using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using TMPro;
using System.Reflection;

public class FocusPage : MonoBehaviour
{
    [Header("页面焦点元素")]
    public List<Selectable> focusElements = new List<Selectable>();

    private int currentFocusIndex = -1;
    private Coroutine focusCoroutine;
    private bool isSwitchingFocus = false;

    private CustomTMPInputField currentCustomInputField;
    private CustomTMPDropdown currentCustomTMPDropdown;
    private bool isDropdownExpanded = false;

    public int FocusCount => focusElements.Count;
    public int CurrentFocusIndex => currentFocusIndex;
    public Selectable CurrentFocus => GetCurrentFocusElement();
    public bool HasPreviousFocus => currentFocusIndex > 0;
    public bool HasNextFocus => currentFocusIndex < FocusCount - 1;

    void OnEnable()
    {
        FocusManager.Instance?.SetCurrentPage(this);
        FindCustomComponents();
        ValidateFocusElements();
        if (FocusCount > 0) SetFocusImmediate(0);
    }

  
    private void FindCustomComponents()
    {
        focusElements.Clear();

        // 获取所有Selectable，包括隐藏的
        Selectable[] allSelectables = GetComponentsInChildren<Selectable>(true);
        foreach (var sel in allSelectables)
        {
            if (sel != null && sel.interactable)
            {
                focusElements.Add(sel);
            }
        }
    }

    void OnDisable()
    {
        if (FocusManager.Instance?.GetCurrentPage() == this) ClearFocus();
    }

    void Update()
    {
        CheckDropdownState();
    }

    #region 焦点切换
    public void FocusNext()
    {
        if (isSwitchingFocus) return;
        if (isDropdownExpanded) { DropdownSelectNext(); return; }
        if (currentFocusIndex + 1 < focusElements.Count) SetFocusDelayed(currentFocusIndex + 1);
    }

    public void FocusPrevious()
    {
        if (isSwitchingFocus) return;
        if (isDropdownExpanded) { DropdownSelectPrevious(); return; }
        if (currentFocusIndex - 1 >= 0) SetFocusDelayed(currentFocusIndex - 1);
    }

    public void FocusFirst() { if (!isSwitchingFocus && FocusCount > 0) SetFocusDelayed(0); }
    public void FocusLast() { if (!isSwitchingFocus && FocusCount > 0) SetFocusDelayed(FocusCount - 1); }

    public bool TryMoveToNext()
    {
        if (isSwitchingFocus || currentFocusIndex + 1 >= FocusCount) return false;
        SetFocusDelayed(currentFocusIndex + 1);
        return true;
    }

    public bool TryMoveToPrevious()
    {
        if (isSwitchingFocus || currentFocusIndex - 1 < 0) return false;
        SetFocusDelayed(currentFocusIndex - 1);
        return true;
    }
    #endregion

    #region 自定义组件访问
    public CustomTMPInputField GetCurrentCustomInputField() => currentCustomInputField;

    public void ActivateCurrentInputField() { currentCustomInputField?.Activate(); }
    public void DeactivateCurrentInputField() { currentCustomInputField?.Deactivate(); }
    public bool HasActiveInputField() => currentCustomInputField != null && currentCustomInputField.HasFocus();
    #endregion

    #region Dropdown
    public void DropdownSelectNext() { if (isDropdownExpanded) currentCustomTMPDropdown?.SelectNext(); }
    public void DropdownSelectPrevious() { if (isDropdownExpanded) currentCustomTMPDropdown?.SelectPrevious(); }
    public void DropdownSubmit() { if (isDropdownExpanded) currentCustomTMPDropdown?.SubmitSelection(); }
    public void DropdownToggle() { if (currentCustomTMPDropdown != null) { currentCustomTMPDropdown.ToggleDropdown(); StartCoroutine(UpdateDropdownNextFrame()); } }

    private IEnumerator UpdateDropdownNextFrame() { yield return null; CheckDropdownState(); FocusManager.Instance?.ForceUpdateButtonStates(); }

    public bool IsDropdownExpanded() => isDropdownExpanded;
    public bool IsOnDropdown() => currentCustomTMPDropdown != null;
    public string GetCurrentDropdownValue() => currentCustomTMPDropdown != null && currentCustomTMPDropdown.options.Count > 0 ? currentCustomTMPDropdown.options[currentCustomTMPDropdown.value].text : "";
    #endregion

