/* Copyright (C) 2008  Emmanuel Varoquaux

   This file is part of XOS.

   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 3 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, see <http://www.gnu.org/licenses/>. */

#include <readline/history.h>

#include "xmalloc.h"

#include <stdlib.h>

#define HISTSIZE 500

#define HISTORY_GROW_SIZE 50

static int history_max_entries = HISTSIZE;

static HIST_ENTRY **history = NULL;
static int history_size = 0;
static int history_length = 0;
static int history_offset;

static void init_hist_entry(HIST_ENTRY *hist_entry, const char *string)
{
  hist_entry->line = xstrdup(string);
  hist_entry->data = NULL;
}

static void destroy_hist_entry(HIST_ENTRY *hist_entry)
{
  free(hist_entry->line);
}

static HIST_ENTRY *alloc_hist_entry(const char *string)
{
  HIST_ENTRY *hist_entry;

  hist_entry = xmalloc(sizeof (HIST_ENTRY));
  init_hist_entry(hist_entry, string);
  return hist_entry;
}

static void free_hist_entry(HIST_ENTRY *hist_entry)
{
  destroy_hist_entry(hist_entry);
  free(hist_entry);
}

void __attribute__ ((weak, visibility ("default"))) using_history()
{
  history_offset = history_length;
}

void __attribute__ ((weak, visibility ("default"))) add_history(const char *string)
{
  int i;

  if (history_length == history_max_entries) {
    if (history_length == 0)
      return;
    free_hist_entry(history[0]);
    for (i = 0; i < history_length - 1; i++)
      history[i] = history[i + 1];
  }
  else {
    if (!history) {
      history = xmalloc(HISTORY_GROW_SIZE * sizeof (HIST_ENTRY *));
      history_size = HISTORY_GROW_SIZE;
    }
    else if (history_length == history_size - 1) {
      history = xrealloc(history, (history_size + HISTORY_GROW_SIZE) * sizeof (HIST_ENTRY *));
      history_size += HISTORY_GROW_SIZE;
    }
    history_length++;
  }
  history[history_length - 1] = alloc_hist_entry(string);
  history[history_length] = NULL;
}

HIST_ENTRY __attribute__ ((weak, visibility ("default"))) **history_list()
{
  return history;
}

int __attribute__ ((weak, visibility ("default"))) where_history()
{
  return history_offset;
}

HIST_ENTRY __attribute__ ((weak, visibility ("default"))) *current_history()
{
  return history ? history[history_offset] : NULL;
}

int __attribute__ ((weak, visibility ("default"))) history_set_pos(int pos)
{
  if (pos < 0 || pos > history_length)
    return 0;
  history_offset = pos;
  return 1;
}

HIST_ENTRY __attribute__ ((weak, visibility ("default"))) *previous_history()
{
  if (history_offset == 0)
    return NULL;
  history_offset--;
  return history[history_offset];
}

HIST_ENTRY __attribute__ ((weak, visibility ("default"))) *next_history()
{
  if (history_offset == history_length)
    return NULL;
  history_offset++;
  return history[history_offset];
}