Add support for fancy diff format

6 files changed, 704 insertions, 53 deletions

diff --git a/cmd/grv/config.go b/cmd/grv/config.go
index b615333..4198d86 100644
--- a/cmd/grv/config.go
+++ b/cmd/grv/config.go
@@ -32,6 +32,7 @@ const (
 	cfGitBinaryFilePathDefaultValue = ""
 	cfCommitLimitDefaultValue       = ""
 	cfDefaultViewDefaultValue       = ""
+	cfDiffDisplayDefaultValue       = "fancy"
 
 	cfAllView             = "All"
 	cfMainView            = "MainView"
@@ -81,6 +82,8 @@ const (
 	CfCommitLimit ConfigVariable = "commit-limit"
 	// CfDefaultView stores the command to generate the default view
 	CfDefaultView ConfigVariable = "default-view"
+	// CfDiffDisplay stores the way diffs are displayed
+	CfDiffDisplay ConfigVariable = "diff-display"
 )
 
 var systemColorValues = map[string]SystemColorValue{
@@ -158,22 +161,31 @@ var themeComponents = map[string]ThemeComponentID{
 	cfCommitView + ".CommitGraphBranch6":     CmpCommitviewGraphBranch6,
 	cfCommitView + ".CommitGraphBranch7":     CmpCommitviewGraphBranch7,
 
-	cfDiffView + ".Title":                 CmpDiffviewTitle,
-	cfDiffView + ".Footer":                CmpDiffviewFooter,
-	cfDiffView + ".Normal":                CmpDiffviewDifflineNormal,
-	cfDiffView + ".CommitAuthor":          CmpDiffviewDifflineDiffCommitAuthor,
-	cfDiffView + ".CommitAuthorDate":      CmpDiffviewDifflineDiffCommitAuthorDate,
-	cfDiffView + ".CommitCommitter":       CmpDiffviewDifflineDiffCommitCommitter,
-	cfDiffView + ".CommitCommitterDate":   CmpDiffviewDifflineDiffCommitCommitterDate,
-	cfDiffView + ".CommitMessage":         CmpDiffviewDifflineDiffCommitMessage,
-	cfDiffView + ".StatsFile":             CmpDiffviewDifflineDiffStatsFile,
-	cfDiffView + ".GitDiffHeader":         CmpDiffviewDifflineGitDiffHeader,
-	cfDiffView + ".GitDiffExtendedHeader": CmpDiffviewDifflineGitDiffExtendedHeader,
-	cfDiffView + ".UnifiedDiffHeader":     CmpDiffviewDifflineUnifiedDiffHeader,
-	cfDiffView + ".HunkStart":             CmpDiffviewDifflineHunkStart,
-	cfDiffView + ".HunkHeader":            CmpDiffviewDifflineHunkHeader,
-	cfDiffView + ".AddedLine":             CmpDiffviewDifflineLineAdded,
-	cfDiffView + ".RemovedLine":           CmpDiffviewDifflineLineRemoved,
+	cfDiffView + ".Title":                   CmpDiffviewTitle,
+	cfDiffView + ".Footer":                  CmpDiffviewFooter,
+	cfDiffView + ".Normal":                  CmpDiffviewDifflineNormal,
+	cfDiffView + ".CommitAuthor":            CmpDiffviewDifflineDiffCommitAuthor,
+	cfDiffView + ".CommitAuthorDate":        CmpDiffviewDifflineDiffCommitAuthorDate,
+	cfDiffView + ".CommitCommitter":         CmpDiffviewDifflineDiffCommitCommitter,
+	cfDiffView + ".CommitCommitterDate":     CmpDiffviewDifflineDiffCommitCommitterDate,
+	cfDiffView + ".CommitMessage":           CmpDiffviewDifflineDiffCommitMessage,
+	cfDiffView + ".StatsFile":               CmpDiffviewDifflineDiffStatsFile,
+	cfDiffView + ".GitDiffHeader":           CmpDiffviewDifflineGitDiffHeader,
+	cfDiffView + ".GitDiffExtendedHeader":   CmpDiffviewDifflineGitDiffExtendedHeader,
+	cfDiffView + ".UnifiedDiffHeader":       CmpDiffviewDifflineUnifiedDiffHeader,
+	cfDiffView + ".HunkStart":               CmpDiffviewDifflineHunkStart,
+	cfDiffView + ".HunkHeader":              CmpDiffviewDifflineHunkHeader,
+	cfDiffView + ".AddedLine":               CmpDiffviewDifflineLineAdded,
+	cfDiffView + ".RemovedLine":             CmpDiffviewDifflineLineRemoved,
+	cfDiffView + ".FancySeparator":          CmpDiffviewFancyDiffLineSeparator,
+	cfDiffView + ".FancyFile":               CmpDiffviewFancyDiffLineFile,
+	cfDiffView + ".FancyLineAdded":          CmpDiffviewFancyDifflineLineAdded,
+	cfDiffView + ".FancyLineRemoved":        CmpDiffviewFancyDifflineLineRemoved,
+	cfDiffView + ".FancyLineAddedChange":    CmpDiffviewFancyDifflineLineAddedChange,
+	cfDiffView + ".FancyLineRemovedChange":  CmpDiffviewFancyDifflineLineRemovedChange,
+	cfDiffView + ".FancyEmptyLineAdded":     CmpDiffviewFancyDifflineEmptyLineAdded,
+	cfDiffView + ".FancyEmptyLineRemoved":   CmpDiffviewFancyDifflineEmptyLineRemoved,
+	cfDiffView + ".FancyTrailingWhitespace": CmpDiffviewFancyDifflineTrailingWhitespace,
 
