridinfo;
  xmlNodePtr layer_node;
  AttributeNode attr;
  DiaLayer *layer;
  xmlNsPtr namespace;
  gchar firstchar;
  Diagram *diagram = DIA_IS_DIAGRAM (data) ? DIA_DIAGRAM (data) : NULL;
  DiaLayer *active_layer = NULL;
  GHashTable* unknown_objects_hash = g_hash_table_new(g_str_hash, g_str_equal);
  int num_layers_added = 0;

  g_return_val_if_fail (data != NULL, FALSE);

  if (g_file_test (filename, G_FILE_TEST_IS_DIR)) {
    dia_context_add_message (ctx,
                             _("You must specify a file, not a directory."));
    return FALSE;
  }

  fd = g_open (filename, O_RDONLY, 0);

  if (fd==-1) {
    dia_context_add_message (ctx,
                             _("Couldn't open: '%s' for reading.\n"),
                             filename);
    return FALSE;
  }

  if (read (fd, &firstchar, 1)) {
    data->is_compressed = (firstchar != '<');
  } else {
    /* Couldn't read a single char?  Set to default. */
    data->is_compressed = prefs.new_diagram.compress_save;
  }

  /* Note that this closing and opening means we can't read from a pipe */
  close (fd);

  doc = diaXmlParseFile (filename, ctx, TRUE);

  if (doc == NULL){
    /* this was talking about unknown file type but it could as well be broken XML */
    dia_context_add_message (ctx, _("Error loading diagram %s."), filename);
    return FALSE;
  }

  root = doc->xmlRootNode;
  /* skip comments */
  while (root && (root->type != XML_ELEMENT_NODE)) {
    root = root->next;
  }

  if (root == NULL) {
    message_error (_("Error loading diagram %s.\nUnknown file type."),
                   dia_message_filename (filename));
    xmlFreeDoc (doc);
    return FALSE;
  }

  namespace = xmlSearchNs (doc, root, (const xmlChar *) "dia");
  if (xmlStrcmp (root->name, (const xmlChar *) "diagram") || (namespace == NULL)) {
    message_error (_("Error loading diagram %s.\nNot a Dia file."),
                   dia_message_filename (filename));
    xmlFreeDoc (doc);
    return FALSE;
  }

  /* Destroy the default layer: */
  if (dia_layer_object_count (dia_diagram_data_get_active_layer (data)) == 0) {
    data_remove_layer (data, dia_diagram_data_get_active_layer (data));
  }

  diagramdata =
    find_node_named (root->xmlChildrenNode, "diagramdata");

  /* Read in diagram data: */
  data->bg_color = prefs.new_diagram.bg_color;
  attr = composite_find_attribute (diagramdata, "background");
  if (attr != NULL) {
    data_color (attribute_first_data (attr), &data->bg_color, ctx);
  }

  if (diagram) {
    diagram->pagebreak_color = prefs.new_diagram.pagebreak_color;
    attr = composite_find_attribute (diagramdata, "pagebreak");
    if (attr != NULL) {
      data_color (attribute_first_data (attr), &diagram->pagebreak_color, ctx);
    }
  }

  /* load paper information from diagramdata section */
  attr = composite_find_attribute (diagramdata, "paper");
  if (attr != NULL) {
    paperinfo = attribute_first_data (attr);

    attr = composite_find_attribute (paperinfo, "name");
    if (attr != NULL) {
      g_clear_pointer (&data->paper.name, g_free);
      data->paper.name = data_string (attribute_first_data (attr), ctx);
    }

    if (data->paper.name == NULL || data->paper.name[0] == '\0') {
      data->paper.name = g_strdup (prefs.new_diagram.papertype);
    }

    /* set default margins for paper size ... */
    dia_page_layout_get_default_margins (data->paper.name,
                                         &data->paper.tmargin,
                                         &data->paper.bmargin,
                                         &data->paper.lmargin,
                                         &data->paper.rmargin);

    attr = composite_find_attribute (paperinfo, "tmargin");
    if (attr != NULL) {
      data->paper.tmargin = data_real (attribute_first_data(attr), ctx);
    }

    attr = composite_find_attribute (paperinfo, "bmargin");
    if (attr != NULL) {
      data->paper.bmargin = data_real (attribute_first_data (attr), ctx);
    }

    attr = composite_find_attribute (paperinfo, "lmargin");
    if (attr != NULL) {
      data->paper.lmargin = data_real (attribute_first_data (attr), ctx);
    }

    attr = composite_find_attribute (paperinfo, "rmargin");
    if (attr != NULL) {
      data->paper.rmargin = data_real (attribute_first_data (attr), ctx);
    }

