Change the blink pattern to use a pattern specified by an object.

src/lib/blink.coffee

@@ -3,37 +3,41 @@ fs = Promise.promisifyAll require 'fs'
 
 # Helps in blinking the LED from the given end point.
 module.exports = exports = (ledFile) ->
-	blink = (ms = 200) ->
+	ledOn = ->
 		fs.writeFileAsync(ledFile, 1)
+	ledOff = ->
+		fs.writeFileAsync(ledFile, 0)
+
+	blink = (ms = 200) ->
+		ledOn()
 		.delay(ms)
-		.then -> fs.writeFileAsync(ledFile, 0)
+		.then(ledOff)
 
 	blink.pattern = do ->
-		started = false
+		pattern =
-		interval = null
+			onDuration: 200
-		timeout = null
+			offDuration: 200
-		# This function lets us have sensible param orders,
+			blinks: 4
-		# and always have a timeout we can cancel.
+			pause: 1000
-		delay = (ms, fn) ->
+		blinking = null
-			timeout = setTimeout(fn, ms)
 		start = ->
-			interval = setInterval(blink, 400)
+			Promise.resolve([0...pattern.blinks]).cancellable()
-			delay 2000, ->
+			.each ->
-				# Clear the blinks after 2 second
+				blink(pattern.onDuration)
-				clearInterval(interval)
+				.delay(pattern.offDuration)
-				delay 2000, ->
+			.delay(pattern.pause)
-					# And then repeat again after another 2 seconds
+			.then ->
 				start()
 		return {
 			start: ->
-				return false if started
+				return false if blinking?
-				started = true
+				blinking = start()
-				start()
+				return
 			stop: ->
-				return false if not started
+				return false if not blinking?
-				started = false
+				blinking.cancel().catch(Promise.CancellationError, ->)
-				clearInterval(interval)
+				ledOff()
-				clearTimeout(timeout)
+				blinking = null
 		}
 
 	return blink