Better error message on unrecognized command

Closes issue #1436

License: MIT
Signed-off-by: Shaun Bruce <shaun.m.bruce@gmail.com>

Godeps/Godeps.json

@@ -279,6 +279,10 @@
 			"ImportPath": "github.com/syndtr/gosnappy/snappy",
 			"Rev": "156a073208e131d7d2e212cb749feae7c339e846"
 		},
+		{
+			"ImportPath": "github.com/texttheater/golang-levenshtein/levenshtein",
+			"Rev": "dfd657628c58d3eeaa26391097853b2473c8b94e"
+		},
 		{
 			"ImportPath": "github.com/whyrusleeping/go-metrics",
 			"Rev": "1cd8009604ec2238b5a71305a0ecd974066e0e16"

Godeps/_workspace/src/github.com/texttheater/golang-levenshtein/levenshtein/levenshtein.go

+package levenshtein
+
+import (
+	"fmt"
+	"os"
+)
+
+type EditOperation int
+
+const (
+	Ins = iota
+	Del
+	Sub
+	Match
+)
+
+type EditScript []EditOperation
+
+type MatchFunction func(rune, rune) bool
+
+type Options struct {
+	InsCost int
+	DelCost int
+	SubCost int
+	Matches MatchFunction
+}
+
+// DefaultOptions is the default options: insertion cost is 1, deletion cost is
+// 1, substitution cost is 2, and two runes match iff they are the same.
+var DefaultOptions Options = Options{
+	InsCost: 1,
+	DelCost: 1,
+	SubCost: 2,
+	Matches: func(sourceCharacter rune, targetCharacter rune) bool {
+		return sourceCharacter == targetCharacter
+	},
+}
+
+func (operation EditOperation) String() string {
+	if operation == Match {
+		return "match"
+	} else if operation == Ins {
+		return "ins"
+	} else if operation == Sub {
+		return "sub"
+	}
+	return "del"
+}
+
+// DistanceForStrings returns the edit distance between source and target.
+func DistanceForStrings(source []rune, target []rune, op Options) int {
+	return DistanceForMatrix(MatrixForStrings(source, target, op))
+}
+
+// DistanceForMatrix reads the edit distance off the given Levenshtein matrix.
+func DistanceForMatrix(matrix [][]int) int {
+	return matrix[len(matrix)-1][len(matrix[0])-1]
+}
+
+// MatrixForStrings generates a 2-D array representing the dynamic programming
+// table used by the Levenshtein algorithm, as described e.g. here:
+// http://www.let.rug.nl/kleiweg/lev/
+// The reason for putting the creation of the table into a separate function is
+// that it cannot only be used for reading of the edit distance between two
+// strings, but also e.g. to backtrace an edit script that provides an
+// alignment between the characters of both strings.
+func MatrixForStrings(source []rune, target []rune, op Options) [][]int {
+	// Make a 2-D matrix. Rows correspond to prefixes of source, columns to
+	// prefixes of target. Cells will contain edit distances.
+	// Cf. http://www.let.rug.nl/~kleiweg/lev/levenshtein.html
+	height := len(source) + 1
+	width := len(target) + 1
+	matrix := make([][]int, height)
+
+	// Initialize trivial distances (from/to empty string). That is, fill
+	// the left column and the top row with row/column indices.
+	for i := 0; i < height; i++ {
+		matrix[i] = make([]int, width)
+		matrix[i][0] = i
+	}
+	for j := 1; j < width; j++ {
+		matrix[0][j] = j
+	}
+
+	// Fill in the remaining cells: for each prefix pair, choose the
+	// (edit history, operation) pair with the lowest cost.
+	for i := 1; i < height; i++ {
+		for j := 1; j < width; j++ {
+			delCost := matrix[i-1][j] + op.DelCost
+			matchSubCost := matrix[i-1][j-1]
+			if !op.Matches(source[i-1], target[j-1]) {
+				matchSubCost += op.SubCost
+			}
+			insCost := matrix[i][j-1] + op.InsCost
+			matrix[i][j] = min(delCost, min(matchSubCost,
+				insCost))
+		}
+	}
+	//LogMatrix(source, target, matrix)
+	return matrix
+}
+
+// EditScriptForStrings returns an optimal edit script to turn source into
+// target.
+func EditScriptForStrings(source []rune, target []rune, op Options) EditScript {
+	return backtrace(len(source), len(target),
+		MatrixForStrings(source, target, op), op)
+}
+
+// EditScriptForMatrix returns an optimal edit script based on the given
+// Levenshtein matrix.
+func EditScriptForMatrix(matrix [][]int, op Options) EditScript {
+	return backtrace(len(matrix[0])-1, len(matrix)-1, matrix, op)
+}
+
+// LogMatrix outputs a visual representation of the given matrix for the given
+// strings on os.Stderr.
+func LogMatrix(source []rune, target []rune, matrix [][]int) {
+	fmt.Fprintf(os.Stderr, "    ")
+	for _, targetRune := range target {
+		fmt.Fprintf(os.Stderr, "  %c", targetRune)
+	}
+	fmt.Fprintf(os.Stderr, "\n")
+	fmt.Fprintf(os.Stderr, "  %2d", matrix[0][0])
+	for j, _ := range target {
+		fmt.Fprintf(os.Stderr, " %2d", matrix[0][j+1])
+	}
+	fmt.Fprintf(os.Stderr, "\n")
+	for i, sourceRune := range source {
+		fmt.Fprintf(os.Stderr, "%c %2d", sourceRune, matrix[i+1][0])
+		for j, _ := range target {
+			fmt.Fprintf(os.Stderr, " %2d", matrix[i+1][j+1])
+		}
+		fmt.Fprintf(os.Stderr, "\n")
+	}
+}
+
+func backtrace(i int, j int, matrix [][]int, op Options) EditScript {
+	if i > 0 && matrix[i-1][j]+op.DelCost == matrix[i][j] {
+		return append(backtrace(i-1, j, matrix, op), Del)
+	}
+	if j > 0 && matrix[i][j-1]+op.InsCost == matrix[i][j] {
+		return append(backtrace(i, j-1, matrix, op), Ins)
+	}
+	if i > 0 && j > 0 && matrix[i-1][j-1]+op.SubCost == matrix[i][j] {
+		return append(backtrace(i-1, j-1, matrix, op), Sub)
+	}
+	if i > 0 && j > 0 && matrix[i-1][j-1] == matrix[i][j] {
+		return append(backtrace(i-1, j-1, matrix, op), Match)
+	}
+	return []EditOperation{}
+}
+
+func min(a int, b int) int {
+	if b < a {
+		return b
+	}
+	return a
+}
+
+func max(a int, b int) int {
+	if b > a {
+		return b
+	}
+	return a
+}

