using ProjectM.Simulation;
using Unity.Entities;
using UnityEngine;
using UnityEngine.UIElements;

namespace ProjectM.Client
{
    /// <summary>
    /// Drives the front-end main menu (UI Toolkit). Lives on a GameObject (with a <c>UIDocument</c>) in
    /// MainMenu.unity — build index 0. On <see cref="Awake"/> it ENSURES a default "menu" world exists (the
    /// bootstrap creates one on first boot, but on return-from-game <c>World.DisposeAllWorlds</c> left none and
    /// <c>Initialize</c> does not re-run), ensures the EventSystem, and assigns the shared PanelSettings; on
    /// enable it builds the menu. Single/Host/Join hand off to <see cref="WorldLauncher"/>.
    /// </summary>
    [RequireComponent(typeof(UIDocument))]
    public class MainMenuController : MonoBehaviour
    {
        UIDocument _doc;
        VisualElement _mainPanel;
        VisualElement _settingsPanel;
        TextField _ipField;
        Label _classLabel;

        void Awake()
        {
            EnsureMenuWorld();
            MenuUi.EnsureEventSystem();
            _doc = GetComponent<UIDocument>();
            if (_doc.panelSettings == null)
                _doc.panelSettings = MenuUi.LoadPanelSettings();
            // The menu owns the cursor.
            UnityEngine.Cursor.lockState = CursorLockMode.None;
            UnityEngine.Cursor.visible = true;
        }

        void OnEnable()
        {
            if (_doc == null) _doc = GetComponent<UIDocument>();
            var root = _doc.rootVisualElement;
            if (root == null) return;
            root.Clear();
            BuildMain(root);
        }

        static void EnsureMenuWorld()
        {
            var w = World.DefaultGameObjectInjectionWorld;
            if (w == null || !w.IsCreated)
                DefaultWorldInitialization.Initialize("MenuWorld", false);
        }

        void BuildMain(VisualElement root)
        {
            _mainPanel = MenuUi.FullScreenRoot(true);
            var card = MenuUi.Card("PROJECT M");
            card.Add(MenuUi.Caption("Frontier colony — co-op"));
            // Slice 2: class picker -> sets WorldLauncher.SelectedClass for the next session (Warrior melee / Ranger ranged).
            _classLabel = new Label(ClassName(WorldLauncher.SelectedClass));
            _classLabel.style.unityTextAlign = TextAnchor.MiddleCenter;
            _classLabel.style.marginTop = 6; _classLabel.style.marginBottom = 2;
            card.Add(_classLabel);
            var classRow = new VisualElement();
            classRow.style.flexDirection = FlexDirection.Row;
            classRow.style.justifyContent = Justify.Center;
            classRow.Add(MenuUi.Button("Warrior", () => SelectClass((byte)CharacterId.Warrior)));
            classRow.Add(MenuUi.Button("Ranger", () => SelectClass((byte)CharacterId.Ranger)));
            card.Add(classRow);

            card.Add(MenuUi.Button("Single Player", () => Launch(SessionMode.Single, false)));

            if (SaveService.HasSave())
                card.Add(MenuUi.Button("Continue", () => Launch(SessionMode.Single, true)));

            card.Add(MenuUi.Button("Host Co-op (LAN)", () => Launch(SessionMode.Host, SaveService.HasSave())));

            _ipField = new TextField("Join IP") { value = "127.0.0.1" };
            _ipField.style.marginTop = 8;
            card.Add(_ipField);
            card.Add(MenuUi.Button("Join", () => Launch(SessionMode.Join, false)));

            card.Add(MenuUi.Button("Settings", ShowSettings));
            card.Add(MenuUi.Button("Quit", Quit));

            _mainPanel.Add(card);
            root.Add(_mainPanel);
        }

        void Launch(SessionMode mode, bool loadSave)
        {
            string ip = _ipField != null ? _ipField.value : "127.0.0.1";
            WorldLauncher.StartSession(mode, ip, loadSave);
        }

        void SelectClass(byte classId)
        {
            WorldLauncher.SelectedClass = classId;
            if (_classLabel != null) _classLabel.text = ClassName(classId);
        }

        static string ClassName(byte classId) => classId == (byte)CharacterId.Ranger ? "CLASS:  Ranger (ranged)" : "CLASS:  Warrior (melee)";

        void ShowSettings()
        {
            _mainPanel.style.display = DisplayStyle.None;
            _settingsPanel = SettingsScreen.Build(HideSettings);
            _doc.rootVisualElement.Add(_settingsPanel);
        }

        void HideSettings()
        {
            if (_settingsPanel != null) { _settingsPanel.RemoveFromHierarchy(); _settingsPanel = null; }
            _mainPanel.style.display = DisplayStyle.Flex;
        }

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