89 lines
1.6 KiB
Go
89 lines
1.6 KiB
Go
package main
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import (
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"bytes"
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"flag"
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"fmt"
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"image"
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"image/color"
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"image/png"
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"log"
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"net/http"
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"os"
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"sync"
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"time"
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)
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var port = flag.Int("port", 8000, "port")
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type Now struct {
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lastUpdated time.Time
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cacheWindow time.Duration
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buffer *bytes.Buffer
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lock sync.RWMutex
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}
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func NewNow(d time.Duration) *Now {
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return &Now{
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cacheWindow: d,
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buffer: &bytes.Buffer{},
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}
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}
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func (n *Now) ServeHTTP(w http.ResponseWriter, req *http.Request) {
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log.Printf("%+v", req.RemoteAddr)
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if time.Now().After(n.lastUpdated.Add(n.cacheWindow)) {
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log.Println("updating image")
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n.Update()
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n.lastUpdated = time.Now()
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}
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n.lock.RLock()
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w.Write(n.buffer.Bytes())
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n.lock.RUnlock()
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}
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func (n *Now) Update() {
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resp, err := http.Get("http://imgs.xkcd.com/comics/now.png")
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if err != nil {
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log.Fatal(err)
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}
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defer resp.Body.Close()
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src, err := png.Decode(resp.Body)
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if err != nil {
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log.Fatal(err)
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}
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bounds := src.Bounds()
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dest := image.NewNRGBA(bounds)
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for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
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for x := bounds.Min.X; x < bounds.Max.X; x++ {
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r, g, b, _ := src.At(x, y).RGBA()
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if r == 0xFFFF && g == 0xFFFF && b == 0xFFFF {
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dest.Set(x, y, color.NRGBA{0, 0, 0, 0})
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} else {
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dest.Set(x, y, src.At(x, y))
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}
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}
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}
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n.lock.Lock()
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png.Encode(n.buffer, dest)
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n.lock.Unlock()
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}
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func main() {
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flag.Parse()
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hostname, err := os.Hostname()
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if err != nil {
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log.Fatal("problem getting hostname:", err)
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}
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log.Printf("serving on: http://%s:%d/", hostname, *port)
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addr := fmt.Sprintf(":%d", *port)
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http.Handle("/", NewNow(15*time.Minute))
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err = http.ListenAndServe(addr, nil)
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if err != nil {
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log.Fatal(err)
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}
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}
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