#ifndef LUASTACK_HPP
#define LUASTACK_HPP

extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
#include "luajit.h"
}

#include <string>

// LuaArgCheck
//
// This is a template that, when given a lua_CFunction that doesn't
// verify the number of arguments on the stack, returns a new lua_CFunction
// that *does* verify the number of arguments on the stack.
//
// In general, your lua_CFunctions should not verify the number of
// arguments on the stack.  Instead, they should assume that the stack
// contains arbitrary stuff underneath the arguments.  That makes your
// lua_CFunctions callable from both C and Lua.  But it is desirable to
// check arguments (only when calling from lua), so it is useful to use
// LuaArgCheck when turning a lua_CFunction into a lua closure.
//
template<int N, lua_CFunction FN>
int LuaArgCheck(lua_State *L) {
    if (lua_gettop(L) != N) {
        lua_pushfstring(L, "expected %d arguments, got %d", N, lua_gettop(L));
        lua_error(L);
    }
    FN(L);
}

// LuaSlot
//
// An LuaSlot contains a lua stack index.  It is initialized by the
// LuaStack and contains the same index until the LuaStack
// is destroyed.  You can convert an LuaSlot into a lua stack index
// by simply coercing it to 'int'.
//
// There are three variants of LuaSlot that you can use: LuaArg (function
// argument), LuaRet (function return value), and LuaVar (function local
// variable).
//
class LuaSlot {
protected:
    int index_;
private:
    inline operator int() const {
        return index_;
    }
public:
    LuaSlot(int n) {
        index_ = n;
    }

    LuaSlot() {
        index_ = 0;
    }

    int index() const {
        return index_;
    }
    
    friend class LuaStack;
};

class LuaArg : public LuaSlot {};
class LuaRet : public LuaSlot {};
class LuaVar : public LuaSlot {};

extern LuaSlot LuaRegistry;
extern LuaSlot LuaGlobals;

class LuaUpvalue : public LuaSlot {
    public:
        LuaUpvalue(int n) {
            index_ = lua_upvalueindex(n);
        }
};

class LuaStack {
private:
    int narg_;
    int ngap_;
    int nvar_;
    int nret_;

    int argpos_;
    int gappos_;
    int varpos_;
    int retpos_;

    int rettop_;
    int finaltop_;
    
    lua_State *L_;

    template<int NARG, int NVAR, int NRET, class... SS>
    void count_slots(LuaArg &v, SS & ... stackslots)
    {
        count_slots<NARG+1, NRET, NVAR>(stackslots...);
    }

    template<int NARG, int NVAR, int NRET, class... SS>
    void count_slots(LuaVar &v, SS & ... stackslots)
    {
        count_slots<NARG, NVAR+1, NRET>(stackslots...);
    }
    template<int NARG, int NVAR, int NRET, class... SS>
    void count_slots(LuaRet &v, SS & ... stackslots)
    {
        count_slots<NARG, NVAR, NRET+1>(stackslots...);
    }

    template<int NARG, int NVAR, int NRET>
    void count_slots() {
        count_slots_finalize(NARG, NVAR, NRET);
    }

    void count_slots_finalize(int narg, int nvar, int nret);

    template<class... SS>
    void assign_slots(int argp, int varp, int retp, LuaArg &v, SS & ... stackslots) {
        v.index_ = argp;
        assign_slots(argp + 1, varp, retp, stackslots...);
    }

    template<class... SS>
    void assign_slots(int argp, int varp, int retp, LuaVar &v, SS & ... stackslots) {
        v.index_ = varp;
        assign_slots(argp, varp+1, retp, stackslots...);
    }
    
    template<class... SS>
    void assign_slots(int argp, int varp, int retp, LuaRet &v, SS & ... stackslots) {
        v.index_ = retp;
        assign_slots(argp, varp, retp+1, stackslots...);
    }

    void assign_slots(int argp, int varp, int retp) {}

    void clear_frame();
    
public:
    template<class... SS>
    LuaStack(lua_State *L, SS & ... stackslots) {
        L_ = L;
        count_slots<0, 0, 0>(stackslots...);
        assign_slots(argpos_, varpos_, retpos_, stackslots...);
        clear_frame();
    }

