initial prototype

.gitignore

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+/terse

Makefile

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+terse: ./url.go ./server.go ./cmd/terse/terse.go
+	go build ./cmd/terse
+
+clean:
+	rm -f ./terse

cmd/terse/terse.go

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+package main
+
+import (
+	"log"
+
+	"github.com/brettlangdon/go-arg"
+	"github.com/brettlangdon/terse"
+)
+
+var args struct {
+	MaxEntries int    `arg:"-m,--max,help:max number of links to keep [default: 1000]"`
+	Bind       string `arg:"-b,--bind,help:\"[host]:<port>\" to bind the server to [default: 127.0.0.1:5892]"`
+}
+
+func main() {
+	args.MaxEntries = 1000
+	args.Bind = "127.0.0.1:5892"
+	arg.MustParse(&args)
+
+	server := terse.NewServer(args.Bind, args.MaxEntries)
+	log.Fatal(server.ListenAndServe())
+}

server.go

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+package terse
+
+import (
+	"bufio"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/golang/groupcache/lru"
+)
+
+type Handler struct {
+	cache *lru.Cache
+}
+
+func (handler *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case "GET":
+		handler.HandleGet(w, r)
+	case "POST":
+		handler.HandlePost(w, r)
+	default:
+		http.Error(w, fmt.Sprintf("Method \"%s\" Not Allowed", r.Method), http.StatusMethodNotAllowed)
+	}
+}
+
+func (handler *Handler) HandleGet(w http.ResponseWriter, r *http.Request) {
+	url := strings.Trim(r.URL.Path, "/")
+	code := strings.SplitN(url, "/", 2)[0]
+	value, ok := handler.cache.Get(code)
+	if ok {
+		switch url := value.(type) {
+		case string:
+			http.Redirect(w, r, url, http.StatusMovedPermanently)
+			return
+		}
+	}
+	http.NotFound(w, r)
+}
+
+func (handler *Handler) HandlePost(w http.ResponseWriter, r *http.Request) {
+	reader := bufio.NewScanner(r.Body)
+	reader.Scan()
+	url, err := url.ParseRequestURI(reader.Text())
+	if err != nil {
+		panic(err)
+	}
+	code := GetShortCode([]byte(url.String()))
+	handler.cache.Add(code, url.String())
+	fmt.Fprintf(w, code)
+}
+
+func NewServer(bind string, maxEntries int) *http.Server {
+	return &http.Server{
+		Addr: bind,
+		Handler: &Handler{
+			cache: lru.New(maxEntries),
+		},
+	}
+}

url.go

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+package terse
+
+import (
+	"bytes"
+	"hash/crc32"
+)
+
+const ALPHABET string = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._~"
+const BASE uint32 = uint32(len(ALPHABET))
+
+func GetShortCode(url []byte) string {
+	var code bytes.Buffer
+	num := crc32.ChecksumIEEE(url)
+	for num > 0 {
+		next := (num % BASE)
+		code.WriteRune(rune(ALPHABET[next]))
+		num = num / 62
+	}
+	return code.String()
+}