git ssb

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var pull = require('pull-stream')
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var Reduce = require('flumeview-reduce')
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var I = require('./valid')
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var deepEquals = require('deep-equals')
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var crypto = require('crypto')
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var ssbKeys = require('ssb-keys')
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var ssbClient = require('ssb-client')
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var types = require('./types')
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function code(err, c) {
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  err.code = 'user-invites:'+c
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  return err
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}
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function all (stream, cb) {
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  return pull(stream, pull.collect(cb))
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}
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function isFunction (f) {
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  return typeof f === 'function'
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}
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function isObject (o) {
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  return o && typeof o == 'object'
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}
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exports.name = 'user-invites'
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exports.version = '1.0.0'
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exports.manifest = {
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  getInvite: 'async',
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  confirm: 'async',
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  create: 'async'
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}
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exports.permissions = {
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//  master: {allow: ['create']}
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}
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// KNOWN BUG: it's possible to accept an invite more than once,
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// but peers will ignore subsequent acceptances. it's possible
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// that this could create confusion in certain situations.
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// (but you'd get a feed that some peers thought was invited by Alice
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// other peers would think a different feed accepted that invite)
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// I guess the answer is to let alice reject the second invite?)
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// that would be easier to do if this was a levelreduce? (keys: reduce, instead of a single reduce?)
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exports.init = function (sbot, config) {
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  var init = false
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  var layer = sbot.friends.createLayer('user-invites')
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  var caps = config.caps || {}
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  caps.userInvite = caps.userInvite || require('./cap')
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  function reduce (acc, data, _seq) {
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    if(!acc) acc = {invited: {}, invites:{}, accepts: {}, hosts: {}}
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    var msg = data.value
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    var invite, accept
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    if(types.isInvite(msg, caps)) {
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      //TODO: validate that this is a msg we understand!
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      invite = msg
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      accept = acc.accepts[data.key]
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    }
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    else if(types.isAccept(msg, caps)) {
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      accept = msg
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      invite = acc.invites[accept.content.receipt]
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    }
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    else if(types.isConfirm(msg, caps)) {
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      //TODO: just for when we are the guest, but we need to make sure at least one confirm exists.
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      accept = msg.content.embed
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      invite = acc.invites[accept.content.receipt]
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    }
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    if(invite && accept) {
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      if(invite === true)
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        return acc
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      var invite_id = accept.content.receipt
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      try { I.verifyAccept(accept, invite, caps) }
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      catch (err) { return acc }
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      //fall through from not throwing
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      //delete matched invites, but _only_ if they are VALID. (returned in the catch if invalid)
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      delete acc.accepts[invite_id]
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      //but remember that this invite has been processed.
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      acc.invites[invite_id] = true
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      acc.hosts[invite.author] = acc.hosts[invite.author] || {}
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      acc.hosts[invite.author][accept.author] = 1
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      if(init) {
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        //interpret accepting an invite as a mutual follow.
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        layer(invite.author, accept.author, 1)
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        layer(accept.author, invite.author, 1)
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      }
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    }
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    else if(invite)
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      acc.invites[data.key] = invite
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    else if(accept)
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      acc.accepts[accept.receipt] = accept
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    return acc
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  }
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  var initial = {invites: {}, accepts: {}, hosts: {}}
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  var state
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  //a hack here, so that we can grab a handle on invites.value.set
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  var invites = sbot._flumeUse('user-invites', function (log, name) {
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    var _invites = Reduce(2, reduce, null, null, initial)(log, name)
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    state = _invites.value
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    return _invites
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  })
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  invites.get(function (_, invites) {
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    var g = {}
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    if(!invites) layer({})
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    else {
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      //interpret accepted invites as two-way, but only store a minimal host->guest data structure
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      for(var j in invites.hosts)
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        for(var k in invites.hosts[j])
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          g[j][k] = g[k][j] = 1
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      init = true
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      layer(g)
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    }
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  })
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  sbot.auth.hook(function (fn, args) {
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    var id = args[0], cb = args[1]
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    invites.get(function (err, v) {
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      if(err) return cb(err)
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      for(var k in v.invites) {
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        if(v.invites[k].content.invite === id) {
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          return cb(null, {
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            allow: ['userInvites.getInvite', 'userInvites.confirm'],
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            deny: null
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          })
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        }
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      }
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      fn.apply(null, args)
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    })
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  })
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  //retrive full invitation.
