#include "turmit.h"

TURMIT_OP(mem_sz)
{
	turmit_int *new;
	turmit_int new_sz, old_sz, new_blc, old_blc;
	
	old_sz = turmit->stack_sz;
	old_blc = (old_sz / TURMIT_STACK_GROW) + 1;

	new_sz = SPOP(turmit);
	new_sz %= TURMIT_STACK_MAX;
	new_sz = new_sz<2?2:new_sz;
	new_blc = (new_sz / TURMIT_STACK_GROW) + 1;

	if(new_blc != old_blc)
	{
		new = realloc(turmit->stack,
			sizeof(turmit_int) * (new_blc * TURMIT_STACK_GROW));
		if(!new) {
			perror("Unable to reallocate memory for stack");
			return; 
		}
		turmit->stack = new;
	}
	turmit->stack_sz = new_sz;
	turmit->stack_cur %= new_sz;
	if(old_sz < new_sz)
	{
		bzero(turmit->stack + old_sz,
			sizeof(turmit_int) * (new_sz - old_sz));
	}
}

TURMIT_OP(add)
{
	turmit_int a = SPOP(turmit), b = SPOP(turmit);
	SPUSH(turmit, a+b);
}

TURMIT_OP(sub)
{
	turmit_int a = SPOP(turmit), b = SPOP(turmit);
	if(turmit->flags & TURMIT_SIGNED)
	{
		fprintf(stderr, "Signed int not implemented\n");
	}
	else
	{
		SPUSH(turmit, a>b?(turmit->int_max - a) + b:b - a);
	}
}

TURMIT_OP(bin_and)
{
	turmit_int a = SPOP(turmit), b = SPOP(turmit);
	SPUSH(turmit, b & a);
}

TURMIT_OP(dup)
{
	turmit_int a = SCUR(turmit);
	SPUSH(turmit, a);
}

TURMIT_OP(lshift)
{
	turmit_int a,b;
	a = SPOP(turmit); b = SPOP(turmit);
	SPUSH(turmit, b << a);
}

TURMIT_OP(mod)
{
	turmit_int a,b;
	a = SPOP(turmit); b = SPOP(turmit);
	a = !a?0:b%a;
	SPUSH(turmit, a);
}

TURMIT_OP(mul)
{
	turmit_int a = SPOP(turmit), b = SPOP(turmit);
	SPUSH(turmit, a*b);
}

TURMIT_OP(div)
{
	turmit_int a, b;
	a = SPOP(turmit);
	b = SPOP(turmit);
	SPUSH(turmit, a==0?0:b/a);
}

TURMIT_OP(bin_or)
{
	turmit_int a = SPOP(turmit), b = SPOP(turmit);
	SPUSH(turmit, a | b);
}

TURMIT_OP(bin_xor)
{
	turmit_int a = SPOP(turmit), b = SPOP(turmit);
	SPUSH(turmit, a ^ b);
}

TURMIT_OP(pop)
{
	SPOP(turmit);
}

TURMIT_OP(swp)
{
	turmit_int a, b;
	a = SPOP(turmit);
	b = SPOP(turmit);
	SPUSH(turmit, a);
	SPUSH(turmit, b);
}

TURMIT_OP(jmp)
{
	turmit_int a;
	a = SPOP(turmit);
	TURMIT_JMP(turmit, a);
}

TURMIT_OP(jz)
{
	turmit_int a, b;
	a = SPOP(turmit);
	b = SPOP(turmit);
	if(b == 0)
	{
		TURMIT_JMP(turmit, a);
	}
}

TURMIT_OP(jcmp)
{
	turmit_int a, b, cnd, offset;
	offset = SPOP(turmit);
	cnd = SPOP(turmit);
	b = SPOP(turmit);
	a = SPOP(turmit);
	if(((cnd & 7) == 0 && a != b) || (cnd > 6) || ((cnd & 1) && a == b) ||
		((cnd & 7) > 2 && a < b) || ((cnd & 7) > 4 && a > b))
	{
		TURMIT_JMP(turmit, offset);
	}
}

turmit_t *turmit_alloc(ssize_t stack_sz, ssize_t int_max, const char *expr,
	unsigned char flags)
{
	turmit_t *res;

	res = malloc(sizeof(struct turmit_s));
	if(!res)
	{
		perror("Unable to allocate memory for turmit");
		return NULL;
	}
	return turmit_init(res, stack_sz, int_max, expr, flags);
}