    #region 内部焦点处理
    private void SetFocusImmediate(int index)
    {
        if (index < 0 || index >= focusElements.Count) return;
        ClearCurrentFocus();
        currentFocusIndex = index;
        Selectable target = focusElements[index];
        if (EventSystem.current != null)
        {
            EventSystem.current.SetSelectedGameObject(target.gameObject);
            HandleSpecialFocus(target, false);
        }
        FocusManager.Instance?.ForceUpdateButtonStates();
    }

    private void SetFocusDelayed(int index, float delay = 0.05f)
    {
        if (focusCoroutine != null) StopCoroutine(focusCoroutine);
        focusCoroutine = StartCoroutine(SetFocusCoroutine(index, delay));
    }

    private IEnumerator SetFocusCoroutine(int index, float delay)
    {
        if (isSwitchingFocus) yield break;
        isSwitchingFocus = true;
        yield return new WaitForSecondsRealtime(delay);
        if (index >= 0 && index < focusElements.Count)
        {
            ClearCurrentFocus();
            currentFocusIndex = index;
            Selectable target = focusElements[index];
            if (EventSystem.current != null && EventSystem.current.currentSelectedGameObject != target.gameObject)
                EventSystem.current.SetSelectedGameObject(target.gameObject);

            HandleSpecialFocus(target, true);
        }
        isSwitchingFocus = false;
        FocusManager.Instance?.ForceUpdateButtonStates();
    }

    private void ClearCurrentFocus()
    {
        currentCustomInputField?.Deactivate();
        CloseDropdown();
        currentCustomInputField = null;
        currentCustomTMPDropdown = null;
        isDropdownExpanded = false;
    }
    private void CloseDropdown()
    {
        if (currentCustomTMPDropdown != null)
        {
            currentCustomTMPDropdown.CloseDropdown(); 
            isDropdownExpanded = false;
            currentCustomTMPDropdown = null;
        }
    }
    private void HandleSpecialFocus(Selectable element, bool autoExpand)
    {
        switch (element)
        {
            case CustomTMPInputField customInputField:
                currentCustomInputField = customInputField;
                currentCustomTMPDropdown = null;
                isDropdownExpanded = false;
                customInputField.Activate();
                break;
            case CustomTMPDropdown customTMPDropdown:
                currentCustomTMPDropdown = customTMPDropdown;
                currentCustomInputField = null;
                if (autoExpand) StartCoroutine(DelayedExpandDropdown());
                break;
            default:
                currentCustomInputField = null;
                currentCustomTMPDropdown = null;
                isDropdownExpanded = false;
                break;
        }
        FocusManager.Instance?.ForceUpdateButtonStates();
    }

    private IEnumerator DelayedExpandDropdown()
    {
        yield return new WaitForSecondsRealtime(0.05f);
        currentCustomTMPDropdown?.OpenDropdown();
        isDropdownExpanded = true;
    }

    private void CheckDropdownState()
    {
        bool wasExpanded = isDropdownExpanded;
        if (currentCustomTMPDropdown != null)
        {
            var dropdownField = typeof(TMP_Dropdown).GetField("m_Dropdown", BindingFlags.NonPublic | BindingFlags.Instance);
            if (dropdownField != null)
            {
                var dropdownGO = dropdownField.GetValue(currentCustomTMPDropdown) as GameObject;
                isDropdownExpanded = dropdownGO != null && dropdownGO.activeInHierarchy;
            }
            else isDropdownExpanded = false;
        }
        else isDropdownExpanded = false;

        if (wasExpanded != isDropdownExpanded)
            FocusManager.Instance?.ForceUpdateButtonStates();
    }

    private Selectable GetCurrentFocusElement() => currentFocusIndex >= 0 && currentFocusIndex < focusElements.Count ? focusElements[currentFocusIndex] : null;

    public void ClearFocus()
    {
        focusElements.Clear();
        ClearCurrentFocus();
        currentFocusIndex = -1;
        if (EventSystem.current != null) EventSystem.current.SetSelectedGameObject(null);
        FocusManager.Instance?.ForceUpdateButtonStates();
    }

    private void ValidateFocusElements() => focusElements.RemoveAll(e => e == null || !e.interactable);
    #endregion
}