#ifndef PL_H
#define PL_H

#include <SWI-Prolog.h>

int Plx(const char *, const char *);
struct Query
{
	Query(module_t ctx, predicate_t p, term_t t0);
	~Query(void);
	int Cut();
	int Close();
	int NextSolution();
private:
	qid_t m_q;
};

#define DLVSIKEY 0
#define DLVSIVALUE 1

/* 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_integer(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(t, PL_new_atom(x)); }
inline int PlPut(term_t t, const char *x) { return PL_put_atom(t, PL_new_atom(x)); }
inline int PlPut(term_t t, int *x) { return -1; }
inline int PlPut(term_t t, long *x) { return -1; }
inline int PlPut(term_t t, long long *x) { return -1; }
inline int PlPut(term_t t, atom_t *x) { return -1; }
inline int PlPut(term_t t, char **x) { return -1; }

inline int PlGet(term_t t, int x) { return -1; }
inline int PlGet(term_t t, long x) { return -1; }
inline int PlGet(term_t t, long long x) { return -1; }
inline int PlGet(term_t t, atom_t x) { return -1; }
inline int PlGet(term_t t, char *x) { return -1; }
inline int PlGet(term_t t, const char *x) { 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); }

/* Helper templates for Plx, Pl. */
template <typename T>
int PlPutv(term_t t, T arg) { return PlPut(t, arg); }
template <typename T, typename ...R>
int PlPutv(term_t t, T arg, R... rest) { return PlPut(t, arg)? PlPutv(t+1, rest...): 0; }
template <typename T>
int PlGetv(term_t t, T arg) { return PlGet(t, arg); }
template <typename T, typename ...R>
int PlGetv(term_t t, T arg, R... rest) { return PlGet(t, arg)? PlGetv(t+1, rest...): 0; }
template <typename T>
int Countv(int i, T arg) { return i+1; }
template <typename T, typename ...R>
int Countv(int i, T arg, R... rest) { return Countv(i+1, rest...); }

/* Call Prolog predicate, propagating Prolog exceptions. */
template <typename ...T>
int Plx(const char *szMod, const char *szPred, T... args)
{
	int iArity = Countv(0, args...);
	term_t t = PL_new_term_refs(iArity);
	if (!PlPutv(t, args...)) return 0;
	Query q(NULL, PL_predicate(szPred, iArity, szMod), t);
	if (!q.NextSolution()) return 0;
	if (!PlGetv(t, args...)) return 0;
	return 1;
}

/* Call Prolog predicate, ignoring Prolog exceptions. */
inline int Pl(const char *szMod, const char *szPred)
{
	try {
		return Plx(szMod, szPred);
	} catch (term_t &t) {
		return 0;
	}
}
template <typename ...T>
int Pl(const char *szMod, const char *szPred, T... args)
{
	try {
		return Plx(szMod, szPred, args...);
	} catch (term_t &t) {
		return 0;
	}
}

#endif