From 8e0b35c0cefbfe6083fc36c59c313d556bc47624 Mon Sep 17 00:00:00 2001
From: Enver Bisevac <enver.bisevac@harness.io>
Date: Fri, 9 Feb 2024 12:20:23 +0000
Subject: [PATCH] [maint] diff with json response contain diff with headers
 (#1035)

---
 git/diff.go      | 15 +++---------
 git/diff/diff.go | 63 ++++++++++++++++++++++++++++++++++--------------
 2 files changed, 48 insertions(+), 30 deletions(-)

diff --git a/git/diff.go b/git/diff.go
index 9eeef696d..c26260f9f 100644
--- a/git/diff.go
+++ b/git/diff.go
@@ -446,20 +446,11 @@ func (s *Service) Diff(
 		defer pr.Close()
 
 		parser := diff.Parser{
-			Reader: bufio.NewReader(pr),
+			Reader:       bufio.NewReader(pr),
+			IncludePatch: params.IncludePatch,
 		}
 
 		err := parser.Parse(func(f *diff.File) error {
-			patch := bytes.Buffer{}
-			if params.IncludePatch {
-				for _, sec := range f.Sections {
-					for _, line := range sec.Lines {
-						if line.Type != diff.DiffLinePlain {
-							patch.WriteString(line.Content)
-						}
-					}
-				}
-			}
 			ch <- &FileDiff{
 				SHA:         f.SHA,
 				OldSHA:      f.OldSHA,
@@ -469,7 +460,7 @@ func (s *Service) Diff(
 				Additions:   int64(f.NumAdditions()),
 				Deletions:   int64(f.NumDeletions()),
 				Changes:     int64(f.NumChanges()),
-				Patch:       patch.Bytes(),
+				Patch:       f.Patch.Bytes(),
 				IsBinary:    f.IsBinary,
 				IsSubmodule: f.IsSubmodule,
 			}
diff --git a/git/diff/diff.go b/git/diff/diff.go
index 90aa5041a..29cbe7411 100644
--- a/git/diff/diff.go
+++ b/git/diff/diff.go
@@ -148,6 +148,7 @@ type File struct {
 
 	IsBinary    bool
 	IsSubmodule bool
+	Patch       bytes.Buffer
 }
 
 func (f *File) Status() string {
@@ -206,18 +207,20 @@ type Parser struct {
 	// of process should go in.
 	buffer []byte
 	isEOF  bool
+
+	IncludePatch bool
+	Patch        bytes.Buffer
 }
 
-func (p *Parser) readLine() error {
+func (p *Parser) readLine() (newLine bool, err error) {
 	if p.buffer != nil {
-		return nil
+		return false, nil
 	}
 
-	var err error
 	p.buffer, err = p.ReadBytes('\n')
 	if err != nil {
 		if !errors.Is(err, io.EOF) {
-			return fmt.Errorf("read string: %w", err)
+			return false, fmt.Errorf("read string: %w", err)
 		}
 
 		p.isEOF = true
@@ -225,16 +228,22 @@ func (p *Parser) readLine() error {
 
 	// Remove line break
 	if len(p.buffer) > 0 && p.buffer[len(p.buffer)-1] == '\n' {
+		newLine = true
 		p.buffer = p.buffer[:len(p.buffer)-1]
 	}
-	return nil
+	return newLine, nil
 }
 
 var diffHead = []byte("diff --git ")
 
 //nolint:gocognit
 func (p *Parser) parseFileHeader() (*File, error) {
+	p.Patch.Reset()
 	submoduleMode := " 160000"
+	if p.IncludePatch && len(p.buffer) > 0 {
+		p.Patch.Write(p.buffer)
+		p.Patch.Write([]byte{'\n'})
+	}
 	line := string(p.buffer)
 	p.buffer = nil
 
@@ -260,14 +269,20 @@ func (p *Parser) parseFileHeader() (*File, error) {
 		Type:    FileChange,
 	}
 
-	// Check file diff type and submodule
-	var err error
 checkType:
 	for !p.isEOF {
-		if err = p.readLine(); err != nil {
+		newLine, err := p.readLine()
+		if err != nil {
 			return nil, err
 		}
 
+		if p.IncludePatch && len(p.buffer) > 0 {
+			p.Patch.Write(p.buffer)
+			if newLine {
+				p.Patch.Write([]byte{'\n'})
+			}
+		}
+
 		subLine := string(p.buffer)
 		p.buffer = nil
 
@@ -365,9 +380,9 @@ func (p *Parser) parseSection() (*Section, error) {
 		rightLine = leftLine
 	}
 
-	var err error
 	for !p.isEOF {
-		if err = p.readLine(); err != nil {
+		newLine, err := p.readLine()
+		if err != nil {
 			return nil, err
 		}
 
@@ -389,6 +404,13 @@ func (p *Parser) parseSection() (*Section, error) {
 			return section, nil
 		}
 
+		if p.IncludePatch && len(p.buffer) > 0 {
+			p.Patch.Write(p.buffer)
+			if newLine {
+				p.Patch.Write([]byte{'\n'})
+			}
+		}
+
 		subLine := string(p.buffer)
 		p.buffer = nil
 
@@ -433,17 +455,13 @@ func (p *Parser) Parse(send func(f *File) error) error {
 	additions := 0
 	deletions := 0
 
-	var (
-		err error
-	)
 	for !p.isEOF {
-		if err = p.readLine(); err != nil {
+		newLine, err := p.readLine()
+		if err != nil {
 			return err
 		}
 
-		if len(p.buffer) == 0 ||
-			bytes.HasPrefix(p.buffer, []byte("+++ ")) ||
-			bytes.HasPrefix(p.buffer, []byte("--- ")) {
+		if len(p.buffer) == 0 {
 			p.buffer = nil
 			continue
 		}
@@ -452,6 +470,7 @@ func (p *Parser) Parse(send func(f *File) error) error {
 		if bytes.HasPrefix(p.buffer, diffHead) {
 			// stream previous file
 			if !file.IsEmpty() && send != nil {
+				_, _ = p.Patch.WriteTo(&file.Patch)
 				err = send(file)
 				if err != nil {
 					return fmt.Errorf("failed to send out file: %w", err)
@@ -471,6 +490,13 @@ func (p *Parser) Parse(send func(f *File) error) error {
 			continue
 		}
 
+		if p.IncludePatch && len(p.buffer) > 0 {
+			p.Patch.Write(p.buffer)
+			if newLine {
+				p.Patch.Write([]byte{'\n'})
+			}
+		}
+
 		if bytes.HasPrefix(p.buffer, []byte("Binary")) {
 			p.buffer = nil
 			file.IsBinary = true
@@ -497,7 +523,8 @@ func (p *Parser) Parse(send func(f *File) error) error {
 
 	// stream last file
 	if !file.IsEmpty() && send != nil {
-		err = send(file)
+		file.Patch.Write(p.Patch.Bytes())
+		err := send(file)
 		if err != nil {
 			return fmt.Errorf("failed to send last file: %w", err)
 		}