/*
** $Id: ltablib.c,v 1.65 2013/03/07 18:17:24 roberto Exp $
** Library for Table Manipulation
** See Copyright Notice in lua.h
*/

#include <limits.h>
#include <stddef.h>

#define ltablib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"


#define aux_getn(L,n) (luaL_checktype(L, n, LUA_TTABLE), luaL_len(L, n))



#if defined(LUA_COMPAT_MAXN)
static int maxn(lua_State *L) {
    lua_Number max = 0;
    luaL_checktype(L, 1, LUA_TTABLE);
    lua_pushnil(L);  /* first key */
    while (lua_next(L, 1)) {
        lua_pop(L, 1);  /* remove value */
        if (lua_type(L, -1) == LUA_TNUMBER) {
            lua_Number v = lua_tonumber(L, -1);
            if (v > max) max = v;
        }
    }
    lua_pushnumber(L, max);
    return 1;
}
#endif


static int tinsert(lua_State *L) {
    int e = aux_getn(L, 1) + 1;  /* first empty element */
    int pos;  /* where to insert new element */
    switch (lua_gettop(L)) {
        case 2: {  /* called with only 2 arguments */
            pos = e;  /* insert new element at the end */
            break;
        }
        case 3: {
            int i;
            pos = luaL_checkint(L, 2);  /* 2nd argument is the position */
            luaL_argcheck(L, 1 <= pos && pos <= e, 2, "position out of bounds");
            for (i = e; i > pos; i--) {  /* move up elements */
                lua_rawgeti(L, 1, i - 1);
                lua_rawseti(L, 1, i);  /* t[i] = t[i-1] */
            }
            break;
        }
        default: {
            return luaL_error(L, "wrong number of arguments to " LUA_QL("insert"));
        }
    }
    lua_rawseti(L, 1, pos);  /* t[pos] = v */
    return 0;
}


static int tremove(lua_State *L) {
    int size = aux_getn(L, 1);
    int pos = luaL_optint(L, 2, size);
    if (pos != size)  /* validate 'pos' if given */
        luaL_argcheck(L, 1 <= pos && pos <= size + 1, 1, "position out of bounds");
    lua_rawgeti(L, 1, pos);  /* result = t[pos] */
    for (; pos < size; pos++) {
        lua_rawgeti(L, 1, pos + 1);
        lua_rawseti(L, 1, pos);  /* t[pos] = t[pos+1] */
    }
    lua_pushnil(L);
    lua_rawseti(L, 1, pos);  /* t[pos] = nil */
    return 1;
}


static void addfield(lua_State *L, luaL_Buffer *b, int i) {
    lua_rawgeti(L, 1, i);
    if (!lua_isstring(L, -1))
        luaL_error(L, "invalid value (%s) at index %d in table for "
                   LUA_QL("concat"), luaL_typename(L, -1), i);
    luaL_addvalue(b);
}


static int tconcat(lua_State *L) {
    luaL_Buffer b;
    size_t lsep;
    int i, last;
    const char *sep = luaL_optlstring(L, 2, "", &lsep);
    luaL_checktype(L, 1, LUA_TTABLE);
    i = luaL_optint(L, 3, 1);
    last = luaL_opt(L, luaL_checkint, 4, luaL_len(L, 1));
    luaL_buffinit(L, &b);
    for (; i < last; i++) {
        addfield(L, &b, i);
        luaL_addlstring(&b, sep, lsep);
    }
    if (i == last)  /* add last value (if interval was not empty) */
        addfield(L, &b, i);
    luaL_pushresult(&b);
    return 1;
}


/*
** {======================================================
** Pack/unpack
** =======================================================
*/

static int pack(lua_State *L) {
    int n = lua_gettop(L);  /* number of elements to pack */
    lua_createtable(L, n, 1);  /* create result table */
    lua_pushinteger(L, n);
    lua_setfield(L, -2, "n");  /* t.n = number of elements */
    if (n > 0) {  /* at least one element? */
        int i;
        lua_pushvalue(L, 1);
        lua_rawseti(L, -2, 1);  /* insert first element */
        lua_replace(L, 1);  /* move table into index 1 */
        for (i = n; i >= 2; i--)  /* assign other elements */
            lua_rawseti(L, 1, i);
    }
    return 1;  /* return table */
}


static int unpack(lua_State *L) {
    int i, e;
    unsigned int n;
    luaL_checktype(L, 1, LUA_TTABLE);
    i = luaL_optint(L, 2, 1);
    e = luaL_opt(L, luaL_checkint, 3, luaL_len(L, 1));
    if (i > e) return 0;  /* empty range */

    n = (unsigned int)e - (unsigned int)i;  /* number of elements minus 1 */

    if (n > (INT_MAX - 10) || !lua_checkstack(L, ++n))
        return luaL_error(L, "too many results to unpack");

    lua_rawgeti(L, 1, i);  /* push arg[i] (avoiding overflow problems) */
    while (i++ < e)  /* push arg[i + 1...e] */
        lua_rawgeti(L, 1, i);
    return n;
}

