#if INPUTSYSTEM_SUPPORT
using System.Collections.Generic;
using AlicizaX.UI.Runtime;

namespace UnityEngine.UI
{
    [DisallowMultipleComponent]
    [AddComponentMenu("UI/UX Navigation Scope")]
    public sealed class UXNavigationScope : MonoBehaviour
    {
        [SerializeField, Header("默认选中控件")] private Selectable _defaultSelectable;

        [SerializeField, Header("显式导航控件列表")] private List<Selectable> _explicitSelectables = new();

        [SerializeField, Header("记住上次选中")] private bool _rememberLastSelection = true;

        [SerializeField, Header("手柄模式必须有选中")] private bool _requireSelectionWhenGamepad = true;

        [SerializeField, Header("阻断下层导航域")] private bool _blockLowerScopes = true;

        [SerializeField, Header("自动选中首个可用控件")] private bool _autoSelectFirstAvailable = true;

        private readonly List<Selectable> _cachedSelectables = new(16);
        private readonly Dictionary<Selectable, Navigation> _baselineNavigation = new();
        private readonly List<Selectable> _removeBuffer = new(8);

        private Canvas _cachedCanvas;
        private UIHolderObjectBase _cachedHolder;
        private Selectable _lastSelected;
        private bool _cacheDirty = true;
        private bool _navigationSuppressed;

        internal ulong ActivationSerial { get; set; }
        internal bool WasAvailable { get; set; }

        public Selectable DefaultSelectable
        {
            get => _defaultSelectable;
            set => _defaultSelectable = value;
        }

        public bool RememberLastSelection => _rememberLastSelection;
        public bool RequireSelectionWhenGamepad => _requireSelectionWhenGamepad;
        public bool BlockLowerScopes => _blockLowerScopes;

        internal Canvas Canvas
        {
            get
            {
                if (_cachedCanvas == null)
                {
                    _cachedCanvas = GetComponentInParent<Canvas>(true);
                }

                return _cachedCanvas;
            }
        }

        internal UIHolderObjectBase Holder
        {
            get
            {
                if (_cachedHolder == null)
                {
                    _cachedHolder = GetComponent<UIHolderObjectBase>();
                    if (_cachedHolder == null)
                    {
                        _cachedHolder = GetComponentInParent<UIHolderObjectBase>(true);
                    }
                }

                return _cachedHolder;
            }
        }

        private void OnEnable()
        {
            _cacheDirty = true;
            UXNavigationRuntime.EnsureInstance().RegisterScope(this);
        }

        private void OnDisable()
        {
            SetNavigationSuppressed(false);
            if (UXNavigationRuntime.TryGetInstance(out var runtime))
            {
                runtime.UnregisterScope(this);
            }
        }

        private void OnDestroy()
        {
            SetNavigationSuppressed(false);
        }

        private void OnTransformChildrenChanged()
        {
            _cacheDirty = true;
        }

#if UNITY_EDITOR
        private void OnValidate()
        {
            _cacheDirty = true;
        }
#endif

        internal int GetHierarchyDepth()
        {
            int depth = 0;
            Transform current = transform;
            while (current != null)
            {
                depth++;
                current = current.parent;
            }

            return depth;
        }

        internal bool Owns(GameObject target)
        {
            if (target == null)
            {
                return false;
            }

            var nearestScope = target.GetComponentInParent<UXNavigationScope>(true);
            return nearestScope == this;
        }

        internal Selectable GetPreferredSelectable()
        {
            RefreshSelectableCache();

            if (_rememberLastSelection && IsSelectableValid(_lastSelected))
            {
                return _lastSelected;
            }

            if (IsSelectableValid(_defaultSelectable))
            {
                return _defaultSelectable;
            }

            if (!_autoSelectFirstAvailable)
            {
                return null;
            }