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  invites.getInvite = function (invite_id, cb) {
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    var self = this
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    invites.get(function (err, v) {
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      var invite = v.invites[invite_id]
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      if(err) return cb(err)
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      if(!invite)
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        cb(code(
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          new Error('unknown invite:'+invite_id),
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          'unknown-invite'
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        ))
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      else if(invite === true)
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        //TODO just retrive all confirmations we know about
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        //via links.
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        sbot.get(invite_id, cb)
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      //only allow the guest to request their own invite.
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      else if(self.id !== invite.content.invite)
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        cb(code(
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          new Error('invite did not match client id'),
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          'invite-mismatch'
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        ))
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      else
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        cb(null, v.invites[invite_id])
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    })
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  }
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  function getResponse (invite_id, test, cb) {
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    return all(
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      sbot.links({dest: invite_id, values: true, keys: false, meta: false}),
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      function (err, confirms) {
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        if(err) cb(err)
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        else cb(null,
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          confirms.filter(function (e) {
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            try {
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              return test(e)
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            } catch (err) {
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              return false
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            }
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          })[0]
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        )
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      }
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    )
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  }
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  var accepted = {}
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  function getConfirm (invite_id, accept, cb) {
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    getResponse(invite_id, function (msg) {
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      return (
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        msg.content.type === 'user-invite/confirm' &&
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        msg.content.embed.content.receipt === invite_id &&
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        deepEquals(msg.content.embed, accept)
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      )
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    }, cb)
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  }
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  function getAccept (invite_id, cb) {
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    getResponse(invite_id, function (msg) {
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      return (
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        msg.content.type === 'user-invite/accept' &&
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        msg.content.receipt === invite_id
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      )
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    }, cb)
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  }
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  //used to request that a server confirms your acceptance.
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  invites.confirm = function (accept, cb) {
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    var invite_id = accept.content.receipt
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    //check if the invite in question hasn't already been accepted.
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    getConfirm(invite_id, accept, function (err, confirm) {
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      if(err) return cb(err)
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      if(confirm) return cb(null, confirm)
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      sbot.get(invite_id, function (err, invite) {
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        try {
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          I.verifyAccept(accept, invite, caps)
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        } catch (err) {
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          return cb(err)
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        }
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        //there is a little race condition here, if accept is called again
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        //before this write completes, it will write twice, so just return an error.
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        if(accepted[invite_id]) return cb(new Error('race condition: try again soon'))
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        accepted[invite_id] = true
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        sbot.publish({
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          type: 'user-invite/confirm',
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          embed: accept,
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          //second pointer back to receipt, so that links can find it
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          //(since it unfortunately does not handle links nested deeper
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          //inside objects. when we look up the message,
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          //confirm that content.embed.content.receipt is the same)
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          receipt: accept.content.receipt
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        }, function (err, data) {
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          delete accepted[invite_id]
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          cb(err, data.value)
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        })
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      })
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    })
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  }
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  //retrive pubs who might be willing to confirm your invite. (used when creating an invte)
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  function getNearbyPubs (opts, cb) {
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    var maxHops = opts.hops || 2
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    sbot.deviceAddress.getState(function (err, state) {
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      if(err) return cb(explain(err, 'could not retrive any device addresses'))
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      sbot.friends.hops({hops: opts.hops, reverse: true}, function (err, hops) {
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        if(err) return cb(explain(err, 'could not retrive nearby friends'))
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        var near = []
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        for(var k in state) {
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          var da = state[k]
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          if(hops[k] <= maxHops) {
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            near.push({
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              id: k,
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              address: da.address,
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              hops: hops[k],
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              availability: da.availability
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            })
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          }
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        }
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        //sort by reverse hops, then by decending availability.
