/*
 * Copyright (c) 2007 Mikko Sysikaski <mikko.sysikaski@gmail.com>
 *                    Toni Spets <toni.spets@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <libxml/parser.h>
#include <libxml/tree.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "prss.h"

#ifndef PARSE_OPTIONS
#define PARSE_OPTIONS 0
#endif

static PRSS* get_data(xmlDocPtr doc);

PRSS* prss_parse_data(const char* xml_data)
{
	xmlDocPtr doc = xmlReadMemory(xml_data, strlen(xml_data), "", NULL, PARSE_OPTIONS);
	if (!doc)
		return NULL;
	
	return get_data(doc);
}
PRSS* prss_parse_file(const char* xml_file)
{
	xmlDocPtr doc = xmlReadFile(xml_file, NULL, PARSE_OPTIONS);
	if (!doc)
		return NULL;
	
	return get_data(doc);
}
void prss_free(PRSS* data)
{
	if (!data)
		return;
	xmlFreeDoc(data->_data);
	free(data->items);
	free(data);
}

static inline void prss_null(PRSS* p)
{
	p->title = p->link = p->description = p->language = NULL;
	p->items = NULL;
	p->item_count = 0;
}
static inline void prss_null_item(PRSS_Item* i)
{
	i->title = i->link = i->description = i->category = i->pubdate = NULL;
}

static inline void read_item(PRSS_Item* res, xmlNodePtr data)
{
	prss_null_item(res);
	
	res->title = res->link = res->description = NULL;
	for(; data; data = data->next) {
		if (data->type != XML_ELEMENT_NODE)
			continue;
		xmlNodePtr child = data->children;
		if (!child)
			continue;
	
		if (!strcmp((char*)data->name, "title")) {
			res->title = (char*)child->content;
		} else if (!strcmp((char*)data->name, "link")) {
			res->link = (char*)child->content;
		} else if (!strcmp((char*)data->name, "description")) {
			res->description = (char*)child->content;
		} else if (!strcmp((char*)data->name, "category")) {
			res->category = (char*)child->content;
		} else if (!strcmp((char*)data->name, "pubDate")) {
			res->pubdate = (char*)child->content;
		} else if (!strcmp((char*)data->name, "guid")) {
			res->guid = (char*)child->content;
		}
	}
}
static inline void read_element(PRSS* res, xmlNodePtr n)
{
	if (n->type != XML_ELEMENT_NODE)
		return;
	xmlNodePtr child = n->children;
	if (!child)
		return;
		
	if (!strcmp((char*)n->name, "title")) {
		res->title = (char*)child->content;
	} else if (!strcmp((char*)n->name, "link")) {
		res->link = (char*)child->content;
	} else if (!strcmp((char*)n->name, "description")) {
		res->description = (char*)child->content;
	} else if (!strcmp((char*)n->name, "language")) {
		res->language = (char*)child->content;
	} else if (!strcmp((char*)n->name, "pubDate")) {
		res->pubdate = (char*)child->content;
	} else if (!strcmp((char*)n->name, "lastBuildDate")) {
		res->lastbuilddate = (char*)child->content;
	} else if (!strcmp((char*)n->name, "generator")) {
		res->generator = (char*)child->content;
	} else if (!strcmp((char*)n->name, "docs")) {
		res->docs = (char*)child->content;
	} else if (!strcmp((char*)n->name, "managingEditor")) {
		res->managingeditor = (char*)child->content;
	} else if (!strcmp((char*)n->name, "webMaster")) {
		res->webmaster = (char*)child->content;
	} else if (!strcmp((char*)n->name, "item")) {
		read_item(&res->items[res->item_count++], n->children);
	}
}

static inline int parse_rss_2_0(PRSS* res, xmlNodePtr root)
{
	xmlNodePtr channel = root->children;
	while(channel && (channel->type!=XML_ELEMENT_NODE || strcmp((char*)channel->name, "channel")))
		channel = channel->next;
	if (!channel)
		return 0;

	int items = 0;
	xmlNodePtr n;
	for(n = channel->children; n; n = n->next)
		if (n->type==XML_ELEMENT_NODE && !strcmp((char*)n->name, "item"))
			++items;
	
	res->items = malloc(items*sizeof(PRSS_Item));
	res->item_count = 0;

	for(n = channel->children; n; n = n->next) {
		read_element(res, n);
	}

	return 1;
}
static inline int parse_rss_1_0(PRSS* res, xmlNodePtr root)
{
	int items = 0;
	xmlNodePtr n;
	for(n = root->children; n; n = n->next) {
		if (n->type==XML_ELEMENT_NODE) {
			if (!strcmp((char*)n->name, "item"))
				++items;
			else if (!strcmp((char*)n->name, "channel")) {
				xmlNodePtr i;
				for(i = n->children; i; i = i->next) {
					read_element(res, i);
				}
			}
		}
	}
	
	res->items = malloc(items*sizeof(PRSS_Item));
	res->item_count = 0;

	for(n = root->children; n; n = n->next) {
		if (n->type==XML_ELEMENT_NODE && !strcmp((char*)n->name, "item"))
			read_item(&res->items[res->item_count++], n->children);
	}
	
	return 1;
}
static inline int parse_rss_0_9x(PRSS* res, xmlNodePtr root)
{
	// almost same...
	return parse_rss_2_0(res, root);
}

PRSS* get_data(xmlDocPtr doc)
{
	xmlNodePtr root = xmlDocGetRootElement(doc);
	PRSS* result = malloc(sizeof(PRSS));
	prss_null(result);
	result->_data = doc;
	do {
		if (root->type == XML_ELEMENT_NODE) {
			if (!strcmp((char*)root->name, "RDF")) {
				// RSS 1.0 document
				if (!parse_rss_1_0(result, root)) {
					free(result);
					return NULL;
				}
				return result;
			} else if (!strcmp((char*)root->name, "rss")) {
				// RSS 2.0 or <1.0 document
				if (!parse_rss_2_0(result, root)) {
					free(result);
					return NULL;
				}
				return result;
			}
		}
		root = root->next;
	} while(root);
	free(result);
	return NULL;
}