feat: add graphviz output (#77)

This PR adds the functionnality to render a cfg analyis to a graphviz
svg file.

closes #37

README.md

@@ -137,7 +137,8 @@ tlin supports several flags to customize its behavior:
 - `-fix`: Automatically fix issues
 - `-dry-run`: Run in dry-run mode (show fixes without applying them)
 - `-confidence <float>`: Set confidence threshold for auto-fixing (0.0 to 1.0, default: 0.75)
-- `-output-json <path>`: Write output in JSON format to the specified file
+- `-o <path>`: Write output to a file instead of stdout
+- `-json-output`: Output results in JSON format
 
 ## Contributing
 

cmd/tlin/main.go

@@ -37,7 +37,8 @@ type Config struct {
 	FuncName             string
 	AutoFix              bool
 	DryRun               bool
-	JsonOutput           string
+	JsonOutput           bool
+	Output               string
 	ConfidenceThreshold  float64
 }
 
@@ -64,19 +65,19 @@ func main() {
 
 	if config.CFGAnalysis {
 		runWithTimeout(ctx, func() {
-			runCFGAnalysis(ctx, logger, config.Paths, config.FuncName)
+			runCFGAnalysis(ctx, logger, config.Paths, config.FuncName, config.Output)
 		})
 	} else if config.CyclomaticComplexity {
 		runWithTimeout(ctx, func() {
-			runCyclomaticComplexityAnalysis(ctx, logger, config.Paths, config.CyclomaticThreshold, config.JsonOutput)
+			runCyclomaticComplexityAnalysis(ctx, logger, config.Paths, config.CyclomaticThreshold, config.JsonOutput, config.Output)
 		})
 	} else if config.AutoFix {
 		runWithTimeout(ctx, func() {
 			runAutoFix(ctx, logger, engine, config.Paths, config.DryRun, config.ConfidenceThreshold)
 		})
 	} else {
 		runWithTimeout(ctx, func() {
-			runNormalLintProcess(ctx, logger, engine, config.Paths, config.JsonOutput)
+			runNormalLintProcess(ctx, logger, engine, config.Paths, config.JsonOutput, config.Output)
 		})
 	}
 }
@@ -92,8 +93,9 @@ func parseFlags(args []string) Config {
 	flagSet.BoolVar(&config.CFGAnalysis, "cfg", false, "Run control flow graph analysis")
 	flagSet.StringVar(&config.FuncName, "func", "", "Function name for CFG analysis")
 	flagSet.BoolVar(&config.AutoFix, "fix", false, "Automatically fix issues")
+	flagSet.StringVar(&config.Output, "o", "", "Output path")
 	flagSet.BoolVar(&config.DryRun, "dry-run", false, "Run in dry-run mode (show fixes without applying them)")
-	flagSet.StringVar(&config.JsonOutput, "json-output", "", "Output issues in JSON format to the specified file")
+	flagSet.BoolVar(&config.JsonOutput, "json", false, "Output issues in JSON format")
 	flagSet.Float64Var(&config.ConfidenceThreshold, "confidence", defaultConfidenceThreshold, "Confidence threshold for auto-fixing (0.0 to 1.0)")
 
 	err := flagSet.Parse(args)
@@ -127,21 +129,21 @@ func runWithTimeout(ctx context.Context, f func()) {
 	}
 }
 
-func runNormalLintProcess(ctx context.Context, logger *zap.Logger, engine lint.LintEngine, paths []string, jsonOutput string) {
+func runNormalLintProcess(ctx context.Context, logger *zap.Logger, engine lint.LintEngine, paths []string, isJson bool, jsonOutput string) {
 	issues, err := lint.ProcessFiles(ctx, logger, engine, paths, lint.ProcessFile)
 	if err != nil {
 		logger.Error("Error processing files", zap.Error(err))
 		os.Exit(1)
 	}
 
