const createDragTree = function (setting) {
    class DragTree {
        /**
         * 构造函数
         */
        constructor(setting) {
            // 无索引
            this.datas = [];
            // 以key为索引indexedDB
            this.items = {};
            // 以排序为索引
            this.nodes = [];
            // 根节点
            this.children = [];
            // 树设置
            this.setting = setting;
        }
        /**
         * 树结构根据显示排序
         */
        sortTreeNode(isResort) {
            const self = this;
            const addSortNodes = function (nodes) {
                if (!nodes) { return }
                for (let i = 0; i < nodes.length; i++) {
                    self.nodes.push(nodes[i]);
                    nodes[i].index = self.nodes.length - 1;
                    if (!isResort) {
                        nodes[i].children = self.getChildren(nodes[i]);
                    } else {
                        nodes[i].children.sort((a, b) => { return a[self.setting.order] - b[self.setting.order]; })
                    }
                    addSortNodes(nodes[i].children);
                }
            };
            this.nodes = [];
            if (!isResort) {
                this.children = this.getChildren();
            } else {
                this.children.sort((a, b) => { return a[self.setting.order] - b[self.setting.order]; });
            }
            addSortNodes(this.children);
        }
        /**
         * 加载数据(初始化), 并给数据添加部分树结构必须数据
         * @param datas
         */
        loadDatas(datas) {
            const self = this;
            // 清空旧数据
            this.items = {};
            this.nodes = [];
            this.datas = [];
            this.children = [];
            // 加载全部数据
            datas.sort(function (a, b) {
                return a[self.setting.level] - b[self.setting.level];
            });
            for (const data of datas) {
                const keyName = itemsPre + data[this.setting.id];
                if (this.items[keyName]) continue;

                const item = JSON.parse(JSON.stringify(data));
                item.children = [];
                item.expanded = true;
                item.visible = true;
                if (item[setting.pid] === setting.rootId) {
                    this.children.push(item);
                } else {
                    const parent = this.getParent(item);
                    if (!parent) continue;
                    parent.children.push(item);
                }
                this.items[keyName] = item;
                this.datas.push(item);
            }
            this.children.sort((a, b) => { return a[self.setting.order] - b[self.setting.order]; });
            this.sortTreeNode(true);
        }

        getItemsByIndex(index) {
            return this.nodes[index];
        }
        /**
         * 根据id获取树结构节点数据
         * @param {Number} id
         * @returns {Object}
         */
        getItems(id) {
            return this.items[itemsPre + id];
        };
        getNodeIndex(node) {
            return this.nodes.indexOf(node);
        }
        /**
         * 查找node的parent
         * @param {Object} node
         * @returns {Object}
         */
        getParent(node) {
            return this.getItems(node[this.setting.pid]);
        };
        getTopParent(node) {
            const parents = this.getAllParents(node);
            parents.sort((a, b) => { return a.level - b.level; });
            return parents[0];
        };
        getAllParents(node) {
            const parents = [];
            if (!node) return parents;

            let vP = this.getParent(node);
            while (vP) {
                parents.push(vP);
                vP = this.getParent(vP);
            }
            return parents;
        }

        /**
         * 查找node的前兄弟节点
         * @param node
         * @returns {*}
         */
        getPreSiblingNode(node) {
            if (!node) return null;
            const parent = this.getParent(node);
            const siblings = parent ? parent.children : this.children;
            const index = siblings.indexOf(node);
            return (index > 0) ? siblings[index - 1] : null;
        }
        /**
         * 查找node的后兄弟节点
         * @param node
         * @returns {*}
         */
        getNextSiblingNode(node) {
            const parent = this.getParent(node);
            const siblings = parent ? parent.children : this.children;
            const index = siblings.indexOf(node);
            if (index >= 0 && index < siblings.length - 1) {
                return siblings[index + 1];
            } else {
                return null;
            }
        }

