Fix up the summary to log as a table

filesystem.go

@@ -0,0 +1,247 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"sync"
+)
+
+var filesystem FileSystem = NewRealFileSystem()
+
+// FileSystem abstracts filesystem operations so we can swap implementations
+type FileSystem interface {
+	Remove(path string) error
+	RemoveAll(path string) error
+	MkdirAll(path string, perm os.FileMode) error
+	Symlink(source, target string) error
+	Link(source, target string) error
+	RecordLinkAttempt(kind string, source, target string, err error, dryRun bool)
+	SummaryLines() []string
+	SummaryRecords() []operationRecord
+	IsDryRun() bool
+}
+
+const (
+	opRemove    = "remove"
+	opRemoveAll = "remove_all"
+	opMkdirAll  = "mkdir_all"
+	opSymlink   = "symlink"
+	opHardlink  = "hardlink"
+)
+
+type operationRecord struct {
+	kind   string
+	source string
+	target string
+	err    error
+	dryRun bool
+}
+
+func (r operationRecord) summaryLine() (string, bool) {
+	detail := r.detail()
+	if detail != "" {
+		return fmt.Sprintf("%s %s → %s (%s) %s",
+			r.kindLabel(),
+			r.formattedSource(),
+			r.formattedTarget(),
+			r.resultLabel(),
+			detail), true
+	}
+
+	return fmt.Sprintf("%s %s → %s (%s)",
+		r.kindLabel(),
+		r.formattedSource(),
+		r.formattedTarget(),
+		r.resultLabel()), true
+}
+
+func (r operationRecord) kindLabel() string {
+	switch r.kind {
+	case opSymlink:
+		return "Symlink"
+	case opHardlink:
+		return "Hardlink"
+	case opRemove:
+		return "Remove"
+	case opRemoveAll:
+		return "RemoveAll"
+	case opMkdirAll:
+		return "MkdirAll"
+	default:
+		return r.kind
+	}
+}
+
+func (r operationRecord) resultLabel() string {
+	if r.err != nil {
+		return fmt.Sprintf("%sFAIL%s", BRed, Reset)
+	}
+	if r.dryRun {
+		return fmt.Sprintf("%sDRY-RUN%s", BCyan, Reset)
+	}
+	return fmt.Sprintf("%sOK%s", BGreen, Reset)
+}
+
+func (r operationRecord) formattedSource() string {
+	if r.source == "" {
+		return "-"
+	}
+	return FormatSourcePath(r.source)
+}
+
+func (r operationRecord) formattedTarget() string {
+	if r.target == "" {
+		return "-"
+	}
+	return FormatTargetPath(r.target)
+}
+
+func (r operationRecord) detail() string {
+	if r.err != nil {
+		return r.err.Error()
+	}
+	if r.dryRun {
+		return "dry-run"
+	}
+	return ""
+}
+
+type baseFileSystem struct {
+	mu         sync.Mutex
+	operations []operationRecord
+}
+
+func (b *baseFileSystem) addOperation(kind, source, target string, err error, dryRun bool) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.operations = append(b.operations, operationRecord{
+		kind:   kind,
+		source: source,
+		target: target,
+		err:    err,
+		dryRun: dryRun,
+	})
+}
+
+func (b *baseFileSystem) snapshot() []operationRecord {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	ops := make([]operationRecord, len(b.operations))
+	copy(ops, b.operations)
+	return ops
+}
+
+func summarizeOperations(records []operationRecord) []string {
+	var lines []string
+	for _, record := range records {
+		if line, ok := record.summaryLine(); ok {
+			lines = append(lines, line)
+		}
+	}
+	return lines
+}
+
+type realFileSystem struct {
+	baseFileSystem
+}
+
+// NewRealFileSystem returns a filesystem implementation that writes to disk
+func NewRealFileSystem() FileSystem {
+	return &realFileSystem{}
+}
+
+func (fs *realFileSystem) Remove(path string) error {
+	err := os.Remove(path)
+	fs.addOperation(opRemove, "", path, err, false)
+	return err
+}
+
+func (fs *realFileSystem) RemoveAll(path string) error {
+	err := os.RemoveAll(path)
+	fs.addOperation(opRemoveAll, "", path, err, false)
+	return err
+}
+
+func (fs *realFileSystem) MkdirAll(path string, perm os.FileMode) error {
+	err := os.MkdirAll(path, perm)
+	fs.addOperation(opMkdirAll, "", path, err, false)
+	return err
+}
+
+func (fs *realFileSystem) Symlink(source, target string) error {
+	err := os.Symlink(source, target)
+	fs.RecordLinkAttempt(opSymlink, source, target, err, false)
+	return err
+}
+
+func (fs *realFileSystem) Link(source, target string) error {
+	err := os.Link(source, target)
+	fs.RecordLinkAttempt(opHardlink, source, target, err, false)
+	return err
+}
+
+func (fs *realFileSystem) RecordLinkAttempt(kind string, source, target string, err error, dryRun bool) {
+	fs.addOperation(kind, source, target, err, dryRun)
+}
+
+func (fs *realFileSystem) SummaryLines() []string {
+	return summarizeOperations(fs.snapshot())
+}
+
+func (fs *realFileSystem) SummaryRecords() []operationRecord {
+	return fs.snapshot()
+}
+
+func (fs *realFileSystem) IsDryRun() bool {
+	return false
+}
+
+type dryRunFileSystem struct {
+	baseFileSystem
+}
+
+// NewDryRunFileSystem returns a filesystem implementation that only records operations
+func NewDryRunFileSystem() FileSystem {
+	return &dryRunFileSystem{}
+}
+
+func (fs *dryRunFileSystem) Remove(path string) error {
+	fs.addOperation(opRemove, "", path, nil, true)
+	return nil
+}
+
+func (fs *dryRunFileSystem) RemoveAll(path string) error {
+	fs.addOperation(opRemoveAll, "", path, nil, true)
+	return nil
+}
+
+func (fs *dryRunFileSystem) MkdirAll(path string, perm os.FileMode) error {
+	fs.addOperation(opMkdirAll, "", path, nil, true)
+	return nil
+}
+
+func (fs *dryRunFileSystem) Symlink(source, target string) error {
+	fs.RecordLinkAttempt(opSymlink, source, target, nil, true)
+	return nil
+}
+
+func (fs *dryRunFileSystem) Link(source, target string) error {
+	fs.RecordLinkAttempt(opHardlink, source, target, nil, true)
+	return nil
+}
+
+func (fs *dryRunFileSystem) RecordLinkAttempt(kind string, source, target string, err error, dryRun bool) {
+	fs.addOperation(kind, source, target, err, dryRun)
+}
+
+func (fs *dryRunFileSystem) SummaryLines() []string {
+	return summarizeOperations(fs.snapshot())
+}
+
+func (fs *dryRunFileSystem) SummaryRecords() []operationRecord {
+	return fs.snapshot()
+}
+
+func (fs *dryRunFileSystem) IsDryRun() bool {
+	return true
+}

