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

char *dictionary = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
char *extensions[] = {"",".0BJ",".ATT",".BIN",".BUF",".CHR",".CUR",".DAT",".EVT",".FAC",".FWL",".GND",".HED",".ICN",".INT",".M",".MOB",".MON",".NAM",".OBJ",".OUT",".PAL",".PTY",".RAW",".SKY",".SRF",".SWL",".TIL",".TXT",".VGA",".VOC",".WAL",".XEN"};
int extCount = 33;

char *buf;
unsigned int buflen;
unsigned char c1, c2;
unsigned long offset;
unsigned int length;
unsigned char xor=0x35;
FILE *fi;

unsigned int hashName(char* fname) {
	unsigned char h0, h1, h2, h3;
	unsigned int temp;

	h0 = h1 = 0;
	while (*fname != 0) {
		// swap h0 and h1
		h2 = h1; h1 = h0; h0 = h2;
		// rotate left
		h2 = (((unsigned int)h0 << 1) & 0xff) | (((unsigned int)h1 >> 7) & 0xff);
		h3 = (((unsigned int)h1 << 1) & 0xff) | (((unsigned int)h0 >> 7) & 0xff);
		h0 = h2;
		h1 = h3;
		// calc toUpper(h1)
		h2 = (*fname++) & 0x7f;
		if (h2 >= 0x60)
		  h2 = h2 - 0x20;
		// add char to h1
		temp = ((unsigned int)h0 << 8) | (unsigned int)h1;
		temp = (temp + h2) & 0xffff;
		h0 = (temp >> 8) & 0xff;
		h1 = temp & 0xff;
	}
	return (h0 << 8) ^ h1;
}

int extract(char* name) {
	int i = 0;
	unsigned int hash = hashName(name);

	printf("Hash for '%s' is 0x%04x.\n", name, hash);
	for (i = 0; i < 8*buflen; i+=8) {
		if (((buf[i] & 0xff) == (hash & 0xFF)) && ((buf[i+1] & 0xFF) == (hash >> 8))) break;

	}
	if (i == 8*buflen) {
		printf("File not found: '%s'.\n", name);
		return 0;
	}
	i += 2;
	offset = (unsigned long)buf[i++] & 0xff;
	offset |= (((unsigned long)buf[i++]) << 8) & 0xff00;
	offset |= (((unsigned long)buf[i++]) << 16) & 0xff0000;
	length = (unsigned long)buf[i++] & 0xff;
	length |= (((unsigned long)buf[i++]) << 8) & 0xff00;
	printf("Entry #%d, offset=%06x, length=%04x\n", i, offset, length);

	FILE *fo = fopen(name, "wb");
	fseek(fi, offset, SEEK_SET);
	for (i = 0; i < length; i++) {
		fputc((fgetc(fi) ^ xor) & 0xff, fo);
	}
	fclose(fo);

}

int extractHash(unsigned int hash) {
	int i = 0;

//	printf("Hash for '%s' is 0x%04x.\n", name, hash);
	for (i = 0; i < 8*buflen; i+=8) {
		if (((buf[i] & 0xff) == (hash & 0xFF)) && ((buf[i+1] & 0xFF) == (hash >> 8))) break;

	}
	if (i == 8*buflen) {
		printf("Hash not found: '%d'.\n", hash);
		return 0;
	}
	i += 2;
	offset = (unsigned long)buf[i++] & 0xff;
	offset |= (((unsigned long)buf[i++]) << 8) & 0xff00;
	offset |= (((unsigned long)buf[i++]) << 16) & 0xff0000;
	length = (unsigned long)buf[i++] & 0xff;
	length |= (((unsigned long)buf[i++]) << 8) & 0xff00;
	printf("Entry #%d, offset=%06x, length=%04x\n", i, offset, length);

	FILE *fo = fopen("hashed", "wb");
	fseek(fi, offset, SEEK_SET);
	for (i = 0; i < length; i++) {
		fputc((fgetc(fi) ^ xor) & 0xff, fo);
	}
	fclose(fo);

}

void decode_buffer(unsigned char *buf, unsigned int l)
{
  unsigned char al, ah=0xAC;
  int i;

  for (i = 0; i < l; i++)
  {
    al = buf[i];
    al = (((int)al << 2) | ((int)al >> 6)) & 0xff;
    al = (al + ah) & 0xff;
    buf[i] = al;
    ah = (ah + 0x67) & 0xff;
  }
}

int main(int argc, char *argv[]) {
	int i;

	if (argc < 3) {
		printf("Syntax: %s infile.cc file.ext\n", argv[0]);
		exit(-1);
	}
	if (argc > 3) {
		char* digit = argv[3];
		xor = 0;
		while (*digit >= '0' && *digit <='9') {
			xor = (xor * 10) + (*digit - '0');
			digit++;
		}
	}

	fi = fopen(argv[1], "rb");


	c1 = fgetc(fi);
	c2 = fgetc(fi);
	buflen = (unsigned int)c1 | ((unsigned int)c2 << 8);
	printf("%s contains %d files.\n", argv[1], buflen);

	buf = (unsigned char *)malloc(8 * buflen);
	fread(buf, 8, buflen, fi);
	decode_buffer(buf, 8*buflen);

	extract(argv[2]);
//	extractHash(46108);
	fclose(fi);
	free(buf);
	return 0;
}