/*
** $Id: ltablib.c,v 1.65.1.1 2013/04/12 18:48:47 roberto Exp $
** Library for Table Manipulation
** See Copyright Notice in lua.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, 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 = e - i + 1;                       /* number of elements */
	if (n <= 0 || !lua_checkstack(L, n)) /* n <= 0 means arith. overflow */
		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;
}