filesystem_test.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSummaryLineMarksFailuresInRed(t *testing.T) {
+	fs := NewRealFileSystem()
+
+	fs.RecordLinkAttempt(opSymlink, "/tmp/source", "/tmp/target", fmt.Errorf("boom"), false)
+
+	lines := fs.SummaryLines()
+	assert.Equal(t, 1, len(lines))
+	assert.Contains(t, lines[0], BRed+"FAIL"+Reset)
+	assert.Contains(t, lines[0], "boom")
+}

instruction.go

@@ -76,12 +76,17 @@ func (instruction *LinkInstruction) Undo() {
 
 	if isSymlink {
 		LogInfo("Removing symlink at %s", FormatTargetPath(instruction.Target))
-		err = os.Remove(instruction.Target)
+		err = filesystem.Remove(instruction.Target)
 		if err != nil {
 			LogError("could not remove symlink at %s; err: %v",
 				FormatTargetPath(instruction.Target), err)
-		}
+		} else {
+			if filesystem.IsDryRun() {
+				LogInfo("[DRY-RUN] Would remove symlink at %s", FormatTargetPath(instruction.Target))
+			} else {
 				LogSuccess("Removed symlink at %s", FormatTargetPath(instruction.Target))
+			}
+		}
 	} else {
 		LogInfo("%s is not a symlink, skipping", FormatTargetPath(instruction.Target))
 	}
@@ -172,19 +177,28 @@ func (instruction *LinkInstruction) RunAsync(status chan (error)) {
 		return
 	}
 
