#include "game_root.hpp"
#include "game_mode.hpp"
#include "godot_macros.h"
#include "level.hpp"
#include "player.hpp"
#include "player_input.hpp"
#include "spawn_point.hpp"
#include <cstdint>
#include <godot_cpp/classes/global_constants.hpp>
#include <godot_cpp/classes/input.hpp>
#include <godot_cpp/classes/packed_scene.hpp>
#include <godot_cpp/classes/scene_state.hpp>
#include <godot_cpp/core/class_db.hpp>
#include <godot_cpp/templates/pair.hpp>
#include <godot_cpp/variant/string_name.hpp>
#include <godot_cpp/variant/utility_functions.hpp>

namespace godot {
void GameRoot3D::_bind_methods() {
#define CLASSNAME GameRoot3D
    GDFUNCTION(reset_game_mode);
    GDPROPERTY_HINTED(first_boot_level, Variant::OBJECT, PROPERTY_HINT_RESOURCE_TYPE, "PackedScene");
    GDSIGNAL("player_connected", PropertyInfo(Variant::OBJECT, "player_input", PROPERTY_HINT_NODE_TYPE, "PlayerInput"));
    GDSIGNAL("player_disconnected", PropertyInfo(Variant::OBJECT, "player_input", PROPERTY_HINT_NODE_TYPE, "PlayerInput"));
    GDSIGNAL("player_spawned",  PropertyInfo(Variant::OBJECT, "player_info", PROPERTY_HINT_NODE_TYPE, "Node"));
}

GameRoot3D *GameRoot3D::get_singleton() {
    return GameRoot3D::singleton_instance;
}

bool GameRoot3D::has_singleton() {
    return GameRoot3D::singleton_instance != nullptr;
}

void GameRoot3D::_enter_tree() { GDGAMEONLY();
    // TODO: Replace this with detecting input devices
    if(this->players.is_empty()) {
        this->player_input_connected();
    }
    this->grab_singleton();
}

void GameRoot3D::_ready() { GDGAMEONLY();
    this->load_level(this->first_boot_level);
}

void GameRoot3D::_exit_tree() { GDGAMEONLY();
    this->release_singleton();
}

void GameRoot3D::player_input_connected() {
    PlayerInput *input = memnew(PlayerInput);
    this->add_child(input);
    this->players.insert(this->next_player_id++, {input, nullptr});
    this->emit_signal(StringName("player_connected"), input);
}

void GameRoot3D::remove_player(uint32_t player_id) {
    if(!this->players.has(player_id))
        return;
    // convert player object to node
    Node *node = this->players.get(player_id).second->to_node();
    if(node == nullptr) {
        UtilityFunctions::push_error("IPlayer::to_node failed for player with id '", player_id, "'");
        return;
    }
    node->queue_free();
    this->players.get(player_id).second = nullptr;
}

void GameRoot3D::remove_all_players() {
    // free all player instances in use
    for(KeyValue<uint32_t, Pair<PlayerInput*, IPlayer*>> &pair : this->players) {
        // skip unused player slots
        if(pair.value.second == nullptr)
            continue;
        else
            this->remove_player(pair.key);
    }
}

bool GameRoot3D::initialize_player(IPlayer *player, uint32_t id) {
    if(!this->players.has(id))
        return false;
    // register the player
    Pair<PlayerInput*, IPlayer*> &found{this->players.get(id)};
    found.second = player;
    // set player id
    player->player_id = id;
    this->emit_signal("player_spawned", player->to_node());
    this->add_child(player->to_node());
    player->setup_player_input(found.first);
    return true;
}

void GameRoot3D::reset_game_mode() {
    this->set_game_mode(Ref<GameMode>());
}

Level3D *GameRoot3D::load_level(Ref<PackedScene> level) {
    return this->load_level_at(level, Transform3D());
}

Level3D *GameRoot3D::load_level_at(Ref<PackedScene> level, Transform3D at) {
    if(!GameRoot3D::is_valid_level(level)) {
        return nullptr;
    }
    Level3D *instance = Object::cast_to<Level3D>(level->instantiate());
    if(instance == nullptr) {
        UtilityFunctions::push_error("Unexpected failure to instantiate level scene '", level->get_path(), "'.");
        return nullptr;
    }
    this->levels.insert(level->get_path(), instance);
    // store and add to tree at desired transform
    // if this is the first level containing a game mode currently active use it's gamemode as a prototype
    bool const switch_game_mode{this->game_mode.is_null()};
    if(switch_game_mode) {
        this->set_game_mode(instance->get_game_mode_prototype());
    }
    this->add_child(instance);
    instance->set_global_transform(at);
    if(switch_game_mode) {
        for(KeyValue<uint32_t, Pair<PlayerInput *, IPlayer *>> const &kvp : this->players) {
            this->place_player_at_spawnpoint(kvp.value.second);
        }
    }
    return instance;
}

