rewriting in go

commands/sha1/sha1.go

@@ -0,0 +1,63 @@
+package sha1
+
+import (
+	"context"
+	"crypto/sha1"
+	"flag"
+	"fmt"
+	"hash_utils/tools"
+	"os"
+	"strings"
+
+	"github.com/google/subcommands"
+)
+
+type (
+	SHA1Cmd struct {
+		file string
+	}
+)
+
+func (*SHA1Cmd) Name() string     { return "sha1" }
+func (*SHA1Cmd) Synopsis() string { return "" }
+func (*SHA1Cmd) Usage() string {
+	return `Usage: hash_utils sha1
+
+Options:
+`
+}
+
+func (p *SHA1Cmd) SetFlags(f *flag.FlagSet) {
+	f.StringVar(&p.file, "file", "", "get the checksum of a file")
+}
+
+func (p *SHA1Cmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) subcommands.ExitStatus {
+	if len(p.file) > 0 {
+		file, err := os.OpenFile(p.file, os.O_RDONLY, 0)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "error: failed to open the file:", err)
+			return subcommands.ExitFailure
+		}
+		defer file.Close()
+
+		h, err := tools.Hash(sha1.New(), file)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "error:", err)
+			return subcommands.ExitFailure
+		}
+		fmt.Printf("%s: %s\n", f.Name(), h)
+
+		return subcommands.ExitSuccess
+	}
+
+	for _, arg := range f.Args() {
+		h, err := tools.Hash(sha1.New(), strings.NewReader(arg))
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "error:", err)
+			return subcommands.ExitFailure
+		}
+		fmt.Printf("%s: %s\n", arg, h)
+	}
+
+	return subcommands.ExitSuccess
+}