#ifndef UTILS_GAME_ROOT_HPP
#define UTILS_GAME_ROOT_HPP

#include "game_mode.hpp"
#include "game_state.hpp"
#include "level.hpp"
#include <godot_cpp/classes/node.hpp>
#include <godot_cpp/classes/packed_scene.hpp>
#include <godot_cpp/classes/random_number_generator.hpp>
#include <godot_cpp/templates/hash_map.hpp>
#include <godot_cpp/templates/hash_set.hpp>
#include <godot_cpp/templates/pair.hpp>
#include <godot_cpp/templates/vector.hpp>

namespace gd = godot;

namespace utils {
class PlayerInput;
class IPlayer;
class SpawnPoint3D;

/*! The root of a game.
 *
 * A game root node that manages levels and input devices.
 * Can be loaded at any point in a game's life, but suggested is setting this as the root of the boot scene.
 */
class GameRoot3D : public gd::Node {
    GDCLASS(GameRoot3D, gd::Node);
    static void _bind_methods();
public:
    //! get the current active singleton instance of GameRoot
    static GameRoot3D *get_singleton();
    //! returns true if there is currently a singleton active for GameRoot
    static bool has_singleton();

    virtual void _enter_tree() override;
    virtual void _ready() override;
    virtual void _exit_tree() override;

    /*! Instantiate a new PlayerInput.
     *
     * Does not automatically spawn a new player, but does notify game mode.
     */
    void player_input_connected();
    /*! Force-disconnect a player
     *
     * Calls queue_free on the IPlayer instance
     */
    void remove_player(uint32_t player_id);
    // calls remove_player for every used player input slot
    void remove_all_players();
    /*! Initialize and register a player instance.
     *
     * The player will be added to the tree and AFTER setup_player_input will be called.
     * This way the player can initialize before setting up input
     */
    bool initialize_player(IPlayer *player, uint32_t id);

    /*! Un-set game mode.
     * Shorthand for `set_game_mode(Ref<PackedScene>())`
     */
    void reset_game_mode();

    //! shorthand for load_level(level, Transform3D())
    Level3D *load_level(gd::Ref<gd::PackedScene> level);
    /*! Load a level, only works if 'level' is a valid scene where the root Node can cast to 'Level3D'.
     *
     * \param at Sets the root node's global transform.
     */
    Level3D *load_level_at(gd::Ref<gd::PackedScene> level, gd::Transform3D at);
    //! Unload all currently loaded levels.
    void unload_all_levels();
    /*! Replace all currently loaded levels with a new level.
     *
     * Shorthand for
     * ```
     * unload_all_levels();
     * load_level(level);
     * ```
     */
    void replace_levels(gd::Ref<gd::PackedScene> level);
    //! Register a spawnpoint for use when spawning players
    void register_spawn_point(SpawnPoint3D *spawn_point);
    // remove a spawnpoint so it can't be used to spawn players
    void unregister_spawn_point(SpawnPoint3D *spawn_point);
    void place_player_at_spawnpoint(IPlayer *player);
    void player_despawned(uint32_t id);

    /*! Override the current gamemode.
     *
     * Replaces game mode requires destroying and respawning all players
     */
    void set_game_mode(gd::Ref<gd::PackedScene> prototype);
    //! get the current active game mode.
    GameMode *get_game_mode() const;
    //! Get the current active game state.
    GameState *get_game_state() const;
    /*! Returns all currently active levels.
     *
     * Levels are identified by their packed scene path.
     */
    gd::HashMap<gd::StringName, Level3D *> &get_levels();
    //! Get the player instance associated with id.
    IPlayer *get_player(uint32_t id);
    //! Get all players in a list.
    gd::Vector<IPlayer*> get_players();
    void set_first_boot_level(gd::Ref<gd::PackedScene> level);
    gd::Ref<gd::PackedScene> get_first_boot_level() const;
    void set_game_state_prototype(gd::Ref<GameState> game_state);
    gd::Ref<GameState> get_game_state_prototype() const;
    gd::RandomNumberGenerator &get_rng();
protected:
    //! Attempt to make 'this' the current singleton instance.
    void grab_singleton();
    /*! Attempt to stop being the active singleton instance.
     *
     * Only works if the current singleton is 'this'.
     */
    void release_singleton();
    //! Find a Player Input device not yet associated with a player.
    uint32_t find_empty_player_slot() const;
    //! Spawn a player to be associated with id.
    IPlayer *spawn_player(uint32_t id);
    //! Callback for a level exiting the tree.
    void level_unloaded(gd::StringName scene_path);
    //! Check if a scene is a valid level.
    static bool is_valid_level(gd::Ref<gd::PackedScene> &level);
private:
    static GameRoot3D *singleton_instance;
    /*! Next available player ID.
     *
     * Default is 1 because 0 is the "invalid" player id.
     */
    uint32_t next_player_id{1};
    /*! All players by id by input device.
     *
     * `get_players()`
     */
    gd::HashMap<uint32_t, gd::Pair<PlayerInput*, IPlayer*>> players{};
    /*! Global random number generator.
     *
     * `&get_rng()`
     */
    gd::Ref<gd::RandomNumberGenerator> rng{};
    /*! All currently active levels.
     *
     * Each identified by their resource paths.
     *
     * `&get_levels()`
     */
    gd::HashMap<gd::StringName, Level3D*> levels{};
    /*! All currently available spawn points.
     */
    gd::Vector<SpawnPoint3D*> spawn_points{};
    /*! Current active gamemode.
     *
     * Replaced when a level is loaded that references a different game mode.
     *
     * `*get_game_mode()`
     */
    GameMode *game_mode{};
    /*! Active game state.
     *
     * Will be assigned loaded save data, or game_state_prototype if no save data is found.
     *
     * `*get_game_mode()`
     */
    gd::Ref<GameState> game_state{};
    /*! The level to boot into on startup.
     *
     * `get_first_boot_level()` `set_first_boot_level(value)`
     */
    gd::Ref<gd::PackedScene> first_boot_level{};
    /*! The default game state data.
     *
     * Duplicated and assigned to game_state if no save data is available.
     *
     * `get_game_state_prototype()` `set_game_state_prototype(value)`
     */
    gd::Ref<GameState> game_state_prototype{};
};
}

#endif // !UTILS_GAME_ROOT_HPP