void GameRoot3D::register_spawn_point(SpawnPoint3D *spawn_point) {
    if(this->spawn_points.has(spawn_point)) {
        UtilityFunctions::push_error("Duplicate attempt to register spawnpoint '", spawn_point->get_path(), "'");
        return;
    }
    this->spawn_points.insert(spawn_point);
}

void GameRoot3D::unregister_spawn_point(SpawnPoint3D *spawn_point) {
    if(!this->spawn_points.has(spawn_point)) {
        UtilityFunctions::push_error("Attempt to unregister spawnpoint '", spawn_point->get_path(), "', which is not registered.");
        return;
    }
    this->spawn_points.erase(spawn_point);
}

void GameRoot3D::place_player_at_spawnpoint(IPlayer *player) {
    if(this->spawn_points.is_empty()) return;
    SpawnPoint3D *spawn_point = *this->spawn_points.begin();
    player->spawn_at_position(spawn_point->get_global_transform());
}

void GameRoot3D::set_game_mode(Ref<GameMode> prototype) {
    this->remove_all_players();
    // allow "unsetting" the gamemode by passing an invalid gamemode
    // shorthand for this behaviour is reset_game_mode
    if(prototype.is_null() || !prototype.is_valid()) {
        if(!this->game_mode.is_null() && this->game_mode.is_valid())
            this->game_mode->_end();
        this->game_mode.unref();
        return;
    }
    // shallow clone the game mode prototype ..
    this->game_mode = prototype->duplicate(false);
    // .. except for the game state, which should be cloned as well
    this->game_mode->set_game_state(prototype->get_game_state()->duplicate(false));
    this->game_mode->_begin();
    uint32_t new_player_id = this->find_empty_player_slot();
    do {
        IPlayer *player = this->spawn_player(new_player_id);
        if(player != nullptr)
            this->initialize_player(player, new_player_id);
        new_player_id = this->find_empty_player_slot();
    } while(new_player_id != 0);
}

Ref<GameMode> GameRoot3D::get_game_mode() const {
    return this->game_mode;
}

Ref<GameState> GameRoot3D::get_game_state() const {
    return this->game_mode->get_game_state();
}

void GameRoot3D::set_first_boot_level(Ref<PackedScene> level) {
    if(level.is_null() || !level.is_valid()) {
        this->first_boot_level.unref();
        return;
    }
    StringName const root_type = level->get_state()->get_node_type(0);
    if(!ClassDB::is_parent_class(root_type, "Level3D")) {
        UtilityFunctions::push_error("First boot level cannot be of type '", root_type, "'. First boot level has to inherit from Level3D");
        this->first_boot_level.unref();
        return;
    }
    this->first_boot_level = level;
}

Ref<PackedScene> GameRoot3D::get_first_boot_level() const {
    return this->first_boot_level;
}

void GameRoot3D::grab_singleton() {
    if(GameRoot3D::has_singleton()) {
        this->set_process_mode(PROCESS_MODE_DISABLED);
        UtilityFunctions::push_error("More than one GameRoot instance active");
    } else {
        GameRoot3D::singleton_instance = this;
    }
}

void GameRoot3D::release_singleton() {
    if(GameRoot3D::singleton_instance == this) {
        GameRoot3D::singleton_instance = nullptr;
    } else {
        UtilityFunctions::push_error("GameRoot instance attempted to release singleton while it is not the singleton instance");
    }
}

uint32_t GameRoot3D::find_empty_player_slot() const {
    for(KeyValue<uint32_t, Pair<PlayerInput*, IPlayer*>> const &kvp : this->players) {
        if(kvp.value.second == nullptr) {
            return kvp.key;
        }
    }
    return 0;
}

IPlayer *GameRoot3D::spawn_player(uint32_t id) {
    if(id == 0) {
        UtilityFunctions::push_error("Failed to find any valid player slot when spawning player");
        return nullptr;
    }
    Node *player_node = this->game_mode->get_player_scene()->instantiate();
    if(player_node == nullptr) {
        UtilityFunctions::push_error("Failed to instantiate player scene '", this->game_mode->get_player_scene()->get_path(), "'");
        return nullptr;
    }
    IPlayer *player = dynamic_cast<IPlayer*>(player_node);
    if(player == nullptr) {
        UtilityFunctions::push_error("Player scene does not implement required IPlayer interface");
        player_node->queue_free();
        return nullptr;
    }
    return player;
}

bool GameRoot3D::is_valid_level(Ref<PackedScene> &level) {
    if(level.is_null() || !level.is_valid() || !level->can_instantiate()) {
        UtilityFunctions::push_error("Can't load level from invalid packed scene");
        return false;
    }
    StringName const root_type = level->get_state()->get_node_type(0);
    if(!ClassDB::is_parent_class(root_type, "Level3D")) {
        UtilityFunctions::push_error("Can't load level with root type '", root_type, "'. Root node has to be of type Level3D");
        return false;
    }
    return true;
}

GameRoot3D *GameRoot3D::singleton_instance{nullptr};
}