feat(global): add authentication support with single admin account

api/auth.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"encoding/json"
+	"github.com/asaskevich/govalidator"
+	"golang.org/x/crypto/bcrypt"
+	"io/ioutil"
+	"log"
+	"net/http"
+)
+
+type (
+	credentials struct {
+		Username string `valid:"alphanum,required"`
+		Password string `valid:"length(8)"`
+	}
+	authResponse struct {
+		JWT string `json:"jwt"`
+	}
+)
+
+func hashPassword(password string) (string, error) {
+	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		return "", nil
+	}
+	return string(hash), nil
+}
+
+func checkPasswordValidity(password string, hash string) error {
+	return bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
+}
+
+// authHandler defines a handler function used to authenticate users
+func (api *api) authHandler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != "POST" {
+		w.Header().Set("Allow", "POST")
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	body, err := ioutil.ReadAll(r.Body)
+	if err != nil {
+		http.Error(w, "Unable to parse request body", http.StatusBadRequest)
+		return
+	}
+
+	var credentials credentials
+	err = json.Unmarshal(body, &credentials)
+	if err != nil {
+		http.Error(w, "Unable to parse credentials", http.StatusBadRequest)
+		return
+	}
+
+	_, err = govalidator.ValidateStruct(credentials)
+	if err != nil {
+		http.Error(w, "Invalid credentials format", http.StatusBadRequest)
+		return
+	}
+
+	var username = credentials.Username
+	var password = credentials.Password
+	u, err := api.dataStore.getUserByUsername(username)
+	if err != nil {
+		log.Printf("User not found: %s", username)
+		http.Error(w, "User not found", http.StatusNotFound)
+		return
+	}
+
+	err = checkPasswordValidity(password, u.Password)
+	if err != nil {
+		log.Printf("Invalid credentials for user: %s", username)
+		http.Error(w, "Invalid credentials", http.StatusUnprocessableEntity)
+		return
+	}
+
+	token, err := api.generateJWTToken(username)
+	if err != nil {
+		log.Printf("Unable to generate JWT token: %s", err.Error())
+		http.Error(w, "Unable to generate JWT token", http.StatusInternalServerError)
+		return
+	}
+
+	response := authResponse{
+		JWT: token,
+	}
+	json.NewEncoder(w).Encode(response)
+}