Fail fast if count value is invalid when count-prompt is not set.

move lottery draw logic into runLottery()

move MarkFlagsMutuallyExclusive into init()

cmd/lottery/main.go

@@ -33,23 +33,16 @@ var rootCmd = &cobra.Command{
 	Use:   "lottery",
 	Short: "A CLI for National Lottery games.",
 	PreRunE: func(cmd *cobra.Command, args []string) error {
-		cmd.MarkFlagsMutuallyExclusive("count", "count-prompt")
-
-		return nil
+		// Fail fast if the count is invalid when the count-prompt flag is not set.
+		return validateNonPromptCount()
 	},
 	RunE: func(cmd *cobra.Command, args []string) error {
 		kindStr := viper.GetString("kind")
 		if kindStr == "" {
-			form := huh.NewForm(
-				huh.NewGroup(
-					huh.NewSelect[string]().
+			if err := huh.NewSelect[string]().
 				Title("Pick a lottery.").
 				Options(kindPromptOptions()...).
-						Value(&kindStr),
-				),
-			)
-			err := form.Run()
-			if err != nil {
+				Value(&kindStr).Run(); err != nil {
 				return err
 			}
 		}
@@ -59,30 +52,53 @@ var rootCmd = &cobra.Command{
 			return err
 		}
 
-		l, err := lottery.New(kind)
+		count, err := resolveCount()
 		if err != nil {
 			return err
 		}
 
-		if countPrompt := viper.GetBool("count-prompt"); countPrompt {
-			var count string
+		return runLottery(kind, count)
+	},
+}
+
+// resolveCount resolves the count of draws to generate, either from the command line flag or by prompting the user.
+func resolveCount() (int, error) {
+	if viper.GetBool("count-prompt") {
+		var count int
 		if err := huh.NewInput().
 			Title("How many draws would you like to generate?").
-				Value(&count).Run(); err != nil {
+			Validate(func(s string) error {
+				parsedCount, err := parseCount(s)
+				if err != nil {
+					return err
+				}
+				count = parsedCount
+				return nil
+			}).
+			Run(); err != nil {
+			return 0, err
+		}
+
+		return count, nil
+	}
+
+	return viper.GetInt("count"), nil
+}
+
+// runLottery runs the lottery draw for the specified kind and count.
+func runLottery(kind lottery.Kind, count int) error {
+	selectedLottery, err := lottery.New(kind)
+	if err != nil {
 		return err
 	}
 
-			viper.Set("count", count)
-		}
-
-		count := viper.GetInt("count")
 	includeDrawHeading := count > 1
 	renders := make([]string, 0, count)
 	drawTitle := "Lottery"
 
 	for i := range count {
-			l.Draw()
-			title, entry := renderDrawEntry(l, i+1, includeDrawHeading)
+		selectedLottery.Draw()
+		title, entry := renderDrawEntry(selectedLottery, i+1, includeDrawHeading)
 		drawTitle = title
 		renders = append(renders, entry)
 	}
@@ -92,9 +108,9 @@ var rootCmd = &cobra.Command{
 	}
 
 	return nil
-	},
 }
 
+// kindPromptLabel returns a user-friendly label for the given lottery kind.
 func kindPromptLabel(kind lottery.Kind) string {
 	switch kind {
 	case lottery.KindLotto:
@@ -112,6 +128,7 @@ func kindPromptLabel(kind lottery.Kind) string {
 	}
 }
 
+// kindPromptOptions returns a slice of options for the lottery kind prompt.
 func kindPromptOptions() []huh.Option[string] {
 	kinds := lottery.AllKinds()
 	options := make([]huh.Option[string], 0, len(kinds))
@@ -125,6 +142,7 @@ func init() {
 	rootCmd.Flags().StringP("kind", "k", "", "Lottery kind to generate draws for.")
 	rootCmd.Flags().IntP("count", "c", 1, "Number of draws to generate.")
 	rootCmd.Flags().BoolP("count-prompt", "C", false, "Prompt for the number of draws to generate.")
+	rootCmd.MarkFlagsMutuallyExclusive("count", "count-prompt")
 
