/* required for NULL */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <grass/gis.h>
#include "pad.h"

static PAD *padlist;

static int free_item(ITEM *item)
{
	LIST *list, *next;

	if (item->name != NULL)
		G_free(item->name);
	for (list = item->list; list != NULL; list = next)
	{
		next = list->next;
		if (list->value)
			G_free(list->value);
		G_free(list);
	}
	G_free(item);

	return 0;
}

static ITEM *new_item(PAD *pad, const char *name)
{
	ITEM *item;

	item = (ITEM *) G_malloc((size_t) sizeof(ITEM));
	if (item == NULL)
		return (ITEM *) NULL;

	item->name = G_store(name);
	if (item->name == NULL)
	{
		G_free(item);
		return (ITEM *) NULL;
	}
	item->list = NULL;
	item->next = pad->items;
	if (item->next != NULL)
		item->next->prev = item;
	item->prev = NULL;
	pad->items = item;

	return item;
}

static int remove_value(ITEM *item, const char *value)
{
	LIST **p = &item->list;
	LIST *l = *p;

	for (l = *p; l; l = *p)
	{
		if (value && l->value && !strcmp(value, l->value))
		{
			*p = l->next;
			if (l->value)
				G_free (l->value);
			G_free (l);
		}
		else
			p = &l->next;
	}

	return 0;
}

int append_item(PAD *pad, const char *name, const char *value, int replace)
{
	ITEM *item;
	LIST *cur, *prev;
	LIST *list;

	if (pad == NULL)
		return 0;

	/* allocate a list struct and put value into it */
	list = (LIST *) G_malloc((size_t) sizeof(LIST));
	if (list == NULL)
		return 0;
	list->next = NULL;
	list->value = G_store(value);
	if (list->value == NULL)
	{
		G_free(list);
		return 0;
	}
	/* find the named item for the current pad */
	item = find_item(pad, name);
	if (item == NULL)
		item = new_item(pad, name);
	if (item == NULL)
		return 0;

	/* remove any existing occurences of the value */
	if (replace)
		remove_value(item, value);

	/* add the LIST at the end of the item LIST */
	prev = NULL;
	for (cur = item->list; cur != NULL; cur = cur->next)
		prev = cur;

	if (prev == NULL)
		item->list = list;
	else
		prev->next = list;

	return 1;
}

int delete_item(PAD *pad, const char *name)
{
	ITEM *item;

	item = find_item(pad, name);
	if (item == NULL)
		return 0;

	if (item->prev == NULL)
		pad->items = item->next;
	else
		item->prev->next = item->next;

	if (item->next != NULL)
		item->next->prev = item->prev;

	/* free the item */
	free_item(item);

	return 1;
}

ITEM *find_item(PAD *pad, const char *name)
{
	ITEM *item;

	if (pad != NULL)
		for (item = pad->items; item != NULL; item = item->next)
			if (strcmp(name, item->name) == 0)
				return item;
	return (ITEM *) NULL;
}

PAD *pad_list(void)
{
	return padlist;
}

static int delink_pad(PAD *pad)
{
	if (pad == NULL)
		return 1;

	if (pad->prev == NULL)
		padlist = pad->next;
	else
		pad->prev->next = pad->next;

	if (pad->next != NULL)
		pad->next->prev = pad->prev;

	return 0;
}

int create_pad(const char *name)
{
	PAD *pad;

	pad = (PAD *) G_malloc((size_t) sizeof(PAD));
	if (pad == NULL)
		return 0;
	pad->name = G_store(name);
	if (pad->name == NULL)
	{
		G_free(pad);
		return 0;
	}
	pad->items = NULL;
	pad->next = padlist;
	if (pad->next != NULL)
		pad->next->prev = pad;
	pad->prev = NULL;
	padlist = pad;
	return 1;
}

int delete_pad(PAD *pad)
{
	ITEM *item, *next;

	if (pad == NULL)
		return 0;

	delink_pad(pad);

	/* free the items */
	for (item = pad->items; item != NULL; item = next)
	{
		next = item->next;
		free_item(item);
	}
	G_free(pad);

	return 1;
}

PAD *find_pad(const char *name)
{
	PAD *pad;

	for (pad = padlist; pad != NULL; pad = pad->next)
		if (strcmp(name, pad->name) == 0)
			return pad;
	return (PAD *) NULL;
}

int invent_pad(char *name)
{
	static int i = 0;

	do
		sprintf(name, "%d", ++i);
	while (find_pad(name) != NULL);

	return 0;
}