    attr = composite_find_attribute (paperinfo, "is_portrait");
    data->paper.is_portrait = TRUE;
    if (attr != NULL) {
      data->paper.is_portrait = data_boolean (attribute_first_data (attr),
                                              ctx);
    }

    attr = composite_find_attribute (paperinfo, "scaling");
    data->paper.scaling = 1.0;
    if (attr != NULL) {
      data->paper.scaling = data_real (attribute_first_data (attr), ctx);
    }

    attr = composite_find_attribute (paperinfo, "fitto");
    data->paper.fitto = FALSE;
    if (attr != NULL) {
      data->paper.fitto = data_boolean (attribute_first_data (attr), ctx);
    }

    attr = composite_find_attribute (paperinfo, "fitwidth");
    data->paper.fitwidth = 1;
    if (attr != NULL) {
      data->paper.fitwidth = data_int (attribute_first_data (attr), ctx);
    }

    attr = composite_find_attribute (paperinfo, "fitheight");
    data->paper.fitheight = 1;
    if (attr != NULL) {
      data->paper.fitheight = data_int (attribute_first_data (attr), ctx);
    }

    /* calculate effective width/height */
    dia_page_layout_get_paper_size (data->paper.name,
                                    &data->paper.width,
                                    &data->paper.height);
    if (!data->paper.is_portrait) {
      float tmp = data->paper.width;

      data->paper.width = data->paper.height;
      data->paper.height = tmp;
    }
    data->paper.width -= data->paper.lmargin;
    data->paper.width -= data->paper.rmargin;
    data->paper.height -= data->paper.tmargin;
    data->paper.height -= data->paper.bmargin;
    data->paper.width /= data->paper.scaling;
    data->paper.height /= data->paper.scaling;
  }

  if (diagram) {
    attr = composite_find_attribute(diagramdata, "grid");
    if (attr != NULL) {
      gridinfo = attribute_first_data(attr);

      attr = composite_find_attribute(gridinfo, "dynamic");
      if (attr != NULL)
         diagram->grid.dynamic = data_boolean(attribute_first_data(attr), ctx);

      attr = composite_find_attribute(gridinfo, "width_x");
      if (attr != NULL)
        diagram->grid.width_x = data_real(attribute_first_data(attr), ctx);
      attr = composite_find_attribute(gridinfo, "width_y");
      if (attr != NULL)
        diagram->grid.width_y = data_real(attribute_first_data(attr), ctx);
      attr = composite_find_attribute(gridinfo, "visible_x");
      if (attr != NULL)
        diagram->grid.visible_x = data_int(attribute_first_data(attr), ctx);
      attr = composite_find_attribute(gridinfo, "visible_y");
      if (attr != NULL)
        diagram->grid.visible_y = data_int(attribute_first_data(attr), ctx);

      diagram->grid.colour = prefs.new_diagram.grid_color;
      attr = composite_find_attribute(diagramdata, "color");
      if (attr != NULL)
        data_color(attribute_first_data(attr), &diagram->grid.colour, ctx);
    }
  }

  if (diagram) {
    attr = composite_find_attribute (diagramdata, "guides");
    if (attr != NULL) {
      DataNode guides_data;

      /* Clear old guides. */
      g_list_free (diagram->guides);
      diagram->guides = NULL;

      /* Load new guides. */
      guides_data = attribute_first_data (attr);
      while (guides_data) {
        real position = 0;
        GtkOrientation orientation = GTK_ORIENTATION_HORIZONTAL;

        attr = composite_find_attribute (guides_data, "position");
        if(attr != NULL) {
          position = data_real (attribute_first_data (attr), ctx);
        }

        attr = composite_find_attribute (guides_data, "orientation");
        if (attr != NULL) {
          orientation = data_int (attribute_first_data (attr), ctx);
        }

        dia_diagram_add_guide (diagram, position, orientation, FALSE);

        guides_data = data_next (guides_data);
      }
    }

    /* Guide color. */
    diagram->guide_color = prefs.new_diagram.guide_color;
    attr = composite_find_attribute (diagramdata, "guide_color");
    if (attr != NULL) {
      data_color (attribute_first_data (attr), &diagram->guide_color, ctx);
    }
  }

