refactor: use better commands and flags name (#7)

* build: update go.mod

* refactor: replace debug with verbose

* refactor: split action from main

* refactor: move all cli app inside pkg cli

* chore(readme): use generate command

Co-authored-by: Tran Hau <ngtranhau@gmail.com>

.gitignore

@@ -1,6 +1,9 @@
 # macOS
 .DS_Store
 
+# Window
+*.exe
+
 # IntelliJ
 .idea/
 

README.md

@@ -26,10 +26,10 @@ GO111module=on go get github.com/haunt98/changeloguru
 changeloguru --help
 
 # Generate changelog v1.0.0
-changeloguru --version v1.0.0
+changeloguru generate --version v1.0.0
 
 # Generate changelog v2.0.0 from HEAD to tag v1.0.0
-changeloguru --to v1.0.0 --version v2.0.0
+changeloguru generate --to v1.0.0 --version v2.0.0
 ```
 
 ## Thanks

go.mod

@@ -6,15 +6,16 @@ require (
 	github.com/cpuguy83/go-md2man/v2 v2.0.0 // indirect
 	github.com/fatih/color v1.10.0
 	github.com/go-git/go-git/v5 v5.3.0
-	github.com/google/go-cmp v0.5.4 // indirect
+	github.com/google/go-cmp v0.5.5 // indirect
 	github.com/kevinburke/ssh_config v1.1.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/sebdah/goldie/v2 v2.5.3
+	github.com/sergi/go-diff v1.2.0 // indirect
 	github.com/stretchr/testify v1.7.0
 	github.com/urfave/cli/v2 v2.3.0
 	golang.org/x/mod v0.4.2
-	golang.org/x/net v0.0.0-20210326220855-61e056675ecf // indirect
+	golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1 // indirect
-	golang.org/x/sys v0.0.0-20210326220804-49726bf1d181 // indirect
+	golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 )

go.sum

@@ -32,8 +32,8 @@ github.com/go-git/go-git-fixtures/v4 v4.0.2-0.20200613231340-f56387b50c12/go.mod
 github.com/go-git/go-git/v5 v5.3.0 h1:8WKMtJR2j8RntEXR/uvTKagfEt4GYlwQ7mntE4+0GWc=
 github.com/go-git/go-git/v5 v5.3.0/go.mod h1:xdX4bWJ48aOrdhnl2XqHYstHbbp6+LFS4r4X+lNVprw=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
-github.com/google/go-cmp v0.5.4 h1:L8R9j+yAqZuZjsqh/z+F1NCffTKKLShY6zXTItVIZ8M=
+github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
-github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/imdario/mergo v0.3.12 h1:b6R2BslTbIEToALKP7LxUvijTsNI9TAe80pLWN2g/HU=
 github.com/imdario/mergo v0.3.12/go.mod h1:jmQim1M+e3UYxmgPu/WyfjB3N3VflVyUjjjwH0dnCYA=
 github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 h1:BQSFePA1RWJOlocH6Fxy8MmwDt+yVQYULKfN0RoTN8A=
@@ -68,8 +68,9 @@ github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQD
 github.com/sebdah/goldie/v2 v2.5.3 h1:9ES/mNN+HNUbNWpVAlrzuZ7jE+Nrczbj8uFRjM7624Y=
 github.com/sebdah/goldie/v2 v2.5.3/go.mod h1:oZ9fp0+se1eapSRjfYbsV/0Hqhbuu3bJVvKI/NNtssI=
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
-github.com/sergi/go-diff v1.1.0 h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=
 github.com/sergi/go-diff v1.1.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
+github.com/sergi/go-diff v1.2.0 h1:XU+rvMAioB0UC3q1MFrIQy4Vo5/4VsRDQQXHsEya6xQ=
+github.com/sergi/go-diff v1.2.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 github.com/sirupsen/logrus v1.4.1/go.mod h1:ni0Sbl8bgC9z8RoU9G6nDWqqs/fq4eDPysMBDgk/93Q=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
@@ -94,8 +95,8 @@ golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210326060303-6b1517762897/go.mod h1:uSPa2vr4CLtc/ILN5odXGNXS6mhrKVzTaCXzk9m6W3k=
-golang.org/x/net v0.0.0-20210326220855-61e056675ecf h1:WUcCxqQqDT0aXO4VnQbfMvp4zh7m1Gb2clVuHUAGGRE=
+golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1 h1:4qWs8cYYH6PoEFy4dfhDFgoMGkwAcETd+MmPdCPMzUc=
