Add command package

pkg/cli/cmd/add/add.go

@@ -20,9 +20,10 @@ package add
 
 import (
 	"database/sql"
-	"time"
 	"os"
+	"time"
 
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/database"
 	"github.com/dnote/dnote/pkg/cli/infra"
@@ -33,7 +34,6 @@ import (
 	"github.com/dnote/dnote/pkg/cli/utils"
 	"github.com/dnote/dnote/pkg/cli/validate"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 var contentFlag string
@@ -52,7 +52,7 @@ var example = `
  pull is fetch with a merge
  EOF`
 
-func preRun(cmd *cobra.Command, args []string) error {
+func preRun(cmd *command.Command, args []string) error {
 	if len(args) != 1 {
 		return errors.New("Incorrect number of argument")
 	}
@@ -61,8 +61,9 @@ func preRun(cmd *cobra.Command, args []string) error {
 }
 
 // NewCmd returns a new add command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
+		Name:    "add",
 		Use:     "add <book>",
 		Short:   "Add a new note",
 		Aliases: []string{"a", "n", "new"},
@@ -106,7 +107,7 @@ func getContent(ctx context.DnoteCtx) (string, error) {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		bookName := args[0]
 		if err := validate.BookName(bookName); err != nil {
 			return errors.Wrap(err, "invalid book name")

pkg/cli/cmd/cat/cat.go

@@ -21,13 +21,13 @@ package cat
 import (
 	"strconv"
 
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/database"
 	"github.com/dnote/dnote/pkg/cli/infra"
 	"github.com/dnote/dnote/pkg/cli/log"
 	"github.com/dnote/dnote/pkg/cli/output"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 var example = `
@@ -40,7 +40,7 @@ var deprecationWarning = `and "view" will replace it in the future version.
  Run "dnote view --help" for more information.
 `
 
-func preRun(cmd *cobra.Command, args []string) error {
+func preRun(cmd *command.Command, args []string) error {
 	if len(args) != 2 {
 		return errors.New("Incorrect number of arguments")
 	}
@@ -49,8 +49,8 @@ func preRun(cmd *cobra.Command, args []string) error {
 }
 
 // NewCmd returns a new cat command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:        "cat <book name> <note index>",
 		Aliases:    []string{"c"},
 		Short:      "See a note",
@@ -65,7 +65,7 @@ func NewCmd(ctx context.DnoteCtx) *cobra.Command {
 
 // NewRun returns a new run function
 func NewRun(ctx context.DnoteCtx, contentOnly bool) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		var noteRowIDArg string
 
 		if len(args) == 2 {

pkg/cli/cmd/edit/edit.go

@@ -19,12 +19,12 @@
 package edit
 
 import (
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/infra"
 	"github.com/dnote/dnote/pkg/cli/log"
 	"github.com/dnote/dnote/pkg/cli/utils"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 var contentFlag string
@@ -49,8 +49,8 @@ var example = `
 `
 
 // NewCmd returns a new edit command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:     "edit <note id|book name>",
 		Short:   "Edit a note or a book",
 		Aliases: []string{"e"},
@@ -67,7 +67,7 @@ func NewCmd(ctx context.DnoteCtx) *cobra.Command {
 	return cmd
 }
 
-func preRun(cmd *cobra.Command, args []string) error {
+func preRun(cmd *command.Command, args []string) error {
 	if len(args) != 1 && len(args) != 2 {
 		return errors.New("Incorrect number of argument")
 	}
@@ -76,7 +76,7 @@ func preRun(cmd *cobra.Command, args []string) error {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		// DEPRECATED: Remove in 1.0.0
 		if len(args) == 2 {
 			log.Plain(log.ColorYellow.Sprintf("DEPRECATED: you no longer need to pass book name to the view command. e.g. `dnote view 123`.\n\n"))

pkg/cli/cmd/find/find.go

@@ -23,11 +23,11 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/infra"
 	"github.com/dnote/dnote/pkg/cli/log"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 var example = `
@@ -43,7 +43,7 @@ var example = `
 
 var bookName string
 
-func preRun(cmd *cobra.Command, args []string) error {
+func preRun(cmd *command.Command, args []string) error {
 	if len(args) != 1 {
 		return errors.New("Incorrect number of argument")
 	}
@@ -52,8 +52,8 @@ func preRun(cmd *cobra.Command, args []string) error {
 }
 
