<!-- el-select & el-tree 下拉树形选择 -->
<template>
    <el-select ref="selectTree" :value="value" v-model="valueName" :multiple="multiple" :clearable="clearable" @clear="clearHandle" @change="changeValue">
        <el-option :value="valueName" class="options">
            <el-tree
                    id="tree-option"
                    ref="selectTree"
                    :accordion="accordion"
                    :data="options"
                    :props="props"
                    :node-key="props.value"
                    @node-click="handleNodeClick">
                <span slot-scope="{ data }">
                    <i :class="[data.color!=null?'ification_col':'']" :style="{'background-color':data.color}"></i>&nbsp;&nbsp;{{ data.name }}
                </span>
            </el-tree>
        </el-option>
    </el-select>
</template>
<script>
    export default {
        name: "el-tree-select",
        props: {
            // 配置项
            props: {
                type: Object,
                default: () => {
                    return {
                        value: 'id',
                        children: 'children',
                        label: 'name'
                    }
                }
            },
            // 选项列表数据(树形结构的对象数组)
            options: {
                type: Array,
                default: () => {
                    return []
                }
            },
            // 初始值（单选）
            value: {
                type: Object,
                default: () => {
                    return {}
                }
            },
            // 初始值（多选）
            valueMultiple: {
                type: Array,
                default: () => {
                    return []
                }
            },
            // 可清空选项
            clearable: {
                type: Boolean,
                default: true
            },
            // 自动收起
            accordion: {
                type: Boolean,
                default: false
            },
            // 是否多选
            multiple: {
                type: Boolean,
                default: false
            }
        },
        data() {
            return {
                resultValue: [], // 传给父组件的数组对象值
                valueName: this.multiple ? [] : '' // 输入框显示值
            }
        },
        watch: {
            value() {
                this.resultValue = this.multiple ? this.valueMultiple : this.value;   // 初始值
                this.initHandle()
            }
        },
        mounted() {
            this.resultValue = this.multiple ? this.valueMultiple : this.value;   // 初始值
            this.initHandle();
        },
        methods: {
            // 初始化显示
            initHandle() {
                if (this.resultValue) {
                    if(this.multiple) {
                        // 多选
                        this.resultValue.forEach(item => this.valueName.push(item.name));
                    } else {
                        // 单选
                        this.valueName = this.resultValue.name;
                    }
                }
                this.initScroll()
            },
            // 初始化滚动条
            initScroll() {
                this.$nextTick(() => {
                    let scrollWrap = document.querySelectorAll('.el-scrollbar .el-select-dropdown__wrap')[0]
                    let scrollBar = document.querySelectorAll('.el-scrollbar .el-scrollbar__bar')
                    scrollWrap.style.cssText = 'margin: 0px; max-height: none; overflow: hidden;'
                    scrollBar.forEach(ele => ele.style.width = 0)
                })
            },
            // 切换选项
            handleNodeClick(node) {
                // 点击叶子节点后被选中
                if(this.multiple) {
                    // 多选（判重后添加）
                    let num = 0;
                    this.valueName.forEach(item => {
                        item == node[this.props.label] ? num++ : num;
                    })
                    if(num == 0) {
                        this.valueName.push(node[this.props.label]); // 输入框显示值
                        this.resultValue.push(node);
                    }
                } else {
                    // 单选
                    this.$refs.selectTree.blur();
                    this.valueName = node[this.props.label];
                    this.resultValue = node;
                }
                this.$emit('getValue', this.resultValue);
            },
            // 从输入框中直接删除某个值时
            changeValue(val) {
                if(this.multiple) {
                    // 多选（同时删掉传给父组件中多余的值，再传给父组件）
                    this.resultValue.map((item, index) => {
                        let i = val.indexOf(item.name)
                        if(i == -1) {
                            this.resultValue.splice(index, 1)
                        }
                    })
                    this.$emit('getValue', this.resultValue);
                } else {
                    // 单选
                    this.$emit('getValue', val);
                }
            },
            // 清除选中
            clearHandle() {
                this.valueName = this.multiple ? [] : ''
                this.resultValue = []
                this.clearSelected()
                this.$emit('getValue', this.resultValue)
            },
            // 清空选中样式
            clearSelected() {
                let allNode = document.querySelectorAll('#tree-option .el-tree-node')
                allNode.forEach((element) => element.classList.remove('is-current'))
            }
        }
    }
</script>
<style scoped>
    .el-scrollbar .el-scrollbar__view .el-select-dropdown__item {
        height: auto;
        max-height: 300px;
        padding: 0;
        overflow: hidden;
        overflow-y: auto;
    }
    .el-select-dropdown__item.selected {
        font-weight: normal;
    }
   .el-tree .el-tree-node__content {
        height: auto;
        padding: 0 20px;
    }
    .el-tree-node__label {
        font-weight: normal;
    }
    .el-tree >>> .is-current .el-tree-node__label {
        color: #409EFF;
        font-weight: 700;
    }
    .el-tree >>> .is-current .el-tree-node__children .el-tree-node__label {
        color: #606266;
        font-weight: normal;
    }
    .el-popper {
        z-index: 9999;
    }
    .ification_col {
        width: 20px;
        height: 10px;
        display: inline-block;
    }
</style>