using UnityEngine;

public class WebViewPanelFollower : MonoBehaviour
{
    public RectTransform panelRect; // 拖拽要跟随的 UI Panel 的 RectTransform
    public Camera uiCamera; // UI 相机，通常是 Canvas 的 Event Camera

    private Rect lastPanelRect;
    private WebViewWin32.RECT lastUnityWindowRect;
    private bool hasLastRect = false;

    // track subscription
    private bool subscribedToWebViewReady = false;

    void OnEnable()
    {
        TrySubscribeWebViewReady();
    }

    void OnDisable()
    {
        if (subscribedToWebViewReady && WebViewLauncher.Instance != null)
        {
            WebViewLauncher.Instance.WebViewReady -= OnWebViewReady;
            subscribedToWebViewReady = false;
        }
    }

    void TrySubscribeWebViewReady()
    {
        if (!subscribedToWebViewReady && WebViewLauncher.Instance != null)
        {
            WebViewLauncher.Instance.WebViewReady += OnWebViewReady;
            subscribedToWebViewReady = true;
        }
    }

    void Update()
    {
        // Ensure subscription in case WebViewLauncher wasn't ready earlier
        TrySubscribeWebViewReady();

        if (panelRect == null || uiCamera == null || WebViewLauncher.Instance == null)
            return;

        // 获取当前 panel 的屏幕矩形
        Rect currentPanelRect = GetPanelScreenRect(panelRect);

        // 获取当前 Unity 窗口位置（仅在 build 中需要）
        WebViewWin32.RECT currentUnityWindowRect = new WebViewWin32.RECT();
#if !UNITY_EDITOR
        if (!WebViewWin32.TryGetClientScreenRect(System.Diagnostics.Process.GetCurrentProcess(), out currentUnityWindowRect))
            return;
#endif

        // 检查是否需要更新
        if (!hasLastRect ||
            !ApproximatelyEqual(currentPanelRect, lastPanelRect)
#if !UNITY_EDITOR
            || !WindowRectsEqual(currentUnityWindowRect, lastUnityWindowRect)
#endif
            )
        {
            int x, y;
#if UNITY_EDITOR
            // 在编辑器中，直接使用屏幕坐标（相对于屏幕左上角）
            x = Mathf.RoundToInt(currentPanelRect.x);
            y = Mathf.RoundToInt(Screen.height - currentPanelRect.y - currentPanelRect.height);
#else
            // 在 build 中，使用 Unity 窗口位置 + 相对坐标
            x = Mathf.RoundToInt(currentUnityWindowRect.Left + currentPanelRect.x);
            y = Mathf.RoundToInt(currentUnityWindowRect.Top + (Screen.height - currentPanelRect.y - currentPanelRect.height));
#endif
            int w = Mathf.RoundToInt(currentPanelRect.width);
            int h = Mathf.RoundToInt(currentPanelRect.height);

            // 更新 WebView 窗口
            bool success = WebViewLauncher.Instance.TryUpdateWebViewRect(x, y, w, h);
            if (success)
            {
                lastPanelRect = currentPanelRect;
#if !UNITY_EDITOR
                lastUnityWindowRect = currentUnityWindowRect;
#endif
                hasLastRect = true;
            }
        }
    }

    void OnWebViewReady()
    {
        // Force next update to recalc and send position, and also perform immediate update
        hasLastRect = false;
        UpdatePositionNow();
    }

    // perform immediate position update (same logic as in Update)
    void UpdatePositionNow()
    {
        if (panelRect == null || uiCamera == null || WebViewLauncher.Instance == null)
            return;

        Rect currentPanelRect = GetPanelScreenRect(panelRect);

        WebViewWin32.RECT currentUnityWindowRect = new WebViewWin32.RECT();
#if !UNITY_EDITOR
        if (!WebViewWin32.TryGetClientScreenRect(System.Diagnostics.Process.GetCurrentProcess(), out currentUnityWindowRect))
            return;
#endif

        int x, y;
#if UNITY_EDITOR
        x = Mathf.RoundToInt(currentPanelRect.x);
        y = Mathf.RoundToInt(Screen.height - currentPanelRect.y - currentPanelRect.height);
#else
        x = Mathf.RoundToInt(currentUnityWindowRect.Left + currentPanelRect.x);
        y = Mathf.RoundToInt(currentUnityWindowRect.Top + (Screen.height - currentPanelRect.y - currentPanelRect.height));
#endif
        int w = Mathf.RoundToInt(currentPanelRect.width);
        int h = Mathf.RoundToInt(currentPanelRect.height);

        bool success = WebViewLauncher.Instance.TryUpdateWebViewRect(x, y, w, h);
        if (success)
        {
            lastPanelRect = currentPanelRect;
#if !UNITY_EDITOR
            lastUnityWindowRect = currentUnityWindowRect;
#endif
            hasLastRect = true;
        }
    }

    Rect GetPanelScreenRect(RectTransform rect)
    {
        Vector3[] corners = new Vector3[4];
        rect.GetWorldCorners(corners);

        Vector2 min = RectTransformUtility.WorldToScreenPoint(uiCamera, corners[0]);
        Vector2 max = RectTransformUtility.WorldToScreenPoint(uiCamera, corners[2]);

        return new Rect(min.x, min.y, max.x - min.x, max.y - min.y);
    }

    bool ApproximatelyEqual(Rect a, Rect b)
    {
        return Mathf.Approximately(a.x, b.x) &&
               Mathf.Approximately(a.y, b.y) &&
               Mathf.Approximately(a.width, b.width) &&
               Mathf.Approximately(a.height, b.height);
    }

    bool WindowRectsEqual(WebViewWin32.RECT a, WebViewWin32.RECT b)
    {
        return a.Left == b.Left && a.Top == b.Top && a.Right == b.Right && a.Bottom == b.Bottom;
    }
}