carthesianMultiplication.js

({ babel: false })

const range = require('lodash/range');

const attributeItems = {
  year: [
    '2018', '2017'
  ],
  quarter: [
    'Q1', 'Q2', 'Q3', 'Q4'
  ],
  country: [
    'CZ', 'SK'
  ],
  manufacturer: [
    'BMW', 'VW', 'Škoda'
  ],
  measureGroup: [ 'MEASURE_1', 'MEASURE_2' ]
};

const resultSpec = {
  dimensions: [
      {
          itemIdentifiers: ['country', 'manufacturer']
      },
      {
          itemIdentifiers: ['year', 'quarter', 'measureGroup']
      }
  ]
};

const result = resultSpec.dimensions.reduce((result, dimension) => {
  const dimensionItems = dimension.itemIdentifiers.reverse().map(itemIdentifier => attributeItems[itemIdentifier]);
  const headers = dimensionItems.reduce((headerItems, dimensionItem, dimensionItemIndex)=>{
    if (headerItems.length === 0) {
      return [dimensionItem];
    }
    const previousValueCount = headerItems[0].length;
    const currentValueCount = dimensionItem.length;
    const multipliedHeaderItems = headerItems.map(headerItemValues => {
      return range(currentValueCount).reduce((itemValues) => {
        return [...itemValues, ...headerItemValues];
      }, []);
    });
    
    const multipliedCurrentValues = range(previousValueCount * currentValueCount).map((itemValueIndex) => {
      return dimensionItem[Math.floor(itemValueIndex / previousValueCount)]
    }, []);

    return [multipliedCurrentValues, ...multipliedHeaderItems];
  }, [] )
  return {
    ...result,
    headerItems: [
      ...result.headerItems,
      headers
    ]
  };
}, { data: [], headerItems: [] });

console.log('rows attributes', result.headerItems[0].length);
console.log(result.headerItems[0]);
console.log('column attributes', result.headerItems[1].length);
console.log(result.headerItems[1]);