[feature] migration generator

README.md

@@ -85,3 +85,9 @@ func main() {
     }
 }
 ```
+### Migration generator
+This library contains helper tool for transports. You can install it via go:
+```sh
+$ go get -u github.com/retailcrm/mg-transport-core/cmd/transport-core-tool
+```
+Currently, it only can generate new migrations for your transport.

cmd/transport-core-tool/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"os"
+
+	"github.com/jessevdk/go-flags"
+	"github.com/retailcrm/mg-transport-core/core"
+)
+
+type Options struct{}
+
+var (
+	options = Options{}
+	parser  = flags.NewParser(&options, flags.Default)
+)
+
+func init() {
+	_, err := parser.AddCommand("migration",
+		"Create new empty migration in specified directory.",
+		"Create new empty migration in specified directory.",
+		&core.NewMigrationCommand{},
+	)
+
+	if err != nil {
+		panic(err.Error())
+	}
+}
+
+func main() {
+	if _, err := parser.Parse(); err != nil {
+		if flagsErr, ok := err.(*flags.Error); ok && flagsErr.Type == flags.ErrHelp {
+			os.Exit(0)
+		} else {
+			os.Exit(1)
+		}
+	}
+}

core/migration_generator.go

@@ -0,0 +1,84 @@
+package core
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var migrationTemplate = `package $package
+
+import (
+	"github.com/jinzhu/gorm"
+	"github.com/retailcrm/mg-transport-core/core"
+	"gopkg.in/gormigrate.v1"
+)
+
+func init() {
+	core.Migrations().Add(&gormigrate.Migration{
+		ID: "$version",
+		Migrate: func(db *gorm.DB) error {
+			// Write your migration code here...
+		},
+		Rollback: func(db *gorm.DB) error {
+			// Write your migration rollback code here...
+		},
+	})
+}
+`
+
+// NewMigrationCommand struct
+type NewMigrationCommand struct {
+	Directory string `short:"d" long:"directory" default:"./migrations" description:"Directory where migration will be created"`
+}
+
+func (x *NewMigrationCommand) FileExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
+}
+
+func (x *NewMigrationCommand) Execute(args []string) error {
+	version := strconv.FormatInt(time.Now().Unix(), 10)
+	directory := path.Clean(x.Directory)
+	packageName := "migrations"
+
+	if _, err := os.Stat(directory); os.IsNotExist(err) {
+		return fmt.Errorf("err: specified directory doesn't exist")
+	}
+
+	if base := path.Base(directory); base != "/" && base != "." {
+		packageName = base
+	}
+
+	filePath := path.Join(directory, version+"_app.go")
+	if x.FileExists(filePath) {
+		return fmt.Errorf("\"%s\" already exists or it's a directory", filePath)
+	}
+
+	migrationData := strings.Replace(
+		strings.Replace(migrationTemplate, "$version", version, 1),
+		"$package",
+		packageName,
+		1,
+	)
+
+	file, err := os.Create(filePath)
+	if err != nil {
+		return err
+	}
+
+	defer file.Close()
+
+	if _, err := file.WriteString(migrationData); err != nil {
+		return err
+	}
+
+	fmt.Println("Created new migration: " + filePath)
+	return nil
+}

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/golang/protobuf v1.3.2 // indirect
 	github.com/google/go-querystring v1.0.0 // indirect
 	github.com/h2non/gock v1.0.10
+	github.com/jessevdk/go-flags v1.4.0 // indirect
 	github.com/jinzhu/gorm v1.9.10
 	github.com/json-iterator/go v1.1.7 // indirect
 	github.com/lib/pq v1.2.0 // indirect

go.sum

@@ -87,6 +87,8 @@ github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ
 github.com/hashicorp/hcl v1.0.0/go.mod h1:E5yfLk+7swimpb2L/Alb/PJmXilQ/rhwaUYs4T20WEQ=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
+github.com/jessevdk/go-flags v1.4.0 h1:4IU2WS7AumrZ/40jfhf4QVDMsQwqA7VEHozFRrGARJA=
+github.com/jessevdk/go-flags v1.4.0/go.mod h1:4FA24M0QyGHXBuZZK/XkWh8h0e1EYbRYJSGM75WSRxI=
 github.com/jinzhu/gorm v1.9.2 h1:lCvgEaqe/HVE+tjAR2mt4HbbHAZsQOv3XAZiEZV37iw=
 github.com/jinzhu/gorm v1.9.2/go.mod h1:Vla75njaFJ8clLU1W44h34PjIkijhjHIYnZxMqCdxqo=
 github.com/jinzhu/gorm v1.9.10 h1:HvrsqdhCW78xpJF67g1hMxS6eCToo9PZH4LDB8WKPac=