Godeps/_workspace/src/github.com/texttheater/golang-levenshtein/levenshtein/levenshtein_test.go

+package levenshtein_test
+
+import (
+	"github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/texttheater/golang-levenshtein/levenshtein"
+	"testing"
+)
+
+var testCases = []struct {
+	source   string
+	target   string
+	distance int
+}{
+	{"", "a", 1},
+	{"a", "aa", 1},
+	{"a", "aaa", 2},
+	{"", "", 0},
+	{"a", "b", 2},
+	{"aaa", "aba", 2},
+	{"aaa", "ab", 3},
+	{"a", "a", 0},
+	{"ab", "ab", 0},
+	{"a", "", 1},
+	{"aa", "a", 1},
+	{"aaa", "a", 2},
+}
+
+func TestLevenshtein(t *testing.T) {
+	for _, testCase := range testCases {
+		distance := levenshtein.DistanceForStrings(
+			[]rune(testCase.source),
+			[]rune(testCase.target),
+			levenshtein.DefaultOptions)
+		if distance != testCase.distance {
+			t.Log(
+				"Distance between",
+				testCase.source,
+				"and",
+				testCase.target,
+				"computed as",
+				distance,
+				", should be",
+				testCase.distance)
+			t.Fail()
+		}
+	}
+}