 	cfGitStatusView + ".Message":         CmpGitStatusMessage,
 	cfGitStatusView + ".StagedTitle":     CmpGitStatusStagedTitle,
@@ -395,6 +407,11 @@ func NewConfiguration(keyBindings KeyBindings, channels Channels, variables GRVV
 			validator:    &defaultViewValidator{config: config},
 			description:  "Command to generate a custom default view on start up",
 		},
+		CfDiffDisplay: {
+			defaultValue: cfDiffDisplayDefaultValue,
+			validator:    &diffDisplayValidator{},
+			description:  "Diff display format",
+		},
 	}
 
 	for _, configVariable := range config.configVariables {
@@ -1216,3 +1233,15 @@ func (defaultViewValidator *defaultViewValidator) validate(value string) (proces
 
 	return
 }
+
+type diffDisplayValidator struct{}
+
+func (diffDisplayValidator *diffDisplayValidator) validate(value string) (processedValue interface{}, err error) {
+	if IsValidDiffProcessorName(value) {
+		processedValue = value
+	} else {
+		err = fmt.Errorf("Invalid %v value %v", CfDiffDisplay, value)
+	}
+
+	return
+}
diff --git a/cmd/grv/diff_view.go b/cmd/grv/diff_view.go
index b15243b..3590a54 100644
--- a/cmd/grv/diff_view.go
+++ b/cmd/grv/diff_view.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
+	"regexp"
 	"strings"
 	"sync"
 
@@ -23,9 +24,19 @@ const (
 	dltDiffCommitCommitterDate
 	dltDiffCommitMessage
 	dltDiffStatsFile
-	dltGitDiffHeader
-	dltGitDiffExtendedHeader
-	dltUnifiedDiffHeader
+	dltDiffStatsSummary
+	dltGitDiffHeaderDiff
+	dltGitDiffHeaderIndex
+	dltGitDiffHeaderNewFile
+	dltGitDiffHeaderOldFile
+	dltGitDiffHeaderNewMode
+	dltGitDiffHeaderOldMode
+	dltGitDiffHeaderNewFileMode
+	dltGitDiffHeaderDeletedFileMode
+	dltGitDiffHeaderSimilarityIndex
+	dltGitDiffHeaderRenameFrom
+	dltGitDiffHeaderRenameTo
+	dltGitDiffHeaderBinaryFile
 	dltHunkStart
 	dltLineAdded
 	dltLineRemoved
@@ -36,8 +47,11 @@ const (
 	dvDiffLoadRequestChannelSize = 100
 )
 
+var diffStatsSummaryRegex = regexp.MustCompile(`^\d+\sfiles?\schanged,`)
+
 type diffLineSection struct {
 	text             string
+	char             AcsChar
 	themeComponentID ThemeComponentID
 }
 
@@ -82,8 +96,10 @@ func newSectionedDiffLineData(sections []*diffLineSection, lineType diffLineType
 }
 
 type diffLines struct {
-	lines   []*diffLineData
-	viewPos ViewPos
+	rawLines []*diffLineData
+	lines    []*diffLineData
+	diffType diffProcessorType
+	viewPos  ViewPos
 }
 
 type diffLoadRequest interface {
@@ -117,6 +133,40 @@ func (stageDiffLoadRequest *stageDiffLoadRequest) diffID() diffID {
 
 type diffID string
 
+type diffProcessor interface {
+	processDiff([]*diffLineData) ([]*diffLineData, error)
+}
+
+type gitDiffProcessor struct{}
+
+func (gitDiffProcessor *gitDiffProcessor) processDiff(lines []*diffLineData) ([]*diffLineData, error) {
+	return lines, nil
+}
+
+type diffProcessorType int
+
+const (
+	dptGit diffProcessorType = iota
+	dptFancy
+)
+
+var diffProcessorNames = map[string]diffProcessorType{
+	"git":   dptGit,
+	"fancy": dptFancy,
+}
+
+var diffProcessors = map[diffProcessorType]diffProcessor{
+	dptGit:   &gitDiffProcessor{},
+	dptFancy: &fancyDiffProcessor{},
+}
+
+// IsValidDiffProcessorName returns true if there exists a diff processor with the
+// specified name
+func IsValidDiffProcessorName(diffProcessorName string) (isValid bool) {
+	_, isValid = diffProcessorNames[diffProcessorName]
+	return
+}
+
 // DiffView contains all state for the diff view
 type DiffView struct {
 	*AbstractWindowView
@@ -165,6 +215,8 @@ func (diffView *DiffView) Initialise() (err error) {
 	diffView.waitGroup.Add(1)
 	go diffView.processDiffLoadRequests()
 