            for (int i = 0; i < _cachedSelectables.Count; i++)
            {
                Selectable selectable = _cachedSelectables[i];
                if (IsSelectableValid(selectable))
                {
                    return selectable;
                }
            }

            return null;
        }

        internal bool HasAvailableSelectable()
        {
            RefreshSelectableCache();

            if (IsSelectableValid(_defaultSelectable))
            {
                return true;
            }

            for (int i = 0; i < _cachedSelectables.Count; i++)
            {
                if (IsSelectableValid(_cachedSelectables[i]))
                {
                    return true;
                }
            }

            return false;
        }

        internal void RecordSelection(GameObject selectedObject)
        {
            if (!_rememberLastSelection || selectedObject == null)
            {
                return;
            }

            Selectable selectable = selectedObject.GetComponent<Selectable>();
            if (selectable == null)
            {
                selectable = selectedObject.GetComponentInParent<Selectable>();
            }

            if (IsSelectableValid(selectable))
            {
                _lastSelected = selectable;
            }
        }

        internal bool IsSelectableOwnedAndValid(GameObject selectedObject)
        {
            if (selectedObject == null || !Owns(selectedObject))
            {
                return false;
            }

            Selectable selectable = selectedObject.GetComponent<Selectable>();
            if (selectable == null)
            {
                selectable = selectedObject.GetComponentInParent<Selectable>();
            }

            return IsSelectableValid(selectable);
        }

        internal void SetNavigationSuppressed(bool suppressed)
        {
            RefreshSelectableCache();
            if (_navigationSuppressed == suppressed)
            {
                return;
            }

            _navigationSuppressed = suppressed;
            for (int i = 0; i < _cachedSelectables.Count; i++)
            {
                Selectable selectable = _cachedSelectables[i];
                if (selectable == null)
                {
                    continue;
                }

                if (!_baselineNavigation.ContainsKey(selectable))
                {
                    _baselineNavigation[selectable] = selectable.navigation;
                }

                if (suppressed)
                {
                    Navigation navigation = selectable.navigation;
                    navigation.mode = Navigation.Mode.None;
                    selectable.navigation = navigation;
                }
                else if (_baselineNavigation.TryGetValue(selectable, out Navigation navigation))
                {
                    selectable.navigation = navigation;
                }
            }
        }

        internal void RefreshSelectableCache()
        {
            if (!_cacheDirty)
            {
                return;
            }

            _cacheDirty = false;
            _cachedSelectables.Clear();

            if (_explicitSelectables != null && _explicitSelectables.Count > 0)
            {
                for (int i = 0; i < _explicitSelectables.Count; i++)
                {
                    TryAddSelectable(_explicitSelectables[i]);
                }
            }
            else
            {
                Selectable[] selectables = GetComponentsInChildren<Selectable>(true);
                for (int i = 0; i < selectables.Length; i++)
                {
                    TryAddSelectable(selectables[i]);
                }
            }

            _removeBuffer.Clear();
            foreach (var pair in _baselineNavigation)
            {
                if (!_cachedSelectables.Contains(pair.Key))
                {
                    _removeBuffer.Add(pair.Key);
                }
            }

            for (int i = 0; i < _removeBuffer.Count; i++)
            {
                _baselineNavigation.Remove(_removeBuffer[i]);
            }
        }

        internal void InvalidateSelectableCache()
        {
            _cacheDirty = true;
        }

        private void TryAddSelectable(Selectable selectable)
        {
            if (selectable == null || !Owns(selectable.gameObject))
            {
                return;
            }

            _cachedSelectables.Add(selectable);
            if (!_baselineNavigation.ContainsKey(selectable) || !_navigationSuppressed)
            {
                _baselineNavigation[selectable] = selectable.navigation;
            }
        }

        private bool IsSelectableValid(Selectable selectable)
        {
            return selectable != null
                   && selectable.IsActive()
                   && selectable.IsInteractable()
                   && Owns(selectable.gameObject);
        }
    }
}
#endif