main.go

package main

import (
	SYS "syscall"
	"time"

	"github.com/go-fsnotify/fsnotify"
	death "github.com/vrecan/death"
)

type state struct {
	stat     stat
	duration time.Duration
}

var emptyState = state{emptyStat, 0}

func whenCreation(
	events <-chan fsnotify.Event) <-chan fsnotify.Event {

	out := make(chan fsnotify.Event)
	write := fsnotify.Write
	create := fsnotify.Create

	go func() {
		for event := range events {
			switch {
			case event.Op&create == create:
				out <- event
			case event.Op&write == write:
				out <- event
			}
		}
	}()

	return out
}

func collect(
	fileReader fileReader,
	decoder func(
		fileReader,
		string,
		stat) (stat, println),
	events <-chan fsnotify.Event,
	ticker <-chan time.Time) <-chan stat {

	stats := make(chan stat)

	go func() {
		state := emptyState

		for {
			select {

			case event := <-events:
				eventTime := time.Now()
				newStat, println :=
					decoder(fileReader, event.Name, state.stat)
				state.duration += time.Since(eventTime)
				state.stat = newStat
				runPrintln(println)

			case <-ticker:
				stats <- calcAvg(state)
				state = emptyState
			}
		}
	}()

	return stats
}

func main() {
	w := logErrors(watchInput("input/"))

	go printStats(collect(
		runReadfile,
		decodeFile,
		whenCreation(w.watcher.Events),
		time.NewTicker(time.Second).C))

	death.NewDeath(SYS.SIGINT, SYS.SIGTERM).WaitForDeath(w)
}