Implement database connection and refactor welcome handler

cmd/admin_backend/main.go

@@ -1,7 +1,8 @@
 package main
 
 import (
-	"admin_dashboard_backend/pkg/handlers"
+	"admin_dashboard_backend/pkg/db"
+	"admin_dashboard_backend/pkg/handlers/welcome"
 	"encoding/json"
 	"fmt"
 	"log"
@@ -27,8 +28,10 @@ func main() {
 		port = "84" // default port
 	}
 
+	// Initialize database connection
+	db.InitDB()
 	// Define routes
-	http.HandleFunc("/welcome", handlers.HandlersWelcome)
+	http.HandleFunc("/welcome", welcome.HandlersWelcome)
 
 	// Start server
 	fmt.Printf("Server is running on port %s...\n", port)

config.json

@@ -4,7 +4,7 @@
   "databaseUser": "root",
   "databasePassword": "1234",
   "database": "app",
-  "databasePort": 3306,
+  "databasePort": "3306",
   "developerMode": true,
   "developerLogin": true,
   "forceDevLogin": true,

go.mod

@@ -1,3 +1,8 @@
 module admin_dashboard_backend
 
 go 1.23.4
+
+require (
+	filippo.io/edwards25519 v1.1.0 // indirect
+	github.com/go-sql-driver/mysql v1.8.1 // indirect
+)

go.sum

@@ -0,0 +1,6 @@
+filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
+filippo.io/edwards25519 v1.1.0/go.mod h1:BxyFTGdWcka3PhytdK4V28tE5sGfRvvvRV7EaN4VDT4=
+github.com/go-sql-driver/mysql v1.8.1 h1:LedoTUt/eveggdHS9qUFC1EFSa8bU2+1pZjSRpvNJ1Y=
+github.com/go-sql-driver/mysql v1.8.1/go.mod h1:wEBSXgmK//2ZFJyE+qWnIsVGmvmEKlqwuVSjsCm7DZg=
+github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
+github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=

pkg/db/db_connection.go

@@ -0,0 +1,51 @@
+package db
+
+import (
+	"database/sql"
+	"encoding/json"
+	"log"
+	"os"
+
+	_ "github.com/go-sql-driver/mysql"
+)
+
+type Config struct {
+	Host     string `json:"databaseHost"`
+	Port     string `json:"databasePort"`
+	User     string `json:"databaseUser"`
+	Password string `json:"databasePassword"`
+	DBName   string `json:"database"`
+}
+
+var DB *sql.DB
+
+func InitDB() {
+	config := loadConfig()
+	dsn := config.User + ":" + config.Password + "@tcp(" + config.Host + ":" + config.Port + ")/" + config.DBName
+
+	var err error
+	DB, err = sql.Open("mysql", dsn)
+	if err != nil {
+		log.Fatal("Error connecting to database:", err)
+	}
+
+	err = DB.Ping()
+	if err != nil {
+		log.Fatal("Error pinging database:", err)
+	}
+}
+
+func loadConfig() Config {
+	file, err := os.ReadFile("config.json")
+	if err != nil {
+		log.Fatal("Error reading config file:", err)
+	}
+
+	var config Config
+	err = json.Unmarshal(file, &config)
+	if err != nil {
+		log.Fatal("Error parsing config file:", err)
+	}
+
+	return config
+}

pkg/db/db_login.go

@@ -0,0 +1,48 @@
+package db
+
+import (
+	"database/sql"
+	"log"
+
+	_ "github.com/go-sql-driver/mysql"
+)
+
+var db *sql.DB
+
+func Init() {
+	var err error
+	db, err = sql.Open("mysql", "user:password@tcp(127.0.0.1:3306)/dbname")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if err = db.Ping(); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func Login(username, password string) (bool, error) {
+	var dbPassword string
+	query := "SELECT password FROM users WHERE username = ?"
+	err := db.QueryRow(query, username).Scan(&dbPassword)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return false, nil
+		}
+		return false, err
+	}
+
+	if dbPassword != password {
+		return false, nil
+	}
+
+	return true, nil
+	var token string
+	query = "SELECT token FROM users WHERE username = ?"
+	err = db.QueryRow(query, username).Scan(&token)
+	if err != nil {
+		return false, err
+	}
+
+	return true, token
+}

pkg/handlers/login/login.go

@@ -0,0 +1,44 @@
+package login
+
+import (
+	"admin_dashboard_backend/pkg/db"
+	"encoding/json"
+	"log"
+	"net/http"
+)
+
+type Request struct {
+	Username string `json:"username"`
+	Password string `json:"password"`
+}
+
+type Response struct {
+	Token string `json:"token"`
+}
+
+func HandlersLogin(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	var request Request
+	if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
+		http.Error(w, "Bad request", http.StatusBadRequest)
+		return
+	}
+
+	token, err := db.Login(request.Username, request.Password)
+	if err != nil {
+		log.Println("Error logging in:", err)
+		http.Error(w, "Internal server error", http.StatusInternalServerError)
+		return
+	}
+
+	response := Response{
+		Token: token,
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(response)
+}

pkg/handlers/welcome/welcome.go

@@ -1,4 +1,4 @@
-package handlers
+package welcome
 
 import (
 	"encoding/json"