-	printIssues(logger, issues, jsonOutput)
+	printIssues(logger, issues, isJson, jsonOutput)
 
 	if len(issues) > 0 {
 		os.Exit(1)
 	}
 }
 
-func runCyclomaticComplexityAnalysis(ctx context.Context, logger *zap.Logger, paths []string, threshold int, jsonOutput string) {
+func runCyclomaticComplexityAnalysis(ctx context.Context, logger *zap.Logger, paths []string, threshold int, isJson bool, jsonOutput string) {
 	issues, err := lint.ProcessFiles(ctx, logger, nil, paths, func(_ lint.LintEngine, path string) ([]tt.Issue, error) {
 		return lint.ProcessCyclomaticComplexity(path, threshold)
 	})
@@ -150,14 +152,14 @@ func runCyclomaticComplexityAnalysis(ctx context.Context, logger *zap.Logger, pa
 		os.Exit(1)
 	}
 
-	printIssues(logger, issues, jsonOutput)
+	printIssues(logger, issues, isJson, jsonOutput)
 
 	if len(issues) > 0 {
 		os.Exit(1)
 	}
 }
 
-func runCFGAnalysis(_ context.Context, logger *zap.Logger, paths []string, funcName string) {
+func runCFGAnalysis(_ context.Context, logger *zap.Logger, paths []string, funcName string, output string) {
 	functionFound := false
 	for _, path := range paths {
 		fset := token.NewFileSet()
@@ -173,7 +175,14 @@ func runCFGAnalysis(_ context.Context, logger *zap.Logger, paths []string, funcN
 					cfgGraph := cfg.FromFunc(fn)
 					var buf strings.Builder
 					cfgGraph.PrintDot(&buf, fset, func(n ast.Stmt) string { return "" })
-					fmt.Printf("CFG for function %s in file %s:\n%s\n", funcName, path, buf.String())
+					if output != "" {
+						err := cfg.RenderToGraphVizFile([]byte(buf.String()), output)
+						if err != nil {
+							logger.Error("Failed to render CFG to GraphViz file", zap.Error(err))
+						}
+					} else {
+						fmt.Printf("CFG for function %s in file %s:\n%s\n", funcName, path, buf.String())
+					}
 					functionFound = true
 					return
 				}
@@ -203,7 +212,7 @@ func runAutoFix(ctx context.Context, logger *zap.Logger, engine lint.LintEngine,
 	}
 }
 
-func printIssues(logger *zap.Logger, issues []tt.Issue, jsonOutput string) {
+func printIssues(logger *zap.Logger, issues []tt.Issue, isJson bool, jsonOutput string) {
 	issuesByFile := make(map[string][]tt.Issue)
 	for _, issue := range issues {
 		issuesByFile[issue.Filename] = append(issuesByFile[issue.Filename], issue)
@@ -215,7 +224,7 @@ func printIssues(logger *zap.Logger, issues []tt.Issue, jsonOutput string) {
 	}
 	sort.Strings(sortedFiles)
 
-	if jsonOutput == "" {
+	if !isJson {
 		for _, filename := range sortedFiles {
 			fileIssues := issuesByFile[filename]
 			sourceCode, err := internal.ReadSourceCode(filename)
@@ -232,16 +241,20 @@ func printIssues(logger *zap.Logger, issues []tt.Issue, jsonOutput string) {
 			logger.Error("Error marshalling issues to JSON", zap.Error(err))
 			return
 		}
-		f, err := os.Create(jsonOutput)
-		if err != nil {
-			logger.Error("Error creating JSON output file", zap.Error(err))
-			return
-		}
-		defer f.Close()
-		_, err = f.Write(d)
-		if err != nil {
-			logger.Error("Error writing JSON output file", zap.Error(err))
-			return
+		if jsonOutput == "" {
+			fmt.Println(string(d))
+		} else {
+			f, err := os.Create(jsonOutput)
+			if err != nil {
+				logger.Error("Error creating JSON output file", zap.Error(err))
+				return
+			}
+			defer f.Close()
+			_, err = f.Write(d)
+			if err != nil {
+				logger.Error("Error writing JSON output file", zap.Error(err))
+				return
+			}
 		}
 	}
 }

