using UnityEngine;
using UnityEngine.UI;

/// <summary>
/// Creates the small per-canvas language switcher used to verify UI localization.
/// The bar is intentionally built from Unity UI primitives so it has no sprite dependency.
/// </summary>
public sealed class LocalizationLanguageTestBar : MonoBehaviour
{
    private const string BarName = "__LocalizationLanguageTestBar";
    private static readonly string[] Labels = { "中文", "EN", "FR", "RU" };
    private static readonly Color[] Colors =
    {
        new Color(0.12f, 0.48f, 0.24f, 0.96f),
        new Color(0.10f, 0.36f, 0.72f, 0.96f),
        new Color(0.48f, 0.20f, 0.64f, 0.96f),
        new Color(0.66f, 0.20f, 0.16f, 0.96f)
    };

    private static Sprite backgroundSprite;
    private static LocalizationLanguageTestBar instance;

    public static void EnsureForActiveCanvases()
    {
        // If we already have a bar, just bring it to front and return.
        if (instance != null)
        {
            instance.transform.SetAsLastSibling();
            return;
        }

        // Find the first valid root ScreenSpace canvas and create one bar there.
        Canvas[] canvases = Resources.FindObjectsOfTypeAll<Canvas>();
        for (int i = 0; i < canvases.Length; i++)
        {
            Canvas canvas = canvases[i];
            if (canvas == null || !canvas.isActiveAndEnabled || !canvas.gameObject.scene.IsValid()) continue;
            // Only place the bar on Screen Space - Overlay canvases.
            if (canvas.renderMode != RenderMode.ScreenSpaceOverlay) continue;
            // Skip sub-canvases (e.g. Dropdown List) to avoid placing debug bars on overlays.
            if (canvas.transform.parent != null && canvas.transform.parent.GetComponentInParent<Canvas>() != null) continue;
            EnsureForCanvas(canvas);
            break;
        }
    }

    private static void EnsureForCanvas(Canvas canvas)
    {
        Transform canvasTransform = canvas.transform;
        
















































































































        for (int i = 0; i < canvasTransform.childCount; i++)
        {
            LocalizationLanguageTestBar existing = canvasTransform.GetChild(i).GetComponent<LocalizationLanguageTestBar>();
            if (existing != null)
            {
                instance = existing;
                existing.transform.SetAsLastSibling();
                return;
            }
        }

        GameObject barObject = new GameObject(BarName, typeof(RectTransform), typeof(LocalizationLanguageTestBar));
        barObject.transform.SetParent(canvasTransform, false);
        RectTransform bar = barObject.GetComponent<RectTransform>();
        bar.anchorMin = new Vector2(0f, 1f);
        bar.anchorMax = new Vector2(0f, 1f);
        bar.pivot = new Vector2(0f, 1f);
        bar.sizeDelta = new Vector2(276f, 30f);
        bar.anchoredPosition = new Vector2(8f, -8f);

        for (int i = 0; i < Labels.Length; i++) CreateButton(bar, Labels[i], i);
        bar.SetAsLastSibling();
        instance = barObject.GetComponent<LocalizationLanguageTestBar>();
    }

    private void OnDestroy()
    {
        if (instance == this) instance = null;
    }

    private static void CreateButton(RectTransform parent, string label, int language)
    {
        GameObject buttonObject = new GameObject("Language_" + label, typeof(RectTransform), typeof(Image), typeof(Button));
        buttonObject.transform.SetParent(parent, false);

        RectTransform rect = buttonObject.GetComponent<RectTransform>();
        rect.anchorMin = new Vector2(0f, 0.5f);
        rect.anchorMax = new Vector2(0f, 0.5f);
        rect.pivot = new Vector2(0f, 0.5f);
        rect.sizeDelta = new Vector2(66f, 28f);
        rect.anchoredPosition = new Vector2(language * 70f, 0f);

        if (backgroundSprite == null)
        {
            Texture2D texture = new Texture2D(1, 1, TextureFormat.RGBA32, false);
            texture.SetPixel(0, 0, Color.white);
            texture.Apply();
            backgroundSprite = Sprite.Create(texture, new Rect(0, 0, 1, 1), new Vector2(0.5f, 0.5f));
        }

        Image image = buttonObject.GetComponent<Image>();
        image.sprite = backgroundSprite;
        image.color = Colors[language];
        image.raycastTarget = true;

        Button button = buttonObject.GetComponent<Button>();
        ColorBlock colors = button.colors;
        colors.normalColor = Color.white;
        colors.highlightedColor = new Color(1f, 1f, 1f, 0.86f);
        colors.pressedColor = new Color(1f, 1f, 1f, 0.66f);
        colors.selectedColor = Color.white;
        colors.disabledColor = new Color(1f, 1f, 1f, 0.4f);
        button.colors = colors;
        int languageIndex = language;
        button.onClick.AddListener(() => LocalizationManager.SetLanguage(languageIndex));

        GameObject textObject = new GameObject("Label", typeof(RectTransform), typeof(Text));
        textObject.transform.SetParent(buttonObject.transform, false);
        RectTransform textRect = textObject.GetComponent<RectTransform>();
        textRect.anchorMin = Vector2.zero;
        textRect.anchorMax = Vector2.one;
        textRect.offsetMin = Vector2.zero;
        textRect.offsetMax = Vector2.zero;

        Text text = textObject.GetComponent<Text>();
        text.text = label;
        text.font = LocalizationManager.UIFont;
        text.fontSize = 15;
        text.alignment = TextAnchor.MiddleCenter;
        text.color = Color.white;
        text.raycastTarget = false;
    }
}