/*
 * libuci - Library for the Unified Configuration Interface
 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
 *
 * this program is free software; you can redistribute it and/or modify
 * it under the terms of the gnu lesser general public license version 2.1
 * as published by the free software foundation
 *
 * 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.
 */

#include <glob.h>

/* initialize a list head/item */
static inline void uci_list_init(struct uci_list *ptr)
{
	ptr->prev = ptr;
	ptr->next = ptr;
}

/* inserts a new list entry after a given entry */
static inline void uci_list_insert(struct uci_list *list, struct uci_list *ptr)
{
	list->next->prev = ptr;
	ptr->prev = list;
	ptr->next = list->next;
	list->next = ptr;
}

/* inserts a new list entry at the tail of the list */
static inline void uci_list_add(struct uci_list *head, struct uci_list *ptr)
{
	/* NB: head->prev points at the tail */
	uci_list_insert(head->prev, ptr);
}

static inline void uci_list_del(struct uci_list *ptr)
{
	struct uci_list *next, *prev;

	next = ptr->next;
	prev = ptr->prev;

	prev->next = next;
	next->prev = prev;

	uci_list_init(ptr);
}

/* 
 * uci_alloc_generic allocates a new uci_element with payload
 * payload is appended to the struct to save memory and reduce fragmentation
 */
static struct uci_element *
uci_alloc_generic(struct uci_context *ctx, int type, const char *name, int size)
{
	struct uci_element *e;
	void *ptr;

	ptr = uci_malloc(ctx, size + strlen(name) + 1);
	e = (struct uci_element *) ptr;
	e->type = type;
	e->name = (char *) ptr + size;
	strcpy(e->name, name);
	uci_list_init(&e->list);

	return e;
}

static void
uci_free_element(struct uci_element *e)
{
	if (!uci_list_empty(&e->list))
		uci_list_del(&e->list);
	free(e);
}

static struct uci_option *
uci_alloc_option(struct uci_section *s, const char *name, const char *value)
{
	struct uci_package *p = s->package;
	struct uci_context *ctx = p->ctx;
	struct uci_option *o;

	o = uci_alloc_element(ctx, option, name, strlen(value) + 1);
	o->value = uci_dataptr(o);
	o->section = s;
	strcpy(o->value, value);
	uci_list_add(&s->options, &o->e.list);

	return o;
}

static inline void
uci_free_option(struct uci_option *o)
{
	uci_free_element(&o->e);
}

static struct uci_section *
uci_alloc_section(struct uci_package *p, const char *type, const char *name)
{
	struct uci_context *ctx = p->ctx;
	struct uci_section *s;
	char buf[16];

	if (!name || !name[0]) {
		snprintf(buf, 16, "cfg%d", p->n_section);
		name = buf;
	}

	s = uci_alloc_element(ctx, section, name, strlen(type) + 1);
	s->type = uci_dataptr(s);
	s->package = p;
	strcpy(s->type, type);
	uci_list_init(&s->options);
	uci_list_add(&p->sections, &s->e.list);

	return s;
}

static void
uci_free_section(struct uci_section *s)
{
	struct uci_element *o, *tmp;

	uci_foreach_element_safe(&s->options, tmp, o) {
		uci_free_option(uci_to_option(o));
	}
	uci_free_element(&s->e);
}

static struct uci_package *
uci_alloc_package(struct uci_context *ctx, const char *name)
{
	struct uci_package *p;

	p = uci_alloc_element(ctx, package, name, 0);
	p->ctx = ctx;
	uci_list_init(&p->sections);
	uci_list_init(&p->history);
	return p;
}

static void
uci_free_package(struct uci_package *p)
{
	struct uci_element *e, *tmp;

	if(!p)
		return;

	uci_foreach_element_safe(&p->sections, tmp, e) {
		uci_free_section(uci_to_section(e));
	}
	uci_free_element(&p->e);
}

/* record a change that was done to a package */
static inline void
uci_add_history(struct uci_context *ctx, struct uci_package *p, int cmd, char *section, char *option, char *value)
{
	struct uci_history *h = (struct uci_history *) uci_malloc(ctx, sizeof(struct uci_history));

	uci_list_init(&h->list);
	h->cmd = cmd;
	h->section = section;
	h->option = option;
	h->value = value;
	uci_list_add(&p->history, &h->list);
}


static struct uci_element *uci_lookup_list(struct uci_context *ctx, struct uci_list *list, char *name)
{
	struct uci_element *e;

	uci_foreach_element(list, e) {
		if (!strcmp(e->name, name))
			return e;
	}
	UCI_THROW(ctx, UCI_ERR_NOTFOUND);
}

int uci_lookup(struct uci_context *ctx, struct uci_element **res, char *package, char *section, char *option)
{
	struct uci_element *e;
	struct uci_package *p;
	struct uci_section *s;
	struct uci_option *o;