 // NewCmd returns a new remove command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:     "find",
 		Short:   "Find notes by keywords",
 		Aliases: []string{"f"},
@@ -154,7 +154,7 @@ func doQuery(ctx context.DnoteCtx, query, bookName string) (*sql.Rows, error) {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		phrase, err := escapePhrase(args[0])
 		if err != nil {
 			return errors.Wrap(err, "escaping phrase")

pkg/cli/cmd/login/login.go

@@ -24,6 +24,7 @@ import (
 	"strconv"
 
 	"github.com/dnote/dnote/pkg/cli/client"
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/consts"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/database"
@@ -31,7 +32,6 @@ import (
 	"github.com/dnote/dnote/pkg/cli/log"
 	"github.com/dnote/dnote/pkg/cli/ui"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 var example = `
@@ -40,8 +40,8 @@ var example = `
 var usernameFlag, passwordFlag string
 
 // NewCmd returns a new login command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:     "login",
 		Short:   "Login to dnote server",
 		Example: example,
@@ -150,7 +150,7 @@ func getGreeting(ctx context.DnoteCtx) string {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		greeting := getGreeting(ctx)
 		log.Plain(greeting)
 

pkg/cli/cmd/logout/logout.go

@@ -22,13 +22,13 @@ import (
 	"database/sql"
 
 	"github.com/dnote/dnote/pkg/cli/client"
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/consts"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/database"
 	"github.com/dnote/dnote/pkg/cli/infra"
 	"github.com/dnote/dnote/pkg/cli/log"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 // ErrNotLoggedIn is an error for logging out when not logged in
@@ -38,8 +38,8 @@ var example = `
   dnote logout`
 
 // NewCmd returns a new logout command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:     "logout",
 		Short:   "Logout from the server",
 		Example: example,
@@ -83,7 +83,7 @@ func Do(ctx context.DnoteCtx) error {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		err := Do(ctx)
 		if err == ErrNotLoggedIn {
 			log.Error("not logged in\n")

pkg/cli/cmd/ls/ls.go

@@ -23,11 +23,11 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/infra"
 	"github.com/dnote/dnote/pkg/cli/log"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 var example = `
@@ -43,7 +43,7 @@ var deprecationWarning = `and "view" will replace it in the future version.
 Run "dnote view --help" for more information.
 `
 
-func preRun(cmd *cobra.Command, args []string) error {
+func preRun(cmd *command.Command, args []string) error {
 	if len(args) > 1 {
 		return errors.New("Incorrect number of argument")
 	}
@@ -52,8 +52,8 @@ func preRun(cmd *cobra.Command, args []string) error {
 }
 
 // NewCmd returns a new ls command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:        "ls <book name?>",
 		Aliases:    []string{"l", "notes"},
 		Short:      "List all notes",
@@ -68,7 +68,7 @@ func NewCmd(ctx context.DnoteCtx) *cobra.Command {
 
 // NewRun returns a new run function for ls
 func NewRun(ctx context.DnoteCtx, nameOnly bool) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		if len(args) == 0 {
 			if err := printBooks(ctx, nameOnly); err != nil {
 				return errors.Wrap(err, "viewing books")

pkg/cli/cmd/remove/remove.go

@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"strconv"
 
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/database"
 	"github.com/dnote/dnote/pkg/cli/infra"
@@ -30,7 +31,6 @@ import (
 	"github.com/dnote/dnote/pkg/cli/ui"
 	"github.com/dnote/dnote/pkg/cli/utils"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 var bookFlag string
@@ -45,8 +45,8 @@ var example = `
 `
 
 // NewCmd returns a new remove command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:     "remove <note id|book name>",
 		Short:   "Remove a note or a book",
 		Aliases: []string{"rm", "d", "delete"},
@@ -64,7 +64,7 @@ func NewCmd(ctx context.DnoteCtx) *cobra.Command {
 	return cmd
 }
 
