#include <expat.h>
#include "tileset.h"
#include "../xml.h"
#include "../logging.h"

/*
 * Problem:
 *     xml_tselem_start(), xml_tileset_end(), etc. may be called with one of two
 *     types of user data.
 * Possible solution:
 *  1. Create a base (struct xml_doc) in src/xml.h:
 *         struct xml_doc {
 *             enum {
 *                 XML_DOC_TMX,
 *                 XML_DOC_TSX
 *             } type;
 *             XML_Parser p;
 *         };
 *  2. Make (struct tmx) and (struct tmx) "extend" it, e.g.:
 *         struct tsx {
 *             struct xml_doc doc;
 *             struct tileset *ts;
 *         };
 *  3. Make xml_tselem_start(), xml_tileset_end(), etc. check the doc.type
 *     member of the user data and find the (struct tileset *) accordingly.
 * Wait, what?!
 * Alternative solution:
 *  1. Declare (struct tmx) in src/resources/map.h.
 *  2. Add to (struct tsx) the following member:
 *         struct tmx *parent_tmx;
 *  3. In xml_mapelem_start() (src/resources/map.c):
 *      1. Allocate a (struct tsx).
 *      2. Set the parent_tmx member of the (struct tsx) to tmx.
 *      3. Set the ts member of the (struct tsx) to ts.
 *      4. Set the (struct tsx) as the user data.
 *  4. In xml_tileset_end() (src/resources/tileset.c), add the following code:
 *         if (tsx->parent_tmx != NULL) {
 *             XML_SetUserData(tsx->p, tsx->parent_tmx);
 *             free(tsx);
 *             XML_SetStartElementHandler(tmx->p, xml_mapelem_start);
 *             XML_SetEndElementHandler(tmx->p, xml_map_end);
 *         }
 * Alternative alternative solution:
 *     Something that doesn't suck.
 */
struct tsx {
	XML_Parser p;
	struct tileset *ts;
};

struct resource_table ts_res;

void XMLCALL
xml_tileset_start(void *data, const char *el, const char **attr)
{
	struct tsx *tsx;

	debug("<%s> (type \"tileset\")", el);

	tsx = (struct tsx *) data;

	if (xml_check_tag(el, "tileset")) {
		xml_get_string_attr(tsx->p, attr, "name",
				&tsx->ts->name, 1);
		xml_get_int_attr(tsx->p, attr, "tilewidth",
				&tsx->ts->tilewidth, 1);
		xml_get_int_attr(tsx->p, attr, "tileheight",
				&tsx->ts->tileheight, 1);
/*		XML_SetStartElementHandler(tsx->p, xml_tselem_start);*/
		XML_SetEndElementHandler(tsx->p, xml_tileset_end);
	} else {
		xml_unexpected_start_tag(tsx->p, el,
				"tileset");
	}
}

void XMLCALL
xml_tileset_end(void *data, const char *el)
{
	struct tsx *tsx;

	debug("</%s> (type \"tileset\")", el);

	tsx = (struct tsx *) data;

	if (xml_check_tag(el, "tileset")) {
		XML_SetStartElementHandler(tsx->p, NULL);
		XML_SetEndElementHandler(tsx->p, NULL);
	} else {
		xml_unexpected_end_tag(tsx->p, el,
				"tileset");
	}
}

struct tileset *
tileset_get(const char *path)
{
	struct tsx tsx;
	FILE *tsx_fp;
	void *tsx_buf;
	size_t len;
	enum XML_Status status;

	memset(&tsx, 0, sizeof(tsx));

	tsx.ts = (struct tileset *) resource_get(&ts_res, path);
	if (tsx.ts != NULL) {
		resource_use((struct resource *) tsx.ts);
		return tsx.ts;
	}

	tsx.ts = resource_alloc(path, sizeof(*tsx.ts));

	tsx.p = XML_ParserCreate(NULL);
	if (tsx.p == NULL) {
		warn("Failed to create TSX parser");
		return NULL;
	}

	XML_SetStartElementHandler(tsx.p, xml_tileset_start);
	XML_SetEndElementHandler(tsx.p, NULL);
	XML_SetCharacterDataHandler(tsx.p, NULL);

	XML_SetUserData(tsx.p, &tsx);

	tsx_fp = fopen(path, "rb");
	if (tsx_fp == NULL) {
		warn("Failed to open TSX file");
		XML_ParserFree(tsx.p);
		return NULL;
	}

	tsx_buf = XML_GetBuffer(tsx.p, 8192);
	if (tsx_buf == NULL) {
		warn("Failed to create TSX parse buffer");
		XML_ParserFree(tsx.p);
		fclose(tsx_fp);
		return NULL;
	}

	while (!feof(tsx_fp)) {
		len = fread(tsx_buf, 1, 8192, tsx_fp);
		status = XML_ParseBuffer(tsx.p, len, feof(tsx_fp));
		if (status == XML_STATUS_OK) {
			continue;
		}
		warn("Failed to parse TSX file (%s)",
				XML_ErrorString(XML_GetErrorCode(tsx.p)));
		XML_ParserFree(tsx.p);
		fclose(tsx_fp);
		return NULL;
	}

	XML_ParserFree(tsx.p);
	fclose(tsx_fp);

	resource_use((struct resource *) tsx.ts);
	resource_add(&ts_res, path, (struct resource *) tsx.ts);

	return tsx.ts;
}