Add UDP-messenger #37

tasks/crud/CRUD_API_README.md

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+
+# 📦 CRUD API with Golang, MongoDB & Gorilla Mux
+
+A lightweight, performant RESTful API in Go designed to handle basic Create, Read, Update, and Delete (CRUD) operations over file metadata using MongoDB as the database and Gorilla Mux as the router.
+
+---
+
+## 🌟 Overview
+
+This project implements a modular and extensible file metadata management service. It provides clean REST endpoints to perform CRUD operations on a MongoDB collection. Designed to be simple yet scalable, the API can be easily integrated into larger systems such as content managers, file explorers, or intelligent search frameworks like FileNest.
+
+---
+
+## 🎯 Key Features
+
+- ⚙️ RESTful API with proper HTTP methods and status codes
+- 🛡️ Input validation and error handling
+- 🗃️ MongoDB integration with BSON support for efficient storage
+- 🔄 Endpoints for Create, Read (all/single), Update, and Delete operations
+- 📎 Built with modular code for easy extension
+- 📫 Tested with Postman and Curl
+
+---
+
+## 🏗️ Project Architecture
+
+```
+crud-api/
+├── controllers/       # API logic and handler functions
+├── models/            # Data model (MongoDB schema)
+├── router/            # Gorilla Mux routing definitions
+├── .env               # MongoDB credentials and configs
+├── go.mod             # Module dependencies
+├── go.sum             # Module checksums
+├── main.go            # Application entrypoint
+└── README.md          # This file
+```
+
+---
+
+## ⚙️ Tech Stack
+
+| Layer          | Tech                          |
+|----------------|-------------------------------|
+| Language       | Golang 1.21+                  |
+| Router         | Gorilla Mux                   |
+| Database       | MongoDB Atlas (or local)      |
+| Driver         | Mongo Go Driver               |
+| Testing Tool   | Postman, Curl                 |
+
+---
+
+## 🚀 Quick Start
+
+### 📋 Prerequisites
+
+- Go 1.21 or higher
+- MongoDB Atlas or local MongoDB instance
+- Git
+
+### 📥 Installation
+
+```bash
+# Download Go dependencies
+go mod tidy
+```
+
+### ⚙️ Environment Setup
+
+Create a `.env` file in the root with the following:
+
+```
+MONGO_URI=mongodb+srv://<username>:<password>@cluster0.mongodb.net/?retryWrites=true&w=majority
+```
+
+### ▶️ Run the Server
+
+```bash
+go run main.go
+```
+
+> Server starts on `http://localhost:8000`
+
+---
+
+## 📡 API Endpoints
+
+| Method | Endpoint            | Description                  |
+|--------|---------------------|------------------------------|
+| GET    | `/api/files`        | Get all file records         |
+| GET    | `/api/files/{id}`   | Get file by ID               |
+| POST   | `/api/files`        | Create new file record       |
+| PUT    | `/api/files/{id}`   | Update file by ID            |
+| DELETE | `/api/files/{id}`   | Delete file by ID            |
+
+---
+
+## 📄 Data Model (FileMetadata)
+
+```go
+type FileMetadata struct {
+  ID          primitive.ObjectID `json:"id,omitempty" bson:"_id,omitempty"`
+  FileName    string             `json:"filename" bson:"filename"`
+  FilePath    string             `json:"filepath" bson:"filepath"`
+  FileSize    int64              `json:"filesize" bson:"filesize"`
+  ContentType string             `json:"content_type" bson:"content_type"`
+  CreatedAt   time.Time          `json:"created_at" bson:"created_at"`
+}
+```
+
+---
+
+## 🧪 Testing
+
+Use [Postman](https://www.postman.com/) or Curl:
+
+### Create File (POST)
+
+```bash
+curl -X POST http://localhost:8000/api/files \
+  -H "Content-Type: application/json" \
+  -d '{"filename":"test.pdf","filepath":"/docs/test.pdf","filesize":1024,"content_type":"application/pdf"}'
+```
+
+### Get All Files (GET)
+
+```bash
+curl http://localhost:8000/api/files
+```
+
+### Update File (PUT)
+
+```bash
+curl -X PUT http://localhost:8000/api/files/<id> \
+  -H "Content-Type: application/json" \
+  -d '{"filename":"updated.pdf"}'
+```
+
+### Delete File (DELETE)
+
+```bash
+curl -X DELETE http://localhost:8000/api/files/<id>
+```
+

