/*
 *  upkg: tool for manipulating Unreal Tournament packages.
 *  Copyright © 2009-2011 Nick Bowler
 *
 *  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 <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "music-module.h"
#include "upkg.h"

struct music_mod {
	struct upkg_file *f;

	unsigned char header[64];
	unsigned long hdrlen;
};

int music_mod_init(void)
{
	return 0;
}

void music_mod_exit(void)
{
}

struct music_mod *music_mod_open(struct upkg_file *f)
{
	struct music_mod *m;

	m = malloc(sizeof *m);
	if (!m) {
		return NULL;
	}
	m->f = f;

	m->hdrlen = upkg_export_read(f, m->header, sizeof m->header);
	return m;
}

void music_mod_close(struct music_mod *m)
{
	free(m);
}

int music_mod_dump(struct music_mod *m, FILE *of)
{
	unsigned char buf[1024];
	size_t rc;

	if (upkg_export_seek(m->f, 0, SEEK_SET) != 0) {
		return -1;
	}

	while (1) {
		rc = upkg_export_read(m->f, buf, sizeof buf);
		if (rc == 0) {
			if (!m->f->eof)
				return -1;
			return 0;
		}

		if (fwrite(buf, rc, 1, of) != 1) {
			if (feof(of)) {
				fprintf(stderr, "unexpected end-of-file.\n");
			} else {
				perror("fwrite");
			}
			return -1;
		}

		if (rc < sizeof buf) {
			if (!m->f->eof)
				return -1;
			return 0;
		}
	}
}

int is_xm(unsigned char *buf, unsigned long len)
{
	static const char head[15] =
		/* ASCII encoding of "Extended Module" */
		"\x45\x78\x74\x65\x6e\x64\x65\x64\x20\x4d\x6f\x64\x75\x6c\x65";

	if (len >= sizeof head && memcmp(head, buf, sizeof head) == 0)
		return 1;
	return 0;
}

int is_it(unsigned char *buf, unsigned long len)
{
	static const char head[4] =
		/* ASCII encoding of "IMPM" */
		"\x49\x4d\x50\x4d";

	if (len >= sizeof head && memcmp(head, buf, sizeof head) == 0)
		return 1;
	return 0;
}

int is_s3m(unsigned char *buf, unsigned long len)
{
	static const char head[4] =
		/* ASCII encoding of "SCRM" */
		"\x53\x43\x52\x4d";

	if (len < 0x2c + sizeof head)
		return 0;
	if (memcmp(head, buf+0x2c, sizeof head) == 0)
		return 1;
	return 0;
}

const char *music_mod_type(struct music_mod *mod)
{
	if (is_xm(mod->header, mod->hdrlen))
		return "xm";
	if (is_it(mod->header, mod->hdrlen))
		return "it";
	if (is_s3m(mod->header, mod->hdrlen))
		return "s3m";

	return "unknown";
}