+	diffView.config.AddOnChangeListener(CfDiffDisplay, diffView)
+
 	return
 }
 
@@ -217,7 +269,11 @@ func (diffView *DiffView) Render(win RenderWindow) (err error) {
 
 		lineBuilder.Append(" ")
 		for _, section := range diffLine.sections {
-			lineBuilder.AppendWithStyle(section.themeComponentID, section.text)
+			if section.char != 0 {
+				lineBuilder.AppendACSChar(section.char, section.themeComponentID)
+			} else {
+				lineBuilder.AppendWithStyle(section.themeComponentID, section.text)
+			}
 		}
 
 		lineIndex++
@@ -289,11 +345,7 @@ func (diffView *DiffView) OnCommitSelected(commit *Commit) (err error) {
 	diffView.lock.Lock()
 	diffView.lastRequestedDiff = diffID
 
-	if diffLines, ok := diffView.diffs[diffID]; ok {
-		diffView.activeDiff = diffID
-		diffView.activeViewPos = diffLines.viewPos
-		diffView.setVariables()
-		diffView.channels.UpdateDisplay()
+	if diffView.switchToDiffIfExists(diffID) {
 		diffView.lock.Unlock()
 		return
 	}
@@ -307,6 +359,32 @@ func (diffView *DiffView) OnCommitSelected(commit *Commit) (err error) {
 	return
 }
 
+func (diffView *DiffView) switchToDiffIfExists(diffID diffID) (exists bool) {
+	diffLines, exists := diffView.diffs[diffID]
+	if exists {
+		if diffLines.diffType != diffView.currentDiffProcessorType() {
+			diffProcessor, diffType := diffView.currentDiffProcessor()
+			lines, err := diffProcessor.processDiff(diffLines.rawLines)
+
+			if err != nil {
+				log.Errorf("Failed to convert diff to format %v: %v", diffType, err)
+				diffLines.diffType = dptGit
+				diffLines.lines = diffLines.rawLines
+			} else {
+				diffLines.diffType = diffType
+				diffLines.lines = lines
+			}
+		}
+
+		diffView.activeDiff = diffID
+		diffView.activeViewPos = diffLines.viewPos
+		diffView.setVariables()
+		diffView.channels.UpdateDisplay()
+	}
+
+	return
+}
+
 // OnFileSelected loads/fetches the diff for the selected file and refreshes the display
 func (diffView *DiffView) OnFileSelected(statusType StatusType, filePath string) {
 	log.Debugf("DiffView loading diff for file %v", filePath)
@@ -454,9 +532,19 @@ func (diffView *DiffView) storeDiff(diffID diffID, lines []*diffLineData) {
 	diffView.lock.Lock()
 	defer diffView.lock.Unlock()
 
+	rawLines := lines
+	diffProcessor, diffType := diffView.currentDiffProcessor()
+	lines, err := diffProcessor.processDiff(lines)
+	if err != nil {
+		log.Errorf("Failed to convert diff to format %v: %v", diffType, err)
+		lines = rawLines
+	}
+
 	diffLines := &diffLines{
-		lines:   lines,
-		viewPos: NewViewPosition(),
+		rawLines: rawLines,
+		lines:    lines,
+		diffType: diffType,
+		viewPos:  NewViewPosition(),
 	}
 
 	diffView.diffs[diffID] = diffLines
@@ -472,6 +560,20 @@ func (diffView *DiffView) storeDiff(diffID diffID, lines []*diffLineData) {
 	return
 }
 
+func (diffView *DiffView) currentDiffProcessorType() diffProcessorType {
+	diffDisplay := diffView.config.GetString(CfDiffDisplay)
+	if diffType, exists := diffProcessorNames[diffDisplay]; exists {
+		return diffType
+	}
+
+	return dptGit
+}
+
+func (diffView *DiffView) currentDiffProcessor() (diffProcessor, diffProcessorType) {
+	diffType := diffView.currentDiffProcessorType()
+	return diffProcessors[diffType], diffType
+}
+
 func (diffView *DiffView) generateDiffLinesForCommit(commit *Commit) (lines []*diffLineData, err error) {
 	author := commit.commit.Author()
 	committer := commit.commit.Committer()
@@ -533,9 +635,14 @@ func (diffView *DiffView) generateDiffLinesForDiff(diff *Diff) (lines []*diffLin
 	for scanner.Scan() {
 		line := scanner.Text()
 
+		if diffStatsSummaryRegex.MatchString(line) {
+			lines = append(lines, newDiffLineData(line, dltDiffStatsSummary, CmpDiffviewDifflineNormal))
+			continue
+		}
+
 		filePart, changePart, err := diffView.splitDiffStatsFileLine(line)
 		if err != nil {
-			lines = append(lines, newNormalDiffLineData(line))
+			log.Warnf("Diff stats line in unexpected format: %v - %v", line, err)
 			continue
 		}
 
@@ -546,23 +653,30 @@ func (diffView *DiffView) generateDiffLinesForDiff(diff *Diff) (lines []*diffLin
 			},
 		}
 
