✨BashCompletionsに対応いたしましたわ～～❗❗❗ #72 (#75)

* add bash completions

* fix

* memo

* fix

README.adoc

@@ -138,6 +138,18 @@ https://github.com/jiro4989/ojosama/releases[Releases]から実行可能ファ
 $ go install github.com/jiro4989/ojosama/cmd/ojosama@latest
 ----
 
+=== タブ補完の有効化
+
+==== Bash
+
+`bash-completion` がインストール済みであれば、
+以下のコマンドでタブ補完を使えるようになります。
+
+[source,bash]
+----
+$ ojosama -completions bash | sudo tee /usr/share/bash-completion/completions/ojosama
+----
+
 == 注意事項
 
 === 変換結果について

cmd/ojosama/cli.go

@@ -8,11 +8,12 @@ import (
 )
 
 type CmdArgs struct {
-	Text     string
-	OutFile  string
-	Version  bool
-	CharCode string
-	Args     []string
+	Text        string
+	OutFile     string
+	Version     bool
+	CharCode    string
+	Completions string
+	Args        []string
 }
 
 func ParseArgs() (*CmdArgs, error) {
@@ -23,6 +24,7 @@ func ParseArgs() (*CmdArgs, error) {
 	flag.StringVar(&opts.OutFile, "o", "", "output file")
 	flag.StringVar(&opts.CharCode, "charcode", "utf8", "input text file encoding. (utf8 or sjis)")
 	flag.BoolVar(&opts.Version, "v", false, "print version")
+	flag.StringVar(&opts.Completions, "completions", "", "print completions file. (bash)")
 	flag.Parse()
 	opts.Args = flag.Args()
 
@@ -35,7 +37,7 @@ func ParseArgs() (*CmdArgs, error) {
 
 func flagHelpMessage() {
 	cmd := os.Args[0]
-	fmt.Fprintln(os.Stderr, fmt.Sprintf("%s convert text to 'ojosama' style.", cmd))
+	fmt.Fprintln(os.Stderr, fmt.Sprintf("%s convert text to '%s' style.", cmd, appName))
 	fmt.Fprintln(os.Stderr, "")
 	fmt.Fprintln(os.Stderr, "Usage:")
 	fmt.Fprintln(os.Stderr, fmt.Sprintf("  %s [OPTIONS] [files...]", cmd))
@@ -56,5 +58,10 @@ func (c *CmdArgs) Validate() error {
 		err := errors.New("charcode must be 'utf8' or 'sjis'.")
 		return err
 	}
+
+	if c.Completions != "" && !isSupportedCompletions(c.Completions) {
+		return fmt.Errorf("illegal completions. completions = %s", c.Completions)
+	}
+
 	return nil
 }

cmd/ojosama/completions.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+)
+
+var (
+	completionsBash = strings.ReplaceAll(`# {{APPNAME}}(1) completion                                       -*- shell-script -*-
+
+_{{APPNAME}}_module() {
+  local cur prev cword
+  _get_comp_words_by_ref -n : cur prev cword
+
+  case "${cword}" in
+    1)
+      local opts="-h -help -t -o -charcode -v -completions"
+      COMPREPLY=($(compgen -W "${opts}" -- "${cur}"))
+      ;;
+    2)
+      case "${prev}" in
+        -o)
+          COMPREPLY=($(compgen -f -- "${cur}"))
+          ;;
+        -charcode)
+          local opts="utf8 sjis"
+          COMPREPLY=($(compgen -W "${opts}" -- "${cur}"))
+          ;;
+        -completions)
+          local opts="bash"
+          COMPREPLY=($(compgen -W "${opts}" -- "${cur}"))
+          ;;
+      esac
+      ;;
+  esac
+}
+
+complete -F _{{APPNAME}}_module {{APPNAME}}`, "{{APPNAME}}", appName)
+
+	completionsMap = map[string]string{
+		"bash": completionsBash,
+	}
+)
+
+func isSupportedCompletions(sh string) bool {
+	_, ok := completionsMap[sh]
+	return ok
+}
+
+func printCompletions(sh string) {
+	sh = strings.ToLower(sh)
+	fmt.Println(completionsMap[sh])
+}

cmd/ojosama/main.go

@@ -10,6 +10,10 @@ import (
 	"golang.org/x/text/transform"
 )
 
+const (
+	appName = "ojosama"
+)
+
 // CIでビルド時に値を埋め込む。
 // 埋め込む値の設定は .goreleaser.yaml を参照。
 var (
@@ -33,14 +37,19 @@ func main() {
 	}
 
 	if args.Version {
-		msg := fmt.Sprintf("ojosama %s (%s)", version, revision)
+		msg := fmt.Sprintf("%s %s (%s)", appName, version, revision)
 		fmt.Println(msg)
 		fmt.Println("")
 		fmt.Println("author:     jiro")
 		fmt.Println("repository: https://github.com/jiro4989/ojosama")
 		os.Exit(exitStatusOK)
 	}
 
+	if args.Completions != "" {
+		printCompletions(args.Completions)
+		return
+	}
+
 	if args.Text != "" {
 		exitStatus, err := run(args.Text, args)
 		if err != nil {