using System;
using System.Collections.Generic;
using System.Reflection;
using UnityEditorInternal;
using UnityEngine;
using UnityEngine.Splines;

namespace UnityEditor.Splines
{
    [InitializeOnLoad]
    static class SplineDataReorderableListUtility
    {
        readonly static string k_DataIndexTooltip = L10n.Tr("The index of the Data Point along the spline and the unit used.");
        readonly static string k_DataValueTooltip = L10n.Tr("The value of the Data Point.");

        static Dictionary<string, ReorderableList> s_ReorderableLists = new Dictionary<string, ReorderableList>();
        static PathIndexUnit s_PathIndexUnit;
        readonly static string[] k_DisplayName = new string[] {"Dist","Path %","Knot"};

        static SplineDataReorderableListUtility()
        {
            Selection.selectionChanged += ClearReorderableLists;
        }

        static void ClearReorderableLists()
        {
            s_ReorderableLists.Clear();
        }

        static void SetSplineDataDirty(SerializedProperty splineDataProperty)
        {
            var splineDataObject = SerializedPropertyUtility.GetSerializedPropertyObject(splineDataProperty);
            var dirtyMethod = splineDataObject.GetType().GetMethod("SetDirty", BindingFlags.Instance | BindingFlags.NonPublic);
            dirtyMethod?.Invoke(splineDataObject, null);
        }

        public static ReorderableList GetDataPointsReorderableList(SerializedProperty splineDataProperty, SerializedProperty dataPointProperty, PathIndexUnit unit)
        {
#if UNITY_6000_4_OR_NEWER
            var key = dataPointProperty.propertyPath + splineDataProperty.serializedObject.targetObject.GetEntityId();
#else
            var key = dataPointProperty.propertyPath + splineDataProperty.serializedObject.targetObject.GetInstanceID();
#endif

            s_PathIndexUnit = unit;

            if(s_ReorderableLists.TryGetValue(key, out var list))
            {
                try
                {
                    SerializedProperty.EqualContents(list.serializedProperty, dataPointProperty);
                    return list;
                }
                catch(NullReferenceException)
                {
                    s_ReorderableLists.Remove(key);
                }
            }

            list = new ReorderableList(dataPointProperty.serializedObject, dataPointProperty, false, false, true, true);
            s_ReorderableLists.Add(key, list);

            list.elementHeightCallback = (int index) =>
            {
                return dataPointProperty.arraySize > 0 && dataPointProperty.GetArrayElementAtIndex(index).isExpanded
                    ? 3 * EditorGUIUtility.singleLineHeight + 2 * EditorGUIUtility.standardVerticalSpacing
                    : EditorGUIUtility.singleLineHeight;
            };

            list.onChangedCallback = reorderableList =>
            {
                SetSplineDataDirty(splineDataProperty);
            };

            list.drawElementCallback =
                (Rect position, int listIndex, bool isActive, bool isFocused) =>
            {
                var ppte = dataPointProperty.GetArrayElementAtIndex(listIndex);

                EditorGUI.indentLevel++;
                var expended = EditorGUI.Foldout(SplineGUIUtility.ReserveSpace(EditorGUIUtility.singleLineHeight, ref position), ppte.isExpanded, new GUIContent($"Data Point [{listIndex}]"), true);
                if (expended != ppte.isExpanded)
                {
                    ppte.isExpanded = expended;
                    if (!isActive)
                        list.index = listIndex;
                    list.GrabKeyboardFocus();
                }

                if (ppte.isExpanded)
                {
                    EditorGUI.indentLevel++;
                    SplineGUIUtility.ReserveSpace(EditorGUIUtility.standardVerticalSpacing, ref position);
                    EditorGUI.BeginChangeCheck();
                    var indexProperty = ppte.FindPropertyRelative("m_Index");
                    EditorGUI.DelayedFloatField(SplineGUIUtility.ReserveSpace(EditorGUIUtility.singleLineHeight, ref position), indexProperty, new GUIContent($"Data Index ({k_DisplayName[(int)s_PathIndexUnit]})", L10n.Tr(k_DataIndexTooltip)));
                    if(EditorGUI.EndChangeCheck())
                    {
                        if (!isActive)
                            return;

                        Undo.SetCurrentGroupName("Modify Spline Data point index");
                        // Apply data point's index change - needs to be applied here so that the sort below is correct.
                        dataPointProperty.serializedObject.ApplyModifiedProperties();
                        var newIndex = ppte.FindPropertyRelative("m_Index").floatValue;

                        var splineDataObject = SerializedPropertyUtility.GetSerializedPropertyObject(splineDataProperty);
                        var sortMethod = splineDataObject.GetType().GetMethod("ForceSort", BindingFlags.Instance | BindingFlags.NonPublic);

                        sortMethod?.Invoke(splineDataObject, null);
                        dataPointProperty.serializedObject.Update();
                        for (int i = 0; i < dataPointProperty.arraySize; i++)
                        {
                            var index = dataPointProperty.GetArrayElementAtIndex(i).FindPropertyRelative("m_Index").floatValue;
                            if (index == newIndex)
                            {
                                list.index = i;
                                break;
                            }
                        }

                        // Apply the changes resulting from data point sort.
                        dataPointProperty.serializedObject.ApplyModifiedProperties();

                        SetSplineDataDirty(splineDataProperty);
                    }

                    SplineGUIUtility.ReserveSpace(EditorGUIUtility.standardVerticalSpacing, ref position);
                    EditorGUI.BeginChangeCheck();
                    var valueProperty = ppte.FindPropertyRelative("m_Value");
                    EditorGUI.PropertyField(SplineGUIUtility.ReserveSpace(EditorGUI.GetPropertyHeight(valueProperty), ref position), valueProperty, new GUIContent("Data Value", L10n.Tr(k_DataValueTooltip)));

                    if (EditorGUI.EndChangeCheck())
                    {
                        Undo.SetCurrentGroupName("Modify Spline Data point value");
                        SetSplineDataDirty(splineDataProperty);
                        if (!isActive)
                            list.index = listIndex;
                    }

                    EditorGUI.indentLevel--;
                }

                EditorGUI.indentLevel--;
            };

            return list;
        }
    }
}