#if UNITY_EDITOR
using System.Linq;
using UnityEditor;
using UnityEditorInternal;
using UnityEngine;

namespace Amanotes.Core
{
    [CustomEditor(typeof(DepthSortGroup))]
    public class DepthSortGroupEditor : Editor
    {
        private ReorderableList _list;
        private const float SeparatorHeight = 8f;
        private const float RowHeight = 20f;

        private void OnEnable()
        {
            var entriesProp = serializedObject.FindProperty("entries");
            _list = new ReorderableList(serializedObject, entriesProp, true, true, true, true);

            _list.drawHeaderCallback = rect => EditorGUI.LabelField(rect,
                "Entries (drag renderers adjacent to merge depth; drag in a separator to split)");

            _list.elementHeightCallback = index =>
            {
                var element = entriesProp.GetArrayElementAtIndex(index);
                var isSeparator = element.FindPropertyRelative("isSeparator").boolValue;
                return isSeparator ? SeparatorHeight + 4f : RowHeight + 4f;
            };

            _list.drawElementCallback = (rect, index, active, focused) =>
            {
                var element = entriesProp.GetArrayElementAtIndex(index);
                var isSeparatorProp = element.FindPropertyRelative("isSeparator");
                var rendererProp = element.FindPropertyRelative("renderer");

                rect.y += 2f;

                if (isSeparatorProp.boolValue)
                {
                    var lineRect = new Rect(rect.x, rect.y + SeparatorHeight * 0.5f, rect.width, 2f);
                    EditorGUI.DrawRect(lineRect, new Color(1f, 0.6f, 0.1f, 0.8f));
                    return;
                }

                var fieldRect = new Rect(rect.x, rect.y, rect.width - 60f, RowHeight);
                EditorGUI.PropertyField(fieldRect, rendererProp, GUIContent.none);

                var groupLabelRect = new Rect(rect.xMax - 55f, rect.y, 55f, RowHeight);
                EditorGUI.LabelField(groupLabelRect, GroupLabelFor(index), EditorStyles.miniLabel);
            };

            _list.onAddDropdownCallback = (buttonRect, list) =>
            {
                var menu = new GenericMenu();
                menu.AddItem(new GUIContent("Renderer"), false, () =>
                {
                    entriesProp.arraySize++;
                    var e = entriesProp.GetArrayElementAtIndex(entriesProp.arraySize - 1);
                    e.FindPropertyRelative("isSeparator").boolValue = false;
                    e.FindPropertyRelative("renderer").objectReferenceValue = null;
                    serializedObject.ApplyModifiedProperties();
                });
                menu.AddItem(new GUIContent("Separator"), false, () =>
                {
                    entriesProp.arraySize++;
                    var e = entriesProp.GetArrayElementAtIndex(entriesProp.arraySize - 1);
                    e.FindPropertyRelative("isSeparator").boolValue = true;
                    serializedObject.ApplyModifiedProperties();
                });
                menu.ShowAsContext();
            };
        }

        // group index = number of separators-with-content before this row, for the inline label
        private string GroupLabelFor(int index)
        {
            var entriesProp = serializedObject.FindProperty("entries");
            var group = 0;
            var groupHasContent = false;
            for (var i = 0; i <= index && i < entriesProp.arraySize; i++)
            {
                var element = entriesProp.GetArrayElementAtIndex(i);
                var isSeparator = element.FindPropertyRelative("isSeparator").boolValue;
                if (isSeparator)
                {
                    if (groupHasContent) { group++; groupHasContent = false; }
                    continue;
                }
                if (i == index) return $"#{group}";
                groupHasContent = true;
            }
            return $"#{group}";
        }

        public override void OnInspectorGUI()
        {
            serializedObject.Update();

            var sortingLayerIDProp = serializedObject.FindProperty("sortingLayerID");
            var layers = SortingLayer.layers;
            var names = layers.Select(l => l.name).ToArray();
            var currentIndex = System.Array.FindIndex(layers, l => l.id == sortingLayerIDProp.intValue);
            if (currentIndex < 0) currentIndex = 0;

            EditorGUI.BeginChangeCheck();
            var newIndex = EditorGUILayout.Popup("Sorting Layer", currentIndex, names);
            if (EditorGUI.EndChangeCheck())
            {
                sortingLayerIDProp.intValue = layers[newIndex].id;
            }

            EditorGUILayout.PropertyField(serializedObject.FindProperty("sortIndex"));
            EditorGUILayout.Space();
            _list.DoLayoutList();

            serializedObject.ApplyModifiedProperties();
        }
    }
}
#endif