  /* parse some display settings */
  if (diagram) {
    attr = composite_find_attribute (diagramdata, "display");

    if (attr != NULL) {
      DataNode dispinfo;

      dispinfo = attribute_first_data (attr);
      /* using the diagramdata object as temporary storage is a bit hacky,
       * and also the magic numbers (keeping 0 as dont care) */

      attr = composite_find_attribute (dispinfo, "antialiased");
      if (attr != NULL) {
        g_object_set_data (G_OBJECT (diagram),
                           "antialiased",
                           GINT_TO_POINTER (data_boolean (attribute_first_data (attr), ctx) ? 1 : -1));
      }

      attr = composite_find_attribute (dispinfo, "snap-to-grid");
      if (attr != NULL) {
        g_object_set_data (G_OBJECT (diagram),
                           "snap-to-grid",
                           GINT_TO_POINTER (data_boolean (attribute_first_data (attr), ctx) ? 1 : -1));
      }

      attr = composite_find_attribute (dispinfo, "snap-to-guides");
      if (attr != NULL) {
        g_object_set_data (G_OBJECT (diagram),
                           "snap-to-guides",
                           GINT_TO_POINTER (data_boolean (attribute_first_data (attr), ctx) ? 1 : -1));
      }

      attr = composite_find_attribute (dispinfo, "snap-to-object");
      if (attr != NULL) {
        g_object_set_data (G_OBJECT (diagram),
                           "snap-to-object",
                           GINT_TO_POINTER (data_boolean (attribute_first_data (attr), ctx) ? 1 : -1));
      }

      attr = composite_find_attribute (dispinfo, "show-grid");
      if (attr != NULL) {
        g_object_set_data (G_OBJECT (diagram),
                           "show-grid",
                           GINT_TO_POINTER (data_boolean (attribute_first_data (attr), ctx) ? 1 : -1));
      }

      attr = composite_find_attribute(dispinfo, "show-guides");
      if (attr != NULL) {
        g_object_set_data (G_OBJECT (diagram),
                           "show-guides",
                           GINT_TO_POINTER (data_boolean (attribute_first_data (attr), ctx) ? 1 : -1));
      }

      attr = composite_find_attribute (dispinfo, "show-connection-points");
      if (attr != NULL) {
        g_object_set_data (G_OBJECT (diagram),
                           "show-connection-points",
                           GINT_TO_POINTER (data_boolean (attribute_first_data(attr), ctx) ? 1 : -1));
      }
    }
  }
  /* Read in all layers: */
  layer_node =
    find_node_named (root->xmlChildrenNode, "layer");

  objects_hash = g_hash_table_new (g_str_hash, g_str_equal);

  while (layer_node != NULL) {
    xmlChar *name;

    if (xmlIsBlankNode (layer_node)) {
      layer_node = layer_node->next;
      continue;
    }

    if (!layer_node) break;

    name = xmlGetProp (layer_node, (const xmlChar *) "name");
    if (!name) break; /* name is mandatory */

    layer = dia_layer_new ((char *) name, data);
    dia_clear_xml_string (&name);

    g_object_set (layer,
                  "visible", _get_bool_prop (layer_node, "visible", FALSE),
                  "connectable", _get_bool_prop (layer_node, "connectable", FALSE),
                  NULL);

    /* Read in all objects: */
    list = read_objects (layer_node, objects_hash, ctx, NULL, unknown_objects_hash);
    dia_layer_add_objects (layer, list);

    data_add_layer (data, layer);
    ++num_layers_added;

    if (_get_bool_prop (layer_node, "active", FALSE)) {
      g_set_object (&active_layer, layer);
    }

    g_clear_object (&layer);

    layer_node = layer_node->next;
  }

  /* Second iteration over layers to restore connections, which might span multiple layers */
  {
    int i = data_layer_count (data) - num_layers_added;
    layer_node = find_node_named (root->xmlChildrenNode, "layer");
    for (; i < data_layer_count (data); ++i) {
      layer = data_layer_get_nth (data, i);

      while (layer_node && xmlStrcmp (layer_node->name, (xmlChar *)"layer") != 0)
        layer_node = layer_node->next;

      if (!layer_node) {
        dia_context_add_message (ctx, _("Error reading connections"));
        break;
      }

      read_connections (dia_layer_get_object_list (layer), layer_node, objects_hash);
      layer_node = layer_node->next;
    }
  }

  if (!active_layer) {
    data_set_active_layer (data, data_layer_get_nth (data, 0));
  } else {
    data_set_active_layer (data, active_layer);
  }

  g_clear_object (&active_layer);
  xmlFreeDoc (doc);

  g_hash_table_foreach (objects_hash, hash_free_string, NULL);

  g_hash_table_destroy (objects_hash);

  if (data_layer_count (data) < 1) {
    message_error (_("Error loading diagram:\n%s.\n"
                     "A valid Dia file defines at least one layer."),
                   dia_message_filename(filename));
    return FALSE;
  } else if (0 < g_hash_table_size (unknown_objects_hash)) {
    GString *unknown_str = g_string_new ("Unknown types while reading diagram file");