+	linkKind := opSymlink
+	if instruction.Hard {
+		linkKind = opHardlink
+	}
+	reportErr := func(err error) {
+		filesystem.RecordLinkAttempt(linkKind, instruction.Source, instruction.Target, err, filesystem.IsDryRun())
+		status <- err
+	}
+
 	if !FileExists(instruction.Source) {
-		status <- fmt.Errorf("instruction source %s does not exist", FormatSourcePath(instruction.Source))
+		reportErr(fmt.Errorf("instruction source %s does not exist", FormatSourcePath(instruction.Source)))
 		return
 	}
 
 	if instruction.Files {
 		info, err := os.Stat(instruction.Source)
 		if err != nil {
-			status <- fmt.Errorf("could not stat source %s; err: %v", FormatSourcePath(instruction.Source), err)
+			reportErr(fmt.Errorf("could not stat source %s; err: %v", FormatSourcePath(instruction.Source), err))
 			return
 		}
 		if info.IsDir() {
-			status <- fmt.Errorf("source %s is a directory but files=true", FormatSourcePath(instruction.Source))
+			reportErr(fmt.Errorf("source %s is a directory but files=true", FormatSourcePath(instruction.Source)))
 			return
 		}
 	}
@@ -202,31 +216,31 @@ func (instruction *LinkInstruction) RunAsync(status chan (error)) {
 	if FileExists(instruction.Target) {
 		if instruction.Files {
 			if info, err := os.Stat(instruction.Target); err == nil && info.IsDir() {
-				status <- fmt.Errorf("target %s is a directory but files=true", FormatTargetPath(instruction.Target))
+				reportErr(fmt.Errorf("target %s is a directory but files=true", FormatTargetPath(instruction.Target)))
 				return
 			}
 		}
 		if instruction.Force {
 			isSymlink, err := IsSymlink(instruction.Target)
 			if err != nil {
-				status <- fmt.Errorf("could not determine whether %s is a sym link or not, stopping; err: %v",
+				reportErr(fmt.Errorf("could not determine whether %s is a sym link or not, stopping; err: %v",
-					FormatTargetPath(instruction.Target), err)
+					FormatTargetPath(instruction.Target), err))
 				return
 			}
 
 			if instruction.Hard {
 				info, err := os.Stat(instruction.Target)
 				if err != nil {
-					status <- fmt.Errorf("could not stat %s, stopping; err: %v",
+					reportErr(fmt.Errorf("could not stat %s, stopping; err: %v",
-						FormatTargetPath(instruction.Target), err)
+						FormatTargetPath(instruction.Target), err))
 					return
 				}
 				if info.Mode().IsRegular() && info.Name() == filepath.Base(instruction.Source) {
 					LogTarget("Overwriting existing file %s", instruction.Target)
-					err := os.Remove(instruction.Target)
+					err := filesystem.Remove(instruction.Target)
 					if err != nil {
-						status <- fmt.Errorf("could not remove existing file %s; err: %v",
+						reportErr(fmt.Errorf("could not remove existing file %s; err: %v",
-							FormatTargetPath(instruction.Target), err)
+							FormatTargetPath(instruction.Target), err))
 						return
 					}
 				}
@@ -234,59 +248,73 @@ func (instruction *LinkInstruction) RunAsync(status chan (error)) {
 
 			if isSymlink {
 				LogTarget("Removing symlink at %s", instruction.Target)
-				err = os.Remove(instruction.Target)
+				err = filesystem.Remove(instruction.Target)
 				if err != nil {
-					status <- fmt.Errorf("failed deleting %s due to %v",
+					reportErr(fmt.Errorf("failed deleting %s due to %v",
-						FormatTargetPath(instruction.Target), err)
+						FormatTargetPath(instruction.Target), err))
 					return
 				}
 			} else {
 				if !instruction.Delete {
-					status <- fmt.Errorf("refusing to delte actual (non symlink) file %s",
+					reportErr(fmt.Errorf("refusing to delte actual (non symlink) file %s",
-						FormatTargetPath(instruction.Target))
+						FormatTargetPath(instruction.Target)))
 					return
 				}
 				LogImportant("Deleting (!!!) %s", instruction.Target)
-				err = os.RemoveAll(instruction.Target)
+				err = filesystem.RemoveAll(instruction.Target)
 				if err != nil {
-					status <- fmt.Errorf("failed deleting %s due to %v",
+					reportErr(fmt.Errorf("failed deleting %s due to %v",
-						FormatTargetPath(instruction.Target), err)
+						FormatTargetPath(instruction.Target), err))
 					return
 				}
 			}
 		} else {
-			status <- fmt.Errorf("target %s exists - handle manually or set the 'forced' flag (3rd field)",
+			reportErr(fmt.Errorf("target %s exists - handle manually or set the 'forced' flag (3rd field)",
-				FormatTargetPath(instruction.Target))
+				FormatTargetPath(instruction.Target)))
 			return
 		}
 	}
 
