using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using UnityEngine.UI.Extensions;

namespace Ichni.Editor
{
    [RequireComponent(typeof(RectTransform))]
    public class KeyframeVisualizer : MonoBehaviour
    {
        [Header("Settings")]
        public Vector2Int resolution = new Vector2Int(512, 256);
        public Color curveColor = Color.green;
        public Color gridColor = new Color(0.3f, 0.3f, 0.3f, 0.5f);
        public float pointSize = 15f;
        public float tangentHandleLength = 40f;
        public float lineThickness = 2f;

        [Header("References")]
        public AnimationCurve curve;
        public UILineRenderer curveLine;
        public UILineRenderer gridLines;
        public UILineRenderer borderLine;

        // 当用户松开鼠标（编辑结束）时触发，用于同步外部UI
        public Action OnEditFinished;

        private List<CurvePoint> _activePoints = new List<CurvePoint>();

        private void Awake()
        {
            // 移除场景/预制体中残留的旧 RawImage 组件
            var oldRawImage = GetComponent<RawImage>();
            if (oldRawImage != null)
                Destroy(oldRawImage);

            SetupUILineRenderers();
        }

        private void SetupUILineRenderers()
        {
            if (curveLine == null)
                curveLine = CreateChildLineRenderer("CurveLine", curveColor);
            if (gridLines == null)
                gridLines = CreateChildLineRenderer("GridLines", gridColor);
            if (borderLine == null)
                borderLine = CreateChildLineRenderer("BorderLine", Color.white);

            curveLine.LineThickness = lineThickness;
            gridLines.LineThickness = 1f;
            borderLine.LineThickness = 1.5f;
        }

        private UILineRenderer CreateChildLineRenderer(string name, Color color)
        {
            GameObject go = new GameObject(name, typeof(RectTransform));
            go.transform.SetParent(transform, false);

            RectTransform rt = go.GetComponent<RectTransform>();
            rt.anchorMin = Vector2.zero;
            rt.anchorMax = Vector2.one;
            rt.offsetMin = Vector2.zero;
            rt.offsetMax = Vector2.zero;

            UILineRenderer line = go.AddComponent<UILineRenderer>();
            line.color = color;
            line.RelativeSize = true;
            line.raycastTarget = false;
            return line;
        }

        private void OnEnable()
        {
            if (curve == null) curve = AnimationCurve.Linear(0, 0, 1, 1);
            RebuildInteractablePoints();
            DrawCurve();
        }

        // === 核心绘制逻辑 (UILineRenderer) ===
        public void DrawCurve()
        {
            if (curve == null) return;

            int sampleCount = Mathf.Max(2, resolution.x);

            // 1. 绘制曲线
            Vector2[] curvePoints = new Vector2[sampleCount];
            for (int i = 0; i < sampleCount; i++)
            {
                float t = (float)i / (sampleCount - 1);
                float val = Mathf.Clamp01(curve.Evaluate(t));
                curvePoints[i] = new Vector2(t, val);
            }
            curveLine.Points = curvePoints;

            // 2. 绘制网格 (0.25, 0.5, 0.75)
            float[] gridPositions = { 0.25f, 0.5f, 0.75f };
            List<Vector2[]> segments = new List<Vector2[]>();
            foreach (float p in gridPositions)
            {
                segments.Add(new Vector2[] { new Vector2(0, p), new Vector2(1, p) }); // 横线
                segments.Add(new Vector2[] { new Vector2(p, 0), new Vector2(p, 1) }); // 竖线
            }
            gridLines.Segments = segments;

            // 3. 绘制边框
            borderLine.Points = new Vector2[]
            {
                new Vector2(0, 0),
                new Vector2(1, 0),
                new Vector2(1, 1),
                new Vector2(0, 1),
                new Vector2(0, 0)
            };
        }

        // === 交互点生成 ===
        public void RebuildInteractablePoints()
        {
            if (curve == null) return;

            // 清理旧点（保留子UILineRenderer）
            var toDestroy = new List<GameObject>();
            foreach (Transform child in transform)
            {
                if (child == curveLine?.transform ||
                    child == gridLines?.transform ||
                    child == borderLine?.transform)
                    continue;
                toDestroy.Add(child.gameObject);
            }
            foreach (var go in toDestroy)
                Destroy(go);
            _activePoints.Clear();

            for (int i = 0; i < curve.length; i++)
            {
                // 关键帧点 (Key)
                var keyPoint = CreatePoint(i, PointType.Key, Color.red, pointSize);

                // 入切线 (In Tangent) - 第一个点通常不需要
                if (i > 0)
                {
                    var inPoint = CreatePoint(i, PointType.InTangent, Color.cyan, pointSize * 0.6f);
                    inPoint.relatedKeyPoint = keyPoint;
                    keyPoint.inHandle = inPoint;
                }

                // 出切线 (Out Tangent) - 最后一个点通常不需要
                if (i < curve.length - 1)
                {
                    var outPoint = CreatePoint(i, PointType.OutTangent, Color.cyan, pointSize * 0.6f);
                    outPoint.relatedKeyPoint = keyPoint;
                    keyPoint.outHandle = outPoint;
                }
            }