    /* show all the unknown types in one message */
    g_hash_table_foreach (unknown_objects_hash,
                          GHFuncUnknownObjects,
                          unknown_str);
    message_warning ("%s", unknown_str->str);
    g_string_free (unknown_str, TRUE);
  }
  g_hash_table_destroy (unknown_objects_hash);

  return TRUE;
}


static gboolean
write_objects(GList *objects, xmlNodePtr objects_node,
	      GHashTable *objects_hash, int *obj_nr,
	      const char *filename, DiaContext *ctx)
{
  char buffer[31];
  ObjectNode obj_node;
  xmlNodePtr group_node;
  GList *list;

  list = objects;
  while (list != NULL) {
    DiaObject *obj = (DiaObject *) list->data;

    if (g_hash_table_lookup(objects_hash, obj))
    {
      list = g_list_next(list);
      continue;
    }

    if (IS_GROUP(obj) && group_objects(obj) != NULL) {
      group_node = xmlNewChild(objects_node, NULL, (const xmlChar *)"group", NULL);
      object_save_props (obj, group_node, ctx);
      write_objects(group_objects(obj), group_node,
		    objects_hash, obj_nr, filename, ctx);
    } else {
      obj_node = xmlNewChild(objects_node, NULL, (const xmlChar *)"object", NULL);

      xmlSetProp(obj_node, (const xmlChar *)"type", (xmlChar *)obj->type->name);
      g_snprintf(buffer, 30, "%d", obj->type->version);
      xmlSetProp(obj_node, (const xmlChar *)"version", (xmlChar *)buffer);

      g_snprintf(buffer, 30, "O%d", *obj_nr);
      xmlSetProp(obj_node, (const xmlChar *)"id", (xmlChar *)buffer);

      (*obj->type->ops->save)(obj, obj_node, ctx);

      /* Add object -> obj_nr to hash table */
      g_hash_table_insert(objects_hash, obj, GINT_TO_POINTER(*obj_nr));
      (*obj_nr)++;

      /*
      if (object_flags_set(obj, DIA_OBJECT_CAN_PARENT) && obj->children)
      {
	int res;
	xmlNodePtr parent_node;
        parent_node = xmlNewChild(obj_node, NULL, "children", NULL);
        res = write_objects(obj->children, parent_node, objects_hash, obj_nr, filename);
	if (!res) return FALSE;
      }
      */
    }

    list = g_list_next(list);
  }
  return TRUE;
}

/* Parents broke assumption that both objects and xml nodes are laid out
 * linearly.
 */

static gboolean
write_connections(GList *objects, xmlNodePtr layer_node,
		  GHashTable *objects_hash)
{
  ObjectNode obj_node;
  GList *list;
  xmlNodePtr connections;
  xmlNodePtr connection;
  char buffer[31];
  int i;

  list = objects;
  obj_node = layer_node->xmlChildrenNode;
  while ((list != NULL) && (obj_node != NULL)) {
    DiaObject *obj = (DiaObject *) list->data;

    while (obj_node && xmlIsBlankNode(obj_node)) obj_node = obj_node->next;
    if (!obj_node) break;

    if IS_GROUP(obj) {
      write_connections(group_objects(obj), obj_node, objects_hash);
    } else {
      connections = NULL;

      for (i=0;i<obj->num_handles;i++) {
	ConnectionPoint *con_point;
	Handle *handle;

	handle = obj->handles[i];
	con_point = handle->connected_to;

	if ( con_point != NULL ) {
	  DiaObject *other_obj;
	  int con_point_nr;

	  other_obj = con_point->object;

	  con_point_nr=0;
	  while (other_obj->connections[con_point_nr] != con_point) {
	    con_point_nr++;
	    if (con_point_nr>=other_obj->num_connections) {
	      g_warning ("Error saving diagram\n con_point_nr >= other_obj->num_connections\n");
	      return FALSE;
	    }
	  }

	  if (connections == NULL)
	    connections = xmlNewChild(obj_node, NULL, (const xmlChar *)"connections", NULL);

	  connection = xmlNewChild(connections, NULL, (const xmlChar *)"connection", NULL);
	  /* from what handle on this object*/
	  g_snprintf(buffer, 30, "%d", i);
	  xmlSetProp(connection, (const xmlChar *)"handle", (xmlChar *)buffer);
	  /* to what object */
	  g_snprintf(buffer, 30, "O%d",
		     GPOINTER_TO_INT(g_hash_table_lookup(objects_hash,
							 other_obj)));