-golang.org/x/net v0.0.0-20210326220855-61e056675ecf/go.mod h1:uSPa2vr4CLtc/ILN5odXGNXS6mhrKVzTaCXzk9m6W3k=
+golang.org/x/net v0.0.0-20210410081132-afb366fc7cd1/go.mod h1:9tjilg8BloeKEkVJvy7fQ90B1CfIiPueXVOjqfkSzI8=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -108,13 +109,15 @@ golang.org/x/sys v0.0.0-20200302150141-5c8b2ff67527/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210320140829-1e4c9ba3b0c4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210324051608-47abb6519492/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210326220804-49726bf1d181 h1:64ChN/hjER/taL4YJuA+gpLfIMT+/NFherRZixbxOhg=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210326220804-49726bf1d181/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57 h1:F5Gozwx4I1xtr/sr/8CFbb57iKi3297KFs0QDbGN60A=
+golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1 h1:v+OssWQX+hTHEmOBgwxdZxK4zHq3yOs8F9J7mk0PY8E=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.3 h1:cokOdA+Jmi5PJGXLlLllQSgYigAEfHXJAERHVMaCc2k=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6 h1:aRYxNxv6iGQlyVaZmk6ZgYEDa+Jg18DxebPSrd6bg1M=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

main.go

@@ -2,40 +2,10 @@ package main
 
 import (
 	"fmt"
-	"log"
 	"os"
-	"path/filepath"
-	"strings"
-	"time"
 
 	"github.com/fatih/color"
-	"github.com/haunt98/changeloguru/pkg/changelog"
+	"github.com/haunt98/changeloguru/pkg/cli"
-	"github.com/haunt98/changeloguru/pkg/convention"
-	"github.com/haunt98/changeloguru/pkg/git"
-	"github.com/urfave/cli/v2"
-	"golang.org/x/mod/semver"
-)
-
-const (
-	appName = "changeloguru"
-
-	currentDir       = "."
-	markdownFiletype = "md"
-
-	defaultRepository = currentDir
-	defaultOutput     = currentDir
-	defaultFilename   = "CHANGELOG"
-	defaultFiletype   = markdownFiletype
-
-	fromFlag       = "from"
-	toFlag         = "to"
-	versionFlag    = "version"
-	scopeFlag      = "scope"
-	repositoryFlag = "repository"
-	outputFlag     = "output"
-	filenameFlag   = "filename"
-	filetypeFlag   = "filetype"
-	debugFlag      = "debug"
 )
 
 var (
@@ -43,215 +13,10 @@ var (
 )
 
 func main() {
-	a := &action{}
+	app := cli.NewApp()
-
-	app := &cli.App{
-		Name:  appName,
-		Usage: "generate changelog from conventional commits",
-		Flags: []cli.Flag{
-			&cli.StringFlag{
-				Name:  fromFlag,
-				Usage: "generate from `COMMIT`",
-			},
-			&cli.StringFlag{
-				Name:  toFlag,
-				Usage: "generate to `COMMIT`",
-			},
-			&cli.StringFlag{
-				Name:  versionFlag,
-				Usage: "`VERSION` to generate, follow Semantic Versioning",
-			},
-			&cli.StringSliceFlag{
-				Name:  scopeFlag,
-				Usage: "scope to generate",
-			},
-			&cli.StringFlag{
-				Name:        repositoryFlag,
-				Usage:       "`REPOSITORY` directory path",
-				DefaultText: defaultRepository,
-			},
-			&cli.StringFlag{
-				Name:        outputFlag,
-				Usage:       "`OUTPUT` directory path",
-				DefaultText: defaultOutput,
-			},
-			&cli.StringFlag{
-				Name:        filenameFlag,
-				Usage:       "output `FILENAME`",
-				DefaultText: defaultFilename,
-			},
-			&cli.StringFlag{
-				Name:        filetypeFlag,
-				Usage:       "output `FILETYPE`",
-				DefaultText: defaultFiletype,
-			},
-			&cli.BoolFlag{
-				Name:    debugFlag,
-				Aliases: []string{"d"},
-				Usage:   "show debugging info",
-			},
-		},
-		Action: a.Run,
-	}
-
 	if err := app.Run(os.Args); err != nil {
 		// Highlight error
-		fmtErr.Printf("[%s error]: ", appName)
+		fmtErr.Printf("[%s error]: ", cli.AppName)