	UCI_HANDLE_ERR(ctx);
	UCI_ASSERT(ctx, res != NULL);
	UCI_ASSERT(ctx, package != NULL);

	e = uci_lookup_list(ctx, &ctx->root, package);
	if (!section)
		goto found;

	p = uci_to_package(e);
	e = uci_lookup_list(ctx, &p->sections, section);
	if (!option)
		goto found;

	s = uci_to_section(e);
	e = uci_lookup_list(ctx, &s->options, option);

found:
	*res = e;
	return 0;
}

int uci_set_element_value(struct uci_context *ctx, struct uci_element **element, char *value)
{
	int size;
	char *str;
	struct uci_list *list;
	struct uci_element *e;

	UCI_HANDLE_ERR(ctx);
	UCI_ASSERT(ctx, value != NULL);
	UCI_ASSERT(ctx, element != NULL);
	UCI_ASSERT(ctx, *element != NULL);

	/* what the 'value' of an element means depends on the type
	 * for a section, the 'value' means its type
	 * for an option, the 'value' means its value string
	 * when changing the value, shrink the element to its actual size
	 * (it may have been allocated with a bigger size, to include
	 *  its buffer)
	 * then duplicate the string passed on the command line and
	 * insert it into the structure.
	 */
	e = *element;
	list = e->list.prev;
	switch(e->type) {
	case UCI_TYPE_SECTION:
		size = sizeof(struct uci_section);
		break;
	case UCI_TYPE_OPTION:
		size = sizeof(struct uci_option);
		break;
	default:
		UCI_THROW(ctx, UCI_ERR_INVAL);
		break;
	}

	uci_list_del(&e->list);
	e = uci_realloc(ctx, e, size);
	str = uci_strdup(ctx, value);
	uci_list_insert(list, &e->list);
	*element = e;

	switch(e->type) {
	case UCI_TYPE_SECTION:
		uci_to_section(e)->type = value;
		break;
	case UCI_TYPE_OPTION:
		uci_to_option(e)->value = value;
		break;
	default:
		break;
	}

	return 0;
}

int uci_set(struct uci_context *ctx, char *package, char *section, char *option, char *value)
{
	struct uci_element *e;
	struct uci_package *p = NULL;
	struct uci_section *s = NULL;
	struct uci_option *o = NULL;
	struct uci_history *h;

	UCI_HANDLE_ERR(ctx);
	UCI_ASSERT(ctx, package != NULL);
	UCI_ASSERT(ctx, section != NULL);

	fprintf(stderr, "uci_set: '%s' '%s' '%s' = '%s'\n", package, section, option, value);

	/*
	 * look up the package, section and option (if set)
	 * if the section/option is to be modified and it is not found
	 * create a new element in the appropriate list
	 */
	UCI_TRAP_SAVE(ctx, notfound);
	e = uci_lookup_list(ctx, &ctx->root, package);
	if (!e)
		goto notfound;

	p = uci_to_package(e);
	e = uci_lookup_list(ctx, &p->sections, section);
	if (!e)
		goto notfound;
	s = uci_to_section(e);

	if (option) {
		e = uci_lookup_list(ctx, &s->options, option);
		if (!e)
			goto notfound;
		o = uci_to_option(e);
	}
	UCI_TRAP_RESTORE(ctx);

	/* 
	 * no unknown element was supplied, assume that we can just update 
	 * an existing entry
	 */
	if (o)
		e = &o->e;
	else
		e = &s->e;

	uci_add_history(ctx, p, UCI_CMD_CHANGE, section, option, value);
	return uci_set_element_value(ctx, &e, value);

notfound:
	/* 
	 * the entry that we need to update was not found,
	 * check if the search failed prematurely.
	 * this can happen if the package was not found, or if
	 * an option was supplied, but the section wasn't found
	 */
	if (!p || (!s && option))
		UCI_THROW(ctx, ctx->errno);

	/* now add the missing entry */
	uci_add_history(ctx, p, UCI_CMD_ADD, section, option, value);
	if (s)
		uci_alloc_option(s, option, value);
	else
		uci_alloc_section(p, section, value);

	return 0;
}

int uci_unload(struct uci_context *ctx, const char *name)
{
	struct uci_element *e;

	UCI_HANDLE_ERR(ctx);
	UCI_ASSERT(ctx, name != NULL);

	uci_foreach_element(&ctx->root, e) {
		if (!strcmp(e->name, name))
			goto found;
	}
	UCI_THROW(ctx, UCI_ERR_NOTFOUND);

found:
	uci_free_package(uci_to_package(e));

	return 0;
}