	  xmlSetProp(connection, (const xmlChar *)"to", (xmlChar *) buffer);
	  /* to what connection_point on that object */
	  g_snprintf(buffer, 30, "%d", con_point_nr);
	  xmlSetProp(connection, (const xmlChar *)"connection", (xmlChar *) buffer);
	}
      }
    }

    if (obj->parent) {
      DiaObject *other_obj = obj->parent;
      xmlNodePtr parent;
      g_snprintf(buffer, 30, "O%d",
		 GPOINTER_TO_INT(g_hash_table_lookup(objects_hash, other_obj)));
      parent = xmlNewChild(obj_node, NULL, (const xmlChar *)"childnode", NULL);
      xmlSetProp(parent, (const xmlChar *)"parent", (xmlChar *)buffer);
    }

    list = g_list_next(list);
    obj_node = obj_node->next;
  }
  return TRUE;
}

/* Filename seems to be junk, but is passed on to objects */
static xmlDocPtr
diagram_data_write_doc(DiagramData *data, const char *filename, DiaContext *ctx)
{
  xmlDocPtr doc;
  xmlNodePtr tree;
  xmlNodePtr pageinfo, gridinfo, guideinfo;
  xmlNodePtr layer_node;
  GHashTable *objects_hash;
  gboolean res;
  int obj_nr;
  AttributeNode attr;
  xmlNs *name_space;
  Diagram *diagram = DIA_IS_DIAGRAM (data) ? DIA_DIAGRAM (data) : NULL;

  g_return_val_if_fail(data!=NULL, NULL);

  doc = xmlNewDoc((const xmlChar *)"1.0");
  doc->encoding = xmlStrdup((const xmlChar *)"UTF-8");
  doc->xmlRootNode = xmlNewDocNode(doc, NULL, (const xmlChar *)"diagram", NULL);

  name_space = xmlNewNs(doc->xmlRootNode,
                        (const xmlChar *)DIA_XML_NAME_SPACE_BASE,
			(const xmlChar *)"dia");
  xmlSetNs(doc->xmlRootNode, name_space);

  tree = xmlNewChild(doc->xmlRootNode, name_space, (const xmlChar *)"diagramdata", NULL);

  attr = new_attribute((ObjectNode)tree, "background");
  data_add_color(attr, &data->bg_color, ctx);

  if (diagram) {
    attr = new_attribute((ObjectNode)tree, "pagebreak");
    data_add_color(attr, &diagram->pagebreak_color, ctx);
  }
  attr = new_attribute((ObjectNode)tree, "paper");
  pageinfo = data_add_composite(attr, "paper", ctx);
  data_add_string(composite_add_attribute(pageinfo, "name"),
		  data->paper.name, ctx);
  data_add_real(composite_add_attribute(pageinfo, "tmargin"),
		data->paper.tmargin, ctx);
  data_add_real(composite_add_attribute(pageinfo, "bmargin"),
		data->paper.bmargin, ctx);
  data_add_real(composite_add_attribute(pageinfo, "lmargin"),
		data->paper.lmargin, ctx);
  data_add_real(composite_add_attribute(pageinfo, "rmargin"),
		data->paper.rmargin, ctx);
  data_add_boolean(composite_add_attribute(pageinfo, "is_portrait"),
		   data->paper.is_portrait, ctx);
  data_add_real(composite_add_attribute(pageinfo, "scaling"),
		data->paper.scaling, ctx);
  data_add_boolean(composite_add_attribute(pageinfo, "fitto"),
		   data->paper.fitto, ctx);
  if (data->paper.fitto) {
    data_add_int(composite_add_attribute(pageinfo, "fitwidth"),
		 data->paper.fitwidth, ctx);
    data_add_int(composite_add_attribute(pageinfo, "fitheight"),
		 data->paper.fitheight, ctx);
  }

  if (diagram) {
    GList *list;
    attr = new_attribute((ObjectNode)tree, "grid");
    gridinfo = data_add_composite(attr, "grid", ctx);
    data_add_boolean(composite_add_attribute(gridinfo, "dynamic"),
          diagram->grid.dynamic, ctx);
    data_add_real(composite_add_attribute(gridinfo, "width_x"),
		  diagram->grid.width_x, ctx);
    data_add_real(composite_add_attribute(gridinfo, "width_y"),
		  diagram->grid.width_y, ctx);
    data_add_int(composite_add_attribute(gridinfo, "visible_x"),
	         diagram->grid.visible_x, ctx);
    data_add_int(composite_add_attribute(gridinfo, "visible_y"),
	         diagram->grid.visible_y, ctx);
    attr = new_attribute((ObjectNode)tree, "color");
    data_add_composite(gridinfo, "color", ctx);
    data_add_color(attr, &diagram->grid.colour, ctx);

