#include <windows.h>
#include <SWI-Prolog.h>

#include "pl.h"

/* Frame: Wrapper for opening and closing Prolog foreign frames. */

Frame::Frame()
{
	m_f = PL_open_foreign_frame();
}

Frame::~Frame()
{
	PL_close_foreign_frame(m_f);
}

void Frame::Close()
{
	PL_close_foreign_frame(m_f);
}

/* Close foreign frame and invalidate associated data. */
void Frame::Discard()
{
	PL_discard_foreign_frame(m_f);
}

void Frame::Rewind()
{
	PL_rewind_foreign_frame(m_f);
}

/* Mark: Wrapper for marking and releasing strings on the Prolog stack. */

Mark::Mark()
{
	PL_mark_string_buffers(&m_m);
}

Mark::~Mark()
{
	PL_release_string_buffers_from_mark(m_m);
}

/* Query: Wrapper for opening, solving and cutting Prolog query. */

Query::Query(const module_t ctx, const predicate_t p, const term_t t0)
{
	m_q = PL_open_query(ctx, PL_Q_CATCH_EXCEPTION, p, t0);
}

Query::~Query()
{
	PL_cut_query(m_q);
}

int Query::Cut()
{
	if (PL_cut_query(m_q)) return 1;
	if (const term_t t = PL_exception(m_q)) throw t;
	return 0;
}

/* Cut query and invalidate associated data. */
int Query::Close()
{
	if (PL_close_query(m_q)) return 1;
	if (const term_t t = PL_exception(m_q)) throw t;
	return 0;
}

int Query::NextSolution()
{
	if (PL_next_solution(m_q)) return 1;
	if (const term_t t = PL_exception(m_q)) throw t;
	return 0;
}

/* Convert Prolog term to normal or wide characters. */
int PL_get_tchars(const term_t t, TCHAR** const pTsz, const int iFlags)
{
#ifdef UNICODE
	size_t len;
	if (!PL_get_wchars(t, &len, pTsz, iFlags))
		return 0;
	return len;
#else
	if (!PL_get_chars(t, pTsz, iFlags))
		return 0;
	return -1;
#endif
}

/* Call nullary Prolog predicate, propagating Prolog exceptions. */
int Plx(const char* const szMod, const char* const szPred)
{
	Frame f;
	const term_t t = PL_new_term_refs(0);
	Query q(NULL, PL_predicate(szPred, 0, szMod), t);
	return q.NextSolution();
}

/* Call nullary Prolog predicate, ignoring Prolog exceptions. */
int Pl(const char* const szMod, const char* const szPred)
{
	try {
		return Plx(szMod, szPred);
	} catch (term_t& t) {
		return 0;
	}
}