Implementing the observable pattern and solving the real problem of listening for button presses

6-overvable-pattern-implementation.js

import {
    BUTTON_UP,
    doButtonPressAction,
} from './actions'

const createButtonObserver = bluetoothAddress => observer => (
    new FlicConnectionChannel(bluetoothAddress)
    .on(
        'buttonUpOrDown',
        buttonPressState => observer.next(buttonPressState)
    )
)

const listenForButtonPress = bluetoothAddress => {
    const buttonUpDown$ = (
        Rx.Observable
        .create(
            createButtonObserver(bluetoothAddress)
        )
    )

    buttonUpDown$
    .buffer(
        buttonUpDown$
        .debounceTime(300)
    )
    .map(buttonStates => (
        buttonStates[0] === BUTTON_UP
        ? buttonStates.slice(1)
        : buttonStates
    ))
    .filter(buttonPressStates => buttonPressStates.length > 0)
    .map(buttonStates => ({
        numDown: getNumberOfDowns(buttonStates),
        numUp: getNumberOfUps(buttonStates),
    }))
    .subscribe(
        doButtonPressAction(bluetoothAddress)
    )
}