"""Game module - core game loop, screen management, and shared asset loading."""
import pygame_gui
import pygame

from game.util import load_image, load_images, load_images_alpha, Animation
from game.tilemap import Tilemap
from game.screens.main_menu import MainMenu
from game.screens.game_play import GamePlay

#constants
FPS=60
WINDOW_SIZE=(960,540)

class Game:
    """Central game class managing the loop, screens, and shared resources.

    Attributes:
        window (pygame.Surface): The main display surface.
        clock (pygame.time.Clock): Controls the frame rate.
        ui_manager (pygame_gui.UIManager): Manages all pygame_gui UI elements.
        tilemap (Tilemap): The active tilemap instance.
        assets (dict): Shared images and animations, keyed by name.
        screens (dict): All available screens, keyed by name.
        current_screen: The screen currently being updated and drawn.
    """
    def __init__(self):

        pygame.init()

        self.window = pygame.display.set_mode(WINDOW_SIZE)
        self.clock = pygame.time.Clock()
        self.ui_manager = pygame_gui.UIManager(
            WINDOW_SIZE,
            "assets/theme/theme.json"
        )
        self.tilemap = Tilemap(self)

        self.assets={
            "base": load_images('/tiles/test'),
            "jungle": load_images('/tiles/jungle'),
            "desert": load_images('/tiles/desert'),
            "enemy": load_image('/entities/enemies/enemy.png'),
            "cannon": load_image('/entities/towers/cannon/shoot/0.png'),
            "red_cannon": load_image('/entities/towers/cannon/red_cannon.png'),
            "cannon/shoot": Animation(load_images_alpha('/entities/towers/cannon/shoot'), 10, False)
        }

        self.screens = {
            "menu": MainMenu(self),
            "game": GamePlay(self)
        }
        self.current_screen = self.screens["menu"]

    def change_screen(self, name):
        """Transition to a different screen by name.
        Hides the current screen and shows the requested one.

        Args:
            name (str): Key of the screen to switch to (e.g. ``"menu"``, ``"game"``).
        """

        self.current_screen.hide()
        self.current_screen = self.screens[name]
        self.current_screen.show()

    def run(self):
        """Start the main game loop and block until the window is closed.

        Each iteration: processes events, updates state, and draws the frame.
        """

        running = True
        while running:
            dt = self.clock.tick(FPS) / 1000.0

            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    running = False

                self.ui_manager.process_events(event)
                self.current_screen.process_event(event)

            self.current_screen.update(dt)
            self.ui_manager.update(dt)
            self.window.fill((20, 20, 20))
            self.current_screen.draw(self.window)
            self.ui_manager.draw_ui(self.window)

            pygame.display.update()
        pygame.quit()