-		for _, char := range changePart {
-			switch char {
-			case '+':
-				sections = append(sections, &diffLineSection{
-					text:             "+",
-					themeComponentID: CmpDiffviewDifflineLineAdded,
-				})
-			case '-':
-				sections = append(sections, &diffLineSection{
-					text:             "-",
-					themeComponentID: CmpDiffviewDifflineLineRemoved,
-				})
-			default:
-				sections = append(sections, &diffLineSection{
-					text:             fmt.Sprintf("%c", char),
-					themeComponentID: CmpDiffviewDifflineNormal,
-				})
+		if strings.Contains(changePart, " -> ") {
+			sections = append(sections, &diffLineSection{
+				text:             changePart,
+				themeComponentID: CmpDiffviewDifflineNormal,
+			})
+		} else {
+			for _, char := range changePart {
+				switch char {
+				case '+':
+					sections = append(sections, &diffLineSection{
+						text:             "+",
+						themeComponentID: CmpDiffviewDifflineLineAdded,
+					})
+				case '-':
+					sections = append(sections, &diffLineSection{
+						text:             "-",
+						themeComponentID: CmpDiffviewDifflineLineRemoved,
+					})
+				default:
+					sections = append(sections, &diffLineSection{
+						text:             fmt.Sprintf("%c", char),
+						themeComponentID: CmpDiffviewDifflineNormal,
+					})
+				}
 			}
 		}
 
@@ -581,11 +695,29 @@ func (diffView *DiffView) generateDiffLinesForDiff(diff *Diff) (lines []*diffLin
 
 		switch {
 		case strings.HasPrefix(line, "diff --git"):
-			diffLine = newDiffLineData(line, dltGitDiffHeader, CmpDiffviewDifflineGitDiffHeader)
+			diffLine = newDiffLineData(line, dltGitDiffHeaderDiff, CmpDiffviewDifflineGitDiffHeader)
+		case strings.HasPrefix(line, "new mode"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderNewMode, CmpDiffviewDifflineNormal)
+		case strings.HasPrefix(line, "old mode"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderOldMode, CmpDiffviewDifflineNormal)
+		case strings.HasPrefix(line, "new file mode"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderNewFileMode, CmpDiffviewDifflineNormal)
+		case strings.HasPrefix(line, "deleted file mode"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderDeletedFileMode, CmpDiffviewDifflineNormal)
+		case strings.HasPrefix(line, "similarity index"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderSimilarityIndex, CmpDiffviewDifflineNormal)
+		case strings.HasPrefix(line, "rename from"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderRenameFrom, CmpDiffviewDifflineNormal)
+		case strings.HasPrefix(line, "rename to"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderRenameTo, CmpDiffviewDifflineNormal)
+		case strings.HasPrefix(line, "Binary files"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderBinaryFile, CmpDiffviewDifflineNormal)
 		case strings.HasPrefix(line, "index"):
-			diffLine = newDiffLineData(line, dltGitDiffExtendedHeader, CmpDiffviewDifflineGitDiffExtendedHeader)
-		case strings.HasPrefix(line, "--- ") || strings.HasPrefix(line, "+++ "):
-			diffLine = newDiffLineData(line, dltUnifiedDiffHeader, CmpDiffviewDifflineUnifiedDiffHeader)
+			diffLine = newDiffLineData(line, dltGitDiffHeaderIndex, CmpDiffviewDifflineGitDiffExtendedHeader)
+		case strings.HasPrefix(line, "+++"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderNewFile, CmpDiffviewDifflineUnifiedDiffHeader)
+		case strings.HasPrefix(line, "---"):
+			diffLine = newDiffLineData(line, dltGitDiffHeaderOldFile, CmpDiffviewDifflineUnifiedDiffHeader)
 		case strings.HasPrefix(line, "@@"):
 			if lineParts := strings.SplitAfter(line, "@@"); len(lineParts) != 3 {
 				log.Warnf("Unable to handle hunk header line: %v", line)
@@ -627,6 +759,16 @@ func (diffView *DiffView) viewPos() ViewPos {
 	return diffView.activeViewPos
 }
 
+func (diffView *DiffView) onConfigVariableChange(configVariable ConfigVariable) {
+	diffView.lock.Lock()
+	defer diffView.lock.Unlock()
+
+	switch configVariable {
+	case CfDiffDisplay:
+		diffView.switchToDiffIfExists(diffView.activeDiff)
+	}
+}
+
 // HandleAction checks if the diff view supports the provided action and executes it if so
 func (diffView *DiffView) HandleAction(action Action) (err error) {
 	log.Debugf("DiffView handling action %v", action)
@@ -749,12 +891,11 @@ func selectDiffLine(diffView *DiffView, action Action) (err error) {
 	}
 
 	filePart = strings.TrimRight(filePart, " ")
-	pattern := fmt.Sprintf("diff --git a/%v b/%v", filePart, filePart)
 
 	for lineIndex++; lineIndex < uint(len(diffLines.lines)); lineIndex++ {
 		diffLine = diffLines.lines[lineIndex]
 
