using System;
using System.Collections.Generic;

using UnityEngine;

using UnityEditor;

/// <summary>
/// AnimationClip의 시작/종료 프레임을 설정하여 해당 구간만 잘라낸 새 클립을 생성합니다.
/// FBX 임포트 클립에는 적용 불가 — 우선 Extract 후 사용하세요.
/// </summary>
public class AnimationClipTrimmerWindow : EditorWindow
{
    private AnimationClip sourceClip;
    private int startFrame;
    private int endFrame;
    private float clipFrameRate;
    private float clipLength;
    private int totalFrames;

    private const string MenuPath = "Tools/Animation/Trim Clip";

    [MenuItem(MenuPath, false, 21)]
    public static void ShowWindow()
    {
        var clips = Selection.GetFiltered<AnimationClip>(SelectionMode.Assets);

        if (clips.Length == 0)
        {
            EditorUtility.DisplayDialog(
                "Trim Animation Clip",
                "AnimationClip을 1개 선택해 주세요.",
                "확인");
            return;
        }

        if (clips.Length > 1)
        {
            EditorUtility.DisplayDialog(
                "Trim Animation Clip",
                "1개의 AnimationClip만 선택해 주세요.",
                "확인");
            return;
        }

        var window = GetWindow<AnimationClipTrimmerWindow>("Clip Trimmer");
        window.sourceClip = clips[0];
        window.clipFrameRate = clips[0].frameRate;
        window.clipLength = clips[0].length;
        window.totalFrames = Mathf.RoundToInt(clips[0].length * clips[0].frameRate);
        window.startFrame = 0;
        window.endFrame = window.totalFrames;
        window.minSize = new Vector2(320, 200);
        window.Show();
    }

    [MenuItem(MenuPath, true)]
    public static bool ValidateShowWindow()
    {
        return Selection.GetFiltered<AnimationClip>(SelectionMode.Assets).Length == 1;
    }

    private void OnGUI()
    {
        if (sourceClip == null)
        {
            EditorGUILayout.HelpBox("AnimationClip을 찾을 수 없습니다.", MessageType.Error);
            return;
        }

        // 소스 클립 정보
        EditorGUILayout.Space(8f);
        EditorGUILayout.LabelField("소스 클립", EditorStyles.boldLabel);
        EditorGUILayout.LabelField($"  이름: {sourceClip.name}");
        EditorGUILayout.LabelField($"  프레임 레이트: {clipFrameRate} FPS");
        EditorGUILayout.LabelField($"  전체 길이: {clipLength:F3}초 ({totalFrames}프레임)");

        EditorGUILayout.Space(12f);

        // 프레임 범위 설정
        EditorGUILayout.LabelField("잘라내기 범위", EditorStyles.boldLabel);
        EditorGUILayout.Space(4f);

        EditorGUI.BeginChangeCheck();

        int newStart = EditorGUILayout.IntField("시작 프레임", startFrame);
        int newEnd = EditorGUILayout.IntField("종료 프레임", endFrame);

        if (EditorGUI.EndChangeCheck())
        {
            startFrame = Mathf.Clamp(newStart, 0, totalFrames);
            endFrame = Mathf.Clamp(newEnd, 0, totalFrames);

            // 시작이 종료보다 크면 교체
            if (startFrame > endFrame)
                (startFrame, endFrame) = (endFrame, startFrame);
        }

        // 시간 표시
        float startTime = startFrame / clipFrameRate;
        float endTime = endFrame / clipFrameRate;
        float duration = endTime - startTime;

        EditorGUILayout.Space(4f);
        EditorGUILayout.LabelField($"  구간: {startTime:F3}초 ~ {endTime:F3}초");
        EditorGUILayout.LabelField($"  길이: {duration:F3}초 ({endFrame - startFrame}프레임)");

        // 유효성 경고
        if (startFrame == 0 && endFrame == totalFrames)
        {
            EditorGUILayout.HelpBox("전체 구간이 선택되었습니다. 변경 후 잘라내기를 진행하세요.", MessageType.Info);
        }

        EditorGUILayout.Space(12f);

        // 잘라내기 버튼
        EditorGUI.BeginDisabledGroup(startFrame == 0 && endFrame == totalFrames);

        if (GUILayout.Button("잘라내기 (새 클립 생성)", GUILayout.Height(32f)))
        {
            PerformTrim();
        }

