/*
 *	Ogg Extractor
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#pragma pack(1)
typedef struct
{
	unsigned long  magic_number;
	unsigned char  version;
	unsigned char  header_type;
	unsigned short granule_position;
	long  _padding1;
	short _padding2;
	unsigned short bitstream_serial_number;
	short _padding3;
	unsigned short page_sequence_number;
	short _padding4;
	unsigned short CRC_checksum;
	short _padding5;
	unsigned char  page_segments;
/*	unsigned char  segment_table[]; */
} ogg_header;
#pragma pack()

#define OGG_MAGIC      0x5367674F /* "OggS" */
#define OGG_TYPE_FIRST 2
#define OGG_TYPE_LAST  4

size_t min(size_t a, size_t b)
{
	return a < b ? a : b;
}

void fcopy(FILE *dest, FILE *src, size_t len)
{
	int buf[1024];
	size_t n;
	for ( ; (n = fread(buf, 1, min(len, sizeof buf), src)) != 0; len -= n)
		fwrite(buf, 1, n, dest);
}

void ogg_extract(const char *filename)
{
	FILE *fin;
	int out_i;
	ogg_header oh;
	if ((fin = fopen(filename, "rb")) == NULL)
		return;
	for (out_i = 0; fread(&oh, 1, sizeof oh, fin) == sizeof oh; out_i++) {
		char outname[FILENAME_MAX];
		FILE *fout;
		int x;
		while (oh.magic_number != OGG_MAGIC
				|| !(oh.header_type & OGG_TYPE_FIRST)) {
			if ((x = fgetc(fin)) == EOF)
				goto end;
			memmove(&oh, (char *)&oh + 1, sizeof oh - 1);
			((char *)&oh)[sizeof oh - 1] = (char)x;
		}
		sprintf(outname, "%s.%04d.ogg", filename, out_i);
		printf("\rExtracting: %s -> %d", filename, out_i);
		if ((fout = fopen(outname, "wb")) == NULL) {
			printf("\n  Failed to create file !!\n");
			abort();
		}
		do {
			unsigned char seg;
			size_t sum;
			fwrite(&oh, 1, sizeof oh, fout);
			for (seg = 0, sum = 0; seg < oh.page_segments; seg++) {
				if ((x = fgetc(fin)) == EOF)
					goto end;
				sum += (unsigned char)x;
				fputc(x, fout);
			}
			fcopy(fout, fin, sum);
			if (oh.header_type & OGG_TYPE_LAST)
				break;
		} while (fread(&oh, 1, sizeof oh, fin) == sizeof oh);
		fclose(fout);
	}
end:
	fclose(fin);
	printf("\n");
}

int main(int argc, char *argv[])
{
	int i;
	for (i = 1; i < argc; i++)
		ogg_extract(argv[i]);
	return 0;
}