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

static char* get_op(int id);
static char* get_value(int id);

static int counter = 0; /* line number */

int
main(int argc, char **argv)
{
	FILE *fp;
	char line[256];
	char *token = NULL;
	char *op1, *op2;

	assert(argc == 2);

	fp = fopen(argv[1], "r");
	assert(fp != NULL);

	while (fgets(line, sizeof(line), fp) != NULL)
	{
		token = strtok(line, "\n\t\r ");
		counter++;

		if (token == NULL || line[0] == ';')
		{
			continue;
		}
		else if (strcmp(token, "NOP") == 0)
		{
			printf("'\n");
		}
		else if (strcmp(token, "MOV") == 0)
		{
			op1 = get_value(1);
			op2 = get_value(2);
			if (strcmp(op2, "Ans") == 0)
			{
				printf("%s\n", op1);
			}
			else
			{
				printf("%s->%s\n", op1, op2);
			}
		}
		else if (strcmp(token, "ADD") == 0)
		{
			op1 = get_value(1);
			printf("Ans+%s\n", op1);
		}
		else if (strcmp(token, "SUB") == 0)
		{
			op1 = get_value(1);
			printf("Ans-%s\n", op1);
		}
		else if (strcmp(token, "MUL") == 0)
		{
			op1 = get_value(1);
			printf("Ans*%s\n", op1);
		}
		else if (strcmp(token, "DIV") == 0)
		{
			op1 = get_value(1);
			printf("Ans/%s\n", op1);
		}
		else if (strcmp(token, "NEG") == 0)
		{
			printf("-Ans\n");
		}
		else if (strcmp(token, "LBL") == 0)
		{
			op1 = get_op(1);
			printf("Lbl %s\n", op1);
		}
		else if (strcmp(token, "JMP") == 0)
		{
			op1 = get_op(1);
			printf("Goto %s\n", op1);
		}
		else if (strcmp(token, "JEZ") == 0)
		{
			op1 = get_op(1);
			printf("Ans=>Goto %s\n", op1);
		}
		else if (strcmp(token, "JNZ") == 0)
		{
			op1 = get_op(1);
			printf("Ans=0=>Goto %s\n", op1);
		}
		else if (strcmp(token, "JMZ") == 0)
		{
			op1 = get_op(1);
			printf("Ans>0=>Goto %s\n", op1);
		}
		else if (strcmp(token, "JLZ") == 0)
		{
			op1 = get_op(1);
			printf("Ans<0=>Goto %s\n", op1);
		}
		else if (strcmp(token, "CLS") == 0)
		{
			printf("ClrText\n");
		}
		else if (strcmp(token, "DSP") == 0)
		{
			printf("AnsDisps");
		}
		else if (strcmp(token, "LOC") == 0)
		{
			printf("Locate X,Y,Ans\n");
		}
		else
		{
			fprintf(stderr, "line %d: unknown token '%s'\n", counter, token);
			return EXIT_FAILURE;
		}
	}

	fclose(fp);

	return EXIT_SUCCESS;
}

static char*
get_op(int id)
{
	char *op = strtok(NULL, "\n\t\r, ");
	if (op == NULL)
	{
		fprintf(stderr, "line %d: missing operand %d\n", counter, id);
		exit(EXIT_FAILURE);
	}
	return op;
}

static char*
get_value(int id)
{
	char *op = get_op(id);
	if (strcmp(op, "ANS") == 0)
	{
		return "Ans";
	}
	if (strcmp(op, "GTK") == 0)
	{
		return "Getkey";
	}
	if (strcmp(op, "INP") == 0)
	{
		return "?";
	}
	return op;
}