using UnityEngine;
using UnityEngine.UIElements;

namespace ProjectM.Client
{
    /// <summary>
    /// In-game pause overlay (UI Toolkit), spawned by <see cref="PauseMenuSystem"/> in the client world. Esc
    /// toggles it; Resume / Settings / Quit-to-Menu / Quit-to-Desktop. Quit-to-Menu hands off to
    /// <see cref="WorldLauncher.TeardownToMenu"/> (autosave + dispose worlds + load MainMenu). Builds its own
    /// UIDocument in code (shared PanelSettings from Resources) above the HUD; the scene swap on Quit-to-Menu
    /// destroys it.
    /// </summary>
    public class PauseMenuController : MonoBehaviour
    {
        UIDocument _doc;
        VisualElement _root;
        VisualElement _pausePanel;
        VisualElement _settingsPanel;
        bool _open;
        /// <summary>True while the pause overlay is shown (BuildSendSystem suspends build-clicks while paused).</summary>
        public static bool Open;

        void Awake()
        {
            MenuUi.EnsureEventSystem();
            _doc = gameObject.AddComponent<UIDocument>();
            _doc.panelSettings = MenuUi.LoadPanelSettings();
            _doc.sortingOrder = 100; // above the in-game HUD
        }

        void Start()
        {
            _root = _doc.rootVisualElement;
            Build();
            SetOpen(false);
        }

        void Update()
        {
            var kb = UnityEngine.InputSystem.Keyboard.current;
            if (kb != null && kb.escapeKey.wasPressedThisFrame)
                SetOpen(!_open);
        }

        void Build()
        {
            _pausePanel = MenuUi.FullScreenRoot(false);
            _pausePanel.style.backgroundColor = new Color(0.02f, 0.03f, 0.05f, 0.72f);
            var card = MenuUi.Card("PAUSED");
            card.Add(MenuUi.Button("Resume", () => SetOpen(false)));
            card.Add(MenuUi.Button("Settings", ShowSettings));
            card.Add(MenuUi.Button("Quit to Menu", WorldLauncher.TeardownToMenu));
            card.Add(MenuUi.Button("Quit to Desktop", Quit));
            _pausePanel.Add(card);
            _root.Add(_pausePanel);
        }

        void SetOpen(bool open)
        {
            _open = open;
            Open = open;
            if (_pausePanel != null) _pausePanel.style.display = open ? DisplayStyle.Flex : DisplayStyle.None;
            if (!open && _settingsPanel != null) { _settingsPanel.RemoveFromHierarchy(); _settingsPanel = null; }
            if (open) { UnityEngine.Cursor.lockState = CursorLockMode.None; UnityEngine.Cursor.visible = true; }
        }

        void ShowSettings()
        {
            _pausePanel.style.display = DisplayStyle.None;
            _settingsPanel = SettingsScreen.Build(() =>
            {
                if (_settingsPanel != null) { _settingsPanel.RemoveFromHierarchy(); _settingsPanel = null; }
                _pausePanel.style.display = DisplayStyle.Flex;
            });
            _root.Add(_settingsPanel);
        }

        static void Quit()
        {
#if UNITY_EDITOR
            UnityEditor.EditorApplication.isPlaying = false;
#else
            Application.Quit();
#endif
        }
    }
}