-func preRun(cmd *cobra.Command, args []string) error {
+func preRun(cmd *command.Command, args []string) error {
 	if len(args) != 1 && len(args) != 2 {
 		return errors.New("Incorrect number of argument")
 	}
@@ -81,7 +81,7 @@ func maybeConfirm(message string, defaultValue bool) (bool, error) {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		// DEPRECATED: Remove in 1.0.0
 		if bookFlag != "" {
 			if err := runBook(ctx, bookFlag); err != nil {

pkg/cli/cmd/root/root.go

@@ -19,21 +19,18 @@
 package root
 
 import (
-	"github.com/spf13/cobra"
+	"github.com/dnote/dnote/pkg/cli/command"
 )
 
-var root = &cobra.Command{
+var root = &command.Command{
 	Use:           "dnote",
 	Short:         "Dnote - a simple command line notebook",
 	SilenceErrors: true,
 	SilenceUsage:  true,
-	CompletionOptions: cobra.CompletionOptions{
-		DisableDefaultCmd: true,
-	},
 }
 
 // Register adds a new command
-func Register(cmd *cobra.Command) {
+func Register(cmd *command.Command) {
 	root.AddCommand(cmd)
 }
 

pkg/cli/cmd/sync/sync.go

@@ -23,6 +23,7 @@ import (
 	"fmt"
 
 	"github.com/dnote/dnote/pkg/cli/client"
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/consts"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/database"
@@ -31,7 +32,6 @@ import (
 	"github.com/dnote/dnote/pkg/cli/migrate"
 	"github.com/dnote/dnote/pkg/cli/upgrade"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 const (
@@ -45,8 +45,8 @@ var example = `
 var isFullSync bool
 
 // NewCmd returns a new sync command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:     "sync",
 		Aliases: []string{"s"},
 		Short:   "Sync data with the server",
@@ -886,7 +886,7 @@ func saveSyncState(tx *database.DB, serverTime int64, serverMaxUSN int) error {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		if ctx.SessionKey == "" {
 			return errors.New("not logged in")
 		}

pkg/cli/cmd/version/version.go

@@ -21,17 +21,17 @@ package version
 import (
 	"fmt"
 
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
-	"github.com/spf13/cobra"
 )
 
 // NewCmd returns a new version command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:   "version",
 		Short: "Print the version number of Dnote",
 		Long:  "Print the version number of Dnote",
-		Run: func(cmd *cobra.Command, args []string) {
+		Run: func(cmd *command.Command, args []string) {
 			fmt.Printf("dnote %s\n", ctx.Version)
 		},
 	}

pkg/cli/cmd/view/view.go

@@ -19,10 +19,10 @@
 package view
 
 import (
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/context"
 	"github.com/dnote/dnote/pkg/cli/infra"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 
 	"github.com/dnote/dnote/pkg/cli/cmd/cat"
 	"github.com/dnote/dnote/pkg/cli/cmd/ls"
@@ -43,7 +43,7 @@ var example = `
 var nameOnly bool
 var contentOnly bool
 
-func preRun(cmd *cobra.Command, args []string) error {
+func preRun(cmd *command.Command, args []string) error {
 	if len(args) > 2 {
 		return errors.New("Incorrect number of argument")
 	}
@@ -52,8 +52,8 @@ func preRun(cmd *cobra.Command, args []string) error {
 }
 
 // NewCmd returns a new view command
-func NewCmd(ctx context.DnoteCtx) *cobra.Command {
-	cmd := &cobra.Command{
+func NewCmd(ctx context.DnoteCtx) *command.Command {
+	cmd := &command.Command{
 		Use:     "view <book name?> <note index?>",
 		Aliases: []string{"v"},
 		Short:   "List books, notes or view a content",
@@ -70,7 +70,7 @@ func NewCmd(ctx context.DnoteCtx) *cobra.Command {
 }
 