            RefreshPointsPosition();
        }

        private CurvePoint CreatePoint(int index, PointType type, Color color, float size)
        {
            GameObject go = new GameObject($"{type}_{index}");
            go.transform.SetParent(transform, false);

            Image img = go.AddComponent<Image>();
            img.color = color;

            RectTransform rt = go.GetComponent<RectTransform>();
            rt.sizeDelta = Vector2.one * size;
            rt.anchorMin = rt.anchorMax = Vector2.zero; // 使用绝对坐标定位

            CurvePoint cp = go.AddComponent<CurvePoint>();
            cp.Init(this, index, type);
            _activePoints.Add(cp);
            return cp;
        }

        // === 坐标同步逻辑 ===
        public void RefreshPointsPosition()
        {
            Vector2 size = ((RectTransform)transform).rect.size;

            foreach (var point in _activePoints)
            {
                Keyframe key = curve.keys[point.keyIndex];
                Vector2 keyNormPos = new Vector2(key.time, key.value);
                Vector2 keyPixelPos = new Vector2(keyNormPos.x * size.x, keyNormPos.y * size.y);

                if (point.type == PointType.Key)
                {
                    point.rectTransform.anchoredPosition = keyPixelPos;
                }
                else
                {
                    float tangent = (point.type == PointType.InTangent) ? key.inTangent : key.outTangent;

                    Vector2 visualDir;
                    if (float.IsInfinity(tangent))
                    {
                        visualDir = new Vector2(0, tangent > 0 ? 1 : -1);
                    }
                    else
                    {
                        // 斜率 = (y / x) * aspect  =>  y = (tangent / aspect) * x
                        // 令视觉上的 x 为 1 或 -1
                        float xDir = (point.type == PointType.InTangent) ? -1f : 1f;
                        float yDir = (tangent / (size.x / size.y)) * xDir;
                        visualDir = new Vector2(xDir, yDir).normalized;
                    }

                    // 顺着计算出的向量方向，放置手柄
                    point.rectTransform.anchoredPosition = keyPixelPos + visualDir * tangentHandleLength;
                }
            }
        }

        // 处理点被拖拽
        public void OnPointDragged(CurvePoint point, Vector2 screenDelta)
        {
            Vector2 size = ((RectTransform)transform).rect.size;
            int index = point.keyIndex;
            Keyframe key = curve.keys[index];

            if (point.type == PointType.Key)
            {
                // 关键帧移动逻辑不变
                Vector2 deltaNorm = new Vector2(screenDelta.x / size.x, screenDelta.y / size.y);
                key.time = Mathf.Clamp01(key.time + deltaNorm.x);
                key.value = Mathf.Clamp01(key.value + deltaNorm.y);
            }
            else
            {
                // === 切线处理优化：基于向量构建 ===
                // 1. 获取关键帧当前的屏幕坐标
                Vector2 keyPos = point.relatedKeyPoint.rectTransform.anchoredPosition;

                // 2. 获取鼠标当前的目标坐标（当前手柄位置 + 增量）
                Vector2 mouseTargetPos = point.rectTransform.anchoredPosition + screenDelta;

                // 3. 计算从关键帧指向鼠标的向量
                Vector2 dirVec = mouseTargetPos - keyPos;

                // 4. 强制方向约束 (InTangent必须在左, OutTangent必须在右)
                if (point.type == PointType.InTangent)
                {
                    if (dirVec.x > -1f) dirVec.x = -1f; // 至少向左偏 1 像素，防止除零或方向翻转
                }
                else if (point.type == PointType.OutTangent)
                {
                    if (dirVec.x < 1f) dirVec.x = 1f;   // 至少向右偏 1 像素
                }

                // 5. 计算斜率 (Tangent)
                float canvasAspect = size.x / size.y;
                float tangent = (dirVec.y / dirVec.x) * canvasAspect;

                if (point.type == PointType.InTangent) key.inTangent = tangent;
                else key.outTangent = tangent;
            }

            curve.MoveKey(index, key);
            DrawCurve();
            RefreshPointsPosition(); // 统一刷新位置，确保手柄视觉表现一致
        }
    }

    public enum PointType { Key, InTangent, OutTangent }

    // 辅助交互类
    public class CurvePoint : MonoBehaviour, IDragHandler, IEndDragHandler
    {
        public KeyframeVisualizer visualizer;
        public int keyIndex;
        public PointType type;
        public RectTransform rectTransform;

        // 引用关联点，方便计算
        public CurvePoint relatedKeyPoint;
        public CurvePoint inHandle;
        public CurvePoint outHandle;

        public void Init(KeyframeVisualizer v, int index, PointType t)
        {
            visualizer = v;
            keyIndex = index;
            type = t;
            rectTransform = GetComponent<RectTransform>();
        }

        public void OnDrag(PointerEventData eventData)
        {
            // 实时更新曲线和画面
            visualizer.OnPointDragged(this, eventData.delta);
        }

        public void OnEndDrag(PointerEventData eventData)
        {
            // 拖拽结束后，通知外部同步 (关键一步)
            visualizer.OnEditFinished?.Invoke();
        }
    }
}