add(sam): migrations code start

sam/db/migrate.go

@@ -0,0 +1,80 @@
+package db
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"regexp"
+	"sort"
+
+	_ "github.com/crusttech/crust/sam/db/mysql"
+	"github.com/pkg/errors"
+	"github.com/rakyll/statik/fs"
+	"github.com/titpetric/factory"
+)
+
+//go:generate statik -p mysql -Z -f -src=schema/mysql
+
+func statements(contents []byte, err error) ([]string, error) {
+	if err != nil {
+		return []string{}, err
+	}
+	return regexp.MustCompilePOSIX(";$").Split(string(contents), -1), nil
+}
+
+func Migrate(db *factory.DB) error {
+	statikFS, err := fs.New()
+	if err != nil {
+		return errors.Wrap(err, "Error creating statik filesystem")
+	}
+
+	var files []string
+
+	fs.Walk(statikFS, "/", func(filename string, info os.FileInfo, err error) error {
+		if len(filename) > 4 && filename[len(filename)-4:] == ".sql" {
+			files = append(files, filename)
+		}
+		return nil
+	})
+
+	sort.Strings(files)
+
+	if len(files) == 0 {
+		return errors.New("No files encoded for migration, need at least one SQL file")
+	}
+
+	// @todo: create table migrations by hand, log each filename status/date
+	/*
+		create table if not exists migrations (
+			filename string, status [ok, fail], message string (may be error text?), stamp datetime
+		)
+	*/
+
+	for _, filename := range files {
+		// @todo: select * from migrations to check if (filename) was processed, skip if yes
+
+		stmts, err := statements(fs.ReadFile(statikFS, filename))
+		if err != nil {
+			return errors.Wrap(err, fmt.Sprintf("Error applying migration %s", filename))
+		}
+
+		up := func() error {
+			log.Println("Running migration for", filename)
+			for _, query := range stmts {
+				if _, err := db.Exec(query); err != nil {
+					return err
+				}
+			}
+			log.Println("Migration done OK")
+
+			// @todo: insert/update into migrations with (filename)
+			return nil
+		}
+
+		if err := db.Transaction(up); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

sam/db/migrate_test.go

@@ -0,0 +1,30 @@
+package db
+
+import (
+	"testing"
+
+	"github.com/joho/godotenv"
+	"github.com/namsral/flag"
+	"github.com/titpetric/factory"
+
+	"github.com/crusttech/crust/internal/config"
+)
+
+func TestMigrations(t *testing.T) {
+	// @todo this is a very optimistic initialization, make it more robust
+	godotenv.Load("../../.env")
+
+	dbConfig := new(config.Database).Init("sam")
+	flag.Parse()
+
+	if err := dbConfig.Validate(); err != nil {
+		t.Fatalf("Error in database config: %+v", err)
+	}
+
+	factory.Database.Add("default", dbConfig.DSN)
+
+	db := factory.Database.MustGet()
+	if err := Migrate(db); err != nil {
+		t.Fatalf("Unexpected error: %#v", err)
+	}
+}