 func newRun(ctx context.DnoteCtx) infra.RunEFunc {
-	return func(cmd *cobra.Command, args []string) error {
+	return func(cmd *command.Command, args []string) error {
 		var run infra.RunEFunc
 
 		if len(args) == 0 {

pkg/cli/command/command.go

@@ -0,0 +1,274 @@
+package command
+
+import (
+	"os"
+	"strings"
+
+	"github.com/dnote/dnote/pkg/cli/log"
+	"github.com/pkg/errors"
+
+	flag "github.com/spf13/pflag"
+)
+
+type Command struct {
+	// Name is the name of the command. This is used to find the subcommand
+	// and is case sensitive.
+	Name string
+
+	// flags is a FlagSet which can parse and hold flags and their values.
+	flags *flag.FlagSet
+
+	// args is a list of arments
+	args []string
+
+	// RunE is a function that contains the logic for the command
+	RunE func(cmd *Command, args []string) error
+
+	// commands is the list of subcommands that this command has.
+	commands []*Command
+
+	// Parent is a pointer to the parent command, if any, of which the command
+	// is a subcommand.
+	Parent *Command
+
+	Use           string
+	Short         string
+	SilenceErrors bool
+	SilenceUsage  bool
+	Example       string
+	Aliases       []string
+	PreRunE       func(cmd *Command, args []string) error
+	Deprecated    string
+	Long          string
+	Run           func(cmd *Command, args []string)
+}
+
+// Flags returns a flag set for the command. If not initialized yet, it initializes
+// one and returns the result.
+func (c *Command) Flags() *flag.FlagSet {
+	if c.flags == nil {
+		c.flags = flag.NewFlagSet(c.Name, flag.ContinueOnError)
+	}
+
+	return c.flags
+}
+
+// ParseFlags parses the given slice of arguments using the flag set of the command.
+func (c *Command) ParseFlags(args []string) error {
+	err := c.Flags().Parse(args)
+	if err != nil {
+		return errors.Wrap(err, "Error parsing flags")
+	}
+
+	return nil
+}
+
+// Root returns the root command of the given command.
+func (c *Command) Root() *Command {
+	if c.Parent != nil {
+		return c.Parent.Root()
+	}
+
+	return c
+}
+
+// flagHasDefaultOption checks whether the given flag has a default value
+// in the given flag set.
+func flagHasDefaultOption(flag *flag.Flag, flagSet *flag.FlagSet) bool {
+	if flag == nil {
+		return false
+	}
+
+	return flag.NoOptDefVal != ""
+}
+
+// isFlagWithAdditionalArg checks whether the given string represents a flag
+// which is followed by an argument. For instance, suppose that there is no
+// default value for a flag "--flag". Then, given "--flag", this function returns
+// true because "--flag" must be followed by an argument. Similar logic applies to
+// a short-hand flag using a single dash. (e.g. "-f")
+func isFlagWithAdditionalArg(flagStr string, flagSet *flag.FlagSet) bool {
+	// --flag arg
+	if strings.HasPrefix(flagStr, "--") && !strings.Contains(flagStr, "=") {
+		flagKey := flagStr[2:]
+		flag := flagSet.Lookup(flagKey)
+
+		return !flagHasDefaultOption(flag, flagSet)
+	}
+
+	// -f arg
+	if strings.HasPrefix(flagStr, "-") && !strings.Contains(flagStr, "=") && len(flagStr) == 2 {
+		flagKey := flagStr[1:]
+		flag := flagSet.ShorthandLookup(flagKey)
+
+		return !flagHasDefaultOption(flag, flagSet)
+	}
+
+	return false
+}
+
+// filterFlags removes flags and their values from the given arguments. It returns
+// a filtered slice which contains only non-flag arguments.
+func filterFlags(args []string, c *Command) []string {
+	ret := []string{}
+	flags := c.Flags()
+
+	idx := 0
+
