#ifndef PL_H
#define PL_H

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

#include "wcharptr.h"

/* Convert Prolog term to wide characters. */
WcharPtr PlString(const term_t t, const int flags = CVT_WRITE);

/* Wrapper for opening and closing Prolog foreign frames. */
struct Frame
{
	Frame();
	~Frame();
	void Close();
	/* Close foreign frame AND invalidate associated data. */
	void Discard();
	void Rewind();
private:
	fid_t m_f;
};

/* Wrapper for marking and releasing strings on the Prolog stack. */
struct Mark
{
	Mark();
	~Mark();
private:
	buf_mark_t m_m;
};

/* Wrapper for opening, solving and cutting Prolog query. */
struct Query
{
	Query(module_t ctx, predicate_t p, term_t t0);
	~Query();
	int Cut();
	int Cut(std::nothrow_t);
	/* Cut query AND invalidate associated data. */
	int Close();
	int Close(std::nothrow_t);
	int NextSolution();
	int NextSolution(std::nothrow_t);
private:
	qid_t m_q;
};

/* Polymorphic aliases for PL_put_*, PL_get_*. */
inline int PlPut(term_t t, int x) { return PL_put_integer(t, x); }
inline int PlPut(term_t t, long x) { return PL_put_integer(t, x); }
inline int PlPut(term_t t, long long x) { return PL_put_int64(t, x); }
inline int PlPut(term_t t, atom_t x) { return PL_put_atom(t, x); }
inline int PlPut(term_t t, char* x) { return PL_put_atom_chars(t, x); }
inline int PlPut(term_t t, const char* x) { return PL_put_atom_chars(t, x); }
inline int PlPut(term_t, int*) { return -1; }
inline int PlPut(term_t, long*) { return -1; }
inline int PlPut(term_t, long long*) { return -1; }
inline int PlPut(term_t, atom_t*) { return -1; }
inline int PlPut(term_t, char**) { return -1; }
inline int PlPut(term_t, WcharPtr*) { return -1; }

inline int PlGet(term_t, int) { return -1; }
inline int PlGet(term_t, long) { return -1; }
inline int PlGet(term_t, long long) { return -1; }
inline int PlGet(term_t, atom_t) { return -1; }
inline int PlGet(term_t, char*) { return -1; }
inline int PlGet(term_t, const char*) { return -1; }
inline int PlGet(term_t t, int* x) { return PL_get_integer(t, x); }
inline int PlGet(term_t t, long* x) { return PL_get_long(t, x); }
inline int PlGet(term_t t, long long* x) { return PL_get_int64(t, x); }
inline int PlGet(term_t t, atom_t* x) { return PL_get_atom(t, x); }
inline int PlGet(term_t t, char** x) { return PL_get_atom_chars(t, x); }
inline int PlGet(term_t t, WcharPtr* x)
{
	Mark m;
	char* s;
	if (!PlGet(t, &s)) return 0;
	*x = WcharPtr::FromNarrow(s);
	return 1;
}

/* Put in or get from a term reference an arbitrary number of values,
 * returning false if any value could not be put/got. */
template <typename = void>
inline bool PlPutN(term_t) { return true; }
template <typename T, typename... U>
inline bool PlPutN(term_t t, T x, U... xs) { return PlPut(t, x) && PlPutN(t+1, xs...); }

template <typename = void>
inline bool PlGetN(term_t) { return true; }
template <typename T, typename... U>
inline bool PlGetN(term_t t, T x, U... xs) { return PlGet(t, x) && PlGetN(t+1, xs...); }

/* Call Prolog predicate. */
template <bool Except = false, typename... T>
int Pl(const char* const mod, const char* const pred, T... xs)
{
	Frame f;
	const term_t t = PL_new_term_refs(sizeof...(T));

	if (!PlPutN(t, xs...)) return 0;
	Query q(nullptr, PL_predicate(pred, sizeof...(T), mod), t);

	if constexpr (Except) {
		if (!q.NextSolution()) return 0;
	} else {
		if (!q.NextSolution(std::nothrow)) return 0;
	}

	if (!PlGetN(t, xs...)) return 0;
	return 1;
}

/* Call Prolog predicate, propagating Prolog exceptions. */
template <typename... T>
int Plx(const char* const mod, const char* const pred, T... xs)
{
	return Pl<true>(mod, pred, xs...);
}

#endif