-		if strings.HasPrefix(diffLine.line, pattern) {
+		if diffLine.lineType == dltGitDiffHeaderDiff && strings.Contains(diffLine.line, filePart) {
 			break
 		}
 	}
diff --git a/cmd/grv/fancy_diff_view.go b/cmd/grv/fancy_diff_view.go
new file mode 100644
index 0000000..77ca83f
--- /dev/null
+++ b/cmd/grv/fancy_diff_view.go
@@ -0,0 +1,376 @@
+package main
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+	"unicode"
+)
+
+const (
+	fileAdded    = "added"
+	fileModified = "modified"
+	fileDeleted  = "deleted"
+	fileRenamed  = "renamed"
+)
+
+var diffHeaderRegex = regexp.MustCompile(`^diff --git \w\/(.+?)(\s|\x00|$)`)
+var hunkStartRegex = regexp.MustCompile(`@@ (-\d+(,\d+)?)? \+(\d+)(,\d+)? @@`)
+var oldNewFileRegex = regexp.MustCompile(`^(\+\+\+|---)\s(\w\/)?`)
+var oldNewModeRegex = regexp.MustCompile(`^(old|new)\smode\s`)
+var renameFromToRegex = regexp.MustCompile(`^rename\s(from|to)\s`)
+var trailingSpaceRegex = regexp.MustCompile(`\s+$`)
+
+var separatorDiffLine *diffLineData
+
+var emptyLineAdded = newDiffLineData(" ", dltLineAdded, CmpDiffviewFancyDifflineEmptyLineAdded)
+var emptyLineRemoved = newDiffLineData(" ", dltLineRemoved, CmpDiffviewFancyDifflineEmptyLineRemoved)
+
+var fileStatusStyling = map[string]ThemeComponentID{
+	fileAdded:    CmpDiffviewFancyDifflineLineAddedChange,
+	fileModified: CmpDiffviewFancyDiffLineFile,
+	fileDeleted:  CmpDiffviewFancyDifflineLineRemovedChange,
+}
+
+func init() {
+	var sections []*diffLineSection
+	for i := 0; i < 1000; i++ {
+		sections = append(sections, &diffLineSection{
+			char:             AcsHline,
+			themeComponentID: CmpDiffviewFancyDiffLineSeparator,
+		})
+	}
+
+	separatorDiffLine = newSectionedDiffLineData(sections, dltNormal)
+}
+
+type fancyDiffProcessor struct{}
+
+func (fancyDiffProcessor *fancyDiffProcessor) processDiff(lines []*diffLineData) (processedLines []*diffLineData, err error) {
+	var generatedLines []*diffLineData
+	var currentFile string
+
+	for lineIndex, line := range lines {
+		switch line.lineType {
+		case dltGitDiffHeaderDiff:
+			if generatedLines, currentFile, err = fancyDiffProcessor.processDiffHeader(lines, lineIndex); err != nil {
+				return
+			}
+
+			processedLines = append(processedLines, generatedLines...)
+		case dltGitDiffHeaderIndex,
+			dltGitDiffHeaderNewFile,
+			dltGitDiffHeaderOldFile,
+			dltGitDiffHeaderNewMode,
+			dltGitDiffHeaderOldMode,
+			dltGitDiffHeaderNewFileMode,
+			dltGitDiffHeaderDeletedFileMode,
+			dltGitDiffHeaderSimilarityIndex,
+			dltGitDiffHeaderRenameFrom,
+			dltGitDiffHeaderRenameTo,
+			dltGitDiffHeaderBinaryFile:
+		case dltHunkStart:
+			if generatedLines, err = fancyDiffProcessor.processHunkStart(lines, lineIndex, currentFile); err != nil {
+				return
+			}
+
+			processedLines = append(processedLines, generatedLines...)
+		case dltLineAdded:
+			processedLines = append(processedLines, newDiffLineData(trimFirstCharacter(line.line), line.lineType, CmpDiffviewFancyDifflineLineAdded))
+		case dltLineRemoved:
+			processedLines = append(processedLines, newDiffLineData(trimFirstCharacter(line.line), line.lineType, CmpDiffviewFancyDifflineLineRemoved))
+		case dltNormal:
+			processedLines = append(processedLines, newDiffLineData(trimFirstCharacter(line.line), line.lineType, line.sections[0].themeComponentID))
+		default:
+			processedLines = append(processedLines, line)
+		}
+	}
+
+	fancyDiffProcessor.highlightChanges(processedLines)
+
+	return
+}
+
+func (fancyDiffProcessor *fancyDiffProcessor) processDiffHeader(lines []*diffLineData, diffHeaderIndex int) (generatedLines []*diffLineData, currentFile string, err error) {
+	var oldFile, newFile, oldFileMode, newFileMode string
+	var isBinary bool
+	status := fileModified
+
+OuterLoop:
+	for lineIndex := diffHeaderIndex; lineIndex < len(lines); lineIndex++ {
+		line := lines[lineIndex]
+
+		switch line.lineType {
+		case dltGitDiffHeaderDiff:
+			matches := diffHeaderRegex.FindStringSubmatch(line.line)
+			if len(matches) != 3 {
+				err = fmt.Errorf("line: \"%v\" doesn't have expected diff header format: %v", line.line, matches)
+				return
+			}
+
+			newFile = matches[1]
+		case dltGitDiffHeaderNewFile:
+			newFile = oldNewFileRegex.ReplaceAllString(line.line, "")
+		case dltGitDiffHeaderOldFile:
+			oldFile = oldNewFileRegex.ReplaceAllString(line.line, "")
+		case dltGitDiffHeaderNewMode:
+			newFileMode = oldNewModeRegex.ReplaceAllString(line.line, "")
+		case dltGitDiffHeaderOldMode:
