cobox-group/lib/handlers/state.js

a p2p private group for files and application-layer data

const Indexer = require('kappa-sparse-indexer')
const Query = require('kappa-view-query')
const sub = require('subleveldown')
const { Header } = require('hypertrie/lib/messages')
const { fromMultifeed } = require('kappa-view-query/util')
const { State } = require('kappa-drive/messages')
const { scopeFeeds, tryDecode } = require('kappa-drive')
const maybe = require('call-me-maybe')
const { EventEmitter } = require('events')
const collect = require('collect-stream')
const crypto = require('cobox-crypto')
const debug = require('debug')('cobox-group:state-handler')

const INDEXES = [
  { key: 'log', value: [['value', 'timestamp']] },
  { key: 'fil', value: [['value', 'filename'], ['value', 'timestamp']] }
]

class StateHandler extends EventEmitter {
  /**
   * create a drive state handler
   * @constructor
   */
  constructor (opts = {}) {
    super()
    this._id = crypto.randomBytes(2).toString('hex')
    this.drive = opts.drive
    this.core = opts.core
    this.feeds = opts.feeds
    this.db = opts.db

    this._validator = this._validator.bind(this)

    this.idx = new Indexer({
      db: sub(this.db, 'idx'),
      name: this._id
    })

    this.view = Query(sub(this.db, 'view'), {
      indexes: INDEXES,
      validator: this._validator,
      getMessage: fromMultifeed(this.feeds, {
        validator: this._validator
      })
    })

    this.core.use('state', this.idx.source(), this.view)
    this.read = this.core.view.state.read

    this.feeds.on('feed', (feed) => {
      if (this.idx.feed(feed.key)) return
      scopeFeeds(feed, (err) => {
        if (!err) this.idx.add(feed, { scan: true })
      })
    })
  }

  ready (callback) {
    return maybe(callback, new Promise((resolve, reject) => {
      this.drive.ready((err) => {
        if (err) return reject(err)

        this._feed = this.drive.metadata

        this.core.ready('state', (err) => {
          if (err) return reject(err)
          return resolve()
        })
      })
    }))
  }

  query (query, opts = {}) {
    if (opts.live) return this.read({ query: [query], live: true, ...opts })

    return new Promise((resolve, reject) => {
      collect(this.read({ query: [query] }), (err, msgs) => {
        if (err) return reject(err)
        resolve(msgs)
      })
    })
  }

  _open (callback) {
  }

  _validator (msg) {
    var value = tryDecode(msg.value)
    if (!value) return false
    msg.value = value
    debug(this._id, msg)
    return msg
  }
}

module.exports = (...args) => new StateHandler(...args)
module.exports.StateHandler = StateHandler