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        //default availibility
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        near.sort(function (a, b) {
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          return (
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            a.hops - b.hops ||
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            b.availability - a.availability
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          )
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        })
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        cb(null, near)
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      })
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    })
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  }
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  invites.create = function (opts, cb) {
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    if(isFunction(opts))
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      return opts(new Error ('user-invites: expected: options *must* be provided.'))
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    getNearbyPubs(opts, function (err, near) {
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      var seed = crypto.randomBytes(32)
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      sbot.identities.publishAs({
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        id: opts.id || sbot.id,
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        content: I.createInvite(seed, opts.id || sbot.id, opts.reveal, opts.private, caps)
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      }, function (err, data) {
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        cb(null, {
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          seed: seed,
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          invite: data.key,
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          pubs: near,
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        })
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      })
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    })
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  }
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  //try each of an array of addresses, and cb the first one that works.
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  function connectFirst (keys, pubs, cb) {
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    var n = 0, err
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    pubs.forEach(function (addr) {
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      n++
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      ssbClient(keys, {
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        remote: addr,
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        caps: caps,
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        manifest: {
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          userInvites: {
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            getInvite: 'async',
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            confirm: 'async'
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          }
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        }
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      }, function (_err, rpc) {
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        if(n > 0 && rpc) {
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          n = -1
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          cb(null, rpc)
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        } else {
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          err = err || _err
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        }
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        if(--n == 0) cb(err)
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      })
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    })
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  }
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  //TODO: check if invite is already held locally
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  //      if so, just get it. when got, update local db.
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  invites.openInvite = function (invite, cb) {
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    invites.getInvite(invite.invite, function (err, msg) {
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      if(msg)
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        next(msg)
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      else {
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        var pubs = invite.pubs
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        var keys = ssbKeys.generate(null, invite.seed)
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        connectFirst(keys, pubs, function (err, rpc) {
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          if(err) return cb(err)
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          rpc.userInvites.getInvite(invite.invite, function (err, msg) {
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            if(err) return cb(err)
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            next(msg)
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          })
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        })
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      }
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      function next (msg) {
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        var invite_id = '%'+ssbKeys.hash(JSON.stringify(msg, null, 2))
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        if(invite.invite !== invite_id)
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          return cb(new Error(
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            'incorrect invite was returned! expected:'+invite.invite+', but got:'+inviteId
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          ))
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        var opened
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        try { opened = I.verifyInvitePrivate(msg, invite.seed, caps) }
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        catch (err) { return cb(err) }
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        //UPDATE REDUCE STATE.
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        // this is a wee bit naughty, because if you rebuild the index it might not have this invite
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        // (until you replicate it, but when you do the value won't change)
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        state.set(reduce(state.value, {key: invite_id, value:msg}, invites.since.value))
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        cb(null, msg, opened)
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      }
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    })
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  }
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  invites.acceptInvite = function (opts, cb) {
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    var invite = isObject(opts.invite) ? opts.invite : opts
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    var invite_id = invite.invite
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    var id = opts.id || sbot.id
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    var pubs = invite.pubs
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    var keys = ssbKeys.generate(null, invite.seed)
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    //check wether this invite is already accepted.
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    //or if the acceptance has been publish, but not yet confirmed.
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    getAccept(invite_id, function (err, accept) {
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      if(accept) next(accept)
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      else {
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        invites.openInvite(invite, function (err, invite_msg, opened) {
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          sbot.identities.publishAs({
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            id: id,
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            content: I.createAccept(invite_msg, invite.seed, id, caps)
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          }, function (err, accept) {
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            if(err) cb(err)
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            else {
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              state.set(reduce(state.value, accept, invites.since.value))
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              next(accept.value)
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            }
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          })
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        })
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      }
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    })
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    function next(accept) {
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      getConfirm(invite_id, accept, function (err, confirm) {
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        if(!confirm)
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          var pubs = invite.pubs
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          var keys = ssbKeys.generate(null, invite.seed)
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          connectFirst(keys, pubs, function (err, rpc) {
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            if(err) return cb(err)
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            rpc.userInvites.confirm(accept, function (err, confirm) {
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              //TODO: store confirms for us in the state.
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              cb(err, confirm)
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            })
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          })
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      })
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    }
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  }
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  return invites
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}
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