#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdarg.h>
#ifdef HAVE_LIBGEN_H
# include <libgen.h>
#endif /* HAVE_LIBGEN_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:
			if (opcode_addr[opcode] & OP_ADDR_A)
			{
				fprintf(output, "%s A\n", opcode_str[opcode]);
			}
			else
			{
				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));
}

void
usage(int retcode)
{
	if (retcode == EXIT_FAILURE)
	{
		fprintf(stderr,
				"Try '%s -h' for more information.\n", prg_name);
	}
	else
	{
		printf("Usage: %s [-hV] [INPUT] [OUTPUT]\n", prg_name);
		printf("Disassemble INPUT to OUTPUT\n\n");
		printf("With no INPUT read standard input.\n");
		printf("With no OUTPUT write standard output.\n\n");
		printf("\t-h\tdisplay this help and exit\n");
		printf("\t-V\toutput version information\n");
		printf("\nReport bugs to <%s>\n", PACKAGE_BUGREPORT);
	}

	exit(retcode);
}

void
version(void)
{
	printf("%s version %s\n", PACKAGE_NAME, PACKAGE_VERSION);
	exit(EXIT_SUCCESS);
}

int
main(int argc, char **argv)
{
#ifdef HAVE_LIBGEN_H
	prg_name = basename(argv[0]);
#else
	prg_name = argv[0];
#endif /* HAVE_LIBGEN_H */
	input = stdin;
	output = stdout;

	while ((argc > 1) && (argv[1][0] == '-'))
	{
		switch (argv[1][1])
		{
		case 'h':
			usage(EXIT_SUCCESS);
			break;
		case 'V':
			version();
			break;
		default:
			usage(EXIT_FAILURE);
			break;
		}

		argv++;
		argc--;
	}

	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);
}