        EditorGUI.EndDisabledGroup();
    }

    /// <summary>
    /// 지정된 프레임 구간만 포함하는 새 AnimationClip을 생성합니다.
    /// </summary>
    private void PerformTrim()
    {
        float startTime = startFrame / clipFrameRate;
        float endTime = endFrame / clipFrameRate;

        // 결과 클립 생성
        string sourcePath = AssetDatabase.GetAssetPath(sourceClip);
        string directory = System.IO.Path.GetDirectoryName(sourcePath);
        string trimmedName = $"{sourceClip.name}_Trimmed_F{startFrame}_F{endFrame}";
        string savePath = System.IO.Path.Combine(directory, trimmedName + ".anim")
            .Replace("\\", "/");
        savePath = AssetDatabase.GenerateUniqueAssetPath(savePath);

        AnimationClip trimmedClip = new AnimationClip
        {
            name = trimmedName,
            frameRate = sourceClip.frameRate,
            legacy = sourceClip.legacy,
            wrapMode = sourceClip.wrapMode
        };

        // 커브 복사 (시간 오프셋 반영)
        EditorCurveBinding[] bindings = AnimationUtility.GetCurveBindings(sourceClip);

        foreach (EditorCurveBinding binding in bindings)
        {
            AnimationCurve sourceCurve = AnimationUtility.GetEditorCurve(sourceClip, binding);
            if (sourceCurve == null || sourceCurve.keys.Length == 0)
                continue;

            AnimationCurve trimmedCurve = TrimCurve(sourceCurve, startTime, endTime);
            if (trimmedCurve.keys.Length > 0)
            {
                trimmedClip.SetCurve(binding.path, binding.type, binding.propertyName, trimmedCurve);
            }
        }

        // AnimationEvent 복사 (시간 오프셋 반영)
        AnimationEvent[] sourceEvents = AnimationUtility.GetAnimationEvents(sourceClip);
        if (sourceEvents.Length > 0)
        {
            List<AnimationEvent> trimmedEvents = new List<AnimationEvent>();

            foreach (AnimationEvent evt in sourceEvents)
            {
                if (evt.time >= startTime && evt.time <= endTime)
                {
                    trimmedEvents.Add(new AnimationEvent
                    {
                        time = evt.time - startTime,
                        functionName = evt.functionName,
                        floatParameter = evt.floatParameter,
                        intParameter = evt.intParameter,
                        stringParameter = evt.stringParameter,
                        objectReferenceParameter = evt.objectReferenceParameter,
                        messageOptions = evt.messageOptions
                    });
                }
            }

            if (trimmedEvents.Count > 0)
                AnimationUtility.SetAnimationEvents(trimmedClip, trimmedEvents.ToArray());
        }

        // 저장
        AssetDatabase.CreateAsset(trimmedClip, savePath);
        AssetDatabase.SaveAssets();

        EditorUtility.FocusProjectWindow();
        Selection.activeObject = trimmedClip;

        Debug.Log(
            $"[AnimationClipTrimmer] 잘라내기 완료: {sourceClip.name} " +
            $"F{startFrame}~F{endFrame} ({endTime - startTime:F3}초) → {savePath}");

        Close();
    }

    /// <summary>
    /// 커브에서 startTime ~ endTime 구간의 키 프레임만 추출하고 시간을 0부터 시작하도록 오프셋합니다.
    /// </summary>
    private static AnimationCurve TrimCurve(AnimationCurve curve, float startTime, float endTime)
    {
        Keyframe[] sourceKeys = curve.keys;
        List<Keyframe> trimmedKeys = new List<Keyframe>();

        foreach (Keyframe key in sourceKeys)
        {
            if (key.time >= startTime && key.time <= endTime)
            {
                trimmedKeys.Add(new Keyframe(
                    key.time - startTime,
                    key.value,
                    key.inTangent,
                    key.outTangent
                ));
            }
        }

        if (trimmedKeys.Count == 0)
            return null;

        return new AnimationCurve(trimmedKeys.ToArray())
        {
            preWrapMode = curve.preWrapMode,
            postWrapMode = curve.postWrapMode
        };
    }
}