db: remove implicit singleton pattern, move functions under a struct object

pkg/db/connect.go

@@ -10,7 +10,7 @@ import (
 	_ "github.com/mattn/go-sqlite3"
 )
 
-var (
+type DBConfig struct {
 	// // Tracks whether the DB connector has been initialized
 	// is_initialized bool
 
@@ -20,7 +20,7 @@ var (
 	// Database starts at version 0.  First migration brings us to version 1
 	migrations     *[]string
 	version_number uint
-)
+}
 
 // Colors for terminal output
 const (
@@ -36,14 +36,15 @@ const (
 	ColorWhite  = "\033[97m"
 )
 
-func Init(schema *string, migrationsList *[]string) {
-	sql_schema = schema
-	migrations = migrationsList
-	version_number = uint(len(*migrations))
-	// is_initialized = true
+func Init(schema *string, migrationsList *[]string) DBConfig {
+	return DBConfig{
+		sql_schema:     schema,
+		migrations:     migrationsList,
+		version_number: uint(len(*migrationsList)),
+	}
 }
 
-func Create(path string) (*sqlx.DB, error) {
+func (c DBConfig) Create(path string) (*sqlx.DB, error) {
 	// First check if the path already exists
 	_, err := os.Stat(path)
 	if err == nil {
@@ -63,14 +64,14 @@ func Create(path string) (*sqlx.DB, error) {
 	if _, err = db.Exec("pragma foreign_keys=on; pragma journal_mode=WAL;"); err != nil {
 		return nil, fmt.Errorf("running pragma statements: %w", err)
 	}
-	if _, err = db.Exec(*sql_schema); err != nil {
+	if _, err = db.Exec(*c.sql_schema); err != nil {
 		return nil, fmt.Errorf("creating schema: %w", err)
 	}
 
 	return db, nil
 }
 
-func Connect(path string) (*sqlx.DB, error) {
+func (c DBConfig) Connect(path string) (*sqlx.DB, error) {
 	db, err := sqlx.Open("sqlite3", path)
 	if err != nil {
 		return nil, fmt.Errorf("opening db: %w", err)
@@ -79,38 +80,38 @@ func Connect(path string) (*sqlx.DB, error) {
 		return nil, fmt.Errorf("running pragma statements: %w", err)
 	}
 
-	err = CheckAndUpdateVersion(db)
+	err = c.CheckAndUpdateVersion(db)
 	return db, err
 }
 
-func CheckAndUpdateVersion(db *sqlx.DB) error {
+func (c DBConfig) CheckAndUpdateVersion(db *sqlx.DB) error {
 	var version uint
 	err := db.Get(&version, "select version from db_version")
 	if err != nil {
 		return fmt.Errorf("couldn't check database version: %w", err)
 	}
 
-	if version > version_number {
-		return VersionMismatchError{version_number, version}
+	if version > c.version_number {
+		return VersionMismatchError{c.version_number, version}
 	}
 
-	if version_number > version {
+	if c.version_number > version {
 		fmt.Print(ColorYellow)
 		fmt.Printf("================================================\n")
 		fmt.Printf("Database version is out of date.  Upgrading database from version %d to version %d!\n", version,
-			version_number)
+			c.version_number)
 		fmt.Print(ColorReset)
-		UpgradeFromXToY(db, version, version_number)
+		c.UpgradeFromXToY(db, version, c.version_number)
 	}
 
 	return nil
 }
 
 // UpgradeFromXToY runs all the migrations from version X to version Y, and update the `database_version` table's `version_number`
-func UpgradeFromXToY(db *sqlx.DB, x uint, y uint) {
+func (c DBConfig) UpgradeFromXToY(db *sqlx.DB, x uint, y uint) {
 	for i := x; i < y; i++ {
 		fmt.Print(ColorCyan)
-		fmt.Println((*migrations)[i])
+		fmt.Println((*c.migrations)[i])
 		fmt.Print(ColorReset)
 
 		// Execute the migration in a transaction
@@ -118,7 +119,7 @@ func UpgradeFromXToY(db *sqlx.DB, x uint, y uint) {
 		if err != nil {
 			panic(err)
 		}
-		tx.MustExec((*migrations)[i])
+		tx.MustExec((*c.migrations)[i])
 		tx.MustExec("update db_version set version = ?", i+1)
 		if err := tx.Commit(); err != nil {
 			panic(err)