Refactor SQL migrations

- Avoid embedding SQL files into binary
- Allow more flexible changes by using Go functions

database/database.go

@@ -6,9 +6,12 @@ package database // import "miniflux.app/database"
 
 import (
 	"database/sql"
+	"fmt"
 
 	// Postgresql driver import
 	_ "github.com/lib/pq"
+
+	"miniflux.app/logger"
 )
 
 // NewConnectionPool configures the database connection pool.
@@ -23,3 +26,51 @@ func NewConnectionPool(dsn string, minConnections, maxConnections int) (*sql.DB,
 
 	return db, nil
 }
+
+// Migrate executes database migrations.
+func Migrate(db *sql.DB) {
+	var currentVersion int
+	db.QueryRow(`SELECT version FROM schema_version`).Scan(&currentVersion)
+
+	fmt.Println("-> Current schema version:", currentVersion)
+	fmt.Println("-> Latest schema version:", schemaVersion)
+
+	for version := currentVersion; version < schemaVersion; version++ {
+		newVersion := version + 1
+		fmt.Println("* Migrating to version:", newVersion)
+
+		tx, err := db.Begin()
+		if err != nil {
+			logger.Fatal("[Migration v%d] %v", newVersion, err)
+		}
+
+		if err := migrations[version](tx); err != nil {
+			tx.Rollback()
+			logger.Fatal("[Migration v%d] %v", newVersion, err)
+		}
+
+		if _, err := tx.Exec(`DELETE FROM schema_version`); err != nil {
+			tx.Rollback()
+			logger.Fatal("[Migration v%d] %v", newVersion, err)
+		}
+
+		if _, err := tx.Exec(`INSERT INTO schema_version (version) VALUES ($1)`, newVersion); err != nil {
+			tx.Rollback()
+			logger.Fatal("[Migration v%d] %v", newVersion, err)
+		}
+
+		if err := tx.Commit(); err != nil {
+			logger.Fatal("[Migration v%d] %v", newVersion, err)
+		}
+	}
+}
+
+// IsSchemaUpToDate checks if the database schema is up to date.
+func IsSchemaUpToDate(db *sql.DB) error {
+	var currentVersion int
+	db.QueryRow(`SELECT version FROM schema_version`).Scan(&currentVersion)
+	if currentVersion < schemaVersion {
+		return fmt.Errorf(`the database schema is not up to date: current=v%d expected=v%d`, currentVersion, schemaVersion)
+	}
+	return nil
+}