// Animancer // https://kybernetik.com.au/animancer // Copyright 2018-2023 Kybernetik //

using System;
using System.Collections.Generic;
using UnityEngine;

#if UNITY_EDITOR
using Animancer.Editor;
using UnityEditor;
#endif

namespace Animancer
{
    /// <summary>A <see cref="ClipTransition"/> which gets its clip from a <see cref="DirectionalAnimationSet"/>.</summary>
    /// <remarks>
    /// Documentation: <see href="https://kybernetik.com.au/animancer/docs/manual/playing/directional-sets">Directional Animation Sets</see>
    /// </remarks>
    /// <example><code>
    /// // Leave the Clip field empty in the Inspector and assign its AnimationSet instead.
    /// [SerializeField] private DirectionalClipTransition _Transition;
    /// 
    /// ...
    /// 
    /// // Then you can just call SetDirection and Play it like any other transition.
    /// // All of the transition's details like Fade Duration and Events will be applied to whichever clip is plays.
    /// _Transition.SetDirection(Vector2.right);
    /// _Animancer.Play(_Transition);
    /// </code></example>
    /// https://kybernetik.com.au/animancer/api/Animancer/DirectionalClipTransition
    /// 
    [Serializable]
    public class DirectionalClipTransition : ClipTransition,
        ICopyable<DirectionalClipTransition>
    {
        /************************************************************************************************************************/

        [SerializeField]
        [Tooltip("The animations which used to determine the " + nameof(Clip))]
        private DirectionalAnimationSet _AnimationSet;

        /// <summary>[<see cref="SerializeField"/>] 
        /// The <see cref="DirectionalAnimationSet"/> used to determine the <see cref="ClipTransition.Clip"/>.
        /// </summary>
        public ref DirectionalAnimationSet AnimationSet
            => ref _AnimationSet;

        /// <inheritdoc/>
        public override UnityEngine.Object MainObject
            => _AnimationSet;

        /************************************************************************************************************************/

        /// <summary>Sets the <see cref="ClipTransition.Clip"/> from the <see cref="AnimationSet"/>.</summary>
        public void SetDirection(Vector2 direction)
            => Clip = _AnimationSet.GetClip(direction);

        /// <summary>Sets the <see cref="ClipTransition.Clip"/> from the <see cref="AnimationSet"/>.</summary>
        public void SetDirection(int direction)
            => Clip = _AnimationSet.GetClip(direction);

        /// <summary>Sets the <see cref="ClipTransition.Clip"/> from the <see cref="AnimationSet"/>.</summary>
        public void SetDirection(DirectionalAnimationSet.Direction direction)
            => Clip = _AnimationSet.GetClip(direction);

        /// <summary>Sets the <see cref="ClipTransition.Clip"/> from the <see cref="AnimationSet"/>.</summary>
        public void SetDirection(DirectionalAnimationSet8.Direction direction)
            => Clip = _AnimationSet.GetClip((int)direction);

        /************************************************************************************************************************/

        /// <inheritdoc/>
        public override void GatherAnimationClips(ICollection<AnimationClip> clips)
        {
            base.GatherAnimationClips(clips);
            clips.GatherFromSource(_AnimationSet);
        }

        /************************************************************************************************************************/

        /// <inheritdoc/>
        public virtual void CopyFrom(DirectionalClipTransition copyFrom)
        {
            base.CopyFrom(copyFrom);

            if (copyFrom == null)
            {
                _AnimationSet = default;
                return;
            }

            _AnimationSet = copyFrom._AnimationSet;
        }

        /************************************************************************************************************************/
#if UNITY_EDITOR
        /************************************************************************************************************************/

        /// <inheritdoc/>
        [CustomPropertyDrawer(typeof(DirectionalClipTransition), true)]
        public new class Drawer : TransitionDrawer
        {
            /************************************************************************************************************************/

            /// <summary>Creates a new <see cref="Drawer"/>.</summary>
            public Drawer() : base(nameof(_AnimationSet)) { }

            /************************************************************************************************************************/

            /// <inheritdoc/>
            protected override void DoChildPropertyGUI(
                ref Rect area,
                SerializedProperty rootProperty,
                SerializedProperty property,
                GUIContent label)
            {
                var width = area.width;

                var path = property.propertyPath;
                if (path.EndsWith($".{ClipFieldName}"))
                {
                    if (property.objectReferenceValue != null)
                    {
                        var removeArea = AnimancerGUI.StealFromRight(
                            ref area, AnimancerGUI.LineHeight, AnimancerGUI.StandardSpacing);

                        using (ObjectPool.Disposable.AcquireContent(out var removeLabel, "X",
                                $"A {nameof(DirectionalClipTransition)} will get its Clip from the Animation Set" +
                                $" at runtime so the Clip might as well be null until then."))
                        {
                            if (GUI.Button(removeArea, removeLabel, AnimancerGUI.MiniButton))
                                property.objectReferenceValue = null;
                        }
                    }

                    if (Context.Transition is DirectionalClipTransition directionalClipTransition &&
                        directionalClipTransition._AnimationSet != null)
                    {
                        var dropdownArea = AnimancerGUI.StealFromRight(
                            ref area, area.height, AnimancerGUI.StandardSpacing);

                        if (GUI.Button(dropdownArea, GUIContent.none, EditorStyles.popup))
                            PickAnimation(property, directionalClipTransition);
                    }
                }

                base.DoChildPropertyGUI(ref area, rootProperty, property, label);

                area.width = width;
            }

            /************************************************************************************************************************/

            /// <summary>Shows a context menu to choose an <see cref="AnimationClip"/> from the `source`.</summary>
            private void PickAnimation(SerializedProperty property, object source)
            {
                var menu = new GenericMenu();

                using (ObjectPool.Disposable.AcquireSet<AnimationClip>(out var clips))
                {
                    clips.GatherFromSource(source);
                    if (clips.Count == 0)
                        return;

                    property = property.Copy();

                    foreach (var clip in clips)
                    {
                        menu.AddPropertyModifierFunction(property, clip.name, true, modify =>
                        {
                            modify.objectReferenceValue = clip;
                        });
                    }
                }

                menu.ShowAsContext();
            }

            /************************************************************************************************************************/
        }

        /************************************************************************************************************************/
#endif
        /************************************************************************************************************************/
    }
}