docs: add comments for all functions

database/db.go

@@ -1,3 +1,5 @@
+// Package database provides database initialization, migration, and management utilities
+// for the 3x-ui panel using GORM with SQLite.
 package database
 
 import (
@@ -45,6 +47,7 @@ func initModels() error {
 	return nil
 }
 
+// initUser creates a default admin user if the users table is empty.
 func initUser() error {
 	empty, err := isTableEmpty("users")
 	if err != nil {
@@ -68,6 +71,7 @@ func initUser() error {
 	return nil
 }
 
+// runSeeders migrates user passwords to bcrypt and records seeder execution to prevent re-running.
 func runSeeders(isUsersEmpty bool) error {
 	empty, err := isTableEmpty("history_of_seeders")
 	if err != nil {
@@ -107,12 +111,14 @@ func runSeeders(isUsersEmpty bool) error {
 	return nil
 }
 
+// isTableEmpty returns true if the named table contains zero rows.
 func isTableEmpty(tableName string) (bool, error) {
 	var count int64
 	err := db.Table(tableName).Count(&count).Error
 	return count == 0, err
 }
 
+// InitDB sets up the database connection, migrates models, and runs seeders.
 func InitDB(dbPath string) error {
 	dir := path.Dir(dbPath)
 	err := os.MkdirAll(dir, fs.ModePerm)
@@ -151,6 +157,7 @@ func InitDB(dbPath string) error {
 	return runSeeders(isUsersEmpty)
 }
 
+// CloseDB closes the database connection if it exists.
 func CloseDB() error {
 	if db != nil {
 		sqlDB, err := db.DB()
@@ -162,14 +169,17 @@ func CloseDB() error {
 	return nil
 }
 
+// GetDB returns the global GORM database instance.
 func GetDB() *gorm.DB {
 	return db
 }
 
+// IsNotFound checks if the given error is a GORM record not found error.
 func IsNotFound(err error) bool {
 	return err == gorm.ErrRecordNotFound
 }
 
+// IsSQLiteDB checks if the given file is a valid SQLite database by reading its signature.
 func IsSQLiteDB(file io.ReaderAt) (bool, error) {
 	signature := []byte("SQLite format 3\x00")
 	buf := make([]byte, len(signature))
@@ -180,6 +190,7 @@ func IsSQLiteDB(file io.ReaderAt) (bool, error) {
 	return bytes.Equal(buf, signature), nil
 }
 
+// Checkpoint performs a WAL checkpoint on the SQLite database to ensure data consistency.
 func Checkpoint() error {
 	// Update WAL
 	err := db.Exec("PRAGMA wal_checkpoint;").Error