implement cli parsing

Makefile

@@ -3,10 +3,10 @@ VERSION := 0.1.16
 NAME := urleap
 DIST := $(NAME)-$(VERSION)
 
-urleap: coverage.out
-	go build -o urleap $(PACKAGE_LIST)
+urleap: coverage.out cmd/urleap/main.go
+	go build -o urleap cmd/urleap/main.go
 
-coverage.out:
+coverage.out: cmd/urleap/main_test.go
 	go test -covermode=count \
 		-coverprofile=coverage.out $(PACKAGE_LIST)
 

cmd/urleap/main.go

@@ -3,12 +3,102 @@ package main
 import (
 	"fmt"
 	"os"
+	"path/filepath"
+
+	flag "github.com/spf13/pflag"
 )
 
 const VERSION = "0.1.16"
 
-func goMain(args []string) int {
+/*
+helpMessage prints the help message.
+This function is used in the small tests, so it may be called with a zero-length slice.
+*/
+func helpMessage(args []string) string {
+	prog := "urleap"
+	if len(args) > 0 {
+		prog = filepath.Base(args[0])
+	}
+	return fmt.Sprintf(`%s [OPTIONS] [URLs...]
+OPTIONS
+    -t, --token <TOKEN>      specify the token for the service. This option is mandatory.
+    -q, --qrcode <FILE>      include QR-code of the URL in the output.
+    -c, --config <CONFIG>    specify the configuration file.
+    -h, --help               print this mesasge and exit.
+    -v, --version            print the version and exit.
+ARGUMENT
+    URL     specify the url for shortening. this arguments accept multiple values.
+            if no arguments were specified, urleap prints the list of available shorten urls.`, prog)
+}
+
+type UrleapError struct {
+	statusCode int
+	message    string
+}
+
+func (e UrleapError) Error() string {
+	return e.message
+}
+
+/*
+This struct holds the values of the options.
+*/
+type options struct {
+	token   string
+	qrcode  string
+	config  string
+	help    bool
+	version bool
+}
+
+/*
+Define the options and return the pointer to the options and the pointer to the flagset.
+*/
+func buildOptions(args []string) (*options, *flag.FlagSet) {
+	opts := &options{}
+	flags := flag.NewFlagSet(args[0], flag.ContinueOnError)
+	flags.Usage = func() { fmt.Println(helpMessage(args)) }
+	flags.StringVarP(&opts.token, "token", "t", "", "specify the token for the service. This option is mandatory.")
+	flags.StringVarP(&opts.qrcode, "qrcode", "q", "", "include QR-code of the URL in the output.")
+	flags.StringVarP(&opts.config, "config", "c", "", "specify the configuration file.")
+	flags.BoolVarP(&opts.help, "help", "h", false, "print this mesasge and exit.")
+	flags.BoolVarP(&opts.version, "version", "v", false, "print the version and exit.")
+	return opts, flags
+}
+
+/*
+parseOptions parses options from the given command line arguments.
+*/
+func parseOptions(args []string) (*options, []string, *UrleapError) {
+	opts, flags := buildOptions(args)
+	flags.Parse(args[1:])
+	if opts.help {
+		fmt.Println(helpMessage(args))
+		return nil, nil, &UrleapError{statusCode: 0, message: ""}
+	}
+	if opts.token == "" {
+		return nil, nil, &UrleapError{statusCode: 3, message: "no token was given"}
+	}
+	return opts, flags.Args(), nil
+}
+
+func perform(opts *options, args []string) *UrleapError {
 	fmt.Println("Hello World")
+	return nil
+}
+
+func goMain(args []string) int {
+	opts, args, err := parseOptions(args)
+	if err != nil {
+		if err.statusCode != 0 {
+			fmt.Println(err.Error())
+		}
+		return err.statusCode
+	}
+	if err := perform(opts, args); err != nil {
+		fmt.Println(err.Error())
+		return err.statusCode
+	}
 	return 0
 }
 

cmd/urleap/main_test.go

@@ -3,13 +3,28 @@ package main
 import "testing"
 
 func Example_Main() {
-	goMain([]string{})
+	goMain([]string{"./urleap", "-t", "token"})
 	// Output:
 	// Hello World
 }
 
+func Example_Help() {
+	goMain([]string{"./urleap", "--help"})
+	// Output:
+	// urleap [OPTIONS] [URLs...]
+	// OPTIONS
+	//     -t, --token <TOKEN>      specify the token for the service. This option is mandatory.
+	//     -q, --qrcode <FILE>      include QR-code of the URL in the output.
+	//     -c, --config <CONFIG>    specify the configuration file.
+	//     -h, --help               print this mesasge and exit.
+	//     -v, --version            print the version and exit.
+	// ARGUMENT
+	//     URL     specify the url for shortening. this arguments accept multiple values.
+	//             if no arguments were specified, urleap prints the list of available shorten urls.
+}
+
 func Test_Main(t *testing.T) {
-	if status := goMain([]string{}); status != 0 {
+	if status := goMain([]string{"./urleap", "-t", "token"}); status != 0 {
 		t.Error("Expected 0, got ", status)
 	}
 }

docs/.gitignore

@@ -0,0 +1 @@
+public

go.mod

@@ -1,3 +1,5 @@
 module github.com/tamada/urleap
 
 go 1.20
+
+require github.com/spf13/pflag v1.0.5 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=