+			oldFileMode = oldNewModeRegex.ReplaceAllString(line.line, "")
+		case dltGitDiffHeaderNewFileMode:
+			status = fileAdded
+		case dltGitDiffHeaderDeletedFileMode:
+			status = fileDeleted
+		case dltGitDiffHeaderSimilarityIndex:
+			status = fileRenamed
+		case dltGitDiffHeaderRenameFrom:
+			oldFile = renameFromToRegex.ReplaceAllString(line.line, "")
+		case dltGitDiffHeaderRenameTo:
+			newFile = renameFromToRegex.ReplaceAllString(line.line, "")
+		case dltGitDiffHeaderBinaryFile:
+			isBinary = true
+		case dltGitDiffHeaderIndex:
+		default:
+			break OuterLoop
+		}
+	}
+
+	if newFile == "" {
+		err = fmt.Errorf("Unable to determine new file from diff headers")
+		return
+	}
+
+	currentFile = newFile
+	if status == fileDeleted && oldFile != "" {
+		currentFile = oldFile
+	}
+
+	sections := []*diffLineSection{}
+
+	if status == fileRenamed {
+		commonPrefix, commonSuffix := determineCommonFixes(oldFile, newFile)
+		oldFileLine := newDiffLineData(oldFile, dltNormal, CmpDiffviewFancyDiffLineFile)
+		newFileLine := newDiffLineData(newFile, dltNormal, CmpDiffviewFancyDiffLineFile)
+		highlightLine(oldFileLine, commonPrefix, commonSuffix, CmpDiffviewFancyDifflineLineRemovedChange)
+		highlightLine(newFileLine, commonPrefix, commonSuffix, CmpDiffviewFancyDifflineLineAddedChange)
+
+		sections = append(sections, &diffLineSection{
+			text:             fmt.Sprintf("%v: ", status),
+			themeComponentID: CmpDiffviewFancyDiffLineFile,
+		})
+		sections = append(sections, oldFileLine.sections...)
+		sections = append(sections, &diffLineSection{
+			text:             " to ",
+			themeComponentID: CmpDiffviewFancyDiffLineFile,
+		})
+		sections = append(sections, newFileLine.sections...)
+	} else {
+		sections = append(sections,
+			&diffLineSection{
+				text:             fmt.Sprintf("%v: ", status),
+				themeComponentID: CmpDiffviewFancyDiffLineFile,
+			},
+			&diffLineSection{
+				text:             currentFile,
+				themeComponentID: fileStatusStyling[status],
+			})
+	}
+
+	if isBinary {
+		sections = append(sections, &diffLineSection{
+			text:             " (binary)",
+			themeComponentID: CmpDiffviewFancyDiffLineFile,
+		})
+	}
+
+	if oldFileMode != "" && newFileMode != "" {
+		modeChange := fmt.Sprintf("%v changed file mode from %v to %v", currentFile, oldFileMode, newFileMode)
+		generatedLines = append(generatedLines, newDiffLineData(modeChange, dltNormal, CmpDiffviewDifflineNormal))
+	}
+
+	generatedLines = append(generatedLines,
+		separatorDiffLine,
+		newSectionedDiffLineData(sections, dltGitDiffHeaderDiff),
+		separatorDiffLine,
+	)
+
+	return
+}
+
+func (fancyDiffProcessor *fancyDiffProcessor) processHunkStart(lines []*diffLineData, hunkStartIndex int, currentFile string) (generatedLines []*diffLineData, err error) {
+	hunkLine := lines[hunkStartIndex]
+	matches := hunkStartRegex.FindStringSubmatch(hunkLine.line)
+	if len(matches) != 5 {
+		err = fmt.Errorf("Hunk start line didn't match expected format, matches: %v", matches)
+		return
+	}
+
+	hunkStartLineNumber, err := strconv.Atoi(matches[3])
+	if err != nil {
+		err = fmt.Errorf("Failed to parse hunk start line number %v: %v", matches[3], err)
+		return
+	}
+
+	var index int
+	for index = hunkStartIndex + 1; index < len(lines); index++ {
+		if lines[index].lineType == dltLineAdded || lines[index].lineType == dltLineRemoved {
+			break
+		}
+
+		hunkStartLineNumber++
+	}
+
+	if index >= len(lines) {
+		err = fmt.Errorf("Failed to find changes in hunk")
+		return
+	}
+
+	hunkStartLineNumber = MaxInt(hunkStartLineNumber, 1)
+
+	hunkParts := strings.Split(hunkLine.line, " @@")
+	if len(hunkParts) != 2 {
+		err = fmt.Errorf("Expected 2 hunk parts but got: %v", hunkParts)
+		return
+	}
+
+	sections := []*diffLineSection{
+		&diffLineSection{
+			text:             fmt.Sprintf("@ %v:%v @", currentFile, hunkStartLineNumber),
+			themeComponentID: CmpDiffviewDifflineHunkStart,
+		},
+		&diffLineSection{
+			text:             hunkParts[1],
+			themeComponentID: CmpDiffviewDifflineHunkHeader,
+		},
+	}
+
+	generatedLines = append(generatedLines, newSectionedDiffLineData(sections, dltHunkStart))
+
+	return
+}
+
+func (fancyDiffProcessor *fancyDiffProcessor) highlightChanges(lines []*diffLineData) {
+	for lineIndex := 0; lineIndex < len(lines); lineIndex++ {
+		if lines[lineIndex].lineType == dltLineRemoved {
+			linesRemoved := []*diffLineData{lines[lineIndex]}
+			for lineIndex++; lineIndex < len(lines) && lines[lineIndex].lineType == dltLineRemoved; lineIndex++ {
