package main

import (
	"http"
	"os"
	"log"
	"time"
)

type State int

const (
	StatePaused = iota
	StateDownloading
	StateComplete
	StateError
)

func (state State) String() string {
	switch state {
	case StatePaused:
		return "Paused"
	case StateDownloading:
		return "Downloading"
	case StateComplete:
		return "Complete"
	case StateError:
		return "Error"
	}
	return "#Unknown"
}

func download(url string, sic, soc chan State) {
	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		log.Print("Error: NewRequest() : " + err.String())
		soc <- StateError
		return
	}

	// Disable keep-alive
	req.Close = true

	rsp, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Print("Error: Get() : " + err.String())
		soc <- StateError
		return
	}
	defer rsp.Body.Close()

	buf := make([]byte, 4096)

	for {
		select {
		case state := <-sic:
			if state != StateDownloading {
				log.Print("State: " + state.String())
				soc <- state
				return
			}
		default:
		}

		n, err := rsp.Body.Read(buf)
		if err != nil {
			if err == os.EOF {
				log.Print("State: Complete")
				soc <- StateComplete
				break
			}
			log.Print("Error: Read() : " + err.String())
			soc <- StateError
			break
		}

		if n > 0 {
			// Write data here
		}
	}
}

func main() {
//	if t, ok := http.DefaultTransport.(*http.Transport); ok {
//		log.Print("Keep-Alive Disabled")
//		t.DisableKeepAlives = true
//	}

	sic := make(chan State)
	soc := make(chan State)

	// Pause download after 5 seconds
	go func() {
		time.Sleep(5e9)
		log.Print("Pausing download...")
		sic <- StatePaused
	}()

	go download("http://mir.archlinux.fr/iso/latest/archlinux-2010.05-core-dual.iso", sic, soc)

	state := <-soc
	log.Print("State Change: " + state.String())

	// Wait to check for open connections
	time.Sleep(20e9)
}