using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

// Editor/PC-only helper — auto-injects at runtime, no need to place in scene.
// On Quest builds this entire class is stripped.
//
// Features:
//   1. Replaces TrackedDeviceGraphicRaycaster → GraphicRaycaster (enables mouse clicks)
//   2. Keeps worldCamera up to date on all World Space canvases
//   3. ESC key navigates back
public class DesktopUIMode : MonoBehaviour
{
#if !UNITY_ANDROID || UNITY_EDITOR

    [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.AfterSceneLoad)]
    private static void AutoCreate()
    {
        if (FindObjectOfType<DesktopUIMode>() != null) return;
        new GameObject("[DesktopUIMode]").AddComponent<DesktopUIMode>();
    }

    private static readonly System.Collections.Generic.Dictionary<string, string> BackMap =
        new()
        {
            { "SongSelect",     "Menu"        },
            { "SongCreator",    "Menu"        },
            { "MapEditorScene", "SongCreator" },
            { "Game",           "SongSelect"  },
        };

    private void Awake()
    {
        if (FindObjectsByType<DesktopUIMode>(FindObjectsSortMode.None).Length > 1)
        { Destroy(gameObject); return; }

        DontDestroyOnLoad(gameObject);
        SceneManager.sceneLoaded += OnSceneLoaded;
        PatchCanvases();
    }

    private void OnDestroy() => SceneManager.sceneLoaded -= OnSceneLoaded;

    private void OnSceneLoaded(Scene s, LoadSceneMode m) => StartCoroutine(PatchAfterFrame());

    private System.Collections.IEnumerator PatchAfterFrame()
    { yield return null; PatchCanvases(); }

    private void Update()
    {
        RefreshCanvasCameras();
        if (Keyboard.current?.escapeKey.wasPressedThisFrame == true) GoBack();
    }

    private static void PatchCanvases()
    {
        foreach (var canvas in FindObjectsByType<Canvas>(FindObjectsSortMode.None))
        {
            if (canvas.renderMode != RenderMode.WorldSpace) continue;

            var tracked = canvas.GetComponent("TrackedDeviceGraphicRaycaster");
            if (tracked != null)
            {
                DestroyImmediate(tracked);
                if (canvas.GetComponent<GraphicRaycaster>() == null)
                    canvas.gameObject.AddComponent<GraphicRaycaster>();
            }
        }

        RemoveDuplicateAudioListeners();
        RefreshCanvasCameras();
    }

    private static void RemoveDuplicateAudioListeners()
    {
        var listeners = FindObjectsByType<AudioListener>(FindObjectsSortMode.None);
        if (listeners.Length <= 1) return;

        AudioListener keep = null;
        foreach (var al in listeners)
            if (al.gameObject.scene.name != "DontDestroyOnLoad") { keep = al; break; }
        keep ??= listeners[0];

        foreach (var al in listeners)
            if (al != keep) DestroyImmediate(al);
    }

    private static void RefreshCanvasCameras()
    {
        Camera cam = Camera.main;
        if (cam == null)
            foreach (var c in FindObjectsByType<Camera>(FindObjectsSortMode.None))
                if (c.enabled && c.gameObject.scene.name != "DontDestroyOnLoad") { cam = c; break; }
        cam ??= FindObjectOfType<Camera>();
        if (cam == null) return;

        foreach (var canvas in FindObjectsByType<Canvas>(FindObjectsSortMode.None))
            if (canvas.renderMode == RenderMode.WorldSpace && canvas.worldCamera != cam)
                canvas.worldCamera = cam;
    }

    private static void GoBack()
    {
        if (BackMap.TryGetValue(SceneManager.GetActiveScene().name, out string target))
            SceneManager.LoadScene(target);
    }

#endif
}