/********************************************************************
 * gnc-html-history.c -- keep a HTML history                        * 
 * Copyright (C) 2000 Bill Gribble <grib@billgribble.com>           *
 *                                                                  *
 * 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, contact:                        *
 *                                                                  *
 * Free Software Foundation           Voice:  +1-617-542-5942       *
 * 59 Temple Place - Suite 330        Fax:    +1-617-542-2652       *
 * Boston, MA  02111-1307,  USA       gnu@gnu.org                   *
 ********************************************************************/

#include "config.h"

#include <glib.h>
#include <string.h>

#include "gnc-html-history.h"

struct _gnc_html_history {
  GList * nodes;
  GList * current_node; 
  GList * last_node;

  /* call this whenever a node is destroyed */
  gnc_html_history_destroy_cb destroy_cb;
  gpointer                    destroy_cb_data;
};

/********************************************************************
 * gnc_html_history_new
 ********************************************************************/

gnc_html_history * 
gnc_html_history_new(void) {
  gnc_html_history * hist = g_new0(gnc_html_history, 1);
  hist->nodes         = NULL;
  hist->current_node  = NULL;
  hist->last_node     = NULL;
  return hist;
}



/********************************************************************
 * gnc_html_history_destroy
 ********************************************************************/

void
gnc_html_history_destroy(gnc_html_history * hist) {
  GList * n;

  for(n = hist->nodes; n ; n=n->next) {
    if(hist->destroy_cb) {
      (hist->destroy_cb)((gnc_html_history_node *)n->data,
                         hist->destroy_cb_data);
    }
    gnc_html_history_node_destroy((gnc_html_history_node *)n->data);
  }
  g_list_free(hist->nodes);

  hist->nodes         = NULL;
  hist->current_node  = NULL;
  hist->last_node     = NULL;
  g_free(hist);
}

/********************************************************************
 * gnc_html_history_set_node_destroy_cb
 ********************************************************************/

void
gnc_html_history_set_node_destroy_cb(gnc_html_history * hist, 
                                     gnc_html_history_destroy_cb cb,
                                     gpointer cb_data) {
  hist->destroy_cb = cb;
  hist->destroy_cb_data = cb_data;
}

static int 
g_strcmp(char * a, char * b) {
  if(!a && b) {
    return 1;
  }
  else if(a && !b) {
    return -1;
  }
  else if(!a && !b) {
    return 0;
  }
  else {
    return strcmp(a, b);
  }
  
}


/********************************************************************
 * gnc_html_history_append
 ********************************************************************/
void 
gnc_html_history_append(gnc_html_history * hist, 
                        gnc_html_history_node * node) {
  GList * n;
  gnc_html_history_node * hn;
  
  if(hist->current_node) {
    hn = hist->current_node->data;    
    if((hn->type == node->type) &&
       !g_strcmp(hn->location, node->location) &&
       !g_strcmp(hn->label, node->label)) {      
      if(hist->destroy_cb) {
        (hist->destroy_cb)(hn, hist->destroy_cb_data);
      }
      gnc_html_history_node_destroy(node);
      return;
    }
    
    /* blow away the history after this point, if there is one */
    for(n=hist->current_node->next; n; n=n->next) {
      if(hist->destroy_cb) {
        (hist->destroy_cb)((gnc_html_history_node *)n->data,
                           hist->destroy_cb_data);
      }
      gnc_html_history_node_destroy((gnc_html_history_node *)n->data); 
    }
    g_list_free(hist->current_node->next);
    hist->current_node->next = NULL;
    hist->last_node = hist->current_node;
  }
  
  n = g_list_alloc();
  n->data = (gpointer) node;
  n->next = NULL;
  n->prev = NULL;

  if(hist->nodes && hist->last_node) {
    n->prev               = hist->last_node;  /* back pointer */ 
    hist->last_node->next = n;                /* add n to the list */ 
    hist->last_node       = n;                /* n is last */ 
    hist->current_node    = n;
  }
  else {
    /* this is the first entry in the list */
    if(hist->nodes) {
      printf("???? hist->nodes non-NULL, but no last_node \n");
    }
    hist->nodes        = n;
    hist->last_node    = n;
    hist->current_node = n;
  }  
}


/********************************************************************
 * gnc_html_history_get_current
 ********************************************************************/

gnc_html_history_node * 
gnc_html_history_get_current(gnc_html_history * hist) {
  if(!hist || !(hist->current_node)) return NULL;

  return hist->current_node->data;
}


/********************************************************************
 * gnc_html_history_forward
 ********************************************************************/

gnc_html_history_node *
gnc_html_history_forward(gnc_html_history * hist) {
  if(!hist || !(hist->current_node)) {
    return NULL;
  }
  
  if(hist->current_node->next) {
    hist->current_node = hist->current_node->next;
  }

  return hist->current_node->data;
}


/********************************************************************
 * gnc_html_history_back
 ********************************************************************/

gnc_html_history_node *
gnc_html_history_back(gnc_html_history * hist) {

  if(!hist || !(hist->current_node)) {
    return NULL;
  }
  
  if(hist->current_node->prev) {
    hist->current_node = hist->current_node->prev;
  }
  
  return hist->current_node->data;
}


/********************************************************************
 * gnc_html_history_back_p
 * is it possible to go back?
 ********************************************************************/

int
gnc_html_history_back_p(gnc_html_history * hist) {
  if(hist && hist->current_node && hist->current_node->prev) {
    return TRUE;
  }
  else {
    return FALSE;
  }
}


/********************************************************************
 * gnc_html_history_forward_p
 * is it possible to go forward?
 ********************************************************************/

int
gnc_html_history_forward_p(gnc_html_history * hist) {
  if(hist && hist->current_node && hist->current_node->next) {
    return TRUE;
  }
  else {
    return FALSE;
  }
}


/********************************************************************
 * gnc_html_history_node_new
 ********************************************************************/

gnc_html_history_node *
gnc_html_history_node_new(URLType type, const gchar * location, 
                          const gchar * label) {
  gnc_html_history_node * rv = g_new0(gnc_html_history_node, 1);
  
  rv->type      = type;
  rv->location  = g_strdup(location);
  rv->label     = g_strdup(label);
  return rv;
}


/********************************************************************
 * gnc_html_history_node_destroy
 ********************************************************************/

void
gnc_html_history_node_destroy(gnc_html_history_node * node) {
  
  /* free the url resources and cached text */
  g_free(node->location);
  g_free(node->label);

  node->location = NULL;
  node->label    = NULL; 

  g_free(node);
}