turmit_t *turmit_init(turmit_t *turmit, ssize_t stack_sz, ssize_t int_max,
	const char *expr, unsigned char flags)
{
	turmit->expr = strndup(expr, TURMIT_EXPR_MAX_SZ);
	turmit->flags = flags;
	turmit->int_max = int_max;
	turmit->op_expr = NULL;
	turmit->op_expr_sz = 0;
	turmit->op_cur = 0;
	turmit->op_end = 0;
	turmit->stack_sz = stack_sz;
	turmit->stack_cur = turmit->stack_sz - 1;
	turmit->err = 0;
	turmit->err_str = NULL;
	turmit->stack = malloc(sizeof(turmit_int) * 
		((turmit->stack_sz / TURMIT_STACK_GROW)+1) * TURMIT_STACK_GROW);

	if(!turmit->stack)
	{
		perror("Unable to allocate turmit's stack's memory");
		return turmit;
	}
	bzero(turmit->stack, sizeof(turmit_int) * turmit->stack_sz);

	if(turmit->flags & TURMIT_AUTOCOMP)
	{
		turmit_compile(turmit);
	}
	return turmit;
}

turmit_t *turmit_copy(turmit_t *turmit)
{
	turmit_t *res;
	turmit_int stack_blck;

	res = malloc(sizeof(turmit_t));
	if(!res)
	{
		perror("Unable to allocate memory for copy");
		return NULL;
	}
	memcpy(res, turmit, sizeof(turmit_t));
	if(turmit->expr)
	{
		res->expr = strdup(turmit->expr);
	}
	if(turmit->stack)
	{
		stack_blck = (res->stack_sz / TURMIT_STACK_GROW) + 1;
		res->stack = malloc(
			sizeof(turmit_int) * stack_blck * TURMIT_STACK_GROW);
		memcpy(res->stack, turmit->stack,
			sizeof(turmit_int) * stack_blck * TURMIT_STACK_GROW);
	}
	if(turmit->op_expr)
	{
		res->op_expr = malloc(sizeof(turmit_op_t) * res->op_expr_sz);
		if(!res->op_expr)
		{
			perror("Unable to allocate memory for expression");
			return res;
		}
		memcpy(res->op_expr, turmit->op_expr,
			sizeof(turmit_op_t) * res->op_expr_sz);
	}
	return res;
}

void turmit_clean(turmit_t *turmit)
{
	if(turmit->stack) { free(turmit->stack); }
	if(turmit->err_str) { free(turmit->err_str); }
	if(turmit->expr) { free(turmit->expr); }
	if(turmit->op_expr) { free(turmit->op_expr); }

}

void turmit_free(turmit_t *turmit)
{
	turmit_clean(turmit);
	free(turmit);
}

turmit_int turmit_exec(turmit_t *turmit, const turmit_int args[5])
{
	turmit_op_t *op;

	turmit->op_cur = 0;
	turmit->op_end = 0;
	while(!turmit->op_end && turmit->op_cur < turmit->op_expr_sz)
	{
		op = &(turmit->op_expr[turmit->op_cur]);
		switch(op->value)
		{
		case TURMIT_SYM_OP:
			op->op.op(turmit);
			break;
		case TURMIT_SYM_VAL:
			SPUSH(turmit, op->op.val);
			break;
		case TURMIT_SYM_VAR:
			SPUSH(turmit, args[op->op.var]);
			break;
		default:
			// Null sym encountered. This sould NOT append
			fprintf(stderr, "Warning NULL sym encountered\n");
			turmit->op_cur = turmit->op_expr_sz;
			break;
		}
//_turmit_stack_dump(turmit);
		turmit->op_cur++;
	}
	return SCUR(turmit);
}

int turmit_compile(turmit_t *turmit)
{
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wmissing-braces"
	turmit_sym_t tsym[] = TURMIT_OP_LST;
#pragma GCC diagnostic pop
	char *cur, *endptr;
	turmit_sym_t *isym;
	ssize_t opcur;
	turmit_op_t *pret;
	long int iret;
	int err;
	int i;

	turmit->op_expr_sz = 64;
	turmit->op_expr = malloc(sizeof(turmit_op_t) * turmit->op_expr_sz);
	bzero(turmit->op_expr, sizeof(turmit_op_t) * turmit->op_expr_sz);
	opcur = 0;

	cur = turmit->expr;
	while(*cur != '\0')
	{
		if(opcur >= turmit->op_expr_sz - 1)
		{	//more space needed
			turmit->op_expr_sz += 64;
			pret = realloc(turmit->op_expr,
				sizeof(turmit_op_t) * turmit->op_expr_sz);
			if(!pret)
			{
				perror("Unable to allocate memory");
				goto turmit_compile_err;
			}
			bzero(pret + opcur - 1,
				64 * sizeof(turmit_op_t));
			turmit->op_expr = pret;
		}
		//Checking for separators
		if(*cur == ' ' || *cur == '\t' || *cur == ' ')
		{
			cur++;
			continue;
		}

