feat: replace placeholder auth with db hash

internal/handler/handlers.go

@@ -14,6 +14,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/golang-jwt/jwt/v5"
 	"github.com/google/uuid"
+	"golang.org/x/crypto/bcrypt"
 )
 
 type Handler struct {
@@ -93,7 +94,7 @@ func (h *Handler) Hello(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"message": "hello from lambdaiot"})
 }
 
-// Login issues a JWT token for demo purposes
+// Login issues a JWT token after validating credentials against the database
 func (h *Handler) Login(c *gin.Context) {
 	var req struct {
 		Username string `json:"username"`
@@ -103,15 +104,31 @@ func (h *Handler) Login(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "invalid json"})
 		return
 	}
-	// demo credentials
-	if req.Username != "admin" || req.Password != "password" {
+
+	// Query user from database
+	var userID string
+	var passwordHash string
+	err := h.DB.QueryRow("SELECT BIN_TO_UUID(id), password_hash FROM users WHERE username = ?", req.Username).Scan(&userID, &passwordHash)
+	if err == sql.ErrNoRows {
 		c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
 		return
 	}
-	// create token
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "database error"})
+		return
+	}
+
+	// Verify password
+	if err := bcrypt.CompareHashAndPassword([]byte(passwordHash), []byte(req.Password)); err != nil {
+		c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid credentials"})
+		return
+	}
+
+	// Create token
 	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
-		"sub": req.Username,
-		"exp": time.Now().Add(time.Hour).Unix(),
+		"sub":     req.Username,
+		"user_id": userID,
+		"exp":     time.Now().Add(24 * time.Hour).Unix(),
 	})
 	signed, err := token.SignedString([]byte(h.JWTSecret))
 	if err != nil {
@@ -841,3 +858,46 @@ func (h *Handler) DeleteSensorReading(c *gin.Context) {
 	}
 	c.JSON(http.StatusOK, gin.H{"message": "sensor reading deleted"})
 }
+
+// Register creates a new user account
+func (h *Handler) Register(c *gin.Context) {
+	var req struct {
+		Username string `json:"username" binding:"required,min=3,max=50"`
+		Password string `json:"password" binding:"required,min=6"`
+		Email    string `json:"email"`
+	}
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+
+	// Check if username already exists
+	var exists int
+	err := h.DB.QueryRow("SELECT COUNT(*) FROM users WHERE username = ?", req.Username).Scan(&exists)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "database error"})
+		return
+	}
+	if exists > 0 {
+		c.JSON(http.StatusConflict, gin.H{"error": "username already exists"})
+		return
+	}
+
+	// Hash password
+	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(req.Password), bcrypt.DefaultCost)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to hash password"})
+		return
+	}
+
+	// Insert user
+	userID := uuid.New()
+	_, err = h.DB.Exec("INSERT INTO users (id, username, password_hash, email) VALUES (UUID_TO_BIN(?), ?, ?, ?)",
+		userID.String(), req.Username, string(hashedPassword), req.Email)
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to create user"})
+		return
+	}
+
+	c.JSON(http.StatusCreated, gin.H{"id": userID.String(), "username": req.Username})
+}