+				linesRemoved = append(linesRemoved, lines[lineIndex])
+			}
+
+			var linesAdded []*diffLineData
+			for ; lineIndex < len(lines) && lines[lineIndex].lineType == dltLineAdded; lineIndex++ {
+				linesAdded = append(linesAdded, lines[lineIndex])
+			}
+			lineIndex--
+
+			if len(linesRemoved) == len(linesAdded) {
+				for i := 0; i < len(linesRemoved); i++ {
+					commonPrefix, commonSuffix := determineCommonFixes(linesRemoved[i].line, linesAdded[i].line)
+					if commonPrefix > 0 || commonSuffix > 0 {
+						highlightLine(linesRemoved[i], commonPrefix, commonSuffix, CmpDiffviewFancyDifflineLineRemovedChange)
+						highlightLine(linesAdded[i], commonPrefix, commonSuffix, CmpDiffviewFancyDifflineLineAddedChange)
+					}
+				}
+			}
+		}
+	}
+
+	for lineIndex := 0; lineIndex < len(lines); lineIndex++ {
+		line := lines[lineIndex]
+		if line.lineType == dltLineAdded {
+			lines[lineIndex] = processWhitespaceLine(line, emptyLineAdded)
+		} else if line.lineType == dltLineRemoved {
+			lines[lineIndex] = processWhitespaceLine(line, emptyLineRemoved)
+		}
+	}
+}
+
+func processWhitespaceLine(line *diffLineData, emptyLine *diffLineData) *diffLineData {
+	if line.line == "" {
+		return emptyLine
+	} else if matchIndexes := trailingSpaceRegex.FindStringIndex(line.line); len(matchIndexes) == 2 {
+		section := line.sections[len(line.sections)-1]
+		matchLength := MinInt(len(section.text), matchIndexes[1]-matchIndexes[0])
+
+		if matchLength >= len(section.text) {
+			section.themeComponentID = CmpDiffviewFancyDifflineTrailingWhitespace
+		} else {
+			section.text = section.text[:len(section.text)-matchLength]
+			line.sections = append(line.sections, &diffLineSection{
+				text:             line.line[len(line.line)-matchLength:],
+				themeComponentID: CmpDiffviewFancyDifflineTrailingWhitespace,
+			})
+		}
+	}
+
+	return line
+}
+
+func determineCommonFixes(lineRemoved, lineAdded string) (commonPrefix, commonSuffix int) {
+	removedChars := []rune(lineRemoved)
+	addedChars := []rune(lineAdded)
+	charLength := MinInt(len(removedChars), len(addedChars))
+
+	for ; commonPrefix < charLength && removedChars[commonPrefix] == addedChars[commonPrefix]; commonPrefix++ {
+	}
+
+	for i, j := len(addedChars)-1, len(removedChars)-1; i > -1 && j > -1 && addedChars[i] == removedChars[j]; i, j = i-1, j-1 {
+		commonSuffix++
+	}
+
+	return
+}
+
+func highlightLine(line *diffLineData, commonPrefix, commonSuffix int, highlightThemeComponentID ThemeComponentID) {
+	lineString := []rune(line.line)
+	lineLength := len(lineString)
+	if commonPrefix+commonSuffix > lineLength {
+		return
+	}
+
+	var commonPrefixString, commonSuffixString string
+	if commonPrefix > 0 {
+		commonPrefixString = string(lineString[:commonPrefix])
+	}
+	if commonSuffix > 0 {
+		commonSuffixString = string(lineString[lineLength-commonSuffix:])
+	}
+
+	if !(commonPrefix == 0 || strings.TrimLeftFunc(commonPrefixString, unicode.IsSpace) != "" &&
+		commonSuffix == 0 || strings.TrimRightFunc(commonSuffixString, unicode.IsSpace) != "") {
+		return
+	}
+
+	sections := []*diffLineSection{}
+	themeComponentID := line.sections[0].themeComponentID
+
+	if commonPrefixString != "" {
+		sections = append(sections, &diffLineSection{
+			text:             commonPrefixString,
+			themeComponentID: themeComponentID,
+		})
+	}
+
+	sections = append(sections, &diffLineSection{
+		text:             string(lineString[commonPrefix : lineLength-commonSuffix]),
+		themeComponentID: highlightThemeComponentID,
+	})
+
+	if commonSuffixString != "" {
+		sections = append(sections, &diffLineSection{
+			text:             commonSuffixString,
+			themeComponentID: themeComponentID,
+		})
+	}
+
+	line.sections = sections
+}
+
+func trimFirstCharacter(line string) string {
+	if line != "" {
+		return line[1:]
+	}
+
+	return line
+}
diff --git a/cmd/grv/theme.go b/cmd/grv/theme.go
index 8716f67..ce0d149 100644
--- a/cmd/grv/theme.go
+++ b/cmd/grv/theme.go
@@ -61,6 +61,15 @@ const (
 	CmpDiffviewDifflineHunkHeader
 	CmpDiffviewDifflineLineAdded
 	CmpDiffviewDifflineLineRemoved
+	CmpDiffviewFancyDiffLineSeparator
+	CmpDiffviewFancyDiffLineFile
+	CmpDiffviewFancyDifflineLineAdded
+	CmpDiffviewFancyDifflineLineRemoved
+	CmpDiffviewFancyDifflineLineAddedChange
+	CmpDiffviewFancyDifflineLineRemovedChange
+	CmpDiffviewFancyDifflineEmptyLineAdded
+	CmpDiffviewFancyDifflineEmptyLineRemoved
+	CmpDiffviewFancyDifflineTrailingWhitespace
 