cmd/tlin/main_test.go

@@ -81,10 +81,19 @@ func TestParseFlags(t *testing.T) {
 		},
 		{
 			name: "JsonOutput",
-			args: []string{"-json-output", "output.json", "file.go"},
+			args: []string{"-json", "file.go"},
 			expected: Config{
 				Paths:               []string{"file.go"},
-				JsonOutput:          "output.json",
+				JsonOutput:          true,
+				ConfidenceThreshold: defaultConfidenceThreshold,
+			},
+		},
+		{
+			name: "Output",
+			args: []string{"-o", "output.svg", "file.go"},
+			expected: Config{
+				Paths:               []string{"file.go"},
+				Output:              "output.svg",
 				ConfidenceThreshold: defaultConfidenceThreshold,
 			},
 		},
@@ -101,6 +110,7 @@ func TestParseFlags(t *testing.T) {
 			assert.Equal(t, tt.expected.ConfidenceThreshold, config.ConfidenceThreshold)
 			assert.Equal(t, tt.expected.Paths, config.Paths)
 			assert.Equal(t, tt.expected.JsonOutput, config.JsonOutput)
+			assert.Equal(t, tt.expected.Output, config.Output)
 		})
 	}
 }
@@ -159,7 +169,7 @@ func ignoredFunc() { 			// 19
 	ctx := context.Background()
 
 	output := captureOutput(t, func() {
-		runCFGAnalysis(ctx, logger, []string{tempFile}, "targetFunc")
+		runCFGAnalysis(ctx, logger, []string{tempFile}, "targetFunc", "")
 	})
 
 	assert.Contains(t, output, "CFG for function targetFunc in file")
@@ -172,7 +182,7 @@ func ignoredFunc() { 			// 19
 	t.Logf("output: %s", output)
 
 	output = captureOutput(t, func() {
-		runCFGAnalysis(ctx, logger, []string{tempFile}, "nonExistentFunc")
+		runCFGAnalysis(ctx, logger, []string{tempFile}, "nonExistentFunc", "")
 	})
 
 	assert.Contains(t, output, "Function not found: nonExistentFunc")
@@ -307,7 +317,7 @@ func TestRunJsonOutput(t *testing.T) {
 	mockEngine := setupMockEngine(expectedIssues, testFile)
 
 	jsonOutput := filepath.Join(tempDir, "output.json")
-	runNormalLintProcess(ctx, logger, mockEngine, []string{testFile}, jsonOutput)
+	runNormalLintProcess(ctx, logger, mockEngine, []string{testFile}, true, jsonOutput)
 }
 
 func createTempFiles(t *testing.T, dir string, fileNames ...string) []string {

go.mod

@@ -10,10 +10,15 @@ require (
 )
 
 require (
+	github.com/fogleman/gg v1.3.0 // indirect
+	github.com/goccy/go-graphviz v0.1.3 // indirect
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
 	go.uber.org/multierr v1.10.0 // indirect
+	golang.org/x/image v0.14.0 // indirect
 	golang.org/x/mod v0.21.0 // indirect
 	golang.org/x/sync v0.8.0 // indirect
 	golang.org/x/sys v0.25.0 // indirect

