#include <SDL2/SDL.h>
#include <iostream>
#include "lua/lua.hpp"

#define WIDTH 1280
#define HEIGHT 720
#define KEYSYM event.key.keysym.sym

SDL_Rect rect = {WIDTH/2, HEIGHT/2, 50, 50};

constexpr char* LUA_FILE = R"(
movementSpeed = 3;

function Setup()
end

function Update()
    if keys[getKeycodeByName("RIGHT")] or keys[getKeycodeByName("D")] then
        movePlayer(movementSpeed, 0)
    end
    if keys[getKeycodeByName("LEFT")] or keys[getKeycodeByName("A")] then
        movePlayer(movementSpeed * -1, 0)
    end
    if keys[getKeycodeByName("DOWN")] or keys[getKeycodeByName("S")] then
        movePlayer(0, movementSpeed)
    end
    if keys[getKeycodeByName("UP")] or keys[getKeycodeByName("W")] then
        movePlayer(0, movementSpeed * -1)
    end
end
)";

int l_move_rect(lua_State* L) {
    int dx = luaL_checkinteger(L, 1);
    int dy = luaL_checkinteger(L, 2);
    rect.x += dx;
    rect.y += dy;
    return 0;
}

int l_keycode_from_string(lua_State* L) {
    const char* keystr = luaL_checkstring(L, 1);
    
    int scancode = -2;
    
    if (strcmp(keystr, "RIGHT") == 0) scancode = SDL_SCANCODE_RIGHT;
    else if (strcmp(keystr, "LEFT") == 0) scancode = SDL_SCANCODE_LEFT;
    else if (strcmp(keystr, "UP") == 0) scancode = SDL_SCANCODE_UP;
    else if (strcmp(keystr, "DOWN") == 0) scancode = SDL_SCANCODE_DOWN;
    else if (strcmp(keystr, "D") == 0) scancode = SDL_SCANCODE_D;
    else if (strcmp(keystr, "A") == 0) scancode = SDL_SCANCODE_A;
    else if (strcmp(keystr, "S") == 0) scancode = SDL_SCANCODE_S;
    else if (strcmp(keystr, "W") == 0) scancode = SDL_SCANCODE_W;
    
    scancode += 1;

    lua_pushinteger(L, scancode);
    return 1;
}

void push_keys_to_lua(lua_State* L, bool keys[SDL_NUM_SCANCODES]) {
    lua_newtable(L);  // create a new table on the stack
    
    for (int i = 0; i < SDL_NUM_SCANCODES; i++) {
        lua_pushinteger(L, i + 1);
        lua_pushboolean(L, keys[i]);
        lua_settable(L, -3);
    }
}

void call_lua_function(lua_State* L, const char* func_name) {
    lua_getglobal(L, func_name);
    if (lua_isfunction(L, -1)) {
        if (lua_pcall(L, 0, 0, 0) != LUA_OK) {
            std::cerr << "Lua Error in " << func_name << ": " << lua_tostring(L, -1) << std::endl;
            lua_pop(L, 1);
        }
    } else {
        lua_pop(L, 1);
    }
}


int main() {
    lua_State* L = luaL_newstate();
    luaL_openlibs(L);
    lua_register(L, "movePlayer", l_move_rect);
    lua_register(L, "getKeycodeByName", l_keycode_from_string);
    luaL_dostring(L, LUA_FILE);

    SDL_Window* window = nullptr;
    SDL_Renderer* renderer = nullptr;
    SDL_Event event;

    bool keys[SDL_NUM_SCANCODES] = {false};
    bool running = true;

    push_keys_to_lua(L, keys);
    lua_setglobal(L, "keys");

    SDL_Init(SDL_INIT_EVERYTHING);
    SDL_CreateWindowAndRenderer(WIDTH, HEIGHT, 0, &window, &renderer);
    SDL_SetWindowTitle(window, "Showdown of the Sticks");

    call_lua_function(L, "Setup");

    while (running) {
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                running = false;
            }

            if (event.type == SDL_KEYDOWN) {
                keys[event.key.keysym.scancode] = true;
            }
            if (event.type == SDL_KEYUP) {
                keys[event.key.keysym.scancode] = false;
            }
        }

        push_keys_to_lua(L, keys);
        lua_setglobal(L, "keys");

        call_lua_function(L, "Update");

        SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
        SDL_RenderClear(renderer);

        SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
        SDL_RenderFillRect(renderer, &rect);

        SDL_RenderPresent(renderer);
        SDL_Delay(10);
    }

    lua_close(L);
    return 0;
}