#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdarg.h>
#include "lib/op.h"

#define OP_ADDR_MODE (OP_ADDR_IMPL | OP_ADDR_REL | OP_ADDR_IND	\
  | OP_ADDR_IMM | OP_ADDR_ABS)

char *prg_name;
FILE *input;
FILE *output;

uint8_t
readu8(void)
{
  uint8_t val;

  if (fread(&val, 1, 1, input) != 1)
    {
      return (-1); /* XXX: TODO */
    }

  return (val);
}

uint16_t
readu16(void)
{
  uint16_t val;

  if (fread(&val, 1, 2, input) != 2)
    {
      return (-1); /* XXX: TODO */
    }

  return (val);
}

uint32_t
readu32(void)
{
  uint32_t val;

  if (fread(&val, 1, 4, input) != 4)
    {
      return (-1); /* XXX: TODO */
    }

  return (val);
}

int16_t
read16(void)
{
  int16_t val;

  if (fread(&val, 1, 2, input) != 2)
    {
      return (-1); /* XXX: TODO */
    }

  return (val);
}

int32_t
read32(void)
{
  int32_t val;

  if (fread(&val, 1, 4, input) != 4)
    {
      return (-1); /* XXX: TODO */
    }

  return (val);
}

void
fatal(const char *str, ...)
{
  va_list ap;

  fprintf(stderr, "%s: ", prg_name);
  va_start(ap, str);
  vfprintf(stderr, str, ap);
  va_end(ap);
  fprintf(stderr, "\n");

  exit(EXIT_FAILURE);
}

void
decode_target_suffix(uint8_t attr)
{
  fprintf(output, ".");
  if (IS_TARGET_ZEXT(attr))
    {
      fprintf(output, "U");
    }

  switch (GET_TARGET_SIZE(attr))
    {
    case SIZE_BYTE:
      fprintf(output, "B");
      break;
    case SIZE_WORD:
      fprintf(output, "W");
      break;
    case SIZE_LONG:
      fprintf(output, "L");
      break;
    }
}

void
decode_address(uint8_t attr)
{
    switch (GET_ADDRESS_SIZE(attr))
    {
    case SIZE_BYTE:
      fprintf(output, " %%%X", readu8());
      break;
    case SIZE_WORD:
      fprintf(output, " %%%hX", readu16());
      break;
    case SIZE_LONG:
      fprintf(output, " %%%X", readu32());
      break;
    default:
      break;
    }
}

void
decode_imm(uint8_t opcode)
{
  uint8_t attr;

  attr = readu8();

  fprintf(output, "%s", opcode_str[opcode]);
  decode_target_suffix(attr);
  switch (GET_TARGET_SIZE(attr))
    {
    case SIZE_BYTE:
      fprintf(output, " #$%X\n", readu8());
      break;
    case SIZE_WORD:
      fprintf(output, " #$%hX\n", readu16());
      break;
    case SIZE_LONG:
      fprintf(output, " #$%X\n", readu32());
      break;
    default:
      break;
    }
}

void
decode_ind(uint8_t opcode)
{
  uint8_t attr;

  fprintf(output, "%s", opcode_str[opcode]);
  attr = readu8();
  if (opcode != OP_JMP_ind)
    {
      decode_target_suffix(attr);
    }
  if (opcode_addr[opcode] & (OP_ADDR_X | OP_ADDR_Y))
    {
      fprintf(output, " (");
    }
  else
    {
      fprintf(output, " ");
    }

  decode_address(attr);

  if (opcode_addr[opcode] & OP_ADDR_X)
    {
      fprintf(output, ", X)");
    }
  else if (opcode_addr[opcode] & OP_ADDR_Y)
    {
      fprintf(output, "), Y");
    }
  fprintf(output, "\n");
}

void
decode_abs(uint8_t opcode)
{
  uint8_t attr;

  fprintf(output, "%s", opcode_str[opcode]);
  attr = readu8();
  if (opcode != OP_JSR_abs
      || opcode != OP_JMP_abs)
    {
      decode_target_suffix(attr);
    }
  decode_address(attr);

  if (opcode_addr[opcode] & OP_ADDR_X)
    {
      fprintf(output, ", X");
    }
  else if (opcode_addr[opcode] & OP_ADDR_Y)
    {
      fprintf(output, ", Y");
    }
  fprintf(output, "\n");
}

void
decode(void)
{
  uint8_t opcode;
  int16_t relative;

  do {
    opcode = readu8();
    if (feof(input)) return;
    switch (opcode_addr[opcode] & OP_ADDR_MODE)
      {
      case OP_ADDR_IMPL:
	fprintf(output, "%s\n", opcode_str[opcode]);
	break;
      case OP_ADDR_REL:
	relative = read16();
	fprintf(output, "%s $%hX\n", opcode_str[opcode], relative);
	break;
      case OP_ADDR_IMM:
	decode_imm(opcode);
	break;
      case OP_ADDR_IND:
	decode_ind(opcode);
	break;
      case OP_ADDR_ABS:
	decode_abs(opcode);
	break;
      default:
	fprintf(output, "???\n", opcode);
	break;
      }
  } while (!feof(input));
}

int
main(int argc, char **argv)
{
  prg_name = argv[0];
  input = stdin;
  output = stdout;

  if (argc > 2)
    {
      output = fopen(argv[2], "w");
      if (output == NULL) fatal("can't open %s.", argv[2]);
    }

  if (argc > 1)
    {
      input = fopen(argv[1], "rb");
      if (input == NULL) fatal("can't open %s.", argv[1]);
    }

  decode();

  return (EXIT_SUCCESS);
}