go.sum

@@ -2,13 +2,21 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fatih/color v1.17.0 h1:GlRw1BRJxkpqUCBKzKOw098ed57fEsKeNjpTe3cSjK4=
 github.com/fatih/color v1.17.0/go.mod h1:YZ7TlrGPkiz6ku9fK3TLD/pl3CpsiFyu8N92HLgmosI=
+github.com/fogleman/gg v1.3.0 h1:/7zJX8F6AaYQc57WQCyN9cAIz+4bCJGO9B+dyW29am8=
+github.com/fogleman/gg v1.3.0/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=
 github.com/fzipp/gocyclo v0.6.0 h1:lsblElZG7d3ALtGMx9fmxeTKZaLLpU8mET09yN4BBLo=
 github.com/fzipp/gocyclo v0.6.0/go.mod h1:rXPyn8fnlpa0R2csP/31uerbiVBugk5whMdlyaLkLoA=
+github.com/goccy/go-graphviz v0.1.3 h1:Pkt8y4FBnBNI9tfSobpoN5qy1qMNqRXPQYvLhaSUasY=
+github.com/goccy/go-graphviz v0.1.3/go.mod h1:pMYpbAqJT10V8dzV1JN/g/wUlG/0imKPzn3ZsrchGCI=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
+github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
@@ -21,6 +29,8 @@ go.uber.org/multierr v1.10.0 h1:S0h4aNzvfcFsC3dRF1jLoaov7oRaKqRGC/pUEJ2yvPQ=
 go.uber.org/multierr v1.10.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
 go.uber.org/zap v1.27.0 h1:aJMhYGrd5QSmlpLMr2MftRKl7t8J8PTZPA732ud/XR8=
 go.uber.org/zap v1.27.0/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
+golang.org/x/image v0.14.0 h1:tNgSxAFe3jC4uYqvZdTr84SZoM1KfwdC9SKIFrLjFn4=
+golang.org/x/image v0.14.0/go.mod h1:HUYqC05R2ZcZ3ejNQsIHQDQiwWM4JBqmm6MKANTp4LE=
 golang.org/x/mod v0.21.0 h1:vvrHzRwRfVKSiLrG+d4FMl/Qi4ukBCE6kZlTUkDYRT0=
 golang.org/x/mod v0.21.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
 golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=

internal/analysis/cfg/cfg.go

@@ -8,6 +8,7 @@ import (
 	"sort"
 	"strings"
 
+	"github.com/goccy/go-graphviz"
 	"golang.org/x/tools/go/ast/astutil"
 )
 
@@ -49,6 +50,21 @@ func FromFunc(f *ast.FuncDecl) *CFG {
 	return NewBuilder().BuildFromFunc(f)
 }
 
+// RenderToGraphVizFile renders the given DOT content to a GraphViz file.
+func RenderToGraphVizFile(dotContent []byte, filename string) error {
+	graph, err := graphviz.ParseBytes(dotContent)
+	if err != nil {
+		return err
+	}
+	g := graphviz.New()
+	defer g.Close()
+	err = g.RenderFilename(graph, graphviz.SVG, filename)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
 func AnalyzeFunction(file *ast.File, fname string) *CFG {
 	for _, decl := range file.Decls {
 		if funcDecl, ok := decl.(*ast.FuncDecl); ok {

internal/analysis/cfg/cfg_test.go

@@ -6,9 +6,13 @@ import (
 	"go/parser"
 	"go/token"
 	"go/types"
+	"os"
+	"path/filepath"
 	"regexp"
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestFromStmts(t *testing.T) {
@@ -991,6 +995,40 @@ splines="ortho";
 	}
 }
 
+func TestRenderToGraphVizFile(t *testing.T) {
+	t.Parallel()
+	tmpDir, err := os.MkdirTemp("", "cfg_test")
+	assert.NoError(t, err)
+	defer os.RemoveAll(tmpDir)
+
+	c := getWrapper(t, `
+  package main
+
+  func main() {
+	i := 5              //1
+	i++                 //2
+  }`)
+
+	var buf bytes.Buffer
+	c.cfg.PrintDot(&buf, c.fset, func(s ast.Stmt) string {
+		if _, ok := s.(*ast.AssignStmt); ok {
+			return "!"
+		} else {
+			return ""
+		}
+	})
+	dot := buf.String()
+
+	svgFile := filepath.Join(tmpDir, "test.svg")
+	err = RenderToGraphVizFile([]byte(dot), svgFile)
+	assert.NoError(t, err)
+
+	content, err := os.ReadFile(svgFile)
+	assert.NoError(t, err)
+
+	assert.NotEmpty(t, content)
+}
+
 func normalizeDotOutput(dot string) string {
 	lines := strings.Split(dot, "\n")
 	var normalized []string