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|
package main
import (
"database/sql"
"encoding/json"
"flag"
"fmt"
_ "github.com/mattn/go-sqlite3"
"log"
"math"
"net"
"net/http"
"os"
"os/exec"
"os/signal"
"strings"
"syscall"
"text/template"
)
type Fruit struct {
Name string `json:"name"`
Img string `json:"img"`
Elo int `json:"elo"`
}
type Context struct {
db *sql.DB
users []string
templatePath string
socketPath string
fruitsPath string
}
type CurriedContextHandler func(*Context, http.ResponseWriter, *http.Request)
func curryContext(context *Context) func(CurriedContextHandler) http.HandlerFunc {
return func(handler CurriedContextHandler) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
log.Println(r.Method, r.URL.Path, r.RemoteAddr)
handler(context, w, r)
}
}
}
func indexHandler(context *Context, resp http.ResponseWriter, req *http.Request) {
// get from POST
winner := req.FormValue("winner")
contestants := req.Form["contestant[]"]
if winner != "" && len(contestants) == 2 {
losingFruitName := string(contestants[0])
if losingFruitName == winner {
losingFruitName = string(contestants[1])
}
winningFruit := fruitByName(context.db, winner)
losingFruit := fruitByName(context.db, losingFruitName)
winningFruit.Elo, losingFruit.Elo = updateElo(winningFruit.Elo, losingFruit.Elo)
updateFruit(context.db, winningFruit)
updateFruit(context.db, losingFruit)
log.Println(winningFruit.Name, "won against", losingFruit.Name, "new elo:", winningFruit.Elo, losingFruit.Elo)
}
fruitOne := randomFruit(context.db)
fruitTwo := randomFruit(context.db)
for fruitOne.Name == fruitTwo.Name {
fruitTwo = randomFruit(context.db)
}
templateFile := context.templatePath + "/vote.html"
vote, err := template.ParseFiles(templateFile)
if err != nil {
panic(err)
}
fruits := []Fruit{fruitOne, fruitTwo}
err = vote.Execute(resp, fruits)
if err != nil {
panic(err)
}
resp.Header().Set("Content-Type", "text/html")
}
func getStatsHandler(context *Context, resp http.ResponseWriter, _req *http.Request) {
rows, err := context.db.Query("SELECT name, img, elo FROM fruits ORDER BY elo DESC")
if err != nil {
panic(err)
}
defer rows.Close()
fruits := []Fruit{}
for rows.Next() {
fruit := Fruit{}
err = rows.Scan(&fruit.Name, &fruit.Img, &fruit.Elo)
if err != nil {
panic(err)
}
fruits = append(fruits, fruit)
}
templateFile := context.templatePath + "/stats.html"
stats, err := template.ParseFiles(templateFile)
if err != nil {
panic(err)
}
err = stats.Execute(resp, fruits)
if err != nil {
panic(err)
}
resp.Header().Set("Content-Type", "text/html")
}
func healthCheckHandler(context *Context, resp http.ResponseWriter, req *http.Request) {
resp.WriteHeader(http.StatusOK)
resp.Write([]byte("healthy"))
}
func main() {
log.Println("starting server...")
log.SetFlags(log.LstdFlags | log.Lshortfile)
context := getArgs()
log.Println("removing socket file", context.socketPath)
os.Remove(context.socketPath)
log.Println("migrating database...")
migrate(context.db)
seedFruits(context.db, context.fruitsPath)
listener, err := net.Listen("unix", context.socketPath)
if err != nil {
panic(err)
}
log.Println("listening on", context.socketPath)
os.Chmod(context.socketPath, 0700)
sigc := make(chan os.Signal, 1)
signal.Notify(sigc, os.Interrupt, os.Kill, syscall.SIGTERM)
go func(c chan os.Signal) {
sig := <-c
log.Printf("caught signal %s: shutting down.", sig)
listener.Close()
os.Exit(0)
}(sigc)
defer listener.Close()
log.Println("setting ACLs for users", context.users)
for _, user := range context.users {
setACL(context.socketPath, user)
}
curriedContext := curryContext(context)
mux := http.NewServeMux()
mux.HandleFunc("/", curriedContext(indexHandler))
mux.HandleFunc("/health", curriedContext(healthCheckHandler))
mux.HandleFunc("/stats", curriedContext(getStatsHandler))
log.Println("serving http...")
