experiment: prototyping new ASP.NET-like controllers;

feat: ControllerMethod struct for storing data about an individual API endpoint;
feat: controllerImpl struct for setting up a controller;
feat: GetRequest method for parsing and validating a request with automatic abortion on binding/validation errors

backend/internal/controllers/controller.go

@@ -0,0 +1,141 @@
+// Copyright (c) 2025 Nikolai Papin
+//
+// This file is part of Easywish
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+// the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package controllers
+
+import (
+	"easywish/internal/dto"
+	errs "easywish/internal/errors"
+	"easywish/internal/middleware"
+	"easywish/internal/services"
+	"easywish/internal/utils/enums"
+	"easywish/internal/validation"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/go-playground/validator/v10"
+	"go.uber.org/zap"
+)
+
+var (
+	GET = "GET"
+	POST = "POST"
+	PUT = "PUT"
+	PATCH = "PATCH"
+	DELETE = "DELETE"
+)
+
+type ControllerMethod struct {
+	HttpMethod string
+	Path string
+	Authorization enums.Role
+	Middleware []gin.HandlerFunc 
+	Function func (c *gin.Context)
+}
+
+type controllerImpl struct {
+	Path string
+	Authorization enums.Role
+	Middleware []gin.HandlerFunc 
+	Methods []ControllerMethod
+}
+
+func (ctrl *controllerImpl) Setup(group *gin.RouterGroup, log *zap.Logger, auth services.AuthService) *gin.RouterGroup {
+	ctrlGroup := group.Group(ctrl.Path)
+	ctrlGroup.Use(middleware.AuthMiddleware(log, auth))
+	ctrlGroup.Use(gin.HandlerFunc(func(c *gin.Context) {
+		ip := c.ClientIP()
+		userAgent := c.Request.UserAgent()
+		sessionInfoFromCtx, ok := c.Get("session_info"); if !ok {
+			c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": "Invalid or missing session data"})
+			return
+		}
+
+		sessionInfo := sessionInfoFromCtx.(dto.SessionInfo)
+
+		if sessionInfo.Role < ctrl.Authorization {
+			c.AbortWithStatusJSON(
+				http.StatusForbidden,
+				gin.H{"error": "Insufficient authorization for this controller"})
+			return
+		}
+
+		c.Set("client_info", dto.ClientInfo{
+			SessionInfo: sessionInfo,
+			IP: ip,
+			UserAgent: userAgent,
+		})
+
+		c.Next()
+	}))
+	ctrlGroup.Use(ctrl.Middleware...)
+
+	for _, method := range ctrl.Methods {
+		ctrlGroup.Handle(
+			method.HttpMethod,
+			method.Path,
+			append(
+				method.Middleware,
+				gin.HandlerFunc(func(c *gin.Context) {
+					clientInfo, _ := c.Get("client_info")
+					if clientInfo.(dto.ClientInfo).Role < method.Authorization {
+						c.AbortWithStatusJSON(
+							http.StatusForbidden,
+							gin.H{"error": "Insufficient authorization for this method"})
+						return
+					}
+				}),
+				method.Function)...,
+		)}
+	return ctrlGroup
+}
+
+type Controller interface {
+	Setup()	
+}
+
+func GetRequest[ModelT any](c *gin.Context) (*dto.Request[ModelT], error) {
+
+	var body ModelT
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return nil, err
+	}
+
+	validate := validation.NewValidator()
+
+	if err := validate.Struct(body); err != nil {
+		errorList := err.(validator.ValidationErrors)
+		c.AbortWithStatusJSON(
+			http.StatusBadRequest,
+			gin.H{"error": errorList})
+		return nil, err
+	}
+
+	cinfoFromCtx, ok := c.Get("client_info"); if !ok {
+		c.AbortWithStatusJSON(
+			http.StatusInternalServerError,
+			gin.H{"error": "Client info was not found"})
+		return nil, errs.ErrClientInfoNotProvided
+	}
+	cinfo := cinfoFromCtx.(*dto.ClientInfo)
+
+	return &dto.Request[ModelT]{
+		Body: body,
+		User: *cinfo,
+	}, nil
+}