Implement PUT /user/{userId}/allowance/{allowanceId} (#52)

Closes #17

Reviewed-on: #52

backend/main.go

@@ -232,6 +232,52 @@ func deleteUserAllowance(c *gin.Context) {
 	c.IndentedJSON(http.StatusOK, gin.H{"message": "History deleted successfully"})
 }
 
+func putUserAllowance(c *gin.Context) {
+	userIdStr := c.Param("userId")
+	allowanceIdStr := c.Param("allowanceId")
+
+	userId, err := strconv.Atoi(userIdStr)
+	if err != nil {
+		log.Printf(ErrInvalidUserID+": %v", err)
+		c.JSON(http.StatusBadRequest, gin.H{"error": ErrInvalidUserID})
+		return
+	}
+
+	allowanceId, err := strconv.Atoi(allowanceIdStr)
+	if err != nil {
+		log.Printf("Invalid allowance ID: %v", err)
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid allowance ID"})
+		return
+	}
+
+	exists, err := db.UserExists(userId)
+	if err != nil {
+		log.Printf(ErrCheckingUserExist, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": ErrInternalServerError})
+		return
+	}
+	if !exists {
+		c.JSON(http.StatusNotFound, gin.H{"error": ErrUserNotFound})
+		return
+	}
+
+	var allowanceRequest UpdateAllowanceRequest
+	if err := c.ShouldBindJSON(&allowanceRequest); err != nil {
+		log.Printf("Error parsing request body: %v", err)
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid request body"})
+		return
+	}
+
+	err = db.UpdateAllowance(userId, allowanceId, &allowanceRequest)
+	if err != nil {
+		log.Printf("Error updating allowance: %v", err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": ErrInternalServerError})
+		return
+	}
+
+	c.IndentedJSON(http.StatusOK, gin.H{"message": "Allowance updated successfully"})
+}
+
 func createTask(c *gin.Context) {
 	var taskRequest CreateTaskRequest
 	if err := c.ShouldBindJSON(&taskRequest); err != nil {
@@ -439,6 +485,7 @@ func start(ctx context.Context, config *ServerConfig) {
 	router.POST("/api/user/:userId/allowance", createUserAllowance)
 	router.GET("/api/user/:userId/allowance/:allowanceId", getUserAllowanceById)
 	router.DELETE("/api/user/:userId/allowance/:allowanceId", deleteUserAllowance)
+	router.PUT("/api/user/:userId/allowance/:allowanceId", putUserAllowance)
 	router.POST("/api/tasks", createTask)
 	router.GET("/api/tasks", getTasks)
 	router.GET("/api/task/:taskId", getTask)