parser.js

import {
  split, pipe, converge, slice, unfold, pair, append, splitAt,
  lte, ifElse, length, concat,
  prop, over, lensProp,
  F,
} from 'ramda'

import {_BOL, _EOL} from './util'

const toTokens = pipe(split(' '), append(_EOL), concat([_BOL, _BOL, _BOL]))
const atLeastFour = pipe(length, lte(4))
const headlessTokens = slice(1, Infinity)

const nextCAW = pipe(slice(0,4), splitAt(-1))
const nextAndRest = converge(pair, [nextCAW, headlessTokens])
const tokensToCAWs = unfold(ifElse(atLeastFour, nextAndRest, F))

export const sentenceToLinks = pipe(toTokens, tokensToCAWs)

export default ({message$}) => ({
  parsed$: message$
    .filter(prop('text'))
    .map(over(lensProp('text'), sentenceToLinks))
    .multicast(),
})