		//Checking for variables
		for(i=0; TURMIT_VAR_L[i] != '\0'; i++)
		{
			if(tolower(*cur) == TURMIT_VAR_L[i])
			{
				turmit->op_expr[opcur].op.var = i;
				turmit->op_expr[opcur].value = TURMIT_SYM_VAR;
				opcur++;
				cur++;
				break;
			}
		}
		if(TURMIT_VAR_L[i] != '\0') { continue; }

		//Checking for values
		//hex
		if(strncasecmp("0x", cur, 2) == 0)
		{
			cur+= 2;
			errno = 0;
			iret = strtol(cur, &endptr, 16);
			err = errno;
			if(err || endptr == cur)
			{
				fprintf(stderr, "Invalid constant %s : %s\n",
					cur-2, strerror(err));
				goto turmit_compile_err;
			}
			turmit->op_expr[opcur].op.val = iret;
			turmit->op_expr[opcur].value = TURMIT_SYM_VAL;
			opcur++;
			cur = endptr;
			continue;
		}
		//decimal
		if(*cur <= '9' && *cur >= '0')
		{
			iret = strtol(cur, &endptr, 10);
			err = errno;
			if(err || endptr == cur)
			{
				fprintf(stderr, "Invalid constant %s : %s\n",
					cur, strerror(err));
				goto turmit_compile_err;
			}
			turmit->op_expr[opcur].op.val = iret;
			turmit->op_expr[opcur].value = TURMIT_SYM_VAL;
			opcur++;
			cur = endptr;
			continue;
		}
		
		//Checking for op
		isym = tsym;
		while(isym->str != NULL)
		{
			endptr = cur;
			if(strncasecmp(isym->str, cur, strlen(isym->str)) == 0)
			{
				endptr = cur+strlen(isym->str);
			}
			else if(isym->alias && strncmp(cur, isym->alias,
					strlen(isym->alias)) == 0)
			{
				endptr = cur+strlen(isym->alias);
			}
			if(cur != endptr)
			{
				cur = endptr;
				turmit->op_expr[opcur].op.op = isym->op_fun;
				turmit->op_expr[opcur].value = TURMIT_SYM_OP;
				opcur++;
				break;
			}
			isym++;
		}
		if(isym->str != NULL)
		{
			continue;
		}
		//unrecognized symbol :'(
		turmit->err = 1;
		if(turmit->err_str) { free(turmit->err_str); }
		turmit->err_str = malloc(sizeof(char) * 256);
		if(!turmit->err_str)
		{
			perror("Unable to allocate memory for error string");
			return -1;
		}
		snprintf(turmit->err_str, 256,
			"Error compiling prog starting at : '%s'", cur);
		goto turmit_compile_err;
	}
	if(!opcur)
	{	//empty expression
		turmit->op_expr_sz = 0;
		free(turmit->op_expr);
		turmit->op_expr = NULL;
		return 0;
	}
	turmit->op_expr_sz = opcur;
	pret = realloc(turmit->op_expr,
		sizeof(turmit_op_t) * turmit->op_expr_sz);
	if(!pret)
	{
		perror("Unable to shrink op_expr");
		return 1;
	}
	else
	{
		turmit->op_expr = pret;
	}
	return 0;

	turmit_compile_err:
		free(turmit->op_expr);
		turmit->op_expr = NULL;
		turmit->op_expr_sz = 0;
		turmit->op_cur = 0;
		return 1;
}

void _turmit_stack_dump(turmit_t *turmit)
{
	int i;
	fprintf(stderr, "Stack cur = %lu\n[", turmit->stack_cur);
	for(i=0; i<turmit->stack_sz; i++)
	{
		fprintf(stderr,"%llu, ", turmit->stack[i]);
	}
	fprintf(stderr, "]\n");
}