 		fmt.Printf("%s\n", err.Error())
 	}
 }
-
-type action struct {
-	flags struct {
-		debug      bool
-		from       string
-		to         string
-		version    string
-		scopes     map[string]struct{}
-		repository string
-		output     string
-		filename   string
-		filetype   string
-	}
-}
-
-func (a *action) Run(c *cli.Context) error {
-	// Show help if there is nothing
-	if c.NArg() == 0 && c.NumFlags() == 0 {
-		return cli.ShowAppHelp(c)
-	}
-
-	a.getFlags(c)
-
-	commits, err := a.getCommits()
-	if err != nil {
-		return err
-	}
-
-	conventionalCommits := a.getConventionalCommits(commits)
-
-	if err := a.generateChangelog(conventionalCommits); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (a *action) getFlags(c *cli.Context) {
-	a.flags.debug = c.Bool(debugFlag)
-	a.flags.from = c.String(fromFlag)
-	a.flags.to = c.String(toFlag)
-	a.flags.version = c.String(versionFlag)
-
-	a.flags.scopes = make(map[string]struct{})
-	for _, scope := range c.StringSlice(scopeFlag) {
-		a.flags.scopes[scope] = struct{}{}
-	}
-
-	a.flags.repository = a.getFlagValue(c, repositoryFlag, defaultRepository)
-	a.flags.output = a.getFlagValue(c, outputFlag, defaultOutput)
-	a.flags.filename = a.getFlagValue(c, filenameFlag, defaultFilename)
-	a.flags.filetype = a.getFlagValue(c, filetypeFlag, defaultFiletype)
-
-	if a.flags.debug {
-		a.logDebug("flags %+v", a.flags)
-	}
-}
-
-func (a *action) getFlagValue(c *cli.Context, flag, fallback string) string {
-	value := c.String(flag)
-	if value == "" {
-		value = fallback
-	}
-
-	return value
-}
-
-func (a *action) getCommits() ([]git.Commit, error) {
-	r, err := git.NewRepository(a.flags.repository)
-	if err != nil {
-		return nil, err
-	}
-
-	return r.Log(a.flags.from, a.flags.to)
-}
-
-func (a *action) getConventionalCommits(commits []git.Commit) []convention.Commit {
-	conventionalCommits := make([]convention.Commit, 0, len(commits))
-	for _, commit := range commits {
-		conventionalCommit, err := convention.NewCommit(commit)
-		if err != nil {
-			a.logDebug("failed to new conventional commits %+v: %s", commit, err)
-			continue
-		}
-
-		conventionalCommits = append(conventionalCommits, conventionalCommit)
-	}
-
-	return conventionalCommits
-}
-
-func (a *action) generateChangelog(commits []convention.Commit) error {
-	realOutput := a.getRealOutput()
-
-	version, err := a.getVersion()
-	if err != nil {
-		return err
-	}
-
-	switch a.flags.filetype {
-	case markdownFiletype:
-		return a.generateMarkdownChangelog(realOutput, version, commits)
-	default:
-		return fmt.Errorf("unknown filetype %s", a.flags.filetype)
-	}
-}
-
-func (a *action) getRealOutput() string {
-	nameWithExt := a.flags.filename + "." + a.flags.filetype
-	realOutput := filepath.Join(a.flags.output, nameWithExt)
-
-	return realOutput
-}
-
-func (a *action) getVersion() (string, error) {
-	if a.flags.version == "" {
-		return "", fmt.Errorf("empty version")
-	}
-
-	if !strings.HasPrefix(a.flags.version, "v") {
-		a.flags.version = "v" + a.flags.version
-	}
-
-	if !semver.IsValid(a.flags.version) {
-		return "", fmt.Errorf("invalid semver %s", a.flags.version)
-	}
-
-	a.logDebug("version %s", a.flags.version)
-
-	return a.flags.version, nil
-}
-
-func (a *action) generateMarkdownChangelog(output, version string, commits []convention.Commit) error {
-	// If CHANGELOG file already exist
-	var oldData string
-	bytes, err := os.ReadFile(output)
-	if err == nil {
-		oldData = string(bytes)
-	}
-
