ADD: added basic backend function plus a mockup for a cli interface

backend/internal/database/database.go

@@ -0,0 +1,97 @@
+package database
+
+import (
+	"database/sql"
+	"fmt"
+	"log"
+	"studia/internal/config"
+
+	_ "github.com/lib/pq" // Import the PostgreSQL driver
+)
+
+var expectedTables = []string{
+	"users",
+}
+
+func New(cfg *config.Config) *sql.DB {
+	db := setupDatabase(cfg)
+
+	existing, err := getExistingTables(db, `
+		SELECT table_name
+		FROM information_schema.tables
+		WHERE table_schema = 'public'
+	`)
+	if err != nil {
+		log.Println("failed to query existing tables:", err)
+	}
+
+	missing := checkTables(expectedTables, existing)
+
+	if len(missing) > 0 {
+		log.Println("Missing tables detected:", missing)
+		// Here you would normally run migrations to create the missing tables
+		// For simplicity, we just log the missing tables
+	} else {
+		log.Println("All expected tables are present.")
+	}
+
+	return db
+}
+
+func setupDatabase(cfg *config.Config) *sql.DB {
+	// Database connection setup logic here
+
+	log.Println(cfg)
+	switch cfg.DatabaseDriver {
+	case "postgres":
+		// Setup Postgres connection
+		log.Println("Setting up Postgres connection")
+		psqlInfo := fmt.Sprintf("host=%s port=%s user=%s password=%s dbname=%s sslmode=disable",
+			cfg.DatabaseHost, cfg.DatabasePort, cfg.DatabaseUser, cfg.DatabasePassword, cfg.DatabaseName)
+		db, err := sql.Open("postgres", psqlInfo)
+		if err != nil {
+			log.Fatal("Failed to connect to database:", err)
+		}
+		return db
+	case "mysql":
+		// Setup MySQL connection
+		dsn := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s",
+			cfg.DatabaseUser, cfg.DatabasePassword, cfg.DatabaseHost, cfg.DatabasePort, cfg.DatabaseName)
+		db, err := sql.Open("mysql", dsn)
+		if err != nil {
+			// Handle error
+		}
+		return db
+	default:
+		// Handle unsupported database driver
+	}
+	return nil
+}
+
+func getExistingTables(db *sql.DB, query string) (map[string]bool, error) {
+	rows, err := db.Query(query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	tables := make(map[string]bool)
+	for rows.Next() {
+		var name string
+		if err := rows.Scan(&name); err != nil {
+			return nil, err
+		}
+		tables[name] = true
+	}
+	return tables, nil
+}
+
+func checkTables(expected []string, existing map[string]bool) []string {
+	var missing []string
+	for _, table := range expected {
+		if !existing[table] {
+			missing = append(missing, table)
+		}
+	}
+	return missing
+}