+	for idx < len(args) {
+		currentArg := args[idx]
+
+		// "--" signifies the end of command line flags
+		if currentArg == "--" {
+			ret = append(ret, args[idx+1:]...)
+			break
+		}
+
+		if isFlagWithAdditionalArg(currentArg, flags) {
+			idx = idx + 2
+			continue
+		}
+
+		if currentArg != "" && !strings.HasPrefix(currentArg, "-") {
+			ret = append(ret, currentArg)
+		}
+
+		idx = idx + 1
+	}
+
+	return ret
+}
+
+// setArgs sets the arguments for the command. It is useful while writing tests.
+func (c *Command) setArgs(args []string) {
+	c.args = args
+}
+
+// Args returns the argument for the command. By default, os.Args[1:] is used.
+func (c *Command) Args() []string {
+	args := c.args
+	if c.args == nil {
+		args = os.Args[1:]
+	}
+
+	return args
+
+}
+
+// Execute runs the root command. It is meant to be called on the root command.
+func (c *Command) Execute() error {
+	// Call Execute on the root command
+	if c.Parent != nil {
+		return c.Root().Execute()
+	}
+
+	args := c.Args()
+	log.Debug("root command received arguments: %s\n", args)
+
+	cmd, flags := c.findSubCommand(args)
+	if cmd == nil {
+		// not found. show suggestion
+		return nil
+	}
+
+	cmd.execute(flags)
+
+	return nil
+}
+
+// execute runs the command.
+func (c *Command) execute(args []string) error {
+	log.Debug("command '%s' called with arguments: %s\n", c.Name, args)
+
+	if err := c.ParseFlags(args); err != nil {
+		return err
+	}
+
+	nonFlagArgs := c.Flags().Args()
+	log.Debug("command '%s' called with non-flag arguments: %s\n", c.Name, nonFlagArgs)
+
+	if err := c.RunE(c, nonFlagArgs); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// hasAlias checks whether the command has the given alias.
+func (c *Command) hasAlias(targetAlias string) bool {
+	for _, alias := range c.Aliases {
+		if alias == targetAlias {
+			return true
+		}
+	}
+
+	return false
+}
+
+// findSubCommand finds and returns an appropriate subcommand to be called, based
+// on the given slice of arguments. It also returns a slice of arguments with which
+// the subcommand should be called.
+func (c *Command) findSubCommand(args []string) (*Command, []string) {
+	nonFlagArgs := filterFlags(args, c)
+	log.Debug("non-flag arguments: %s\n", nonFlagArgs)
+
+	subCommand := nonFlagArgs[0]
+	log.Debug("sub-command: '%s'\n", subCommand)
+
+	for _, cmd := range c.commands {
+		if cmd.Name == subCommand || cmd.hasAlias(subCommand) {
+			return cmd, c.argsWithout(args, subCommand)
+		}
+	}
+
+	return nil, []string{}
+}
+
+// argsWithout removes the fist non-flag occurrence of the given key in the
+// given slice of arguments. It does not modify the given slice.
+func (c *Command) argsWithout(args []string, key string) []string {
+	flags := c.Flags()
+
+	idx := -1
+	pos := 0
+
+	for pos < len(args) {
+		currentArg := args[pos]
+
+		// "--" signifies the end of command line flags
+		if currentArg == "--" {
+			break
+		}
+
+		if isFlagWithAdditionalArg(currentArg, flags) {
+			pos = pos + 2
+			continue
+		}
+
+		if !strings.HasPrefix(currentArg, "-") {
+			if currentArg == key {
+				idx = pos
+				break
+			}
+		}
+
+		pos = pos + 1
+	}
+
+	if idx == -1 {
+		return args
+	}
+
+	ret := []string{}
+	ret = append(ret, args[:pos]...)
+	ret = append(ret, args[pos+1:]...)
+
+	return ret
+}
+
+// AddCommand adds the given command as a subcommand.
+func (c *Command) AddCommand(cmd *Command) {
+	cmd.Parent = c
+
+	c.commands = append(c.commands, cmd)
+}