-	markdownGenerator := changelog.NewMarkdownGenerator(oldData, version, time.Now())
-	newData := markdownGenerator.Generate(commits, a.flags.scopes)
-
-	if err := os.WriteFile(output, []byte(newData), 0o644); err != nil {
-		return fmt.Errorf("failed to write file %s: %w", output, err)
-	}
-
-	return nil
-}
-
-func (a *action) logDebug(format string, v ...interface{}) {
-	if a.flags.debug {
-		log.Printf(format, v...)
-	}
-}

pkg/cli/action.go

@@ -0,0 +1,71 @@
+package cli
+
+import (
+	"log"
+
+	"github.com/urfave/cli/v2"
+)
+
+const (
+	currentDir       = "."
+	markdownFiletype = "md"
+
+	defaultRepository = currentDir
+	defaultOutput     = currentDir
+	defaultFilename   = "CHANGELOG"
+	defaultFiletype   = markdownFiletype
+)
+
+type action struct {
+	flags struct {
+		verbose    bool
+		from       string
+		to         string
+		version    string
+		scopes     map[string]struct{}
+		repository string
+		output     string
+		filename   string
+		filetype   string
+	}
+}
+
+func (a *action) RunHelp(c *cli.Context) error {
+	return cli.ShowAppHelp(c)
+}
+
+func (a *action) getFlags(c *cli.Context) {
+	a.flags.verbose = c.Bool(verboseFlag)
+	a.flags.from = c.String(fromFlag)
+	a.flags.to = c.String(toFlag)
+	a.flags.version = c.String(versionFlag)
+
+	a.flags.scopes = make(map[string]struct{})
+	for _, scope := range c.StringSlice(scopeFlag) {
+		a.flags.scopes[scope] = struct{}{}
+	}
+
+	a.flags.repository = a.getFlagValue(c, repositoryFlag, defaultRepository)
+	a.flags.output = a.getFlagValue(c, outputFlag, defaultOutput)
+	a.flags.filename = a.getFlagValue(c, filenameFlag, defaultFilename)
+	a.flags.filetype = a.getFlagValue(c, filetypeFlag, defaultFiletype)
+
+	if a.flags.verbose {
+		a.log("flags %+v", a.flags)
+	}
+}
+
+func (a *action) getFlagValue(c *cli.Context, flag, fallback string) string {
+	value := c.String(flag)
+	if value == "" {
+		value = fallback
+	}
+
+	return value
+}
+
+func (a *action) log(format string, v ...interface{}) {
+	if a.flags.verbose {
+		log.Printf(format, v...)
+	}
+}

pkg/cli/action_generate.go

@@ -0,0 +1,120 @@
+package cli
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/haunt98/changeloguru/pkg/changelog"
+	"github.com/haunt98/changeloguru/pkg/convention"
+	"github.com/haunt98/changeloguru/pkg/git"
+	"github.com/urfave/cli/v2"
+	"golang.org/x/mod/semver"
+)
+
+func (a *action) RunGenerate(c *cli.Context) error {
+	// Show help if there is nothing
+	if c.NumFlags() == 0 {
+		return cli.ShowAppHelp(c)
+	}
+
+	a.getFlags(c)
+
+	commits, err := a.getCommits()
+	if err != nil {
+		return err
+	}
+
+	conventionalCommits := a.getConventionalCommits(commits)
+
+	if err := a.generateChangelog(conventionalCommits); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (a *action) getCommits() ([]git.Commit, error) {
+	r, err := git.NewRepository(a.flags.repository)
+	if err != nil {
+		return nil, err
+	}
+
+	return r.Log(a.flags.from, a.flags.to)
+}
+
+func (a *action) getConventionalCommits(commits []git.Commit) []convention.Commit {
+	conventionalCommits := make([]convention.Commit, 0, len(commits))
+	for _, commit := range commits {
+		conventionalCommit, err := convention.NewCommit(commit)
+		if err != nil {
+			a.log("failed to new conventional commits %+v: %s", commit, err)
+			continue
+		}
+
+		conventionalCommits = append(conventionalCommits, conventionalCommit)
+	}
+
+	return conventionalCommits
+}
+
+func (a *action) generateChangelog(commits []convention.Commit) error {
+	realOutput := a.getRealOutput()
+