/* }====================================================== */



/*
** {======================================================
** Quicksort
** (based on `Algorithms in MODULA-3', Robert Sedgewick;
**  Addison-Wesley, 1993.)
** =======================================================
*/


static void set2(lua_State *L, int i, int j) {
    lua_rawseti(L, 1, i);
    lua_rawseti(L, 1, j);
}

static int sort_comp(lua_State *L, int a, int b) {
    if (!lua_isnil(L, 2)) {  /* function? */
        int res;
        lua_pushvalue(L, 2);
        lua_pushvalue(L, a - 1); /* -1 to compensate function */
        lua_pushvalue(L, b - 2); /* -2 to compensate function and `a' */
        lua_call(L, 2, 1);
        res = lua_toboolean(L, -1);
        lua_pop(L, 1);
        return res;
    } else /* a < b? */
        return lua_compare(L, a, b, LUA_OPLT);
}

static void auxsort(lua_State *L, int l, int u) {
    while (l < u) {  /* for tail recursion */
        int i, j;
        /* sort elements a[l], a[(l+u)/2] and a[u] */
        lua_rawgeti(L, 1, l);
        lua_rawgeti(L, 1, u);
        if (sort_comp(L, -1, -2))  /* a[u] < a[l]? */
            set2(L, l, u);  /* swap a[l] - a[u] */
        else
            lua_pop(L, 2);
        if (u - l == 1) break; /* only 2 elements */
        i = (l + u) / 2;
        lua_rawgeti(L, 1, i);
        lua_rawgeti(L, 1, l);
        if (sort_comp(L, -2, -1))  /* a[i]<a[l]? */
            set2(L, i, l);
        else {
            lua_pop(L, 1);  /* remove a[l] */
            lua_rawgeti(L, 1, u);
            if (sort_comp(L, -1, -2))  /* a[u]<a[i]? */
                set2(L, i, u);
            else
                lua_pop(L, 2);
        }
        if (u - l == 2) break; /* only 3 elements */
        lua_rawgeti(L, 1, i);  /* Pivot */
        lua_pushvalue(L, -1);
        lua_rawgeti(L, 1, u - 1);
        set2(L, i, u - 1);
        /* a[l] <= P == a[u-1] <= a[u], only need to sort from l+1 to u-2 */
        i = l;
        j = u - 1;
        for (;;) {  /* invariant: a[l..i] <= P <= a[j..u] */
            /* repeat ++i until a[i] >= P */
            while (lua_rawgeti(L, 1, ++i), sort_comp(L, -1, -2)) {
                if (i >= u) luaL_error(L, "invalid order function for sorting");
                lua_pop(L, 1);  /* remove a[i] */
            }
            /* repeat --j until a[j] <= P */
            while (lua_rawgeti(L, 1, --j), sort_comp(L, -3, -1)) {
                if (j <= l) luaL_error(L, "invalid order function for sorting");
                lua_pop(L, 1);  /* remove a[j] */
            }
            if (j < i) {
                lua_pop(L, 3);  /* pop pivot, a[i], a[j] */
                break;
            }
            set2(L, i, j);
        }
        lua_rawgeti(L, 1, u - 1);
        lua_rawgeti(L, 1, i);
        set2(L, u - 1, i); /* swap pivot (a[u-1]) with a[i] */
        /* a[l..i-1] <= a[i] == P <= a[i+1..u] */
        /* adjust so that smaller half is in [j..i] and larger one in [l..u] */
        if (i - l < u - i) {
            j = l;
            i = i - 1;
            l = i + 2;
        } else {
            j = i + 1;
            i = u;
            u = j - 2;
        }
        auxsort(L, j, i);  /* call recursively the smaller one */
    }  /* repeat the routine for the larger one */
}

static int sort(lua_State *L) {
    int n = aux_getn(L, 1);
    luaL_checkstack(L, 40, "");  /* assume array is smaller than 2^40 */
    if (!lua_isnoneornil(L, 2))  /* is there a 2nd argument? */
        luaL_checktype(L, 2, LUA_TFUNCTION);
    lua_settop(L, 2);  /* make sure there is two arguments */
    auxsort(L, 1, n);
    return 0;
}

/* }====================================================== */


static const luaL_Reg tab_funcs[] = {
    {"concat", tconcat},
#if defined(LUA_COMPAT_MAXN)
    {"maxn", maxn},
#endif
    {"insert", tinsert},
    {"pack", pack},
    {"unpack", unpack},
    {"remove", tremove},
    {"sort", sort},
    {NULL, NULL}
};


LUAMOD_API int luaopen_table(lua_State *L) {
    luaL_newlib(L, tab_funcs);
#if defined(LUA_COMPAT_UNPACK)
    /* _G.unpack = table.unpack */
    lua_getfield(L, -1, "unpack");
    lua_setglobal(L, "unpack");
#endif
    return 1;
}