 	viper.SetEnvKeyReplacer(strings.NewReplacer("-", "_"))
 	viper.SetEnvPrefix("LOTTERY")

cmd/lottery/validate.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/spf13/viper"
+)
+
+// validateNonPromptCount checks if the count is valid when the count-prompt flag is not set.
+func validateNonPromptCount() error {
+	if viper.GetBool("count-prompt") {
+		return nil
+	}
+
+	return validateCount(viper.GetInt("count"))
+}
+
+// validateCount checks if the count is valid.
+func validateCount(count int) error {
+	if count < 1 {
+		return fmt.Errorf("count must be greater than 0")
+	}
+
+	return nil
+}
+
+// parseCount parses the count from a string and validates it.
+func parseCount(raw string) (int, error) {
+	count, err := strconv.Atoi(strings.TrimSpace(raw))
+	if err != nil {
+		return 0, fmt.Errorf("count must be a whole number")
+	}
+
+	if err := validateCount(count); err != nil {
+		return 0, err
+	}
+
+	return count, nil
+}

go.mod

@@ -16,9 +16,9 @@ require (
 	github.com/atotto/clipboard v0.1.4 // indirect
 	github.com/catppuccin/go v0.3.0 // indirect
 	github.com/charmbracelet/colorprofile v0.4.3 // indirect
-	github.com/charmbracelet/ultraviolet v0.0.0-20260720091822-7cc6674724ac // indirect
+	github.com/charmbracelet/ultraviolet v0.0.0-20260730003005-19049f296fa9 // indirect
 	github.com/charmbracelet/x/ansi v0.11.7 // indirect
-	github.com/charmbracelet/x/exp/charmtone v0.0.0-20260726004341-482a56510f1b // indirect
+	github.com/charmbracelet/x/exp/charmtone v0.0.0-20260730164118-7e2d3e6c5238 // indirect
 	github.com/charmbracelet/x/exp/ordered v0.1.0 // indirect
 	github.com/charmbracelet/x/exp/strings v0.1.0 // indirect
 	github.com/charmbracelet/x/term v0.2.2 // indirect
@@ -30,7 +30,7 @@ require (
 	github.com/fsnotify/fsnotify v1.10.1 // indirect
 	github.com/go-viper/mapstructure/v2 v2.5.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
-	github.com/lucasb-eyer/go-colorful v1.4.0 // indirect
+	github.com/lucasb-eyer/go-colorful v1.4.1 // indirect
 	github.com/mattn/go-runewidth v0.0.27 // indirect
 	github.com/mitchellh/hashstructure/v2 v2.0.2 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect

go.sum

@@ -18,16 +18,16 @@ github.com/charmbracelet/colorprofile v0.4.3 h1:QPa1IWkYI+AOB+fE+mg/5/4HRMZcaXex
 github.com/charmbracelet/colorprofile v0.4.3/go.mod h1:/zT4BhpD5aGFpqQQqw7a+VtHCzu+zrQtt1zhMt9mR4Q=
 github.com/charmbracelet/fang v1.0.0 h1:jESBY40agJOlLYnnv9jE0mLqDGTxEk0hkOnx7YGyRlQ=
 github.com/charmbracelet/fang v1.0.0/go.mod h1:P5/DNb9DddQ0Z0dbc0P3ol4/ix5Po7Ofr2KMBfAqoCo=
-github.com/charmbracelet/ultraviolet v0.0.0-20260720091822-7cc6674724ac h1:BP8qMDGjmOejoVTklEXXTHI0OwMIt8JHPSPHxscFFwA=
-github.com/charmbracelet/ultraviolet v0.0.0-20260720091822-7cc6674724ac/go.mod h1:psnCZIfwwxVs6v6DhUc6NJ8AQ3ejvs2ejKwoOMeVmUk=
+github.com/charmbracelet/ultraviolet v0.0.0-20260730003005-19049f296fa9 h1:4Hue6xu7UHYStXmrtNDX93FI2I9Ztjv8qa9tkMSQG30=
+github.com/charmbracelet/ultraviolet v0.0.0-20260730003005-19049f296fa9/go.mod h1:psnCZIfwwxVs6v6DhUc6NJ8AQ3ejvs2ejKwoOMeVmUk=
 github.com/charmbracelet/x/ansi v0.11.7 h1:kzv1kJvjg2S3r9KHo8hDdHFQLEqn4RBCb39dAYC84jI=
 github.com/charmbracelet/x/ansi v0.11.7/go.mod h1:9qGpnAVYz+8ACONkZBUWPtL7lulP9No6p1epAihUZwQ=
 github.com/charmbracelet/x/conpty v0.1.1 h1:s1bUxjoi7EpqiXysVtC+a8RrvPPNcNvAjfi4jxsAuEs=
 github.com/charmbracelet/x/conpty v0.1.1/go.mod h1:OmtR77VODEFbiTzGE9G1XiRJAga6011PIm4u5fTNZpk=
 github.com/charmbracelet/x/errors v0.0.0-20240508181413-e8d8b6e2de86 h1:JSt3B+U9iqk37QUU2Rvb6DSBYRLtWqFqfxf8l5hOZUA=
 github.com/charmbracelet/x/errors v0.0.0-20240508181413-e8d8b6e2de86/go.mod h1:2P0UgXMEa6TsToMSuFqKFQR+fZTO9CNGUNokkPatT/0=
-github.com/charmbracelet/x/exp/charmtone v0.0.0-20260726004341-482a56510f1b h1:KXyKTg/2+ktNqnc/UZ6hpwfhjWK3EIPjenZNhmCK4WY=
-github.com/charmbracelet/x/exp/charmtone v0.0.0-20260726004341-482a56510f1b/go.mod h1:nsExn0DGyX0lh9LwLHTn2Gg+hafdzfSXnC+QmEJTZFY=
+github.com/charmbracelet/x/exp/charmtone v0.0.0-20260730164118-7e2d3e6c5238 h1:4uVU3ql5by/93xXLBBrHR/8NU0TVVWwUZvfaAKtpG7U=
+github.com/charmbracelet/x/exp/charmtone v0.0.0-20260730164118-7e2d3e6c5238/go.mod h1:nsExn0DGyX0lh9LwLHTn2Gg+hafdzfSXnC+QmEJTZFY=
 github.com/charmbracelet/x/exp/golden v0.0.0-20250806222409-83e3a29d542f h1:pk6gmGpCE7F3FcjaOEKYriCvpmIN4+6OS/RD0vm4uIA=
 github.com/charmbracelet/x/exp/golden v0.0.0-20250806222409-83e3a29d542f/go.mod h1:IfZAMTHB6XkZSeXUqriemErjAWCCzT0LwjKFYCZyw0I=
 github.com/charmbracelet/x/exp/ordered v0.1.0 h1:55/qLwjIh0gL0Vni+QAWk7T/qRVP6sBf+2agPBgnOFE=
@@ -67,8 +67,8 @@ github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
-github.com/lucasb-eyer/go-colorful v1.4.0 h1:UtrWVfLdarDgc44HcS7pYloGHJUjHV/4FwW4TvVgFr4=
-github.com/lucasb-eyer/go-colorful v1.4.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
+github.com/lucasb-eyer/go-colorful v1.4.1 h1:1EO+WB73+EH8EVbzlrG3KLAfEypQWVHIBqlTf+2hNss=
+github.com/lucasb-eyer/go-colorful v1.4.1/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
 github.com/mattn/go-runewidth v0.0.27 h1:Feg/Oou5zI/wnpgDF6omIU0OokC9GxLC/WRknhVlIR0=
 github.com/mattn/go-runewidth v0.0.27/go.mod h1:3qAiGCV4Koz/yuveO58qUefmUTRm8r0IGEXZ9jeHp/8=
 github.com/mitchellh/hashstructure/v2 v2.0.2 h1:vGKWl0YJqUNxE8d+h8f6NJLcCJrgbhC4NcD46KavDd4=