        /**
         * 查询node的已下载子节点
         * @param {Object} node
         * @returns {Array}
         */
        getChildren(node) {
            const setting = this.setting;
            const pid = node ? node[setting.id] : setting.rootId;
            const children = this.datas.filter(function (x) {
                return x[setting.pid] === pid;
            });
            children.sort((a, b) => { return a[setting.order] - b[setting.order]; });
            return children;
        };
        /**
         * 递归方式 查询node的已下载的全部后代 (兼容full_path不存在的情况)
         * @param node
         * @returns {*}
         * @private
         */
        _recursiveGetPosterity(node) {
            let posterity = node.children;
            for (const c of node.children) {
                posterity = posterity.concat(this._recursiveGetPosterity(c));
            }
            return posterity;
        };
        /**
         * 查询node的已下载的全部后代
         * @param {Object} node
         * @returns {Array}
         */
        getPosterity(node) {
            const self = this;
            const posterity = this._recursiveGetPosterity(node);
            posterity.sort(function (x, y) {
                return self.getNodeIndex(x) - self.getNodeIndex(y);
            });
            return posterity;
        };

        /**
         * 查询node是否是父节点的最后一个子节点
         * @param {Object} node
         * @returns {boolean}
         */
        isLastSibling(node) {
            const siblings = this.getChildren(this.getParent(node));
            return (siblings && siblings.length > 0) ? node[this.setting.order] === siblings[siblings.length - 1][this.setting.order] : false;
        };
        /**
         * 查询node是否是父节点的最后一个可见子节点
         * @param {Object} node
         * @returns {boolean}
         */
        isLastViewSibling(node) {
            const siblings = (this.getChildren(this.getParent(node))).filter(x => { return !x.filter });
            return (siblings && siblings.length > 0) ? node.order === siblings[siblings.length - 1].order : false;
        };

        /**
         * 得到树结构构成id
         * @param node
         * @returns {*}
         */
        getNodeKey(node) {
            return node[this.setting.id];
        };
        /**
         * 刷新子节点是否可见
         * @param {Object} node
         * @private
         */
        _refreshChildrenVisible(node) {
            if (!node.children) {
                node.children = this.getChildren(node);
            }
            if (node.children && node.children.length > 0) {
                for (const child of node.children) {
                    child.visible = node.expanded && node.visible && !child.filter;
                    this._refreshChildrenVisible(child);
                }
            }
        };
        /**
         * 设置节点是否展开, 并控制子节点可见
         * @param {Object} node
         * @param {Boolean} expanded
         */
        setExpanded(node, expanded) {
            node.expanded = expanded;
            this._refreshChildrenVisible(node);
        };
        /**
         * 递归 设置节点展开状态
         * @param {Array} nodes - 需要设置状态的节点
         * @param {Object} parent - nodes的父节点
         * @param {Function} checkFun - 判断节点展开状态的方法
         * @private
         */
        _recursiveExpand(nodes, parent, checkFun) {
            for (const node of nodes) {
                const expanded = checkFun(node);
                if (node.expanded !== expanded) {
                    node.expanded = expanded;
                }
                node.visible = parent ? (parent.expanded && parent.visible && !node.filter) : !node.filter;
                this._recursiveExpand(node.children, node, checkFun);
            }
        }
        /**
         * 自定义展开规则
         * @param checkFun
         */
        expandByCustom(checkFun) {
            this._recursiveExpand(this.children, null, checkFun);
            // this._saveMarkExpandFold();
        }
        /**
         * 展开到第几层
         * @param {Number} level - 展开层数
         */
        expandByLevel(level) {
            const levelField = this.setting.level;
            this.expandByCustom(function (n) {
                return n[levelField] < level;
            });
        }

        /**
         * 自动展开节点node
         * @param node
         * @returns {*}
         */
        autoExpandNode(node) {
            const parents = this.getAllParents(node);
            const reload = [];
            for (const p of parents) {
                if (!p.expanded) {
                    reload.push(p);
                    this.setExpanded(p, true);
                }
            }
            return reload;
        }

