index.js

const crypto = require('@ddatabase/crypto')
const ddatabase = require('ddatabase')
const storage = require('./storage')

module.exports = multiKey

function multiKey (feed, keyPair, opts) {
  if (!keyPair) keyPair = crypto.keyPair()

  const key = keyPair.key || keyPair.publicKey
  const other = ddatabase(storage(feed, keyPair), key, opts)

  feed.ready(function () {
    other.ready(function () {
      other.bitfield = feed.bitfield
      other.tree = feed.tree
    })
  })

  feed.on('download', ondownload)
  feed.on('append', onappend)

  other.on('close', function () {
    feed.removeListener('download', ondownload)
    feed.removeListener('append', onappend)
  })

  return other

  function ondownload (index, data) {
    other._announce({ start: index }, null)
    other.emit('download', index, data, null)
  }

  function onappend () {
    const offset = other.length
    other.length = feed.length
    other.byteLength = feed.byteLength
    if (!feed.writable) return other.emit('append')

    const message = other.length - offset > 1
      ? { start: offset, length: other.length - offset }
      : { start: offset }

    other._announce(message)
    other.emit('append')
  }
}