#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <math.h>

#include "util.h"

#define SPECIALFORMSNUM 2
int isSpecialForm(char *symbol)
{
	int result = 0;
	char *specialForms[] =
	{
		"навод",
		"дефиниши"
	};

	for (int i = 0; i < SPECIALFORMSNUM; ++i)
	{
		if (!strcmp(symbol, specialForms[i]))
		{
			result = 1;
		}
	}

	return result;
}

int properList(object list)
{
	object *current = &list;
	while (TYPE(*current) == consObject)
	{
		current = &CDR(*current);
	}
	return TYPE(*current) == nilObject;
}

int listLength(object list)
{
	object *current = &list;
	int i = 0;
	while (TYPE(*current) != nilObject)
	{
		current = &CDR(*current);
		++i;
	}
	return i;
}

void deleteObject(object input)
{
	if ((TYPE(input) == symbolObject) && SYM(input) != NULL)
	{
		free(SYM(input));
		SYM(input) = NULL;
	}
	else if (TYPE(input) == consObject)
	{
		deleteObject(CAR(input));
		deleteObject(CDR(input));
		free(CONS(input));
		CONS(input) = NULL;
	}

	TYPE(input) = nilObject;
}

object copyObject(object input)
{
	object result;
	TYPE(result) = TYPE(input);
	if (TYPE(input) == errorObject)
	{
		ERR(result) = ERR(input);
	}
	else if (TYPE(input) == numberObject)
	{
		NUM(result) = NUM(input);
	}
	else if (TYPE(input) == symbolObject)
	{
		SYM(result) =
			malloc(sizeof(char) * (strlen(SYM(input)) + 1));
		strcpy(SYM(result), SYM(input));
	}
	else if (TYPE(input) == consObject)
	{
		CONS(result) = malloc(sizeof(cons));
		CAR(result) = copyObject(CAR(input));
		CDR(result) = copyObject(CDR(input));
	}

	return result;
}

object longlongToNumber(long long int input)
{
	object result;
	TYPE(result) = numberObject;
	NUM_TYPE(result) = fractionNum;
	NUM_NUMER(result) = input;
	NUM_DENOM(result) = 1LL;

	return result;
}

object exactToInexactNum(object a)
{
	object result = copyObject(a);

	if (TYPE(result) == numberObject && NUM_TYPE(result) == fractionNum)
	{
		NUM_TYPE(result) = realNum;
		NUM_REAL(result) = (long double) NUM_NUMER(result) /
			(long double) NUM_DENOM(result);
	}

	return result;
}

object inexactToExactNum(object a)
{
	object result = copyObject(a);

	if (TYPE(result) == numberObject && NUM_TYPE(result) == realNum)
	{
		long long int divisor = 1;
		while (NUM_REAL(result) != floorl(NUM_REAL(result)) &&
				divisor <= INT_MAX)
		{
			NUM_REAL(result) *= 10.0L;
			divisor *= 10LL;
		}

		NUM_TYPE(result) = fractionNum;
		NUM_NUMER(result) = (long long int) floorl(NUM_REAL(result));
		NUM_DENOM(result) = divisor;

		result = shortenFractionNum(result);
	}

	return result;
}

long long int gcd(long long int a, long long int b)
/* највећи заједнички делилац */
{
	if (b == 0LL)
	{
		return a;
	}
	else
	{
		return gcd(b, a - b * (a / b));
	}
}
long long int lcm(long long int a, long long int b)
/* најмањи заједнички садржалац */
{
	if (a == 0LL && b == 0LL)
	{
		return 0L;
	}
	else
	{
		return llabs(a * b) / gcd(a, b);
	}
}

object shortenFractionNum(object a)
/* скраћује разломак, враћа грешку ако је неправилан разломак, уколико улаз
 * заиста јесте дат као разломак */
{
	object result = copyObject(a);

	if (TYPE(result) == numberObject && NUM_TYPE(result) == fractionNum)
	{
		if (NUM_DENOM(result) == 0)
		{
			deleteObject(result);
			TYPE(result) = errorObject;
			ERR(result) = divisionByZeroError;
		}
		else if (NUM_NUMER(result) == 0)
		{
			NUM_DENOM(result) = 1;
		}
		else
		{
			long long int divisor =
				gcd(NUM_NUMER(result), NUM_DENOM(result));
			NUM_NUMER(result) /= divisor;
			NUM_DENOM(result) /= divisor;
		}
	}

	return result;
}

object plusNum(object a, object b)
{
	object result;
	TYPE(result) = numberObject;

	if (NUM_TYPE(a) == fractionNum && NUM_TYPE(b) == fractionNum)
	{
		NUM_TYPE(result) = fractionNum;
		NUM_NUMER(result) = NUM_NUMER(a) * NUM_DENOM(b) + NUM_NUMER(b) * NUM_DENOM(a);
		NUM_DENOM(result) = NUM_DENOM(a) * NUM_DENOM(b);
/*
 * TODO: имплементирати оптималнији начин множења разломака
		long long int denominator = lcm(NUM_DENOM(a), NUM_DENOM(b));
		NUM_NUMER(result) =
			NUM_NUMER(a) * (denominator / NUM_DENOM(a)) +
			NUM_NUMER(b) * (denominator / NUM_DENOM(b));
*/
		result =  shortenFractionNum(result);
	}
	else
	{
		NUM_TYPE(result) = realNum;
		NUM_REAL(result) = NUM_REAL(exactToInexactNum(a))
			+ NUM_REAL(exactToInexactNum(b));
	}

	return result;
}

object minusNum(object a)
{
	object result;
	result = copyObject(a);

	if (NUM_TYPE(result) == fractionNum)
	{
		NUM_NUMER(result) = -NUM_NUMER(result);
	}
	else if (NUM_TYPE(result) == realNum)
	{
		NUM_REAL(result) = -NUM_REAL(result);
	}

	return result;
}

object timesNum(object a, object b)
{
	object result;
	TYPE(result) = numberObject;

	if (NUM_TYPE(a) == fractionNum && NUM_TYPE(b) == fractionNum)
	{
		NUM_TYPE(result) = fractionNum;
		NUM_NUMER(result) = NUM_NUMER(a) * NUM_NUMER(b);
		NUM_DENOM(result) = NUM_DENOM(a) * NUM_DENOM(b);
		result = shortenFractionNum(result);
	}
	else
	{
		NUM_TYPE(result) = realNum;
		NUM_REAL(result) = NUM_REAL(exactToInexactNum(a)) *
			NUM_REAL(exactToInexactNum(b));
	}

	return result;
}

object inverseNum(object a)
{
	object result;
	result = copyObject(a);

	if (NUM_TYPE(result) == fractionNum)
	{
		if (NUM_NUMER(result) == 0)
		{
			deleteObject(result);
			TYPE(result) = errorObject;
			ERR(result) = divisionByZeroError;
		}
		else
		{
			NUM_NUMER(result) = NUM_DENOM(a);
			NUM_DENOM(result) = NUM_NUMER(a);
		}
	}
	else if (NUM_TYPE(result) == realNum)
	{
		NUM_REAL(result) = 1.0L/NUM_REAL(result);
	}

	return result;
}