using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEditor;
using MaskIntr = UnityEngine.SpriteMaskInteraction;

namespace Coffee.UISoftMask
{
    internal enum MaskInteraction : int
    {
        VisibleInsideMask = (1 << 0) + (1 << 2) + (1 << 4) + (1 << 6),
        VisibleOutsideMask = (2 << 0) + (2 << 2) + (2 << 4) + (2 << 6),
        Custom = -1,
    }

    /// <summary>
    /// SoftMaskable editor.
    /// </summary>
    [CustomEditor(typeof(SoftMaskable))]
    [CanEditMultipleObjects]
    public class SoftMaskableEditor : Editor
    {
        private static readonly List<Mask> s_TmpMasks = new List<Mask>();
        private static GUIContent s_MaskWarning;
        private SerializedProperty _spMaskInteraction;
        private bool _custom;

        private MaskInteraction maskInteraction
        {
            get
            {
                var value = _spMaskInteraction.intValue;
                return _custom
                    ? MaskInteraction.Custom
                    : System.Enum.IsDefined(typeof(MaskInteraction), value)
                        ? (MaskInteraction) value
                        : MaskInteraction.Custom;
            }
            set
            {
                _custom = (value == MaskInteraction.Custom);
                if (!_custom)
                {
                    _spMaskInteraction.intValue = (int) value;
                }
            }
        }


        private void OnEnable()
        {
            _spMaskInteraction = serializedObject.FindProperty("m_MaskInteraction");
            _custom = (maskInteraction == MaskInteraction.Custom);

            if (s_MaskWarning == null)
            {
                s_MaskWarning = new GUIContent(EditorGUIUtility.FindTexture("console.warnicon.sml"), "This is not a SoftMask component.");
            }
        }

        private void DrawMaskInteractions()
        {
            var softMaskable = target as SoftMaskable;
            if (softMaskable == null) return;

            softMaskable.GetComponentsInParent<Mask>(true, s_TmpMasks);
            s_TmpMasks.RemoveAll(x => !x.enabled);
            s_TmpMasks.Reverse();

            maskInteraction = (MaskInteraction) EditorGUILayout.EnumPopup("Mask Interaction", maskInteraction);
            if (!_custom) return;

            var l = EditorGUIUtility.labelWidth;
            EditorGUIUtility.labelWidth = 45;

            using (var ccs = new EditorGUI.ChangeCheckScope())
            {
                var intr0 = DrawMaskInteraction(0);
                var intr1 = DrawMaskInteraction(1);
                var intr2 = DrawMaskInteraction(2);
                var intr3 = DrawMaskInteraction(3);

                if (ccs.changed)
                {
                    _spMaskInteraction.intValue = (intr0 << 0) + (intr1 << 2) + (intr2 << 4) + (intr3 << 6);
                }
            }

            EditorGUIUtility.labelWidth = l;
        }

        private int DrawMaskInteraction(int layer)
        {
            var mask = layer < s_TmpMasks.Count ? s_TmpMasks[layer] : null;
            var intr = (MaskIntr) ((_spMaskInteraction.intValue >> layer * 2) & 0x3);
            if (!mask)
            {
                return (int) intr;
            }

            GUILayout.BeginHorizontal();
            EditorGUILayout.LabelField(mask is SoftMask ? GUIContent.none : s_MaskWarning, GUILayout.Width(16));
            GUILayout.Space(-5);
            EditorGUILayout.ObjectField("Mask " + layer, mask, typeof(Mask), false);
            GUILayout.Space(-15);
            intr = (MaskIntr) EditorGUILayout.EnumPopup(intr);
            GUILayout.EndHorizontal();

            return (int) intr;
        }

        public override void OnInspectorGUI()
        {
            base.OnInspectorGUI();

            serializedObject.Update();
            DrawMaskInteractions();

            serializedObject.ApplyModifiedProperties();

            var current = target as SoftMaskable;
            if (current == null) return;

            var mask = current.softMask;
            if (mask) return;

            GUILayout.BeginHorizontal();
            EditorGUILayout.HelpBox("This is unnecessary SoftMaskable.\nCan't find any SoftMask components above.", MessageType.Warning);
            if (GUILayout.Button("Remove", GUILayout.Height(40)))
            {
                DestroyImmediate(current);
                EditorUtils.MarkPrefabDirty();
            }

            GUILayout.EndHorizontal();
        }
    }
}