tomll: port to v2 (#727)

Fixes #721

internal/cli/cli.go

@@ -1,22 +1,32 @@
 package cli
 
 import (
+	"bytes"
 	"flag"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 )
 
 type ConvertFn func(r io.Reader, w io.Writer) error
 
-func Execute(usage string, fn ConvertFn) {
-	flag.Usage = func() { fmt.Fprintf(os.Stderr, usage) }
-	flag.Parse()
-	os.Exit(processMain(flag.Args(), os.Stdin, os.Stdout, os.Stderr, fn))
+type Program struct {
+	Usage string
+	Fn    ConvertFn
+	// Inplace allows the command to take more than one file as argument and
+	// perform convertion in place on each provided file.
+	Inplace bool
 }
 
-func processMain(files []string, input io.Reader, output, error io.Writer, f ConvertFn) int {
-	err := run(files, input, output, f)
+func (p *Program) Execute() {
+	flag.Usage = func() { fmt.Fprintf(os.Stderr, p.Usage) }
+	flag.Parse()
+	os.Exit(p.main(flag.Args(), os.Stdin, os.Stdout, os.Stderr))
+}
+
+func (p *Program) main(files []string, input io.Reader, output, error io.Writer) int {
+	err := p.run(files, input, output)
 	if err != nil {
 		fmt.Fprintln(error, err.Error())
 		return -1
@@ -24,8 +34,11 @@ func processMain(files []string, input io.Reader, output, error io.Writer, f Con
 	return 0
 }
 
-func run(files []string, input io.Reader, output io.Writer, convert ConvertFn) error {
+func (p *Program) run(files []string, input io.Reader, output io.Writer) error {
 	if len(files) > 0 {
+		if p.Inplace {
+			return p.runAllFilesInPlace(files)
+		}
 		f, err := os.Open(files[0])
 		if err != nil {
 			return err
@@ -33,5 +46,31 @@ func run(files []string, input io.Reader, output io.Writer, convert ConvertFn) e
 		defer f.Close()
 		input = f
 	}
-	return convert(input, output)
+	return p.Fn(input, output)
+}
+
+func (p *Program) runAllFilesInPlace(files []string) error {
+	for _, path := range files {
+		err := p.runFileInPlace(path)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p *Program) runFileInPlace(path string) error {
+	in, err := ioutil.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	out := new(bytes.Buffer)
+
+	err = p.Fn(bytes.NewReader(in), out)
+	if err != nil {
+		return err
+	}
+
+	return ioutil.WriteFile(path, out.Bytes(), 0600)
 }