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

namespace Superlazy.UI
{
    [RequireComponent(typeof(Button))]
    public class SLUIDragButton : SLUIComponent, IPointerEnterHandler, IPointerExitHandler, IPointerDownHandler, IPointerUpHandler, ISelectHandler, IDeselectHandler, IBeginDragHandler, IDragHandler, IEndDragHandler
    {
        public static bool globalDragging;
        public static GameObject currentDragObject;
        public static string currentDragCancelCommand;
        private static PointerEventData currentPoint;

        public string command;
        public bool useGrayScale;
        public bool focus;
        public string focusBind;
        public bool fastClick;
        public SLValueComparison comparison;

        public string clickSound = "SoundEffect/SE_UI_click";

        public string cancelCommand;

        [NonSerialized]
        public Button button;

        private Graphic[] childImages;
        private Color[] childImageColors; // TODO: SLUIColorSelect 대비해야함
        private TextMeshProUGUI[] childTexts;
        private Color[] childTextColors;
        private DateTime clickedTime = DateTime.MinValue;

        // drag

        private bool dragging = false;

        private enum ButtonState
        {
            Normal,
            Highlighted,
            Pressed,
            Disabled
        }

        private ButtonState currentButtonState;

        private bool isPointerInside;
        private bool isPointerDown;

        protected override void Validate()
        {
            button = GetComponent<Button>();

            childImages = GetComponentsInChildren<Image>(true).Where(i => i.transform != transform).ToArray();
            childImageColors = new Color[childImages.Length];
            var i = 0;
            foreach (var image in childImages)
            {
                childImageColors[i] = image.color;
                i += 1;
            }
            childTexts = GetComponentsInChildren<TextMeshProUGUI>(true).Where(i => i.transform != transform).ToArray();
            childTextColors = new Color[childTexts.Length];
            i = 0;
            foreach (var text in childTexts)
            {
                childTextColors[i] = text.color;
                i += 1;
            }
        }

        protected override void Init()
        {
            button.onClick.AddListener(ButtonAction);
        }

        public void ButtonAction()
        {
            if (bindParent.Active == false) return;

            if (globalDragging)
            {
                EndDrag();
                return;
            }

            if (fastClick == false)
            {
                var now = SLSystem.Now;
                if (SLUIButton.globalClickedTime.AddSeconds(0.1f) > now) return;
                if (clickedTime.AddSeconds(0.15f) > now) return;

                SLUIButton.globalClickedTime = now;
                clickedTime = now;
            }
            SLSound.PlaySound(clickSound, "UI", false, false, true, 0.5f);
            if (string.IsNullOrEmpty(command)) return;
            SLGame.Command(command, SLGame.SessionGet(bindParent.BindPath));

            currentDragCancelCommand = cancelCommand;
            currentDragObject = gameObject;
            globalDragging = true;

            {
                var canvas = GetComponentInParent<Canvas>();
                Camera uiCamera;
                if (canvas.renderMode == RenderMode.ScreenSpaceCamera || canvas.renderMode == RenderMode.WorldSpace)
                {
                    uiCamera = canvas.worldCamera; // Camera가 필요함
                }
                else
                {
                    uiCamera = null; // ScreenSpace-Overlay는 Camera가 필요 없음
                }
                var scrrenPosition = RectTransformUtility.WorldToScreenPoint(uiCamera, transform.position);
                SLGame.Session["DragBeginPosition"]["X"] = scrrenPosition.x;
                SLGame.Session["DragBeginPosition"]["Y"] = scrrenPosition.y;
            }
        }

        protected override void Enable()
        {
            if (comparison.useCheckValue)
            {
                comparison.OnEnable(bindParent.BindPath, OnChange);
            }
            else
            {
                if (focus && button.interactable)
                {
                    button.Select();
                }
            }

            if (string.IsNullOrEmpty(focusBind) == false)
            {
                SLGame.AddNotify(bindParent.BindPath.CombinePath(focusBind), OnFocusChange);
            }
        }

        protected override void Disable()
        {
            if (comparison.useCheckValue)
            {
                comparison.OnDisable();
            }

            if (dragging) // CCC
            {
                EndDrag(); // Dragged == false 체크 이미 되어있음
            }

            if (string.IsNullOrEmpty(focusBind) == false)
            {
                SLGame.RemoveNotify(bindParent.BindPath.CombinePath(focusBind), OnFocusChange);
            }
        }