    /* Guides. */
    attr = new_attribute ((ObjectNode) tree, "guides");
    list = diagram->guides;
    while (list) {
      DiaGuide *guide = list->data;

      guideinfo = data_add_composite (attr, "guide", ctx);

      data_add_real (composite_add_attribute (guideinfo, "position"), guide->position, ctx);
      data_add_int (composite_add_attribute (guideinfo, "orientation"), guide->orientation, ctx);

      list = g_list_next (list);
    }

    if (diagram) {
      attr = new_attribute ((ObjectNode) tree, "guide_color");
      data_add_color (attr, &diagram->guide_color, ctx);
    }

    if (g_slist_length (diagram->displays) == 1) {
      xmlNodePtr dispinfo;
      /* store some display attributes */
      DDisplay *ddisp = diagram->displays->data;

      attr = new_attribute((ObjectNode)tree, "display");
      dispinfo = data_add_composite(attr, "display", ctx);
      data_add_boolean(composite_add_attribute(dispinfo, "antialiased"),
                       ddisp->aa_renderer, ctx);
      data_add_boolean(composite_add_attribute(dispinfo, "snap-to-grid"),
		       ddisp->grid.snap, ctx);
      data_add_boolean(composite_add_attribute(dispinfo, "snap-to-guides"),
		       ddisp->guides_snap, ctx);
      data_add_boolean(composite_add_attribute(dispinfo, "snap-to-object"),
		       ddisp->mainpoint_magnetism, ctx);
      data_add_boolean(composite_add_attribute(dispinfo, "show-grid"),
		       ddisp->grid.visible, ctx);
      data_add_boolean (composite_add_attribute (dispinfo, "show-guides"),
                        ddisp->guides_visible, ctx);
      data_add_boolean(composite_add_attribute(dispinfo, "show-connection-points"),
		       ddisp->show_cx_pts, ctx);
    }
  }

  objects_hash = g_hash_table_new(g_direct_hash, g_direct_equal);

  obj_nr = 0;

  DIA_FOR_LAYER_IN_DIAGRAM (data, layer, i, {
    layer_node = xmlNewChild (doc->xmlRootNode,
                              name_space,
                              (const xmlChar *) "layer", NULL);
    xmlSetProp (layer_node,
                (const xmlChar *) "name",
                (xmlChar *) dia_layer_get_name (layer));

    xmlSetProp (layer_node,
                (const xmlChar *) "visible",
                (const xmlChar *) (dia_layer_is_visible (layer) ? "true" : "false"));
    xmlSetProp (layer_node,
                (const xmlChar *) "connectable",
                (const xmlChar *) (dia_layer_is_connectable (layer) ? "true" : "false"));

    if (layer == dia_diagram_data_get_active_layer (data)) {
      xmlSetProp (layer_node,
                  (const xmlChar *) "active",
                  (const xmlChar *) "true");
    }

    write_objects (dia_layer_get_object_list (layer),
                   layer_node,
                   objects_hash,
                   &obj_nr,
                   filename,
                   ctx);
  });
  /* The connections are stored per layer in the file format, but connections are not any longer
   * restricted to objects on the same layer. So we iterate over all the layer (nodes) again to
   * 'know' all objects we might have to connect to
   */
  layer_node = doc->xmlRootNode->children;
  DIA_FOR_LAYER_IN_DIAGRAM (data, layer, i, {
    while (layer_node && xmlStrcmp (layer_node->name, (xmlChar *) "layer") != 0) {
      layer_node = layer_node->next;
    }
    if (!layer_node) {
      dia_context_add_message (ctx,
                               _("Error saving connections to layer '%s'"),
                               dia_layer_get_name (layer));
      break;
    }
    res = write_connections (dia_layer_get_object_list (layer),
                             layer_node,
                             objects_hash);
    if (!res) {
      dia_context_add_message (ctx,
                               _("Connection saving is incomplete for layer '%s'"),
                               dia_layer_get_name (layer));
    }
    layer_node = layer_node->next;
  });

  g_hash_table_destroy (objects_hash);

  if (data->is_compressed) {
    xmlSetDocCompressMode (doc, 9);
  } else {
    xmlSetDocCompressMode (doc, 0);
  }

  return doc;
}


/** This tries to save the diagram into a file, without any backup
 * Returns >= 0 on success.
 * Only for internal use. */
static int
diagram_data_raw_save(DiagramData *data, const char *filename, DiaContext *ctx)
{
  xmlDocPtr doc;
  int ret;

