gofigure/lib/processor/merger.js

Configuration library for node

const _ = require('lodash');
const processorHelper = require('./processorHelper');

const { getFlattenedObject } = processorHelper;

const _emitChanges = (config, deletedKeys, changedKeyValues, eventEmitter) => {
  const changedObjects = changedKeyValues
    .map((kv) => kv.key)
    .reduce((changed, key) => {
      // split the key
      const keyParts = key.split('.');
      // if its a single path just return the orginal
      if (keyParts.length <= 1) {
        return changed;
      }
      // create all parent key paths so we can emit changes for not only the original changed
      // key but the parent key paths also
      const objectKeys = keyParts.slice(0, keyParts.length - 1).reduce((paths, keyPath) => {
        if (!paths.length) {
          // if its the first part of the key just initialize it
          return [keyPath];
        }
        // return the paths array plus the new key path
        return [...paths, `${_.last(paths)}.${keyPath}`];
      }, []);
      return _.uniq([...changed, ...objectKeys]);
    }, [])
    .map((key) => ({ key, value: _.get(config, key) }));
  // emit for each deleted key
  deletedKeys.forEach((key) => eventEmitter.emit(key, undefined));
  // get all changes unique by the path and sort by the path
  const allChanges = _.sortBy(_.uniq([...changedKeyValues, ...changedObjects], 'key'), 'key');
  // emit the events
  allChanges.forEach((kv) => eventEmitter.emit(kv.key, kv.value));
};

const _merge = (path, oldConfig, sourceConfig, opts) => {
  const options = opts || {};
  const { eventEmitter } = options;
  // check for deleted values
  const oldKeyMap = getFlattenedObject(oldConfig);
  const oldKeyMapKeys = Object.keys(oldKeyMap).sort();
  const sourceKeyMap = getFlattenedObject(sourceConfig);
  const sourceKeyMapKeys = Object.keys(sourceKeyMap).sort();
  const deletedKeys = _.difference(oldKeyMapKeys, sourceKeyMapKeys);
  const changedKeys = [];
  const mergedConfig = sourceKeyMapKeys.reduce((config, key) => {
    const oldValue = oldKeyMap[key];
    const newValue = sourceKeyMap[key];
    if (!_.isEqual(oldValue, newValue)) {
      changedKeys.push({ key, value: newValue });
    }
    _.set(config, key, newValue);
    return config;
  }, {});
  if (eventEmitter) {
    _emitChanges(mergedConfig, deletedKeys, changedKeys, eventEmitter);
  }
  return mergedConfig;
};

const merger = (oldConfig, newConfig, eventEmitter) =>
  _merge('', _.cloneDeep(oldConfig), _.cloneDeep(newConfig), eventEmitter);

module.exports = merger;