Created url-shortener

.gitignore

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+shortened-urls.json

README.md

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+# url-shortener
+This is other of my personal projects, this is just a pretty basic url shortener.
+
+It works with base64 and sha256 encoding to generate the shorten URL. It works only locally so you can't share the link to others. But hey, it still works.
+
+## Usage
+Run `go run . -url=<YOUR_URL>` to execute the program. Once you do this, the program will show you the shorten URL in the output so you can copy or just write it in your browser.
+
+> [!IMPORTANT]
+> The shorten URLs are saved on a JSON file. You have to create it manually. Name it as `shortened-urls.json`.

go.mod

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+module github.com/Osaka/url-shortener
+
+go 1.23.4

httpserver.go

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+package main
+
+import (
+	"log"
+	"net/http"
+	"strings"
+)
+
+func redirectURL(w http.ResponseWriter, r *http.Request) {
+	urlPath := r.PathValue("hashurl")
+
+	// For some reason, the browser is requesting the favicon.ico when I visit
+	// the root path 🤷‍♂️
+	if strings.HasPrefix(urlPath, "favicon.ico") {
+		http.NotFound(w, r)
+		return
+	}
+
+	allURLs := GetAllURLs()
+	targetURL, ok := allURLs[urlPath]
+
+	if !ok {
+		http.NotFound(w, r)
+		return
+	}
+
+	log.Println("Redirecting to", targetURL)
+	http.Redirect(w, r, targetURL, http.StatusSeeOther)
+}
+
+func ServeServer() {
+	http.HandleFunc("/{hashurl}", redirectURL)
+	http.ListenAndServe(":8080", nil)
+}

main.go

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+package main
+
+import (
+	"flag"
+	"log"
+)
+
+var (
+	URL string
+)
+
+func init() {
+	flag.StringVar(&URL, "url", "", "URL to shorten")
+	flag.Parse()
+}
+
+func main() {
+	if URL == "" {
+		panic("URL is required")
+	}
+	hashedURL := HashURL(URL)
+
+	log.Println("Shortened URL:", "localhost:8080/"+hashedURL)
+
+	SaveURLToFile(hashedURL, URL)
+	ServeServer()
+}

url_shortener.go

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+package main
+
+import (
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"log"
+	"math/rand"
+	"os"
+)
+
+func GetAllURLs() map[string]string {
+	content, err := os.ReadFile("shortened-urls.json")
+
+	if err != nil {
+		return make(map[string]string)
+	}
+
+	// Parse the JSON content
+	urlsMap := make(map[string]string)
+
+	err = json.Unmarshal(content, &urlsMap)
+
+	if err != nil {
+		return make(map[string]string)
+	}
+
+	return urlsMap
+}
+
+func SaveURLToFile(hashedUrl, originalUrl string) {
+	alreadySavedURLs := GetAllURLs()
+	alreadySavedURLs[hashedUrl] = originalUrl
+
+	// Convert the map to JSON
+	jsonContent, err := json.Marshal(alreadySavedURLs)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = os.WriteFile("shortened-urls.json", jsonContent, 0644)
+
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func HashURL(urlToShorten string) string {
+	randomStr := randomString(8)
+	combined := urlToShorten + randomStr
+	hash := sha256.Sum256([]byte(combined))
+	encoded := base64.URLEncoding.EncodeToString(hash[:])
+
+	return encoded[:8] // Take the first 8 characters for a shorter URL
+}
+
+func randomString(length int) string {
+	letters := []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
+	b := make([]rune, length)
+
+	for i := range b {
+		b[i] = letters[rand.Intn(len(letters))]
+	}
+
+	return string(b)
+}