        private void OnChange()
        {
            if (bindParent.Active == false) return;
            var sessionRoot = SLGame.SessionGet(bindParent.BindPath);
            if (sessionRoot == false) return; // TEMP: 세션루트가 삭제되었지만, 삭제되되기전 코루틴 처리가 있을 수 있음

            var result = true;
            if (comparison.useCheckValue)
            {
                result = comparison.Result;
            }

            button.interactable = result;

            if (result == false)
            {
                if (dragging)
                {
                    EndDrag(); // Dragged == false 체크 이미 되어있음
                    dragging = false;
                }
            }

            if (focus && button.interactable)
            {
                button.Select();
            }

            if (string.IsNullOrEmpty(focusBind) == false)
            {
                OnFocusChange();
            }

            UpdateGrayScale();
        }

        private void UpdateGrayScale()
        {
            if (useGrayScale == false) return;
            if (button.targetGraphic == null) return;

            if (button.interactable && (button.targetGraphic.material == SLUIButton.grayMaterial || button.targetGraphic.material == SLUIButton.grayTextMaterial))
            {
                button.targetGraphic.material = null;

                foreach (var child in childImages)
                {
                    child.material = null;
                }
                foreach (var child in childTexts)
                {
                    child.material = null;
                }
            }
            else if (button.interactable == false && button.targetGraphic.material != SLUIButton.grayMaterial && button.targetGraphic.mainTexture != SLUIButton.grayTextMaterial)
            {
                button.targetGraphic.material = SLUIButton.grayMaterial;

                foreach (var child in childImages)
                {
                    child.material = SLUIButton.grayMaterial;
                }
                foreach (var child in childTexts)
                {
                    child.material = SLUIButton.grayTextMaterial;
                }
            }
        }

        public void OnPointerEnter(PointerEventData eventData)
        {
            currentPoint = eventData;

            if (bindParent.Active == false) return;
            if (button.interactable == false) return;

            button.Select();
            isPointerInside = true;
        }

        public void OnPointerExit(PointerEventData eventData)
        {
            currentPoint = eventData;
            isPointerInside = false;
        }

        public void OnPointerDown(PointerEventData eventData)
        {
            currentPoint = eventData;
            isPointerDown = true;
        }

        public void OnPointerUp(PointerEventData eventData)
        {
            currentPoint = eventData;
            isPointerDown = false;
        }

        private void OnFocusChange()
        {
            if (bindParent.Active == false) return;
            if (button.interactable == false) return;

            bool focusResult = SLGame.SessionGet(bindParent.BindPath.CombinePath(focusBind));

            if (focusResult)
            {
                button.Select();
            }
            else
            {
                if (EventSystem.current.currentSelectedGameObject == button.gameObject)
                {
                    EventSystem.current.SetSelectedGameObject(null);
                }
            }
        }

        public void OnSelect(BaseEventData eventData)
        {
            if (bindParent.Active == false) return;
            if (button.interactable == false) return;
            if (string.IsNullOrEmpty(focusBind)) return;

            SLGame.SessionGet(bindParent.BindPath).Set(focusBind, true);
        }

        public void OnDeselect(BaseEventData eventData)
        {
            if (bindParent.Active == false) return;
            if (button.interactable == false) return;
            if (string.IsNullOrEmpty(focusBind)) return;

            SLGame.SessionGet(bindParent.BindPath).Set(focusBind, false);
        }

        private void Update()
        {
            if (button.transition != Selectable.Transition.ColorTint) return;

            var newState = GetButtonState();

            if (newState != currentButtonState)
            {
                currentButtonState = newState;

                var color = button.colors.normalColor;
                switch (currentButtonState)
                {
                    case ButtonState.Normal:
                        color = button.colors.normalColor;
                        break;

                    case ButtonState.Highlighted:
                        color = button.colors.highlightedColor;
                        break;

                    case ButtonState.Pressed:
                        color = button.colors.pressedColor;
                        break;

                    case ButtonState.Disabled:
                        color = button.colors.disabledColor;
                        break;
                }

                var i = 0;
                foreach (var image in childImages)
                {
                    image.color = childImageColors[i] * color * button.colors.colorMultiplier;
                    i += 1;
                }

                i = 0;
                foreach (var text in childTexts)
                {
                    text.color = childTextColors[i] * color * button.colors.colorMultiplier;
                    i += 1;
                }
            }
        }

        private ButtonState GetButtonState()
        {
            if (!button.interactable)
            {
                return ButtonState.Disabled;
            }

            if (isPointerDown)
            {
                return ButtonState.Pressed;
            }

            if (isPointerInside)
            {
                return ButtonState.Highlighted;
            }

            return ButtonState.Normal;
        }

        // Drag

        private void BeginDrag()
        {
            if (comparison.useCheckValue && comparison.Result == false) return;

