Merge pull request #25 from k1LoW/init

Add `init` command to generate .gostyle.yml

.gostyle.yml

@@ -0,0 +1,3 @@
+analyzers:
+  disable:
+    - mixedcaps # disable mixedcaps analyzer. because the underscores analyzer is more detailed.

main.go

@@ -1,16 +1,61 @@
 package main
 
 import (
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+
 	"github.com/k1LoW/gostyle/analyzer/decisions/pkgnames"
 	"github.com/k1LoW/gostyle/analyzer/decisions/recvnames"
 	"github.com/k1LoW/gostyle/analyzer/decisions/underscores"
 	"github.com/k1LoW/gostyle/analyzer/effective/ifacenames"
 	"github.com/k1LoW/gostyle/analyzer/guide/mixedcaps"
 	"github.com/k1LoW/gostyle/config"
 	"golang.org/x/tools/go/analysis/unitchecker"
+
+	_ "embed"
 )
 
+const configPath = ".gostyle.yml"
+
+//go:embed .gostyle.yml
+var defaultConfig []byte
+
 func main() {
+	progname := filepath.Base(os.Args[0])
+
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, `%[1]s is a set of analyzers for coding styles.
+
+Usage of %[1]s:
+	%.16[1]s unit.cfg	# execute analysis specified by config file
+	%.16[1]s help    	# general help, including listing analyzers and flags
+	%.16[1]s help name	# help on specific analyzer and its flags
+	%.16[1]s init    	# generate config file for -gostyle.config flag
+`, progname)
+		os.Exit(1)
+	}
+
+	flag.Parse()
+	args := flag.Args()
+	if len(args) == 0 {
+		flag.Usage()
+	}
+
+	if args[0] == "init" {
+		if _, err := os.Stat(configPath); err == nil {
+			_, _ = fmt.Fprintf(os.Stderr, "%s already exists\n", configPath)
+			os.Exit(1)
+		}
+		if err := os.WriteFile(configPath, defaultConfig, os.ModePerm); err != nil {
+			_, _ = fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+		fmt.Printf("%s is generated\n", configPath)
+		os.Exit(0)
+	}
+
 	unitchecker.Main(
 		config.Loader,
 		ifacenames.Analyzer,