    ~LuaStack() {};

    int result();
    
public:
    static void reg(lua_State *L, const char *classname, const char *funcname, lua_CFunction fn);

    void setnil(LuaSlot target) const;
    void setboolean(LuaSlot target, bool b) const;
    void setboolean(LuaSlot target, int b) const;
    void setstring(LuaSlot target, const char *str) const;
    void setstring(LuaSlot target, const std::string &str) const;
    void setnumber(LuaSlot target, double value) const;

    bool isboolean(LuaSlot s) { return lua_isboolean(L_, s); }
    bool iscfunction(LuaSlot s) { return lua_iscfunction(L_, s); }
    bool isfunction(LuaSlot s) { return lua_isfunction(L_, s); }
    bool islightuserdata(LuaSlot s) { return lua_islightuserdata(L_, s); }
    bool isnil(LuaSlot s) { return lua_isnil(L_, s); }
    bool isnumber(LuaSlot s) { return lua_isnumber(L_, s); }
    bool isstring(LuaSlot s) { return lua_isstring(L_, s); }
    bool istable(LuaSlot s) { return lua_istable(L_, s); }
    bool isthread(LuaSlot s) { return lua_isthread(L_, s); }
    bool isuserdata(LuaSlot s) { return lua_isuserdata(L_, s); }

    bool toboolean(LuaSlot s) { return lua_toboolean(L_, s); }
    int tointeger(LuaSlot s) { return lua_tointeger(L_, s); }
    double tonumber(LuaSlot s) { return lua_tonumber(L_, s); }
    std::string tostring(LuaSlot s);
    lua_State *tothread(LuaSlot s) { return lua_tothread(L_, s); }

    int checkint(LuaSlot s) { return luaL_checkint(L_, s); }
    long checklong(LuaSlot s) { return luaL_checklong(L_, s); }
    double checknumber(LuaSlot s) { return luaL_checknumber(L_, s); }
    std::string checkstring(LuaSlot s);
    void checktype(LuaSlot s, int t) { return luaL_checktype(L_, s, t); }

    void clearmetatable(LuaSlot tab) {
        lua_pushnil(L_);
        lua_setmetatable(L_, tab);
    }

    void setmetatable(LuaSlot tab, LuaSlot mt) {
        lua_pushvalue(L_, mt);
        lua_setmetatable(L_, tab);
    }

    void rawget(LuaSlot target, LuaSlot tab, LuaSlot key) const {
        lua_pushvalue(L_, key);
        lua_rawget(L_, tab);
        lua_replace(L_, target);
    }

    void rawset(LuaSlot tab, LuaSlot key, LuaSlot value) const {
        lua_pushvalue(L_, key);
        lua_pushvalue(L_, value);
        lua_rawset(L_, tab);
    }


    int next(LuaSlot tab, LuaSlot key, LuaSlot value) const {
        lua_pushvalue(L_, key);
        int ret = lua_next(L_, tab);
        if (ret != 0) {
            lua_replace(L_, value);
            lua_replace(L_, key);
        }
        return ret;
    }
    

    void setfield(LuaSlot tab, const char *field, LuaSlot value) const {
        lua_pushvalue(L_, value);
        lua_setfield(L_, tab, field);
    }

    void setfield(LuaSlot tab, const char *field, const char *value) const {
        lua_pushstring(L_, value);
        lua_setfield(L_, tab, field);
    }

    void setfield(LuaSlot tab, const char *field, const std::string &value) const {
        lua_pushlstring(L_, value.c_str(), value.size());
        lua_setfield(L_, tab, field);
    }
        
    void getfield(LuaSlot target, LuaSlot tab, const char *field) const {
        lua_getfield(L_, tab, field);
        lua_replace(L_, target);
    }

    void newtable(LuaSlot target) const {
        lua_newtable(L_);
        lua_replace(L_, target);
    }

    void checknometa(LuaSlot index) const {
        if (lua_istable(L_, index)) {
            if (!lua_getmetatable(L_, index)) {
                return;
            }
        }
        luaL_error(L_, "expected simple table with no metatable");
    }
};


#endif // LUASTACK_HPP