using UnityEngine;
using UnityEditor;
using UnityEditorInternal;

namespace YKMoonEditor
{
    /// <summary>
    /// 描绘可拖拽List
    /// </summary>
    public class UReorderableList
    {
        private ReorderableList m_ReorderableList;
        public SerializedObject serializedObject { get; private set; }
        public SerializedProperty elements { get; private set; }

        public bool showResize = false;

        private float elementHeight;

        private ReorderableList.ElementCallbackDelegate drawElementCallback;

        public UReorderableList(SerializedObject serializedObject, SerializedProperty elements, float elementHeight, ReorderableList.ElementCallbackDelegate drawElementCallback = null)
        {
            this.serializedObject = serializedObject;
            this.elements = elements;
            this.elementHeight = elementHeight;
            
            if (drawElementCallback == null) {
                this.drawElementCallback = DrawElementWithIndex;
            } else {
                this.drawElementCallback = drawElementCallback;
            }
            m_ReorderableList = new ReorderableList(serializedObject, elements, true, true, true, true);
            m_ReorderableList.drawHeaderCallback = this.DrawEventHeader;
            m_ReorderableList.drawElementCallback = this.DrawEventListener;
            m_ReorderableList.drawFooterCallback = this.FooterCallback;
        }

        private void UpdateExpanded()
        {
            if(elements.isExpanded) {
                m_ReorderableList.displayAdd = true;
                m_ReorderableList.displayRemove = true;
                m_ReorderableList.elementHeight = elementHeight;
                m_ReorderableList.footerHeight = 13f;
            } else {
                m_ReorderableList.displayAdd = false;
                m_ReorderableList.displayRemove = false;
                m_ReorderableList.elementHeight = 0f;
                m_ReorderableList.footerHeight = 0;
            }
        }

        public void DoLayoutList()
        {
            UpdateExpanded();
            m_ReorderableList.DoLayoutList();
        }

        public void DoList(Rect rect)
        {
            UpdateExpanded();
            m_ReorderableList.DoList(rect);
        }

        protected virtual void DrawEventHeader(Rect headerRect)
        {
            float offsetWidth = 10;
            headerRect.xMin += offsetWidth;
            {
                Rect rect = headerRect;
                GUIContent content = new GUIContent(string.Format("{0} ({1})", elements.name, m_ReorderableList.count), elements.tooltip);
                elements.isExpanded = EditorGUI.BeginFoldoutHeaderGroup(rect, elements.isExpanded, content);
            }
            EditorGUI.EndFoldoutHeaderGroup();
        }

        /// <summary>
        /// 描绘子物体
        /// </summary>
        private void DrawEventListener(Rect rect, int index, bool isactive, bool isfocused)
        {
            if(!elements.isExpanded) {
                return;
            }
            drawElementCallback?.Invoke(rect, index, isactive, isfocused);
        }

        private void DoResize(ReorderableList list, int size)
        {
            size = Mathf.Max(0, size);
            if (list.serializedProperty != null) {
                list.serializedProperty.arraySize = size;
                if(list.index >= (list.serializedProperty.arraySize - 1)) {
                    list.index = list.serializedProperty.arraySize - 1;
                }
            } else {
                if(size < list.list.Count) {
                    while(size < list.list.Count) {
                        list.list.RemoveAt(list.list.Count - 1);
                    }
                }else if(size > list.list.Count) {
                    while(size > list.list.Count) {
                        ReorderableList.defaultBehaviours.DoAddButton(list);
                    }
                }

                if(list.index >= (list.list.Count - 1)) {
                    list.index = list.list.Count - 1;
                }
            }
        }

        /// <summary>
        /// 描绘下边
        /// </summary>
        /// <param name="rect"></param>
        private void FooterCallback(Rect rect)
        {
            if (!elements.isExpanded) {
                return;
            }

            var list = m_ReorderableList;

            float xMax = rect.xMax;
            float x = rect.xMax - 8f;
            float buttonSize = 25f;
            if(showResize) {
                x -= buttonSize;
            }
            if(list.displayAdd) {
                x -= buttonSize;
            }
            if(list.displayRemove) {
                x -= buttonSize;
            }
            rect = new Rect(x, rect.y, xMax - x, rect.height);
            if(Event.current.type == UnityEngine.EventType.Repaint) {
                ReorderableList.defaultBehaviours.footerBackground.Draw(rect, false, false, false, false);
            }

            Rect pos = new Rect(x + 4f, rect.y - 3f, 25f, 13f);
            //resize
            if (showResize) {
                pos.height = 16f;
                int newCount = EditorGUI.IntField(pos, list.count);
                if (newCount != list.count) {
                    DoResize(list, newCount);
                    if(list.onChangedCallback != null) {
                        list.onChangedCallback(list);
                    }
                }
                pos.x += buttonSize;
            }
            //addButton
            if(list.displayAdd) {
                pos.width = 25f;
                pos.height = 13f;
                using(new EditorGUI.DisabledScope((list.onCanAddCallback != null) && !list.onCanAddCallback(list))) {
                    if(GUI.Button(pos, (list.onAddDropdownCallback == null) ? ReorderableList.defaultBehaviours.iconToolbarPlus : ReorderableList.defaultBehaviours.iconToolbarPlusMore, ReorderableList.defaultBehaviours.preButton)) {
                        if(list.onAddDropdownCallback != null) {
                            list.onAddDropdownCallback(pos, list);
                        } else if(list.onAddCallback != null) {
                            list.onAddCallback(list);
                        } else {
                            ReorderableList.defaultBehaviours.DoAddButton(list);
                        }
                        if(list.onChangedCallback != null) {
                            list.onChangedCallback(list);
                        }
                    }
                }
                pos.x += buttonSize;
            }            
            //removeButton
            if(list.displayRemove) {
                pos.width = 25f;
                pos.height = 13f;                
                using(new EditorGUI.DisabledScope(((list.index < 0) || (list.index >= list.count)) || ((list.onCanRemoveCallback != null) && !list.onCanRemoveCallback(list)))) {
                    if(GUI.Button(pos, ReorderableList.defaultBehaviours.iconToolbarMinus, ReorderableList.defaultBehaviours.preButton)) {
                        if(list.onRemoveCallback == null) {
                            ReorderableList.defaultBehaviours.DoRemoveButton(list);
                        } else {
                            list.onRemoveCallback(list);
                        }
                        if(list.onChangedCallback != null) {
                            list.onChangedCallback(list);
                        }
                    }
                }
                pos.x += buttonSize;
            }
        }

        #region DefaultDrawer
        public void DrawElementWithIndex(Rect drawRectInput, int index, bool isactive, bool isfocused)
        {
            var elementProperty = m_ReorderableList.serializedProperty.GetArrayElementAtIndex(index);

            drawRectInput.xMax -= 32;
            Rect drawRect = drawRectInput;
            //Index
            {
                var rect = drawRect;
                rect.width = 30;
                GUI.Label(rect, index.ToString());
                drawRect.x += rect.width;
            }
            drawRect.yMin += 2;
            drawRect.yMax -= 2;
            EditorGUI.PropertyField(drawRect, elementProperty, GUIContent.none);
        }

        #endregion
    }
}