printing: commit some refactors (probably broken)

printer/printer.go

@@ -0,0 +1,43 @@
+package printer
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/mmcloughlin/avo"
+)
+
+type Printer interface {
+	Print(*avo.File) ([]byte, error)
+}
+
+type Builder func(Config) Printer
+
+type Config struct {
+	Name string
+	Argv []string
+	Pkg  string
+}
+
+func NewDefaultConfig() Config {
+	cfg := Config{
+		Argv: os.Args,
+	}
+	if cwd, err := os.Getwd(); err == nil {
+		cfg.Pkg = filepath.Base(cwd)
+	}
+	return cfg
+}
+
+func (c Config) GeneratedBy() string {
+	if c.Argv == nil {
+		return c.Name
+	}
+	return fmt.Sprintf("command: %s", strings.Join(c.Argv, " "))
+}
+
+func (c Config) GeneratedWarning() string {
+	return fmt.Sprintf("Code generated by %s. DO NOT EDIT.", c.GeneratedBy())
+}