            ButtonAction();
        }

        private void Drag()
        {
            if (comparison.useCheckValue && comparison.Result == false) return;
            if (dragging == false) return;
        }

        private void EndDrag()
        {
            SLGame.Session["DragBeginPosition"] = false;
            if (currentPoint == null)
            {
                UpdateExternalDrag(null, null);
                return;
            }
            var pointerData = new PointerEventData(EventSystem.current)
            {
                position = currentPoint.position,
                pointerId = currentPoint.pointerId,
                pointerEnter = currentPoint.pointerEnter,
                eligibleForClick = true
            };

            var results = new List<RaycastResult>();

            EventSystem.current.RaycastAll(pointerData, results);

            var canceled = true;
            foreach (var result in results)
            {
                var targetObject = result.gameObject;
                if (targetObject == currentDragObject) // 드래그를 넘 멀리 안했다면 짧은 클릭으로 인식
                {
                    dragging = false;
                    return;
                }
                else if (targetObject.TryGetComponent<SLUIDragClickTarget>(out var target))
                {
                    if (target.CanClick())
                    {
                        // target.Click 에서 EndDrag가 또 불리지 않게끔 미리 드래그 해제
                        currentPoint = null;
                        currentDragCancelCommand = null;
                        currentDragObject = null;
                        globalDragging = false;

                        target.Click();
                        canceled = false;
                        return;
                    }

                    break;
                }
            }

            if (canceled)
            {
                SLGame.Command(currentDragCancelCommand, bindParent.BindPath);
            }

            currentPoint = null;
            currentDragCancelCommand = null;
            currentDragObject = null;
            globalDragging = false;
        }

        public void OnBeginDrag(PointerEventData eventData)
        {
            currentPoint = eventData;
            BeginDrag();
            dragging = true;
        }

        public void OnDrag(PointerEventData eventData)
        {
            currentPoint = eventData;
            Drag();
        }

        public void OnEndDrag(PointerEventData eventData)
        {
            currentPoint = eventData;
            if (dragging == false) return;
            EndDrag();
            dragging = false;
        }

        // 중복제거할수도 있지만, 세션이슈나 커맨드 실행등의 이슈
        public static bool UpdateExternalDrag(GameObject obj, string cancelCommand)
        {
            if (obj == currentDragObject)
            {
                return false;
            }
            else if (globalDragging)
            {
                SLGame.Command(currentDragCancelCommand, SLEntity.Empty);

                currentPoint = null;
                currentDragObject = null;
                currentDragCancelCommand = null;
                globalDragging = false;

                return false;
            }
            else
            {
                if (cancelCommand != null)
                {
                    currentDragCancelCommand = cancelCommand;
                    currentDragObject = obj;
                    globalDragging = true;

                    return true;
                }
                return false;
            }
        }

        public static void EndExternalDrag(PointerEventData point)
        {
            currentPoint = point;

            var pointerData = new PointerEventData(EventSystem.current)
            {
                position = currentPoint.position,
                pointerId = currentPoint.pointerId,
                pointerEnter = currentPoint.pointerEnter,
                eligibleForClick = true
            };

            var results = new List<RaycastResult>();

            EventSystem.current.RaycastAll(pointerData, results);

            var canceled = true;
            foreach (var result in results)
            {
                var targetObject = result.gameObject;
                if (targetObject == currentDragObject) // 드래그를 넘 멀리 안했다면 짧은 클릭으로 인식
                {
                    //dragging = false;
                    return;
                }
                else
                if (targetObject.TryGetComponent<SLUIDragClickTarget>(out var target))
                {
                    if (target.CanClick())
                    {
                        // target.Click 에서 EndDrag가 또 불리지 않게끔 미리 드래그 해제
                        currentPoint = null;
                        currentDragCancelCommand = null;
                        currentDragObject = null;
                        globalDragging = false;

                        target.Click();
                        canceled = false;
                        return;
                    }

                    break;
                }
            }

            if (canceled)
            {
                SLGame.Command(currentDragCancelCommand, SLEntity.Empty); // TODO: 캔슬커맨드 컨텍스트 없음
            }

            currentPoint = null;
            currentDragCancelCommand = null;
            currentDragObject = null;
            globalDragging = false;
        }
    }
}