An incomplete example of syncing lenses

lens-sync-example.js

const PouchDB = require('pouchdb')
const tmp = require('tmp');
const assert = require('assert');
const R = require('ramda')
PouchDB.plugin(require('crypto-pouch'));

// Create a temporary directory
var tmpobj = tmp.dirSync();
let dbLoc = `${tmpobj.name + '/mydb'}`
console.log(`dbLoc = ${dbLoc}`)


let myProfile = {
  _id: 'profile',
  firstName: 'Homer',
  lastName: 'Simpson',
  Addresses: [{
    label: 'home',
    street: '1234 Fake St.',
    state: 'Unknown',
    city: 'Springfield'
  }],
  phones: [{
      label: 'home',
      number: '15051234567'
    },
    {
      label: 'cell',
      number: '15057654321'
    }
  ],
  emails: [{
      label: 'personal',
      email: 'maxpower@hotmail.com'
    },
    {
      label: 'work',
      email: 'hjsimp@nuclear.com'
    }
  ]
}


async function createData(db, data) {
  let newData = Object.assign({}, data)
  newData['lensRefs'] = [] // What lenses reference this data
  newData['dateCreated'] = new Date().getTime()
  newData['lastModified'] = new Date().getTime()
  let result = await db.put(newData)
  console.log('create Data = ', result)
  return result
}

async function updateData(db, id, newData, updateLensFunc) {
  newData['lastModified'] = new Date().getTime()
  await db.put(newData)
  newData.lensRefs.map(ref => {
    updateLens(db, ref, updateLensFunc)
  })
}

async function updateLens(db, lensId, updateLensFunc) {
  try {
    let lensRef = await db.get(lensId)
    let lens = {}
    let a = lensRef.dataRefs.map(async ref => {
      let result = await getData(db, ref.id)
      console.log('result = ', result)
      if (ref.srcPaths.length !== ref.destPaths.length) {
        throw (new Error('Src path length must match destination path length'))
      }

      R.zip(ref.srcPaths, ref.destPaths).map(([src, dest]) => {
        console.log(`src = '${src}, dest = ${dest}'`)
        try {
          let val = R.path(src, result)
          lens[dest] = val

        } catch (e) {
          console.log('Could not retrieve path for src data, skipping for output data')
        }
      })
    })

    await Promise.all(a).catch(e => {
      console.log('e = ', e)
    })
    // update the Lens with the new data.
    await updateLensFunc(lensRef.lensPath, lens)
    lensRef.lastModified = new Date().getTime()
  } catch (e) {
    console.log('e = ', e)
  }
}

async function getData(db, id) {
  let result = await db.get(id)
  return result
}


async function createLens(db, lensLabel, lensDescription, dataRefs, createLensFunc) {

  let lens = {}
  let lensId = `lenses/${lensLabel}`

  let a = dataRefs.map(async ref => {
    let result = await getData(db, ref.id)
    if (ref.srcPaths.length !== ref.destPaths.length) {
      throw (new Error('Src path length must match destination path'))
    }

    R.zip(ref.srcPaths, ref.destPaths).map(([src, dest]) => {
      console.log(`src = '${src}, dest = ${dest}'`)
      let val = R.path(src, result)
      if (!val) throw (new Error(`Source path "${src}" does not have a value associated with it`))
      lens[dest] = val
    })
    // Reference this lens in the original data set
    result.lensRefs.push(lensId)
    let newData = await db.put(result)
    console.log('updated new data: ', newData)
  })

  await Promise.all(a)

  // Use the createLensFunc to create a lens
  console.log('lens = ', lens)
  let newLens = await createLensFunc(lens)
  let lensData = {
    _id: lensId,
    lensDescription: lensDescription,
    lensPath: newLens.lensPath, // Location to new lens locally, i.e. /lumen
    lensUrl: newLens.lensUrl, // URL of where the lens can be found, i.e. dat://1234...
    dataRefs: dataRefs, // could be more than on data ref
    dateCreated: new Date().getTime(),
    lastModified: new Date().getTime()
  }
  await db.put(lensData)

  return lensData
}

async function test() {
  try {
    let pouch = new PouchDB(dbLoc);
    pouch.crypto('passwords');

    let created = await createData(pouch, myProfile)
    let result = await getData(pouch, created.id)

    // attempt to get DB with bad password
    try {
      pouch.crypto('bad password')
      assert(false, 'Bad password should fail here!')
      // let badResult = getData(pouch, created.id)
    } catch (e) {
      pouch.crypto('passwords');
      assert(true, 'Could not get data because bad password!')
    }

    // Test Create a lens

    // These are the desired paths to share. The source paths
    let srcPaths = [
      ['firstName'],
      ['phones', 0, 'number'],
      ['emails', 1, 'email']
    ]

    // The destination paths
    let destPaths = [
      ['name'],
      ['preferredPhoneNumber'],
      ['preferredEmail']
    ]

    let dataRef = {
      id: created.id,
      srcPaths: srcPaths,
      destPaths: destPaths
    }
    // A lens can be composed of references to multiple data sources
    let dataRefs = [dataRef]

    // This function would create the dat url and host it.
    function createLensFunc(data) {
      return {
        lensPath: '/some/path/lens.obj',
        lensUrl: 'dat://1234....'
      }
    }

    // This would update the lens DB and also generate the dat url and
    // local lens location
    let lensInfo = await createLens(pouch, 'Lowes Data',
      'Some information needed by Lowes', dataRefs, createLensFunc)

    let orig = await pouch.get(created.id)
    orig.firstName = 'Max'
    orig.lastName = 'Power'

    function updateLensFunc(lensPath, data) {
      console.log('updating lens at location', lensPath)
      console.log('with data ', data)
    }
    console.log('the orig = ', orig)
    // Make sure that if we update data, that the lens is updated as well.
    await updateData(pouch, created.id, orig, updateLensFunc)


    console.log('lensInfo =', lensInfo)
  } catch (e) {
    assert(false, 'Received an error in test: ' + e)
  }
}

test().catch(e => {
  console.log('There was an issue: ', e)
})