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

static const char codechars[] = "ABCDEFHILSTUbdhn";

static double videopos[65536];

static short nibble_count[65536][16];

static int xvalue(char c)
{
  if (c >= '0' && c <= '9')
    return c - '0';
  else if (c >= 'A' && c <= 'F')
    return c + 10 - 'A';
  else if (c >= 'a' && c <= 'f')
    return c + 10 - 'a';
  else
    return 0;
}

static int parse_logfile(const char* name)
{
  FILE* logfile;
  char lines[7][64];
  int i, j, v, guess, best, addr;
  int vscore[16];
  int lastaddr = 0;
  double lastvpos;

  logfile = fopen(name, "r");
  if (!logfile) {
    perror(name);
    return 1;
  }

  while (fgets(lines[0], sizeof(lines[0]), logfile)) {
    if (lines[0][0] == '(') {
      sscanf(lines[0], "(%lf)", &lastvpos);
    }
    if (lines[0][0] == '?' || isxdigit(lines[0][0])) {
      for (i = 1; i < 7; i++) {
	if (!fgets(lines[i], sizeof(lines[0]), logfile)) {
	  fclose(logfile);
	  fprintf(stderr, "premature EOF\n");
	  return 1;
	}
      }

      /* determine address, 4 bits at a time */

      addr = 0;

      for (j = 0; j < 4; j++) {
	for (i = 0; i < 16; i++)
	  vscore[i] = 0;
	vscore[(lastaddr >> (4 * j)) % 16] = 2;
	vscore[((lastaddr + 6) >> (4 * j)) % 16] = 2;

	for (i = 0; i < 7; i++) {
	  if (isxdigit(lines[i][3 - j])) {
	    guess = (xvalue(lines[i][3 - j])
		     + 15 * ((addr + i * 6) >> (4 * j)));
	    vscore[guess % 16]++;
	  }
	}

	best = 0;
	for (i = 0; i < 16; i++) {
	  if (vscore[i] >= vscore[best]) {
	    best = i;
	  }
	}

	if (vscore[best] >= 4)
	  addr |= (best << (4 * j));
	else
	  break;
      }

      if (j < 4) {
	fprintf(stderr, "*** After %04X: unable to determine address\n", lastaddr);
	continue;
      }

      if (addr != lastaddr && addr != lastaddr + 6)
	fprintf(stderr, "*** After %04X: continuing at %04X\n", lastaddr, addr);

      lastaddr = addr;
      videopos[addr] = lastvpos;

      for (i = 0; i < 7; i++) {
	for (j = 0; j < 12; j++) {
	  if (lines[i][j + 4] >= '0' && lines[i][j + 4] <= '9')
	    v = lines[i][j + 4] - '0';
	  else if (lines[i][j + 4] >= 'A' && lines[i][j + 4] <= 'F')
	    v = lines[i][j + 4] - 'A' + 10;
	  else
	    continue;

	  nibble_count[(addr * 2 + i * 12 + j) & 0xffff][v]++;
	}
      }
    }
  }

  fclose(logfile);
  return 0;
}

static int guess_nibble(int nibaddr)
{
  int j, total, max, maxj, mcount;
  short *c = nibble_count[nibaddr];

  total = max = maxj = 0;
  mcount = 1;
  for (j = 0; j < 16; j++) {
    if (c[j] > max) {
      max = c[j];
      maxj = j;
      mcount = 1;
    }
    else if (c[j] == max)
      mcount++;
    total += c[j];
  }

  if (max < 5 || mcount != 1 || max < ((3 * total) / 4))
    return -1;

  for (j = 0; j < 16; j++)
    if (c[j] != max && c[j] >= max / 4)
      return -1;

  return maxj;
}

int main(int argc, char** argv)
{
  FILE* binfile;
  char cmdbuf[1024];
  int i, j, k, addr, bnum;
  int prev = 0;
  int started_display = 0;

  if (argc < 2 || argc > 4) {
    fprintf(stderr, "Usage: %s log-file [bin-file] [video-file]\n", argv[0]);
    return 1;
  }

  for (i = 0; i < 65536; i++)
    videopos[i] = 0.0;

  if (parse_logfile(argv[1]))
    return 1;

  if (argc > 2) {
    binfile = fopen(argv[2], "wb");
    if (!binfile) {
      perror(argv[2]);
      return 1;
    }

    for (i = 0; i < 65536; i++) {
      j = guess_nibble(i);

      if (j == -1) {
	printf("\nUnable to determine value at %04X (%s).\n", i / 2, i % 2 ? "ls" : "ms");
	printf("Please locate the indicated line in the video file,\n"
	       "and type the correct character below.\n  ");

	if (i < 0x400)
	  addr = 0x8000 + i / 2;
	else
	  addr = i / 2;
	bnum = addr % 6;
	addr -= bnum;

	if (argc > 3 && videopos[addr - 18] >= 1.0) {
	  snprintf(cmdbuf, sizeof(cmdbuf), "ffmpeg -ss %g -i %s -an -vframes 1"
		   " -vcodec ppm /tmp/81-collect-tmp.ppm 2> /dev/null",
		   videopos[addr - 18], argv[3]);
	  system(cmdbuf);
	  if (!started_display) {
	    snprintf(cmdbuf, sizeof(cmdbuf),
		     "display -update 1 /tmp/81-collect-tmp.ppm &");
	    system(cmdbuf);
	    started_display = 1;
	  }
	}

	for (k = 12; k >= 0; k -= 4)
	  putchar(codechars[(addr >> k) % 16]);

	for (k = 0; k < 12; k++) {
	  j = guess_nibble((addr * 2 + k) & 0xffff);
	  if (k == bnum * 2 + (i % 2))
	    putchar('*');
	  else if (j == -1)
	    putchar('?');
	  else
	    putchar(codechars[j]);
	}

	printf("\n      ");
	for (k = 0; k < bnum * 2 + (i % 2); k++)
	  putchar(' ');
	printf("^\n\n");

	do {
	  printf("> ");

	  do {
	    k = getchar();
	  } while (k == '\n' || k == '\r');

	  if (argc > 3 && videopos[addr - 18] >= 1.0) {
	    if (k == '>') {
	      videopos[addr - 18]++;
	      snprintf(cmdbuf, sizeof(cmdbuf), "ffmpeg -ss %g -i %s -an -vframes 1"
		       " -vcodec ppm /tmp/81-collect-tmp.ppm 2> /dev/null",
		       videopos[addr - 18], argv[3]);
	      system(cmdbuf);
	    }
	    else if (k == '<') {
	      videopos[addr - 18]--;
	      snprintf(cmdbuf, sizeof(cmdbuf), "ffmpeg -ss %g -i %s -an -vframes 1"
		       " -vcodec ppm /tmp/81-collect-tmp.ppm 2> /dev/null",
		       videopos[addr - 18], argv[3]);
	      system(cmdbuf);
	    }
	  }

	  for (j = 0; j < 16; j++)
	    if (codechars[j] == k)
	      break;
	} while (j == 16);
      }

      if (i % 2) {
	fputc(prev | j, binfile);
      }
      else {
	prev = j << 4;
      }
    }

    fclose(binfile);
  }
  else {
    for (i = 0; i < 65536; i++) {
      printf("%04X ", (i / 2));

      j = guess_nibble(i);
      if (j == -1)
	printf("??? ");
      else
	printf("(%X) ", j);

      for (j = 0; j < 16; j++) {
	for (k = 0; k < nibble_count[i][j]; k++) {
	  printf("%X", j);
	}
      }
      putchar('\n');
    }
  }

  return 0;
}