http.Serve(listener, mux)
}
func calculateRatingDelta(winnerRating int, loserRating int, K int) (int, int) {
winnerRatingFloat := float64(winnerRating)
loserRatingFloat := float64(loserRating)
expectedScoreWinner := 1 / (1 + math.Pow(10, (loserRatingFloat-winnerRatingFloat)/400))
expectedScoreLoser := 1 - expectedScoreWinner
changeWinner := int(math.Round(float64(K) * (1 - expectedScoreWinner)))
changeLoser := -int(math.Round(float64(K) * (expectedScoreLoser)))
return changeWinner, changeLoser
}
func updateElo(winnerElo int, loserElo int) (int, int) {
const K = 32
changeWinner, changeLoser := calculateRatingDelta(winnerElo, loserElo, K)
newWinnerElo := winnerElo + changeWinner
newLoserElo := loserElo + changeLoser
return newWinnerElo, newLoserElo
}
func seedFruits(db *sql.DB, fruitsPath string) {
log.Println("seeding fruits (haha)...")
fruitsContents, err := os.ReadFile(fruitsPath)
if err != nil {
panic(err)
}
jsonFruits := []Fruit{}
err = json.Unmarshal(fruitsContents, &jsonFruits)
if err != nil {
panic(err)
}
for _, fruit := range jsonFruits {
// insert if not exists
_, err := db.Exec("INSERT OR IGNORE INTO fruits (name, img) VALUES (?, ?)", fruit.Name, fruit.Img)
if err != nil {
panic(err)
}
}
}
func migrate(db *sql.DB) {
log.Println("creating fruits table...")
_, err := db.Exec(`
CREATE TABLE IF NOT EXISTS fruits (
name TEXT PRIMARY KEY,
img TEXT,
elo INTEGER DEFAULT 1400
);
`)
if err != nil {
panic(err)
}
}
func randomFruit(db *sql.DB) Fruit {
fruit := Fruit{}
err := db.QueryRow("SELECT name, img, elo FROM fruits ORDER BY RANDOM() LIMIT 1").Scan(&fruit.Name, &fruit.Img, &fruit.Elo)
if err != nil {
panic(err)
}
return fruit
}
func fruitByName(db *sql.DB, name string) Fruit {
fruit := Fruit{}
err := db.QueryRow("SELECT name, img, elo FROM fruits WHERE name = ?", name).Scan(&fruit.Name, &fruit.Img, &fruit.Elo)
if err != nil {
panic(err)
}
return fruit
}
func updateFruit(db *sql.DB, fruit Fruit) {
_, err := db.Exec("UPDATE fruits SET img = ?, elo = ? WHERE name = ?", fruit.Img, fruit.Elo, fruit.Name)
if err != nil {
panic(err)
}
}
func setACL(socketPath, user string) {
cmd := exec.Command("setfacl", "-m", "u:"+user+":rwx", socketPath)
if err := cmd.Run(); err != nil {
panic("failed to set ACL: " + err.Error())
}
}
func getArgs() *Context {
socketPath := flag.String("socket-path", "/tmp/go-server.sock", "Path to the Unix socket")
users := flag.String("users", "", "Comma-separated list of users for ACL")
database := flag.String("database-path", "/tmp/go-server.db", "Path to the SQLite database")
fruitsPath := flag.String("fruits", "/dev/null", "Path to the fruits file")
templatePath := flag.String("template", "", "Path to the template directory")
flag.Parse()
if *users == "" {
fmt.Println("You must specify at least one user with --users")
os.Exit(1)
}
if *templatePath == "" {
fmt.Println("You must specify a template directory with --template")
os.Exit(1)
}
log.Println("opening database at", *database, "with foreign keys enabled")
db, err := sql.Open("sqlite3", *database+"?_foreign_keys=on")
if err != nil {
panic(err)
}
return &Context{
db: db,
users: strings.Split(*users, ","),
socketPath: *socketPath,
fruitsPath: *fruitsPath,
templatePath: *templatePath,
}
}
|
