text: import jsonDiffer from 'fast-json-patch'
  import { cloneDeep } from 'lodash'
  
  /**
    converts non-initial history entries into diffs
    @param {array} longHistory
    @returns {array}
  */
  export function migrateFromSnapshotsToDiffs (longHistory) {
    return (
      longHistory
      // convert non-initial history entries into diffs
        .map((entry, index) => {
          if (index === 0) {
            return entry
          }
          return generateHistoryEntry(longHistory[index - 1], entry)
        })
    )
  }
  
  /**
    Generates an array of history objects sense the previous state.
    The object has the keys
      op (the operation performed),
      path (the key and if a nested object then each key will be separated with a `/`)
      value
    with the first entry having the note and a timestamp when the change took place
    @param {Object} previousState - the previous state of the object
    @param {Object} newState - the update object
    @param {string} [note] - a optional note for the state change
    @returns {array}
  */
  export function generateHistoryEntry (previousState, newState, note) {
    const entry = jsonDiffer.compare(previousState, newState)
    // Add a note to the first op, since it breaks if we append it to the entry
    if (entry[0]) {
      if (note) {
        entry[0].note = note
      }
  
      entry[0].timestamp = Date.now()
    }
    return entry
  }
  
  /**
    Recovers previous txMeta state obj
    @returns {Object}
  */
  export function replayHistory (_shortHistory) {
    const shortHistory = cloneDeep(_shortHistory)
    return shortHistory.reduce((val, entry) => jsonDiffer.applyPatch(val, entry).newDocument)
  }
  
  /**
   * Snapshot {@code txMeta}
   * @param {Object} txMeta - the tx metadata object
   * @returns {Object} a deep clone without history
   */
  export function snapshotFromTxMeta (txMeta) {
    const shallow = { ...txMeta }
    delete shallow.history
    return cloneDeep(shallow)
  }
  