pkg/cli/command/command_test.go

@@ -0,0 +1,187 @@
+package command
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/dnote/dnote/pkg/assert"
+)
+
+func TestAddCommand(t *testing.T) {
+	cmd := Command{Name: "root command"}
+	assert.Equal(t, len(cmd.commands), 0, "Commands length mismatch")
+
+	subCommand1 := Command{Name: "foo"}
+	cmd.AddCommand(&subCommand1)
+	assert.Equal(t, subCommand1.Parent, &cmd, "subCommand1 Parent mismatch")
+	assert.Equal(t, len(cmd.commands), 1, "Commands length mismatch")
+	assert.Equal(t, cmd.commands[0], &subCommand1, "commands[0] mismatch")
+
+	subCommand2 := Command{Name: "bar"}
+	cmd.AddCommand(&subCommand2)
+	assert.Equal(t, len(cmd.commands), 2, "Commands length mismatch")
+	assert.Equal(t, subCommand2.Parent, &cmd, "subCommand2 Parent mismatch")
+	assert.Equal(t, cmd.commands[0], &subCommand1, "commands[0] mismatch")
+	assert.Equal(t, cmd.commands[1], &subCommand2, "commands[1] mismatch")
+}
+
+func TestHasAlias(t *testing.T) {
+	cmd := Command{
+		Name:    "foo",
+		Aliases: []string{"f", "bar"},
+	}
+
+	assert.Equal(t, cmd.hasAlias("f"), true, "Command should have 'f' alias")
+	assert.Equal(t, cmd.hasAlias("F"), false, "Command should not have 'F' alias")
+	assert.Equal(t, cmd.hasAlias("bar"), true, "Command should have 'bar' alias")
+	assert.Equal(t, cmd.hasAlias("BAR"), false, "Command should have 'BAR' alias")
+	assert.Equal(t, cmd.hasAlias("baz"), false, "Command should not have 'baz' alias")
+	assert.Equal(t, cmd.hasAlias(""), false, "Command should not have an empty alias")
+}
+
+func TestHasAlias_withoutAlias(t *testing.T) {
+	cmd := Command{
+		Name: "foo",
+	}
+
+	assert.Equal(t, cmd.hasAlias("f"), false, "Command should not have any alias")
+	assert.Equal(t, cmd.hasAlias(""), false, "Command should not have any alias")
+}
+
+func TestCommandRoot(t *testing.T) {
+	subCommand2 := Command{
+		Name: "baz",
+	}
+	subCommand1 := Command{
+		Name: "bar",
+		commands: []*Command{
+			&subCommand2,
+		},
+	}
+	cmd := Command{
+		Name: "foo",
+		commands: []*Command{
+			&subCommand1,
+		},
+	}
+
+	subCommand1.Parent = &cmd
+	subCommand2.Parent = &subCommand1
+
+	assert.Equal(t, cmd.Root(), &cmd, "Command should already be a root")
+	assert.Equal(t, subCommand1.Root(), &cmd, "subCommand1 root mismatch")
+	assert.Equal(t, subCommand2.Root(), &cmd, "subCommand2 root mismatch")
+}
+
+func TestFindSubcommand(t *testing.T) {
+	subCommand1 := Command{
+		Name:    "bar",
+		Aliases: []string{"quz"},
+	}
+	subCommand2 := Command{
+		Name: "baz",
+	}
+	cmd := Command{
+		Name: "foo",
+		commands: []*Command{
+			&subCommand1,
+			&subCommand2,
+		},
+	}
+
+	subcommandResult1, subcommandArgResult1 := cmd.findSubCommand([]string{"bar"})
+	assert.Equal(t, subcommandResult1, &subCommand1, "Subcommand 'bar' mismatch")
+	assert.DeepEqual(t, subcommandArgResult1, []string{}, "Subcommand arg for 'bar' mismatch")
+
+	subcommandResult2, subcommandArgResult2 := cmd.findSubCommand([]string{"baz", "echo"})
+	assert.Equal(t, subcommandResult2, &subCommand2, "Subcommand 'baz' mismatch")
+	assert.DeepEqual(t, subcommandArgResult2, []string{"echo"}, "Subcommand arg for 'baz' mismatch")
+
+	// Should match an alias
+	subcommandResult3, subcommandArgResult3 := cmd.findSubCommand([]string{"quz"})
