communication.js

var fold = require("reducers/fold")
var expand = require("reducers/expand")
var merge = require("reducers/merge")
var send = require("event/send")
var Emitter = require("./emitter-reduce")

var console = require("console")

var SignalChannel = require("signal-channel")
var FullyConnected = require("topology/fully")
var Model = require("scuttlebutt/model")

module.exports = communication

function communication(appState, identity) {
    var channel = SignalChannel("Colingo~colingo-feed~feed-demo")
    var model = Model()
    var seen = {}
    identity = identity || defaultIdentity

    FullyConnected(channel, function (conn, opener) {
        var peerId = conn.peerId

        console.log("connected to peer", peerId)

        if (opener) {
            hookUp(conn.createStream("model"))
        } else {
            conn.on("connection", function (stream) {
                if (stream.meta === "model") {
                    hookUp(stream)
                }
            })
        }
    })

    return merge([
        expand(Emitter(model, "change"), function (tuple) {
            var key = tuple[0]
            var item = tuple[1]
            var id = identity(item)

            if (!id) {
                throw new Error("got item that does not have id from Model")
            }

            if (seen[id]) {
                return
            }

            console.log("got a value", key, item)

            seen[id] = true

            return item
        })
        , expand(appState, function (item) {
            var id = identity(item)

            if (!id) {
                throw new Error("got item that does not have id from feed")
            }

            if (seen[id]) {
                return
            }

            console.log("setting a value (item)", item)

            seen[id] = true

            model.set(id, item)
        })
    ])

    function hookUp(stream) {
        console.log("hookedUp", stream.meta)

        stream.
            pipe(model.createStream()).
            pipe(stream)
    }
}

function defaultIdentity(item) {
    return item.value.id
}