makeStreamConfig.js.flow

import _ from 'lodash';
import getBorderCharacters from './getBorderCharacters';
import validateConfig from './validateConfig';

/**
 * Merges user provided border characters with the default border ("honeywell") characters.
 *
 * @param {Object} border
 * @returns {Object}
 */
const makeBorder = (border = {}) => {
  return Object.assign({}, getBorderCharacters('honeywell'), border);
};

/**
 * Creates a configuration for every column using default
 * values for the missing configuration properties.
 *
 * @param {number} columnCount
 * @param {Object} columns
 * @param {Object} columnDefault
 * @returns {Object}
 */
const makeColumns = (columnCount, columns = {}, columnDefault = {}) => {
  _.times(columnCount, (index) => {
    if (_.isUndefined(columns[index])) {
      columns[index] = {};
    }

    columns[index] = Object.assign({
      alignment: 'left',
      paddingLeft: 1,
      paddingRight: 1,
      truncate: Infinity,
      wrapWord: false
    }, columnDefault, columns[index]);
  });

  return columns;
};

/**
 * @typedef {Object} columnConfig
 * @property {string} alignment
 * @property {number} width
 * @property {number} truncate
 * @property {number} paddingLeft
 * @property {number} paddingRight
 */

/**
 * @typedef {Object} streamConfig
 * @property {columnConfig} columnDefault
 * @property {Object} border
 * @property {columnConfig[]}
 * @property {number} columnCount Number of columns in the table (required).
 */

/**
 * Makes a new configuration object out of the userConfig object
 * using default values for the missing configuration properties.
 *
 * @param {streamConfig} userConfig
 * @returns {Object}
 */
export default (userConfig = {}) => {
  validateConfig('streamConfig.json', userConfig);

  const config = _.cloneDeep(userConfig);

  if (!config.columnDefault || !config.columnDefault.width) {
    throw new Error('Must provide config.columnDefault.width when creating a stream.');
  }

  if (!config.columnCount) {
    throw new Error('Must provide config.columnCount.');
  }

  config.border = makeBorder(config.border);
  config.columns = makeColumns(config.columnCount, config.columns, config.columnDefault);

  return config;
};