 	targetDir := filepath.Dir(instruction.Target)
 	if _, err := os.Stat(targetDir); os.IsNotExist(err) {
-		err = os.MkdirAll(targetDir, 0755)
+		err = filesystem.MkdirAll(targetDir, 0755)
 		if err != nil {
-			status <- fmt.Errorf("failed creating directory %s due to %v",
+			reportErr(fmt.Errorf("failed creating directory %s due to %v",
-				FormatTargetPath(targetDir), err)
+				FormatTargetPath(targetDir), err))
 			return
 		}
 	}
 
+	linkType := "symlink"
+	if instruction.Hard {
+		linkType = "hardlink"
+	}
+
 	var err error
 	if instruction.Hard {
-		err = os.Link(instruction.Source, instruction.Target)
+		err = filesystem.Link(instruction.Source, instruction.Target)
 	} else {
-		err = os.Symlink(instruction.Source, instruction.Target)
+		err = filesystem.Symlink(instruction.Source, instruction.Target)
 	}
 	if err != nil {
-		status <- fmt.Errorf("failed creating symlink between %s and %s with error %v",
+		status <- fmt.Errorf("failed creating %s between %s and %s with error %v",
+			linkType,
 			FormatSourcePath(instruction.Source),
 			FormatTargetPath(instruction.Target),
 			err)
 		return
 	}
-	LogSuccess("Created symlink between %s and %s",
+	if filesystem.IsDryRun() {
+		LogInfo("[DRY-RUN] Would create %s between %s and %s",
+			linkType,
 			FormatSourcePath(instruction.Source),
 			FormatTargetPath(instruction.Target))
+	} else {
+		LogSuccess("Created %s between %s and %s",
+			linkType,
+			FormatSourcePath(instruction.Source),
+			FormatTargetPath(instruction.Target))
+	}
 
 	status <- nil
 }

instruction_test.go

@@ -394,6 +394,35 @@ func TestLinkInstruction_RunAsync(t *testing.T) {
 		assert.Contains(t, err.Error(), "files=true")
 		assert.True(t, FileExists(targetDir))
 	})
+
+	t.Run("Dry run does not modify filesystem", func(t *testing.T) {
+		originalFS := filesystem
+		filesystem = NewDryRunFileSystem()
+		defer func() {
+			filesystem = originalFS
+		}()
+
+		target := filepath.Join(testDir, "dryrun-link.txt")
+		instruction := LinkInstruction{
+			Source: srcFile,
+			Target: target,
+			Force:  true,
+			Delete: true,
+		}
+
+		status := make(chan error)
+		go instruction.RunAsync(status)
+
+		err := <-status
+		assert.NoError(t, err)
+		assert.False(t, FileExists(target))
+
+		summary := filesystem.SummaryLines()
+		assert.Equal(t, 1, len(summary))
+		assert.Contains(t, summary[0], "DRY-RUN")
+		assert.Contains(t, summary[0], FormatSourcePath(srcFile))
+		assert.Contains(t, summary[0], FormatTargetPath(target))
+	})
 }
 
 func TestLinkInstruction_Undo(t *testing.T) {

main.go

@@ -3,11 +3,16 @@ package main
 import (
 	"bufio"
 	"flag"
+	"fmt"
 	"io"
 	"log"
 	"os"
 	"path/filepath"
+	"regexp"
+	"runtime/debug"
+	"strings"
 	"sync/atomic"
+
 	utils "git.site.quack-lab.dev/dave/cyutils"
 )
 
@@ -19,19 +24,36 @@ const ImportantColor = BRed
 const DefaultColor = Reset
 const PathColor = Green
 
-var programName = os.Args[0]
+var (
-var undo = false
+	programName = os.Args[0]
+	undo        = false
+	version     = "dev"
+)
 
 func main() {
 	recurse := flag.String("r", "", "recurse into directories")
 	file := flag.String("f", "", "file to read instructions from")
 	debug := flag.Bool("d", false, "debug")
 	undoF := flag.Bool("u", false, "undo")
+	versionFlag := flag.Bool("v", false, "print version and exit")
+	dryRun := flag.Bool("n", false, "dry run (no filesystem changes)")
 	flag.Parse()
 	undo = *undoF
 
