using System;
using System.Collections.Generic;
#if UNITY_EDITOR
using UnityEditor;
#endif

namespace UnityEngine.Timeline
{
    static class TimelineCreateUtilities
    {
#if UNITY_EDITOR
        [System.ThreadStatic]
        static List<Object> s_TempObjectList;

        public static string GenerateUniqueActorName(List<ScriptableObject> tracks, string name)
        {
            if (s_TempObjectList == null)
                s_TempObjectList = new List<Object>(tracks.Count);
            else
                s_TempObjectList.Clear();

            if (s_TempObjectList.Capacity < tracks.Count)
                s_TempObjectList.Capacity = tracks.Count;

            for (int i = 0; i < tracks.Count; i++)
                s_TempObjectList.Add(tracks[i]);

            string uniqueName = ObjectNames.GetUniqueObjectName(s_TempObjectList, name);
            s_TempObjectList.Clear();
            return uniqueName;
        }
#endif

        public static void SaveAssetIntoObject(Object childAsset, Object masterAsset)
        {
            if (childAsset == null || masterAsset == null)
                return;

            if ((masterAsset.hideFlags & HideFlags.DontSave) != 0)
            {
                childAsset.hideFlags |= HideFlags.DontSave;
            }
            else
            {
                childAsset.hideFlags |= HideFlags.HideInHierarchy;
#if UNITY_EDITOR
                if (!AssetDatabase.Contains(childAsset) && AssetDatabase.Contains(masterAsset))
                    AssetDatabase.AddObjectToAsset(childAsset, masterAsset);
#endif
            }
        }

        public static void RemoveAssetFromObject(Object childAsset, Object masterAsset)
        {
            if (childAsset == null || masterAsset == null)
                return;

#if UNITY_EDITOR
            if (AssetDatabase.Contains(childAsset) && AssetDatabase.Contains(masterAsset))
                AssetDatabase.RemoveObjectFromAsset(childAsset);
#endif
        }

        public static AnimationClip CreateAnimationClipForTrack(string name, TrackAsset track, bool isLegacy)
        {
            var timelineAsset = track != null ? track.timelineAsset : null;
            var trackFlags = track != null ? track.hideFlags : HideFlags.None;

            var curves = new AnimationClip
            {
                legacy = isLegacy,

                name = name,

                frameRate = timelineAsset == null
                    ? (float)TimelineAsset.EditorSettings.kDefaultFrameRate
                    : (float)timelineAsset.editorSettings.frameRate
            };

            SaveAssetIntoObject(curves, timelineAsset);
            curves.hideFlags = trackFlags & ~HideFlags.HideInHierarchy; // Never hide in hierarchy

            TimelineUndo.RegisterCreatedObjectUndo(curves, "Create Curves");

            return curves;
        }

        public static bool ValidateParentTrack(TrackAsset parent, Type childType)
        {
            if (childType == null || !typeof(TrackAsset).IsAssignableFrom(childType))
                return false;

            // no parent is valid for any type
            if (parent == null)
                return true;

            // A track supports layers if it implements ILayerable. Only supported for parents that are
            // the same exact type as the child class, and 1 level of nesting only
            if (parent is ILayerable && !parent.isSubTrack && parent.GetType() == childType)
                return true;

            var attr = Attribute.GetCustomAttribute(parent.GetType(), typeof(SupportsChildTracksAttribute)) as SupportsChildTracksAttribute;
            if (attr == null)
                return false;

            // group track case, accepts all
            if (attr.childType == null)
                return true;

            // specific case. Specifies nesting level
            if (childType == attr.childType)
            {
                int nestCount = 0;
                var p = parent;
                while (p != null && p.isSubTrack)
                {
                    nestCount++;
                    p = p.parent as TrackAsset;
                }

                return nestCount < attr.levels;
            }
            return false;
        }
    }
}