'use strict'

const debug = require('debug')
const log = Object.assign(debug('libp2p:ping'), {
  error: debug('libp2p:ping:err')
})
const errCode = require('err-code')
const { codes } = require('../errors')
const crypto = require('libp2p-crypto')
const { pipe } = require('it-pipe')
// @ts-ignore it-buffer has no types exported
const { toBuffer } = require('it-buffer')
const { collect, take } = require('streaming-iterables')
const { equals } = require('uint8arrays/equals')

const { PROTOCOL_NAME, PING_LENGTH, PROTOCOL_VERSION } = require('./constants')

/**
 * @typedef {import('../')} Libp2p
 * @typedef {import('multiaddr').Multiaddr} Multiaddr
 * @typedef {import('peer-id')} PeerId
 * @typedef {import('libp2p-interfaces/src/stream-muxer/types').MuxedStream} MuxedStream
 */

class PingService {
  /**
   * @param {import('../')} libp2p
   */
  static getProtocolStr (libp2p) {
    return `/${libp2p._config.protocolPrefix}/${PROTOCOL_NAME}/${PROTOCOL_VERSION}`
  }

  /**
   * @param {Libp2p} libp2p
   */
  constructor (libp2p) {
    this._libp2p = libp2p
  }

  /**
   * A handler to register with Libp2p to process ping messages
   *
   * @param {Object} options
   * @param {MuxedStream} options.stream
   */
  handleMessage ({ stream }) {
    return pipe(stream, stream)
  }

  /**
   * Ping a given peer and wait for its response, getting the operation latency.
   *
   * @param {PeerId|Multiaddr} peer
   * @returns {Promise<number>}
   */
  async ping (peer) {
    const protocol = `/${this._libp2p._config.protocolPrefix}/${PROTOCOL_NAME}/${PROTOCOL_VERSION}`
    // @ts-ignore multiaddr might not have toB58String
    log('dialing %s to %s', protocol, peer.toB58String ? peer.toB58String() : peer)

    const connection = await this._libp2p.dial(peer)
    const { stream } = await connection.newStream(protocol)

    const start = Date.now()
    const data = crypto.randomBytes(PING_LENGTH)

    const [result] = await pipe(
      [data],
      stream,
      (/** @type {MuxedStream} */ stream) => take(1, stream),
      toBuffer,
      collect
    )
    const end = Date.now()

    if (!equals(data, result)) {
      throw errCode(new Error('Received wrong ping ack'), codes.ERR_WRONG_PING_ACK)
    }

    return end - start
  }
}

module.exports = PingService