1 files changed, 72 insertions, 39 deletions

diff --git a/model/database.go b/model/database.go
index 7490f7b..84ed497 100644
--- a/model/database.go
+++ b/model/database.go
@@ -2,12 +2,11 @@ package model
 
 import (
 	"database/sql"
+	"embed"
 	"fmt"
 	"log"
 
 	_ "github.com/mattn/go-sqlite3"
-
-	"xengineering.eu/ceres/model/migrations"
 )
 
 type DB sql.DB
@@ -48,8 +47,6 @@ func (db *DB) Transaction(f func(*sql.Tx) error) error {
 }
 
 func (db *DB) IsEmpty(tx *sql.Tx) (bool, error) {
-	var number int
-
 	cmd := `SELECT COUNT(*) FROM sqlite_master WHERE type='table'`
 	rows, err := tx.Query(cmd)
 	if err != nil {
@@ -61,6 +58,7 @@ func (db *DB) IsEmpty(tx *sql.Tx) (bool, error) {
 		return false, fmt.Errorf("Result set is empty")
 	}
 
+	var number int
 	err = rows.Scan(&number)
 	if err != nil {
 		return false, fmt.Errorf("Failed to scan numerical value: %w", err)
@@ -69,69 +67,104 @@ func (db *DB) IsEmpty(tx *sql.Tx) (bool, error) {
 	return number == 0, nil
 }
 
-func (db *DB) setupMinimal(tx *sql.Tx, execVersion string) error {
-	cmd := `
-CREATE TABLE metadata (
-	key   TEXT PRIMARY KEY,
-	value TEXT
-);
-INSERT INTO metadata
-	(key, value)
-VALUES
-	('version', ?);
-`
-	_, err := tx.Exec(cmd, execVersion)
-	return err
-}
-
 func (db *DB) SchemaVersion(tx *sql.Tx) (int, error) {
 	empty, err := db.IsEmpty(tx)
 	if err != nil {
 		return 0, fmt.Errorf("Failed to check if DB is empty: %w", err)
 	}
-
 	if empty {
 		return 0, nil
 	}
 
 	rows, err := tx.Query(`SELECT value FROM metadata WHERE key='version';`)
 	if err != nil {
-		return 0, fmt.Errorf("Select call failed: %w", err)
+		return 0, fmt.Errorf("Select call for version failed: %w", err)
 	}
 	defer rows.Close()
-
 	if rows.Next() {
 		return 1, nil // version field was only present in one schema version
 	}
 
-	return 0, fmt.Errorf("Unknown schema version")
+	rows, err = tx.Query(`SELECT value FROM metadata WHERE key='schema_version';`)
+	if err != nil {
+		return 0, fmt.Errorf("Select call for schema_version failed: %w", err)
+	}
+	defer rows.Close()
+	if !rows.Next() {
+		return 0, fmt.Errorf("No schema_version entry in metadata table")
+	}
+	var number int
+	err = rows.Scan(&number)
+	if err != nil {
+		return 0, fmt.Errorf("Failed to scan schema_version: %w", err)
+	}
+
+	return number, nil
+}
+
+//go:embed sql/migration*.sql
+var migrationSQL embed.FS
+
+func getMigrations() ([]func(tx *sql.Tx) error, error) {
+	migrations := make([]func(tx *sql.Tx) error, 0)
+
+	entries, err := migrationSQL.ReadDir("sql")
+	if err != nil {
+		return nil, fmt.Errorf("Failed to read embedded migration SQL FS: %w", err)
+	}
+	amount := len(entries)
+
+	for i := 0; i < amount; i++ {
+		file := fmt.Sprintf("sql/migration%03d.sql", i)
+		data, err := migrationSQL.ReadFile(file)
+		if err != nil {
+			return nil, fmt.Errorf("Failed to read migration SQL code: %w", err)
+		}
+		migrations = append(
+			migrations,
+			func(tx *sql.Tx) error {
+				_, err := tx.Exec(string(data))
+				return err
+			},
+		)
+	}
+
+	return migrations, nil
 }
 
-func (db *DB) Migrate(execVersion string) error {
+func (db *DB) Migrate() error {
+	migrations, err := getMigrations()
+	if err != nil {
+		return fmt.Errorf("Failed to get migrations: %w", err)
+	}
+
 	return db.Transaction(func(tx *sql.Tx) error {
-		for {
-			schema, err := db.SchemaVersion(tx)
+		var version int
+		for index, migration := range migrations {
+			var err error
+			version, err = db.SchemaVersion(tx)
 			if err != nil {
 				return fmt.Errorf("Failed to get DB schema version: %w", err)
 			}
-			switch schema {
-			case 0:
-				log.Println("Starting with empty database")
-				err := db.setupMinimal(tx, execVersion)
-				if err != nil {
-					return fmt.Errorf("Failed to setup minimal database schema: %w", err)
-				}
-				log.Println("Executing initial migration")
-				err = migrations.Migration001(tx)
+
+			if version == index {
+				log.Printf("Starting database migration for schema version %d", version)
+				err = migration(tx)
 				if err != nil {
 					return err
 				}
-			case 1:
-				return nil
-			default:
-				return fmt.Errorf("Cannot migrate database to a matching schema version")
 			}
 		}
+		version, err := db.SchemaVersion(tx)
+		if err != nil {
+			return fmt.Errorf("Failed to get DB schema version: %w", err)
+		}
+		target := len(migrations)
+		if version != target {
+			return fmt.Errorf("Expected schema version %d but detected %d", target, version)
+		}
+		log.Printf("Database schema version: %d\n", version)
+		return nil
 	})
 }