+	if *versionFlag {
+		fmt.Println(getVersionString())
+		return
+	}
+
 	setupLogging(*debug)
 
+	if *dryRun {
+		filesystem = NewDryRunFileSystem()
+		LogInfo("Dry run mode enabled - no filesystem changes will be made")
+	} else {
+		filesystem = NewRealFileSystem()
+	}
+
 	instructions := make(chan *LinkInstruction, 1000)
 	status := make(chan error)
 
@@ -43,9 +65,11 @@ func main() {
 
 	if instructionsDone == 0 {
 		LogInfo("No instructions were processed")
+		printSummary(filesystem)
 		os.Exit(1)
 	}
 	LogInfo("All done")
+	printSummary(filesystem)
 }
 
 // setupLogging configures logging based on debug flag
@@ -162,6 +186,80 @@ func processInstructions(instructions chan *LinkInstruction) int32 {
 	return instructionsDone
 }
 
+func printSummary(fs FileSystem) {
+	records := fs.SummaryRecords()
+	if len(records) == 0 {
+		return
+	}
+
+	header := []string{"RESULT", "OPERATION", "SOURCE", "TARGET", "DETAIL"}
+	widths := make([]int, len(header))
+	for i, h := range header {
+		widths[i] = len(h)
+	}
+
+	type row struct {
+		values []string
+		err    error
+	}
+	rows := make([]row, len(records))
+
+	for i, record := range records {
+		values := []string{
+			record.resultLabel(),
+			record.kindLabel(),
+			FormatSourcePath(record.source),
+			FormatTargetPath(record.target),
+			record.detail(),
+		}
+		rows[i] = row{values: values, err: record.err}
+
+		for j, val := range values {
+			if l := visibleLength(val); l > widths[j] {
+				widths[j] = l
+			}
+		}
+	}
+
+	LogInfo("Summary:")
+	var lineBuilder strings.Builder
+
+	writeSummaryRow(&lineBuilder, header, widths)
+	for _, line := range strings.Split(strings.TrimRight(lineBuilder.String(), "\n"), "\n") {
+		LogInfo("%s", line)
+	}
+
+	for _, r := range rows {
+		lineBuilder.Reset()
+		writeSummaryRow(&lineBuilder, r.values, widths)
+		line := strings.TrimRight(lineBuilder.String(), "\n")
+		LogInfo("%s", line)
+	}
+}
+
+func writeSummaryRow(b *strings.Builder, cols []string, widths []int) {
+	for i, val := range cols {
+		if val == "" {
+			val = "-"
+		}
+		b.WriteString(val)
+		pad := widths[i] - visibleLength(val)
+		if pad < 0 {
+			pad = 0
+		}
+		if i < len(cols)-1 {
+			b.WriteString(strings.Repeat(" ", pad+2))
+		}
+	}
+	b.WriteByte('\n')
+}
+
+var ansiRegexp = regexp.MustCompile(`\x1b\[[0-9;]*m`)
+
+func visibleLength(s string) int {
+	return len(ansiRegexp.ReplaceAllString(s, ""))
+}
+
 func IsPipeInput() bool {
 	info, err := os.Stdin.Stat()
 	if err != nil {
@@ -226,6 +324,44 @@ func ReadFromFilesRecursively(input string, output chan *LinkInstruction, status
 	}
 }
 
+func getVersionString() string {
+	if version != "" && version != "dev" {
+		return version
+	}
+
+	if info, ok := debug.ReadBuildInfo(); ok {
+		if info.Main.Version != "" && info.Main.Version != "(devel)" {
+			return info.Main.Version
+		}
+
+		var revision, modified, vcsTime string
+		for _, setting := range info.Settings {
+			switch setting.Key {
+			case "vcs.revision":
+				revision = setting.Value
+			case "vcs.modified":
+				modified = setting.Value
+			case "vcs.time":
+				vcsTime = setting.Value
+			}
+		}
+		if revision != "" {
+			if len(revision) > 7 {
+				revision = revision[:7]
+			}
+			if modified == "true" {
+				revision += "-dirty"
+			}
+			if vcsTime != "" {
+				revision += " (" + vcsTime + ")"
+			}
+			return revision
+		}
+	}
+
+	return "dev"
+}
+
 func ReadFromFile(input string, output chan *LinkInstruction, status chan error, doclose bool) {
 	if doclose {
 		defer close(output)