+	version, err := a.getVersion()
+	if err != nil {
+		return err
+	}
+
+	switch a.flags.filetype {
+	case markdownFiletype:
+		return a.generateMarkdownChangelog(realOutput, version, commits)
+	default:
+		return fmt.Errorf("unknown filetype %s", a.flags.filetype)
+	}
+}
+
+func (a *action) getRealOutput() string {
+	nameWithExt := a.flags.filename + "." + a.flags.filetype
+	realOutput := filepath.Join(a.flags.output, nameWithExt)
+
+	return realOutput
+}
+
+func (a *action) getVersion() (string, error) {
+	if a.flags.version == "" {
+		return "", fmt.Errorf("empty version")
+	}
+
+	if !strings.HasPrefix(a.flags.version, "v") {
+		a.flags.version = "v" + a.flags.version
+	}
+
+	if !semver.IsValid(a.flags.version) {
+		return "", fmt.Errorf("invalid semver %s", a.flags.version)
+	}
+
+	a.log("version %s", a.flags.version)
+
+	return a.flags.version, nil
+}
+
+func (a *action) generateMarkdownChangelog(output, version string, commits []convention.Commit) error {
+	// If CHANGELOG file already exist
+	var oldData string
+	bytes, err := os.ReadFile(output)
+	if err == nil {
+		oldData = string(bytes)
+	}
+
+	markdownGenerator := changelog.NewMarkdownGenerator(oldData, version, time.Now())
+	newData := markdownGenerator.Generate(commits, a.flags.scopes)
+
+	if err := os.WriteFile(output, []byte(newData), 0o644); err != nil {
+		return fmt.Errorf("failed to write file %s: %w", output, err)
+	}
+
+	return nil
+}

pkg/cli/app.go

@@ -0,0 +1,93 @@
+package cli
+
+import "github.com/urfave/cli/v2"
+
+const (
+	AppName = "changeloguru"
+
+	// flags
+	fromFlag       = "from"
+	toFlag         = "to"
+	versionFlag    = "version"
+	scopeFlag      = "scope"
+	repositoryFlag = "repository"
+	outputFlag     = "output"
+	filenameFlag   = "filename"
+	filetypeFlag   = "filetype"
+	verboseFlag    = "verbose"
+
+	// commands
+	generateCommand = "generate"
+)
+
+var (
+	// flags
+	verboseAliases = []string{"v"}
+
+	// commands
+	generateAliases = []string{"gen"}
+)
+
+func NewApp() *cli.App {
+	a := &action{}
+
+	app := &cli.App{
+		Name:  AppName,
+		Usage: "generate changelog from conventional commits",
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name:    verboseFlag,
+				Aliases: verboseAliases,
+				Usage:   "show what is going on",
+			},
+		},
+		Commands: []*cli.Command{
+			{
+				Name:    generateCommand,
+				Aliases: generateAliases,
+				Flags: []cli.Flag{
+					&cli.StringFlag{
+						Name:  fromFlag,
+						Usage: "generate from `COMMIT`",
+					},
+					&cli.StringFlag{
+						Name:  toFlag,
+						Usage: "generate to `COMMIT`",
+					},
+					&cli.StringFlag{
+						Name:  versionFlag,
+						Usage: "`VERSION` to generate, follow Semantic Versioning",
+					},
+					&cli.StringSliceFlag{
+						Name:  scopeFlag,
+						Usage: "scope to generate",
+					},
+					&cli.StringFlag{
+						Name:        repositoryFlag,
+						Usage:       "`REPOSITORY` directory path",
+						DefaultText: defaultRepository,
+					},
+					&cli.StringFlag{
+						Name:        outputFlag,
+						Usage:       "`OUTPUT` directory path",
+						DefaultText: defaultOutput,
+					},
+					&cli.StringFlag{
+						Name:        filenameFlag,
+						Usage:       "output `FILENAME`",
+						DefaultText: defaultFilename,
+					},
+					&cli.StringFlag{
+						Name:        filetypeFlag,
+						Usage:       "output `FILETYPE`",
+						DefaultText: defaultFiletype,
+					},
+				},
+				Action: a.RunGenerate,
+			},
+		},
+		Action: a.RunHelp,
+	}
+
+	return app
+}