commands/cli/cmd_suggestion.go

+package cli
+
+import (
+	"sort"
+	"strings"
+
+	levenshtein "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/texttheater/golang-levenshtein/levenshtein"
+	cmds "github.com/ipfs/go-ipfs/commands"
+)
+
+// Make a custom slice that can be sorted by its levenshtein value
+type suggestionSlice []*suggestion
+
+type suggestion struct {
+	cmd         string
+	levenshtein int
+}
+
+func (s suggestionSlice) Len() int {
+	return len(s)
+}
+
+func (s suggestionSlice) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s suggestionSlice) Less(i, j int) bool {
+	return s[i].levenshtein < s[j].levenshtein
+}
+
+func suggestUnknownCmd(args []string, root *cmds.Command) []string {
+	arg := args[0]
+	var suggestions []string
+	sortableSuggestions := make(suggestionSlice, 0)
+	var sFinal []string
+	const MIN_LEVENSHTEIN = 3
+
+	var options levenshtein.Options = levenshtein.Options{
+		InsCost: 1,
+		DelCost: 3,
+		SubCost: 2,
+		Matches: func(sourceCharacter rune, targetCharacter rune) bool {
+			return sourceCharacter == targetCharacter
+		},
+	}
+
+	// Start with a simple strings.Contains check
+	for name, _ := range root.Subcommands {
+		if strings.Contains(arg, name) {
+			suggestions = append(suggestions, name)
+		}
+	}
+
+	// If the string compare returns a match, return
+	if len(suggestions) > 0 {
+		return suggestions
+	}
+
+	for name, _ := range root.Subcommands {
+		lev := levenshtein.DistanceForStrings([]rune(arg), []rune(name), options)
+		if lev <= MIN_LEVENSHTEIN {
+			sortableSuggestions = append(sortableSuggestions, &suggestion{name, lev})
+		}
+	}
+	sort.Sort(sortableSuggestions)
+
+	for _, j := range sortableSuggestions {
+		sFinal = append(sFinal, j.cmd)
+	}
+	return sFinal
+}

commands/cli/parse.go

@@ -41,7 +41,7 @@ func Parse(input []string, stdin *os.File, root *cmds.Command) (cmds.Request, *c
 		}
 	}
 
-	stringArgs, fileArgs, err := parseArgs(stringVals, stdin, cmd.Arguments, recursive)
+	stringArgs, fileArgs, err := parseArgs(stringVals, stdin, cmd.Arguments, recursive, root)
 	if err != nil {
 		return req, cmd, path, err
 	}
@@ -196,7 +196,7 @@ func parseOpts(args []string, root *cmds.Command) (
 	return
 }
 
-func parseArgs(inputs []string, stdin *os.File, argDefs []cmds.Argument, recursive bool) ([]string, []files.File, error) {
+func parseArgs(inputs []string, stdin *os.File, argDefs []cmds.Argument, recursive bool, root *cmds.Command) ([]string, []files.File, error) {
 	// ignore stdin on Windows
 	if runtime.GOOS == "windows" {
 		stdin = nil
@@ -231,7 +231,15 @@ func parseArgs(inputs []string, stdin *os.File, argDefs []cmds.Argument, recursi
 	// and the last arg definition is not variadic (or there are no definitions), return an error
 	notVariadic := len(argDefs) == 0 || !argDefs[len(argDefs)-1].Variadic
 	if notVariadic && len(inputs) > len(argDefs) {
-		return nil, nil, fmt.Errorf("Expected %v arguments, got %v: %v", len(argDefs), len(inputs), inputs)
+		suggestions := suggestUnknownCmd(inputs, root)
+
+		if len(suggestions) > 1 {
+			return nil, nil, fmt.Errorf("Unknown Command \"%s\"\n\nDid you mean any of these?\n\n\t%s", inputs[0], strings.Join(suggestions, "\n\t"))
+		} else if len(suggestions) > 0 {
+			return nil, nil, fmt.Errorf("Unknown Command \"%s\"\n\nDid you mean this?\n\n\t%s", inputs[0], suggestions[0])
+		} else {
+			return nil, nil, fmt.Errorf("Unknown Command \"%s\"\n", inputs[0])
+		}
 	}
 
 	stringArgs := make([]string, 0, numInputs)

test/sharness/t0150-clisuggest.sh

+#!/bin/sh
+
+test_description="Test ipfs cli cmd suggest"
+
+. lib/test-lib.sh
+
+test_suggest() {
+
+
+    test_expect_success "test command fails" '
+        test_must_fail ipfs kog 2>actual
+    '
+
+    test_expect_success "test one command is suggested" '
+        grep "Did you mean this?" actual &&
+        grep "log" actual ||
+        test_fsh cat actual
+    '
+
+    test_expect_success "test command fails" '
+        test_must_fail ipfs lis 2>actual
+    '
+
+    test_expect_success "test multiple commands are suggested" '
+        grep "Did you mean any of these?" actual &&
+        grep "ls" actual &&
+        grep "id" actual ||
+        test_fsh cat actual
+    '
+
+}
+
+test_init_ipfs
+
+test_suggest
+
+test_launch_ipfs_daemon
+
+test_suggest
+
+test_kill_ipfs_daemon
+
+test_done