  doc = diagram_data_write_doc(data, filename, ctx);

  ret = xmlDiaSaveFile (filename, doc);
  xmlFreeDoc(doc);

  return ret;
}

/** This saves the diagram, using a backup in case of failure.
 * @param data
 * @param filename
 * @returns TRUE on successfull save, FALSE otherwise.  If a failure is
 * indicated, an error message will already have been given to the user.
 */
static gboolean
diagram_data_save(DiagramData *data, DiaContext *ctx, const char *user_filename)
{
  FILE *file;
  char *bakname=NULL,*tmpname=NULL,*dirname=NULL,*p;
  char *filename = (char *)user_filename;
  int mode,_umask;
  int fildes;
  int ret = 0;

  /* Once we depend on GTK 2.8+, we can use these tests. */
#if !defined G_OS_WIN32
  /* Check that we're allowed to write to the target file at all. */
  /* not going to work with 'My Docments' - read-only but still useable, see bug #504469 */
  if (   g_file_test(filename, G_FILE_TEST_EXISTS)
      && g_access(filename, W_OK) != 0) {
    dia_context_add_message (ctx, _("Not allowed to write to output file %s\n"),
			     dia_context_get_filename(ctx));
    goto CLEANUP;
  }
#endif

  if (g_file_test(user_filename, G_FILE_TEST_IS_SYMLINK)) {
    GError *error = NULL;
    filename = g_file_read_link(user_filename, &error);
    if (!filename) {
      dia_context_add_message (ctx, "%s", error->message);
      g_clear_error (&error);
      goto CLEANUP;
    }
  }

  /* build the temporary and backup file names */
  dirname = g_strdup(filename);
  p = strrchr((char *)dirname,G_DIR_SEPARATOR);
  if (p) {
    *(p+1) = 0;
  } else {
    g_clear_pointer (&dirname, g_free);
    dirname = g_strdup("." G_DIR_SEPARATOR_S);
  }
  tmpname = g_strconcat(dirname,"__diaXXXXXX",NULL);
  bakname = g_strconcat(filename,"~",NULL);

#if !defined G_OS_WIN32
  /* Check that we can create the other files */
  if (   g_file_test(dirname, G_FILE_TEST_EXISTS)
      && g_access(dirname, W_OK) != 0) {
    dia_context_add_message (ctx, _("Not allowed to write temporary files in %s\n"),
			    dia_message_filename(dirname));
    goto CLEANUP;
  }
#endif

  /* open a temporary name, and fix the modes to match what fopen() would have
     done (mkstemp() is (rightly so) a bit paranoid for what we do).  */
  fildes = g_mkstemp(tmpname);
  /* should not be necessary anymore on *NIXas well, because we are using g_mkstemp ? */
  _umask = umask(0); umask(_umask);
  mode = 0666 & ~_umask;
#ifndef G_OS_WIN32
  ret = fchmod(fildes,mode);
#else
  ret = 0; /* less paranoia on windoze */
#endif
  file = fdopen(fildes,"wb");

  /* Now write the data in the temporary file name. */

  if (file==NULL) {
    dia_context_add_message_with_errno (ctx, errno,
					_("Can't open output file %s"),
					dia_message_filename(tmpname));
    goto CLEANUP;
  }
  fclose(file);

  ret = diagram_data_raw_save(data, tmpname, ctx);

  if (ret < 0) {
    /* Save failed; we clean our stuff up, without touching the file named
       "filename" if it existed. */
    dia_context_add_message(ctx, _("Internal error %d writing file %s\n"),
			    ret, dia_message_filename(tmpname));
    g_unlink(tmpname);
    goto CLEANUP;
  }
  /* save succeeded. We kill the old backup file, move the old file into
     backup, and the temp file into the new saved file. */
  g_unlink(bakname);
  g_rename(filename,bakname);
  ret = g_rename(tmpname,filename);
  if (ret < 0) {
    dia_context_add_message_with_errno(ctx, errno, _("Can't rename %s to final output file %s"),
				       dia_message_filename(tmpname),
				       dia_context_get_filename(ctx));
  }
CLEANUP:
  if (filename != user_filename)
    g_clear_pointer (&filename, g_free);
  g_clear_pointer (&tmpname, g_free);
  g_clear_pointer (&dirname, g_free);
  g_clear_pointer (&bakname, g_free);
  return (ret?FALSE:TRUE);
}

int
diagram_save(Diagram *dia, const char *filename, DiaContext *ctx)
{
  gboolean res = FALSE;