        /**
         * 加载数据(动态)，只加载不同部分
         * @param {Array} datas
         * @return {Array} 加载到树的数据
         * @privateA
         */
        _updateData(datas) {
            datas = datas instanceof Array ? datas : [datas];
            let loadedData = [];
            for (const data of datas) {
                let node = this.getItems(data[this.setting.id]);
                if (node) {
                    for (const prop in data) {
                        if (data[prop] !== undefined && data[prop] !== node[prop]) {
                            if (prop === this.setting.pid) {
                                loadedData.push(this.getItems(node[this.setting.pid]));
                                loadedData.push(this.getItems(data[this.setting.pid]));
                            }
                            if (prop === this.setting.order) {
                                loadedData = loadedData.concat(this.getPosterity(node));
                            }
                            node[prop] = data[prop];
                        }
                    }
                    loadedData.push(node);
                }
            }
            loadedData = _.uniq(loadedData);
            for (const node of loadedData) {
                if (node) {
                    node.children = this.getChildren(node);
                    node.expanded = node.children.length === 0 ? true : node.children[0].visible;
                } else {
                    this.children = this.getChildren(null);
                }
            }
            this.sortTreeNode(true);
            return loadedData;
        };
        /**
         * 加载数据(动态)，只加载不同部分
         * @param {Array} datas
         * @return {Array} 加载到树的数据
         * @privateA
         */
        _loadData(datas) {
            datas = datas instanceof Array ? datas : [datas];
            const loadedData = [], resortData = [];
            for (const data of datas) {
                let node = this.getItems(data[this.setting.id]);
                if (node) {
                    const parent = this.getItems(node[this.setting.pid]);
                    for (const prop in data) {
                        if (data[prop] !== undefined && data[prop] !== node[prop]) {
                            node[prop] = data[prop];
                            if (parent && resortData.indexOf(parent) === -1) {
                                resortData.push(parent);
                            }
                        }
                    }
                    loadedData.push(node);
                } else {
                    const keyName = itemsPre + data[this.setting.id];
                    const node = JSON.parse(JSON.stringify(data));
                    this.items[keyName] = node;
                    this.datas.push(node);
                    node.expanded = true;
                    node.visible = true;
                    loadedData.push(node);
                    if (resortData.indexOf(node) === -1) {
                        resortData.push(node);
                    }
                    const parent = this.getItems(node[this.setting.pid]);
                    if (parent && resortData.indexOf(parent) === -1) {
                        resortData.push(parent);
                    } else {
                        resortData.push(this.setting.rootId);
                    }
                }
            }
            for (const node of resortData) {
                if (node && node !== this.setting.rootId) {
                    node.children = this.getChildren(node);
                } else {
                    this.children = this.getChildren(null);
                }
            }
            this.sortTreeNode(true);
            for (const node of loadedData) {
                if (!node.expanded) {
                    this.setExpanded(node, true);
                }
            }
            return loadedData;
        };
        /**
         * 清理数据(动态)
         * @param datas
         * @private
         */
        _freeData(datas) {
            datas = datas instanceof Array ? datas : [datas];
            const freeDatas = [];
            const removeArrayData = function (array, data) {
                const index = array.indexOf(data);
                array.splice(index, 1);
            };
            for (const data of datas) {
                const node = this.getItems(data);
                if (node) {
                    freeDatas.push(node);
                    node.deleteIndex = this.nodes.indexOf(node);
                    delete this.items[itemsPre + node[this.setting.id]];
                    if (node[this.setting.pid] !== this.setting.rootId) {
                        const parent = this.getItems(node[this.setting.pid]);
                        if (parent) {
                            removeArrayData(parent.children, node);
                        }
                    } else {
                        removeArrayData(this.children, node);
                    }
                    removeArrayData(this.datas, node);
                }
            }
            for (const node of freeDatas) {
                removeArrayData(this.nodes, node);
            }
            return freeDatas;
        };

        /**
         * 因为提交其他数据，引起的树结构数据更新，调用该方法
         *
         * @param data - 更新的数据 {update, create, delete}
         * @returns {{}}
         */
        loadPostData(data) {
            const result = {};
            if (data.delete) {
                result.delete = this._freeData(data.delete);
            }
            if (data.create) {
                result.create = this._loadData(data.create);
            }
            if (data.update) {
                result.update = this._updateData(data.update);
            }
            return result;
        }

        recursiveFun(children, fun) {
            if (!fun) return;
            if (!children || children.length === 0) return;

            for (const c of children) {
                this.recursiveFun(c.children, fun);
                fun(c);
            }
        }
    }
    return new DragTree(setting);
};