#include "lua_lsup.h"

#define check_triple(L) \
    *(LSUP_Triple **)luaL_checkudata(L, 1, "LSUP.Triple")


/*
 * Factory methods.
 */

static int new (lua_State *L)
{
    LSUP_Triple **trp_p = lua_newuserdatauv (L, sizeof (*trp_p), 1);
    luaL_getmetatable (L, "LSUP.Triple");
    LSUP_Term
        *s = *(LSUP_Term **)luaL_checkudata(L, 2, "LSUP.Term"),
        *p = *(LSUP_Term **)luaL_checkudata(L, 3, "LSUP.Term"),
        *o = *(LSUP_Term **)luaL_checkudata(L, 4, "LSUP.Term");

    lua_setmetatable (L, -4);

    *trp_p = LSUP_triple_new (s, p, o);
    if (!*trp_p) luaL_error (L, "Error while creating a triple!");

    return 1;
}


/*
 * Class methods.
 */

static int gc (lua_State *L)
{
    LSUP_Triple *trp = check_triple (L);
    if (trp) LSUP_triple_free (trp);

    return 0;
}


static int get_term (lua_State *L)
{
    const LSUP_Triple *trp = check_triple (L);
    const int pos = luaL_checkinteger (L, 2);
    if (pos < TRP_POS_S || pos > TRP_POS_O)
        luaL_error(L, "Out of range position: %d.", pos);

    lua_pushlightuserdata (L, LSUP_triple_pos (trp, (LSUP_TriplePos)pos));

    return 1;
}


static int set_term (lua_State *L)
{
    LSUP_Triple *trp = check_triple (L);
    const int pos = luaL_checkinteger (L, 2);
    const LSUP_Term *t = *(LSUP_Term **)luaL_checkudata(L, 3, "LSUP.Term");

    LSUP_Term *new_t = LSUP_term_copy (t);

    if (pos == TRP_POS_S) {
        LSUP_term_free (trp->s);
        trp->s = new_t;
    } else if (pos == TRP_POS_P) {
        LSUP_term_free (trp->p);
        trp->p = new_t;
    } else if (pos == TRP_POS_O) {
        LSUP_term_free (trp->o);
        trp->o = new_t;
    } else return luaL_error(L, "Out of range position: %d.", pos);

    return 1;
}


/*
 * Library setup.
 */

static const struct luaL_Reg triple_lib_fn [] = {
    {"new", new},
    {NULL}
};


static const struct luaL_Reg triple_lib_meth [] = {
    {"__gc", gc},

    {NULL}
};


int luaopen_triple (lua_State *L)
{
    luaL_newmetatable (L, "LSUP.Triple");
    lua_pushvalue (L, -1);
    lua_setfield (L, -2, "__index");
    luaL_setfuncs (L, triple_lib_meth, 0);

    // Enums
    lua_pushvalue (L, TRP_POS_S);
    lua_setfield (L, -1, "TRP_POS_S");
    lua_pushvalue (L, TRP_POS_P);
    lua_setfield (L, -1, "TRP_POS_P");
    lua_pushvalue (L, TRP_POS_O);
    lua_setfield (L, -1, "TRP_POS_O");

    luaL_newlib (L, triple_lib_fn);

    return 1;
}