  if (diagram_data_save(dia->data, ctx, filename)) {
    dia->unsaved = FALSE;
    undo_mark_save(dia->undo);
    diagram_set_modified (dia, FALSE);

    diagram_cleanup_autosave(dia);

    res = TRUE;
  }

  return res;
}


/* Autosave stuff.  Needs to use low-level save to avoid setting and resetting flags */
void
diagram_cleanup_autosave (Diagram *dia)
{
  char *savefile;

  savefile = dia->autosavefilename;
  if (savefile == NULL) return;
#ifdef TRACES
  g_printerr ("Cleaning up autosave %s for %s\n",
              savefile,
              dia->filename ? dia->filename : "<no name>");
#endif
  if (g_file_test (savefile, G_FILE_TEST_EXISTS)) {
    /* Success */
    g_unlink (savefile);
  }
  g_clear_pointer (&savefile, g_free);
  dia->autosavefilename = NULL;
  dia->autosaved = FALSE;
}


typedef struct {
  DiagramData *clone;
  gchar       *filename;
  DiaContext  *ctx;
} AutoSaveInfo;
/*!
 * Efficient and easy to implement autosave in a thread:
 *  - make a copy (cow?) of the whole diagram, pixbufs would not be copied but only referenced
 *  - pass it to a saving thread as data and release it afterwards
 *  - should show some progress, or at least not start another autosave before the previous one finished
 *  - still must check thread safety of every function called by diagram_data_raw_save()
 *    - e.g. all (message_*) to vanish (or make it use thread local storage?)
 *    - no use of static data (no write access)
 *    - ...
 *  - the editing could continue after the synchronuous copying, which should be vastly faster
 *    than the in memory XML creation (diagram_data_write_doc) and the writing to a possibly
 *    slow storage (xmlDiaSaveFile)
 */
static gpointer
_autosave_in_thread (gpointer data)
{
  AutoSaveInfo *asi = (AutoSaveInfo *)data;

  diagram_data_raw_save(asi->clone, asi->filename, asi->ctx);
  g_clear_object (&asi->clone);
  g_clear_pointer (&asi->filename, g_free);
  /* FIXME: this is throwing away potential messages ... */
  dia_context_reset (asi->ctx);
  /* ... to avoid creating a message_box within this thread */
  dia_context_release (asi->ctx);
  g_clear_pointer (&asi, g_free);

  return NULL;
}


/**
 * diagram_autosave:
 * @dia: the #Diagram
 *
 * Absolutely autosave a diagram.
 * Called (in the GUI thread) after a periodic check at the first idleness.
 *
 * Since: dawn-of-time
 */
void
diagram_autosave (Diagram *dia)
{
  char *save_filename;

  /* Must check if the diagram is still valid, or Death Ensues! */
  GList *diagrams = dia_open_diagrams();
  Diagram *diagram;
  while (diagrams != NULL) {
    diagram = (Diagram *) diagrams->data;
    if (diagram == dia &&
        diagram_is_modified (diagram) &&
        !diagram->autosaved) {
      save_filename = g_strdup_printf ("%s.autosave", dia->filename);

      g_clear_pointer (&dia->autosavefilename, g_free);

      dia->autosavefilename = save_filename;
#ifdef G_THREADS_ENABLED
      {
        AutoSaveInfo *asi = g_new (AutoSaveInfo, 1);
        GError *error = NULL;

        asi->clone = diagram_data_clone (dia->data);
        asi->filename = g_strdup (save_filename);
        asi->ctx = dia_context_new (_("Auto save"));

        if (!g_thread_try_new ("Autosave", _autosave_in_thread, asi, &error)) {
          message_error ("%s", error->message);
          g_clear_error (&error);
        }
        /* FIXME: need better synchronization */
        dia->autosaved = TRUE;
      }
#else
      {
        DiaContext *ctx = dia_context_new (_("Auto save"));
        dia_context_set_filename (ctx, save_filename);
        diagram_data_raw_save (dia->data, save_filename, ctx);
        dia->autosaved = TRUE;
        dia_context_release (ctx);
      }
#endif
      return;
    }
    diagrams = g_list_next(diagrams);
  }
}

/* --- filter interfaces --- */
static gboolean
export_native(DiagramData *data, DiaContext *ctx,
	      const gchar *filename, const gchar *diafilename,
	      void* user_data)
{
  return diagram_data_save(data, ctx, filename);
}

static const gchar *extensions[] = { "dia", NULL };
DiaExportFilter dia_export_filter = {
  N_("Dia Diagram File"),
  extensions,
  export_native
};
DiaImportFilter dia_import_filter = {
  N_("Dia Diagram File"),
  extensions,
  diagram_data_load
};