tasks/crud/controllers/filecontroller.go

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+package controllers
+
+import (
+	"context"
+	"crud-api/models"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/gorilla/mux"
+	"github.com/joho/godotenv"
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+	"go.mongodb.org/mongo-driver/mongo"
+	"go.mongodb.org/mongo-driver/mongo/options"
+)
+
+const (
+	dbName  = "FileDb"
+	colName = "Files"
+)
+
+var collection *mongo.Collection
+
+// Initializes MongoDB connection and sets the collection.
+func init() {
+	if err := godotenv.Load(); err != nil {
+		log.Fatal("Error loading .env file")
+	}
+
+	connectionString := os.Getenv("MONGODB_URI")
+	clientOptions := options.Client().ApplyURI(connectionString)
+
+	client, err := mongo.Connect(context.TODO(), clientOptions)
+	if err != nil {
+		log.Fatal("Mongo connection error:", err)
+	}
+
+	fmt.Println("MongoDB connection successful")
+	collection = client.Database(dbName).Collection(colName)
+}
+
+// Inserts a new file document into MongoDB.
+func createFile(file *models.FileMetadata) error {
+	file.ID = primitive.NewObjectID()
+	file.CreatedAt = time.Now()
+	file.UpdatedAt = time.Now()
+
+	_, err := collection.InsertOne(context.Background(), file)
+	return err
+}
+
+// Updates a file document by ID with non-empty fields and returns updated doc.
+func updateFile(file *models.FileMetadata, id string) error {
+	objID, err := primitive.ObjectIDFromHex(id)
+	if err != nil {
+		return fmt.Errorf("invalid ID: %v", err)
+	}
+
+	updateFields := bson.M{}
+	if file.FileName != "" {
+		updateFields["filename"] = file.FileName
+	}
+	if file.FilePath != "" {
+		updateFields["filepath"] = file.FilePath
+	}
+	if file.FileSize != 0 {
+		updateFields["filesize"] = file.FileSize
+	}
+	if file.ContentType != "" {
+		updateFields["content_type"] = file.ContentType
+	}
+	updateFields["updated_at"] = time.Now()
+
+	_, err = collection.UpdateOne(context.Background(), bson.M{"_id": objID}, bson.M{"$set": updateFields})
+	if err != nil {
+		return err
+	}
+
+	return collection.FindOne(context.Background(), bson.M{"_id": objID}).Decode(file)
+}
+
+// Deletes a single file document by ID.
+func deleteOneFile(fileID string) error {
+	objID, err := primitive.ObjectIDFromHex(fileID)
+	if err != nil {
+		return err
+	}
+
+	_, err = collection.DeleteOne(context.Background(), bson.M{"_id": objID})
+	return err
+}
+
+// Retrieves all file documents from the collection.
+func getAllFiles() ([]models.FileMetadata, error) {
+	cursor, err := collection.Find(context.Background(), bson.M{})
+	if err != nil {
+		return nil, err
+	}
+	defer cursor.Close(context.Background())
+
+	var files []models.FileMetadata
+	for cursor.Next(context.Background()) {
+		var file models.FileMetadata
+		if err := cursor.Decode(&file); err != nil {
+			log.Println("Decode error:", err)
+			continue
+		}
+		files = append(files, file)
+	}
+
+	return files, nil
+}
+
+// Retrieves a single file document by ID.
+func getFileByID(fileID string) (*models.FileMetadata, error) {
+	objID, err := primitive.ObjectIDFromHex(fileID)
+	if err != nil {
+		return nil, err
+	}
+
+	var file models.FileMetadata
+	err = collection.FindOne(context.Background(), bson.M{"_id": objID}).Decode(&file)
+	return &file, err
+}
+
+// HTTP: Returns all files.
+func GetAllFiles(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+
+	files, err := getAllFiles()
+	if err != nil {
+		http.Error(w, "Failed to fetch files", http.StatusInternalServerError)
+		return
+	}
+
+	json.NewEncoder(w).Encode(files)
+}
+
+// HTTP: Returns a file by ID.
+func GetFile(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	id := mux.Vars(r)["id"]
+
+	file, err := getFileByID(id)
+	if err != nil {
+		http.Error(w, "File not found", http.StatusNotFound)
+		return
+	}
+
+	json.NewEncoder(w).Encode(file)
+}
+
+// HTTP: Creates a new file.
+func CreateFile(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+
+	var file models.FileMetadata
+	if err := json.NewDecoder(r.Body).Decode(&file); err != nil {
+		http.Error(w, "Invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	if err := createFile(&file); err != nil {
+		http.Error(w, "Failed to create file", http.StatusInternalServerError)
+		return
+	}
+
+	json.NewEncoder(w).Encode(file)
+}
+
+// HTTP: Updates a file by ID.
+func UpdateFile(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	id := mux.Vars(r)["id"]
+
+	var file models.FileMetadata
+	if err := json.NewDecoder(r.Body).Decode(&file); err != nil {
+		http.Error(w, "Invalid request body", http.StatusBadRequest)
+		return
+	}
+
+	if err := updateFile(&file, id); err != nil {
+		http.Error(w, "Failed to update file", http.StatusInternalServerError)
+		return
+	}
+
+	json.NewEncoder(w).Encode(file)
+}
+
+// HTTP: Deletes a file by ID.
+func DeleteFile(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	id := mux.Vars(r)["id"]
+
+	if err := deleteOneFile(id); err != nil {
+		http.Error(w, "Failed to delete file", http.StatusInternalServerError)
+		return
+	}
+
+	json.NewEncoder(w).Encode(map[string]string{"deleted_id": id})
+}

tasks/crud/go.mod

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+module crud-api
+
+go 1.22.2
+
+require (
+	github.com/gorilla/mux v1.8.1
+	github.com/joho/godotenv v1.5.1
+	go.mongodb.org/mongo-driver v1.17.4
+)
+
+require (
+	github.com/golang/snappy v1.0.0 // indirect
+	github.com/klauspost/compress v1.16.7 // indirect
+	github.com/montanaflynn/stats v0.7.1 // indirect
+	github.com/xdg-go/pbkdf2 v1.0.0 // indirect
+	github.com/xdg-go/scram v1.1.2 // indirect
+	github.com/xdg-go/stringprep v1.0.4 // indirect
+	github.com/youmark/pkcs8 v0.0.0-20240726163527-a2c0da244d78 // indirect
+	golang.org/x/crypto v0.33.0 // indirect
+	golang.org/x/sync v0.11.0 // indirect
+	golang.org/x/text v0.22.0 // indirect
+)