Implement CLI scaffold

.gitignore

@@ -0,0 +1 @@
+/cli/mailfull/mailfull

cmd/mailfull/command/init.go

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+package command
+
+import (
+	"fmt"
+
+	"github.com/directorz/mailfull-go"
+)
+
+// InitCommand represents a InitCommand.
+type InitCommand struct {
+	Meta
+}
+
+// Synopsis returns a one-line synopsis.
+func (c *InitCommand) Synopsis() string {
+	return "Initializes current directory as a Mailfull repository."
+}
+
+// Help returns long-form help text.
+func (c *InitCommand) Help() string {
+	txt := fmt.Sprintf(`
+Usage:
+    %s %s
+
+Description:
+    Initializes current directory as a Mailfull repository.
+`,
+		c.CmdName, c.SubCmdName)
+
+	return txt[1:]
+}
+
+// Run runs the command and returns the exit status.
+func (c *InitCommand) Run(args []string) int {
+	if err := mailfull.InitRepository("."); err != nil {
+		fmt.Fprintf(c.UI.ErrorWriter, "[ERR] %v\n", err)
+		return 1
+	}
+
+	return 0
+}

cmd/mailfull/command/main.go

@@ -0,0 +1,13 @@
+package command
+
+import (
+	"github.com/mitchellh/cli"
+)
+
+// Meta is for `*Command` struct.
+type Meta struct {
+	UI         *cli.BasicUi
+	CmdName    string
+	SubCmdName string
+	Version    string
+}

cmd/mailfull/main.go

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+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/directorz/mailfull-go"
+	"github.com/directorz/mailfull-go/cmd/mailfull/command"
+	"github.com/mitchellh/cli"
+)
+
+var (
+	version = mailfull.Version
+	gittag  = ""
+)
+
+func init() {
+	if gittag != "" {
+		version = version + "-" + gittag
+	}
+}
+
+func main() {
+	c := &cli.CLI{
+		Name:    filepath.Base(os.Args[0]),
+		Version: version,
+		Args:    os.Args[1:],
+	}
+
+	meta := command.Meta{
+		UI: &cli.BasicUi{
+			Reader:      os.Stdin,
+			Writer:      os.Stdout,
+			ErrorWriter: os.Stderr,
+		},
+		CmdName: c.Name,
+		Version: c.Version,
+	}
+
+	c.Commands = map[string]cli.CommandFactory{
+		"init": func() (cli.Command, error) {
+			meta.SubCmdName = c.Subcommand()
+			return &command.InitCommand{Meta: meta}, nil
+		},
+	}
+
+	exitCode, err := c.Run()
+	if err != nil {
+		fmt.Fprintf(meta.UI.ErrorWriter, "%v\n", err)
+	}
+
+	os.Exit(exitCode)
+}