feat: add better suggests when commands don't match

Author: stainless-app[bot]

pkg/cmd/cmd.go

@@ -30,6 +30,7 @@ stl auth login
 stl init
 stl dev
 stl builds create --branch <branch>`,
+		Suggest: true,
 		Version: Version,
 		Flags: []cli.Flag{
 			&cli.BoolFlag{

pkg/cmd/suggest.go

@@ -0,0 +1,126 @@
+package cmd
+
+import (
+	"fmt"
+	"math"
+	"slices"
+	"strings"
+
+	"github.com/urfave/cli/v3"
+)
+
+// This entire file is mostly taken from urfave/cli/v3's source, with the exception of suggestCommand which is
+// modified for a nicer error message.
+
+// jaroDistance is the measure of similarity between two strings. It returns a
+// value between 0 and 1, where 1 indicates identical strings and 0 indicates
+// completely different strings.
+//
+// Adapted from https://github.com/xrash/smetrics/blob/5f08fbb34913bc8ab95bb4f2a89a0637ca922666/jaro.go.
+func jaroDistance(a, b string) float64 {
+	if len(a) == 0 && len(b) == 0 {
+		return 1
+	}
+	if len(a) == 0 || len(b) == 0 {
+		return 0
+	}
+
+	lenA := float64(len(a))
+	lenB := float64(len(b))
+	hashA := make([]bool, len(a))
+	hashB := make([]bool, len(b))
+	maxDistance := int(math.Max(0, math.Floor(math.Max(lenA, lenB)/2.0)-1))
+
+	var matches float64
+	for i := 0; i < len(a); i++ {
+		start := int(math.Max(0, float64(i-maxDistance)))
+		end := int(math.Min(lenB-1, float64(i+maxDistance)))
+
+		for j := start; j <= end; j++ {
+			if hashB[j] {
+				continue
+			}
+			if a[i] == b[j] {
+				hashA[i] = true
+				hashB[j] = true
+				matches++
+				break
+			}
+		}
+	}
+	if matches == 0 {
+		return 0
+	}
+
+	var transpositions float64
+	var j int
+	for i := 0; i < len(a); i++ {
+		if !hashA[i] {
+			continue
+		}
+		for !hashB[j] {
+			j++
+		}
+		if a[i] != b[j] {
+			transpositions++
+		}
+		j++
+	}
+
+	transpositions /= 2
+	return ((matches / lenA) + (matches / lenB) + ((matches - transpositions) / matches)) / 3.0
+}
+
+// jaroWinkler is more accurate when strings have a common prefix up to a
+// defined maximum length.
+//
+// Adapted from https://github.com/xrash/smetrics/blob/5f08fbb34913bc8ab95bb4f2a89a0637ca922666/jaro-winkler.go.
+func jaroWinkler(a, b string) float64 {
+	const (
+		boostThreshold = 0.7
+		prefixSize     = 4
+	)
+	jaroDist := jaroDistance(a, b)
+	if jaroDist <= boostThreshold {
+		return jaroDist
+	}
+
+	prefix := int(math.Min(float64(len(a)), math.Min(float64(prefixSize), float64(len(b)))))
+
+	var prefixMatch float64
+	for i := 0; i < prefix; i++ {
+		if a[i] == b[i] {
+			prefixMatch++
+		} else {
+			break
+		}
+	}
+	return jaroDist + 0.1*prefixMatch*(1.0-jaroDist)
+}
+
+// suggestCommand takes a list of commands and a provided string to suggest a
+// command name
+func suggestCommand(commands []*cli.Command, provided string) string {
+	distance := 0.0
+	var lineage []*cli.Command
+	for _, command := range commands {
+		for _, name := range command.Names() {
+			newDistance := jaroWinkler(name, provided)
+			if newDistance > distance {
+				distance = newDistance
+				lineage = command.Lineage()
+			}
+		}
+	}
+
+	var parts []string
+	for _, command := range lineage {
+		parts = append(parts, command.Name)
+	}
+	slices.Reverse(parts)
+	return fmt.Sprintf("Did you mean '%s'?", strings.Join(parts, " "))
+}
+
+func init() {
+	cli.SuggestCommand = suggestCommand
+}