/**
 * 合并相同数据，导出合并行所需的方法(只适合el-table)
 * @param {Array} dataArray el-table表数据源
 * @param {Array} mergeRowProp 合并行的列prop
 * @param {Array} sameRuleRowProp 相同合并规则行的列prop
 */
 export function getSpanMethod(dataArray, mergeRowProp, sameRuleRowProp) {

    /**
     * 要合并行的数据
     */
    const rowspanNumObject = {};

    //初始化 rowspanNumObject
    mergeRowProp.map(item => {
        rowspanNumObject[item] = new Array(dataArray.length).fill(1, 0, 1).fill(0, 1);
        rowspanNumObject[`${item}-index`] = 0;
    });

    //计算相关的合并信息
    for (let i = 1; i < dataArray.length; i++) {
        mergeRowProp.map(key => {
            const index = rowspanNumObject[`${key}-index`];
            if (dataArray[i][key] === dataArray[i - 1][key]) {
                rowspanNumObject[key][index]++;
            } else {
                rowspanNumObject[`${key}-index`] = i;
                rowspanNumObject[key][i] = 1;
            }

        });
    }

    /**
     * 添加同规则合并行的数据
     */
    if (sameRuleRowProp !== undefined) {
        let k = Object.keys(rowspanNumObject).filter(key => {
            if (!key.includes('index')) {
                return key
            }
        })[0]
        for (let prop of sameRuleRowProp) {
            rowspanNumObject[prop] = rowspanNumObject[k]
            rowspanNumObject[`${prop}-index`] = rowspanNumObject[`${k}-index`]
            mergeRowProp.push(prop)
        }
    }

    /**
     * 导出合并方法
     */
    const spanMethod = function ({row, column, rowIndex, columnIndex}) {
        if (mergeRowProp.includes(column['property'])) {
            const rowspan = rowspanNumObject[column['property']][rowIndex];
            if (rowspan > 0) {
                return {rowspan: rowspan, colspan: 1}
            }
            return {rowspan: 0, colspan: 0}
        }
        return {rowspan: 1, colspan: 1}
    };

    return spanMethod;
}