+	assert.Equal(t, subcommandResult3, &subCommand1, "Subcommand 'quz' mismatch")
+	assert.DeepEqual(t, subcommandArgResult3, []string{}, "Subcommand arg for 'quz' mismatch")
+
+	// Should not match if not exists
+	subcommandResult4, subcommandArgResult4 := cmd.findSubCommand([]string{"qux"})
+	assert.Equal(t, subcommandResult4, (*Command)(nil), "Subcommand 'qux' mismatch")
+	assert.DeepEqual(t, subcommandArgResult4, []string{}, "Subcommand arg for 'qux' mismatch")
+
+	// Should not match itself
+	subcommandResult5, subcommandArgResult5 := subCommand1.findSubCommand([]string{"bar"})
+	assert.Equal(t, subcommandResult5, (*Command)(nil), "Subcommand 'bar' should not exist on 'bar'")
+	assert.DeepEqual(t, subcommandArgResult5, []string{}, "Subcommand arg for 'bar' should be empty when there is no match")
+}
+
+func executeCommand(root *Command, args ...string) error {
+	return root.Execute()
+}
+
+func TestFilterFlags(t *testing.T) {
+	testCases := []struct {
+		arguments []string
+		expected  []string
+	}{
+		{
+			arguments: []string{"a", "b", "c"},
+			expected:  []string{"a", "b", "c"},
+		},
+		{
+			arguments: []string{"-b", "cmd"},
+			expected:  []string{"cmd"},
+		},
+		{
+			arguments: []string{"foo", "-b", "--str"},
+			expected:  []string{"foo"},
+		},
+		{
+			arguments: []string{"foo", "-b", "baz"},
+			expected:  []string{"foo", "baz"},
+		},
+		{
+			arguments: []string{"foo", "-i", "123"},
+			expected:  []string{"foo"},
+		},
+		{
+			arguments: []string{"-b", "bar", "-i", "1", "a"},
+			expected:  []string{"bar", "a"},
+		},
+		{
+			arguments: []string{"a", "-b", "bar", "-i", "1"},
+			expected:  []string{"a", "bar"},
+		},
+		{
+			arguments: []string{"--foo", "b", "-baz"},
+			expected:  []string{},
+		},
+		{
+			arguments: []string{"--s=hello", "foo"},
+			expected:  []string{"foo"},
+		},
+		{
+			arguments: []string{"-shello", "foo"},
+			expected:  []string{"foo"},
+		},
+		{
+			arguments: []string{"-shello", "foo", "-i1"},
+			expected:  []string{"foo"},
+		},
+		{
+			arguments: []string{"-si", "foo"},
+			expected:  []string{"foo"},
+		},
+	}
+
+	cmd := Command{}
+	cmd.Flags().StringP("str", "s", "", "")
+	cmd.Flags().IntP("int", "i", 1, "")
+	cmd.Flags().BoolP("bool", "b", false, "")
+	// Default 'bool' to "true"
+	cmd.Flags().Lookup("bool").NoOptDefVal = "true"
+
+	for idx, testCase := range testCases {
+		got := filterFlags(testCase.arguments, &cmd)
+
+		assert.DeepEqual(t, got, testCase.expected, fmt.Sprintf("result mismatch for test case %d", idx))
+	}
+}

pkg/cli/infra/init.go

@@ -28,6 +28,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/dnote/dnote/pkg/cli/command"
 	"github.com/dnote/dnote/pkg/cli/config"
 	"github.com/dnote/dnote/pkg/cli/consts"
 	"github.com/dnote/dnote/pkg/cli/context"
@@ -38,11 +39,10 @@ import (
 	"github.com/dnote/dnote/pkg/cli/utils"
 	"github.com/dnote/dnote/pkg/clock"
 	"github.com/pkg/errors"
-	"github.com/spf13/cobra"
 )
 
 // RunEFunc is a function type of dnote commands
-type RunEFunc func(*cobra.Command, []string) error
+type RunEFunc func(*command.Command, []string) error
 
 func checkLegacyDBPath() (string, bool) {
 	legacyDnoteDir := getLegacyDnotePath(dirs.Home)