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main.go
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main.go
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package main
import (
"fmt"
"github.com/gorilla/mux"
"html/template"
"log"
"net"
"net/http"
"os"
"regexp"
"strconv"
"strings"
"time"
)
var (
cookieExpires time.Time
Assigned = make(map[string]string)
)
func usage() {
Name := os.Args[0]
fmt.Println(
`USAGE: `+Name+` [OPTIONS] NAMES...\n`,
`NAMES are the names of the participants\n\n`,
` --file FILE The path to a file with constraints for the matching`,
` --seed INT The initial seed`,
` --max_attempts INT Maximum number of seeds to try before giving up`,
)
}
func GetIp(r *http.Request) string {
if fwd := r.Header.Get("x-forwarded-for"); fwd != "" {
ips := strings.SplitN(fwd, ",", 2)
if len(ips) > 0 {
return strings.TrimSpace(ips[0])
}
}
addr := r.RemoteAddr
ip := strings.SplitN(addr, ":", 2)[0]
return strings.TrimSpace(ip)
}
func GetCookie(name string, r *http.Request) string {
cookie, err := r.Cookie(name)
switch err {
case nil:
return cookie.Value
case http.ErrNoCookie:
return ""
default:
panic(err)
}
}
func SetCookie(name, value string, w http.ResponseWriter) {
http.SetCookie(w, &http.Cookie{
Name: name,
Value: value,
Path: "/",
Expires: cookieExpires,
})
}
func DeleteCookie(name string, w http.ResponseWriter, r *http.Request) {
cookie, err := r.Cookie(name)
if err != nil {
panic(err)
}
http.SetCookie(w, &http.Cookie{
Name: name,
Value: "",
Path: "/",
Expires: cookie.Expires,
MaxAge: -1,
})
}
func ExecuteTemplate(w http.ResponseWriter, name string, data interface{}) {
t, err := template.ParseFiles("templates/page.gohtml")
if err != nil {
panic(err)
}
t, err = t.Parse("{{template \"head\" .}}{{template \"" + name + "\" .}}{{template \"foot\" .}}")
if err != nil {
panic(err)
}
err = t.Execute(w, data)
if err != nil {
panic(err)
}
}
func ErrorHandler(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
defer func() {
if x := recover(); x != nil {
log.Println(x)
s := http.StatusInternalServerError
http.Error(w, http.StatusText(s), s)
}
}()
next.ServeHTTP(w, r)
})
}
func ResetHandler(w http.ResponseWriter, r *http.Request) {
if claim := GetCookie("claim", r); claim == "" {
w.WriteHeader(http.StatusBadRequest)
return
}
DeleteCookie("claim", w, r)
http.Redirect(w, r, "/", http.StatusPermanentRedirect)
}
func NameHandler(w http.ResponseWriter, r *http.Request) {
name := mux.Vars(r)["name"]
claim := GetCookie("claim", r)
ip := GetIp(r)
if claim == "" {
claim = "none"
} else if claim != name {
ExecuteTemplate(w, "wrong-name", map[string]interface{}{"Name": name})
log.Printf("%v %v claim=%v", ip, name, claim)
return
}
ExecuteTemplate(w, "name", map[string]interface{}{"Name": name})
log.Printf("%v %v claim=%v", ip, name, claim)
}
func RevealHandler(w http.ResponseWriter, r *http.Request) {
name := mux.Vars(r)["name"]
claim := GetCookie("claim", r)
ip := GetIp(r)
if claim == "" {
SetCookie("claim", name, w)
http.Redirect(w, r, "/"+name+"/reveal", http.StatusPermanentRedirect)
} else if claim == name {
ExecuteTemplate(w, "reveal", map[string]interface{}{"Name": name, "Assigned": Assigned})
log.Printf("%v %v claim=%v", ip, name, claim)
}
}
func RootHandler(w http.ResponseWriter, r *http.Request) {
if name := GetCookie("claim", r); name != "" {
http.Redirect(w, r, "/"+name, http.StatusPermanentRedirect)
return
}
ExecuteTemplate(w, "root", map[string]interface{}{"Assigned": Assigned})
}
func init() {
year := time.Now().Year()
month := int(time.December)
day := 25
err := func() error {
val, ok := os.LookupEnv("COOKIE_EXPIRES")
if !ok {
return nil
}
re := regexp.MustCompile(`^(\d{4})(\d{2})(\d{2})$`)
res := re.FindStringSubmatch(val)
if len(res) != 4 {
return fmt.Errorf("invalid format string %v", val)
}
var err error
if year, err = strconv.Atoi(res[1]); err != nil {
return fmt.Errorf("invalid year format: %v", res[1])
}
if month, err = strconv.Atoi(res[2]); err != nil {
return fmt.Errorf("invalid month format: %v", res[2])
}
if day, err = strconv.Atoi(res[3]); err != nil {
return fmt.Errorf("invalid day format: %v", res[3])
}
return nil
}()
if err != nil {
log.Fatalf("error parsing COOKIE_EXPIRES: %v", err)
}
cookieExpires = time.Date(year, time.December, 25, 0, 0, 0, 0, time.Local)
}
func main() {
defer func() {
if r := recover(); r != nil {
log.Printf("error: %v", r)
usage()
}
}()
args, err := ParseArgs(os.Args[1:])
if err != nil {
panic(err)
}
log.Printf("starting with the following participants")
for name, constraints := range args.Constraints {
if len(constraints) == 0 {
log.Printf(" •%v", name)
} else {
log.Printf(" •%v (will not be assigned to %v)", name, strings.Join(constraints, ", "))
}
}
assigned, err := args.Assign()
if err != nil {
panic(err)
}
if len(assigned) == 0 {
panic(fmt.Errorf("no participants"))
}
router := mux.NewRouter()
router.Use(ErrorHandler)
router.HandleFunc("/{name}/reset", ResetHandler)
router.HandleFunc("/{name}/reveal", RevealHandler)
router.HandleFunc("/{name}", NameHandler)
router.HandleFunc("/", RootHandler)
server := &http.Server{Handler: router}
l, err := net.Listen("tcp4", ":8081")
if err != nil {
panic(err)
}
err = server.Serve(l)
log.Printf("server stopped: %v", err)
}