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server.go
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server.go
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package main
import (
"fmt"
"github.com/nfnt/resize"
"image"
_ "image/gif"
_ "image/jpeg"
"image/png"
"io"
"log"
"net/http"
"net/url"
"regexp"
"runtime"
"strings"
"github.com/google/uuid"
)
const (
TRIES = 30
MUTATIONS = 10000
PIXELSAMPLING = 8
MAXSIZE = 300
)
var urlArg = regexp.MustCompile("url=(.*)")
var sessionManager = NewSessionManager()
//
// Server code
//
func getSessionID(r *http.Request) (uuid.UUID, error) {
cookies := r.Cookies()
for i := 0; i < len(cookies); i++ {
if cookies[i].Name == "Session-ID" {
return uuid.Parse(cookies[i].Value)
}
}
return uuid.UUID{}, &NoSessionFound{}
}
// Returns the url query parameter
// e.g. in /remote/img?url=wwww.google.com, returns www.google.com
func urlParam(r *http.Request) (string, error) {
m := urlArg.FindStringSubmatch(r.URL.String())
if m == nil || len(m) < 1 {
return "", fmt.Errorf("Invalid regex.", r.URL.String())
}
if _, err := url.Parse(m[1]); err != nil {
return "", fmt.Errorf("Invalid url", m[1])
}
return m[1], nil
}
// Serves the image from the URL in the request.
// This allows us to get around CORS issues.
func remoteHandler(w http.ResponseWriter, r *http.Request) {
img, err := getImg(r)
if err != nil {
log.Println(err)
w.Write([]byte(err.Error()))
return
}
defer img.Close()
_target, _, err := image.Decode(img)
ci := make(chan image.Image)
go preprocessImage(_target, ci)
preprocessedImage := <-ci
png.Encode(w, preprocessedImage)
}
// Serves the image generated by approximate() on the URL in the request.
func approxHandler(w http.ResponseWriter, r *http.Request) {
sessionID, err := getSessionID(r)
broadcastChannel := make(chan *Event)
if err == nil {
if session, ok := sessionManager.sessions[sessionID]; ok {
broadcastChannel = session.broadcast
}
}
broadcastChannel <- &Event{Name: "log", Properties: map[string]string{
"text": "Starting approximation",
}}
img, err := getImg(r)
if err != nil {
log.Println(err)
w.Write([]byte(err.Error()))
return
}
defer img.Close()
// read the image into target (type image.Image)
_target, _, err := image.Decode(img)
if err != nil {
w.Write([]byte("err"))
fmt.Println(err)
return
}
ci := make(chan image.Image)
go preprocessImage(_target, ci)
preprocessedTarget := <-ci
target := toRGBA(preprocessedTarget)
approximation, score := approximate(
target,
TRIES,
MUTATIONS,
PIXELSAMPLING,
broadcastChannel,
)
fmt.Println(float64(score) / 1000000)
png.Encode(w, approximation)
broadcastChannel <- &Event{Name: "log", Properties: map[string]string{
"text": "Approximation complete",
}}
}
func preprocessImage(image image.Image, cr chan image.Image) {
if dx, dy := image.Bounds().Dx(), image.Bounds().Dy(); dx > MAXSIZE || dy > MAXSIZE {
// Resample the image down to MAXSIZE
msg := fmt.Sprintf("Image of size %v.%v is too large (max size is %v). Downsampling.", dx, dy, MAXSIZE)
log.Println(msg)
cr <- resize.Thumbnail(MAXSIZE,
MAXSIZE,
image,
resize.NearestNeighbor)
} else {
cr <- image
}
}
// Serve a static file.
func fileHandler(w http.ResponseWriter, r *http.Request) {
http.SetCookie(w, &http.Cookie{
Name: "Session-ID",
Value: uuid.New().String()})
http.ServeFile(w, r, r.URL.Path[1:])
}
func statsHandler(w http.ResponseWriter, r *http.Request) {
msg := fmt.Sprintf("%v iterations of %v mutations each, sampling 1/%v pixels.", TRIES, MUTATIONS, PIXELSAMPLING)
io.Copy(w, strings.NewReader(msg))
}
// Returns the image from a URL.
func getImg(r *http.Request) (io.ReadCloser, error) {
// Get the URL of the target image
url, err := urlParam(r)
if err != nil {
return nil, err
}
// Fetch the image
resp, err := http.Get(url)
if err != nil {
return nil, err
}
return resp.Body, nil
}
func main() {
runtime.GOMAXPROCS(4)
port := "0.0.0.0:4000"
fmt.Println("Running on", port)
http.HandleFunc("/", fileHandler)
http.HandleFunc("/remote/", remoteHandler)
http.HandleFunc("/approx/", approxHandler)
http.HandleFunc("/stats/", statsHandler)
http.HandleFunc("/status/", statusHandler)
err := http.ListenAndServe(port, nil)
if err != nil {
log.Fatal(err)
}
}