 	CmpGitStatusMessage
 	CmpGitStatusStagedTitle
diff --git a/cmd/grv/themes.go b/cmd/grv/themes.go
index 5899795..48db135 100644
--- a/cmd/grv/themes.go
+++ b/cmd/grv/themes.go
@@ -164,6 +164,49 @@ func NewClassicTheme() MutableTheme {
 				bgcolor: NewSystemColor(ColorNone),
 				fgcolor: NewSystemColor(ColorRed),
 			},
+			CmpDiffviewFancyDiffLineSeparator: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorYellow),
+			},
+			CmpDiffviewFancyDiffLineFile: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorYellow),
+			},
+			CmpDiffviewFancyDifflineLineAdded: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorGreen),
+				style:   ThemeStyle{styleTypes: TstBold},
+			},
+			CmpDiffviewFancyDifflineLineRemoved: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorRed),
+				style:   ThemeStyle{styleTypes: TstBold},
+			},
+			CmpDiffviewFancyDifflineLineAddedChange: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorGreen),
+				style:   ThemeStyle{styleTypes: TstBold | TstReverse},
+			},
+			CmpDiffviewFancyDifflineLineRemovedChange: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorRed),
+				style:   ThemeStyle{styleTypes: TstBold | TstReverse},
+			},
+			CmpDiffviewFancyDifflineEmptyLineAdded: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorGreen),
+				style:   ThemeStyle{styleTypes: TstReverse},
+			},
+			CmpDiffviewFancyDifflineEmptyLineRemoved: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorRed),
+				style:   ThemeStyle{styleTypes: TstReverse},
+			},
+			CmpDiffviewFancyDifflineTrailingWhitespace: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewSystemColor(ColorRed),
+				style:   ThemeStyle{styleTypes: TstReverse},
+			},
 			CmpRefviewTitle: {
 				bgcolor: NewSystemColor(ColorNone),
 				fgcolor: NewSystemColor(ColorCyan),
@@ -605,6 +648,49 @@ func NewSolarizedTheme() MutableTheme {
 				bgcolor: NewSystemColor(ColorNone),
 				fgcolor: NewColorNumber(solarizedRed),
 			},
+			CmpDiffviewFancyDiffLineSeparator: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewColorNumber(solarizedYellow),
+			},
+			CmpDiffviewFancyDiffLineFile: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewColorNumber(solarizedYellow),
+			},
+			CmpDiffviewFancyDifflineLineAdded: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewColorNumber(solarizedGreen),
+				style:   ThemeStyle{styleTypes: TstBold},
+			},
+			CmpDiffviewFancyDifflineLineRemoved: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewColorNumber(solarizedRed),
+				style:   ThemeStyle{styleTypes: TstBold},
+			},
+			CmpDiffviewFancyDifflineLineAddedChange: {
+				bgcolor: NewColorNumber(22),
+				fgcolor: NewColorNumber(10),
+				style:   ThemeStyle{styleTypes: TstBold},
+			},
+			CmpDiffviewFancyDifflineLineRemovedChange: {
+				bgcolor: NewColorNumber(52),
+				fgcolor: NewColorNumber(9),
+				style:   ThemeStyle{styleTypes: TstBold},
+			},
+			CmpDiffviewFancyDifflineEmptyLineAdded: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewColorNumber(solarizedGreen),
+				style:   ThemeStyle{styleTypes: TstReverse},
+			},
+			CmpDiffviewFancyDifflineEmptyLineRemoved: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewColorNumber(solarizedRed),
+				style:   ThemeStyle{styleTypes: TstReverse},
+			},
+			CmpDiffviewFancyDifflineTrailingWhitespace: {
+				bgcolor: NewSystemColor(ColorNone),
+				fgcolor: NewColorNumber(solarizedRed),
+				style:   ThemeStyle{styleTypes: TstReverse},
+			},
 			CmpRefviewTitle: {
 				bgcolor: NewSystemColor(ColorNone),
 				fgcolor: NewColorNumber(solarizedCyan),
diff --git a/doc/documentation.md b/doc/documentation.md
index e4fb6e4..6ac1507 100644
--- a/doc/documentation.md
+++ b/doc/documentation.md
@@ -209,6 +209,7 @@ They are specified using the set command in the grvrc file or at the command pro
  commit-limit         | string |               | Limit the number of commits loaded. Allowed values: number, date, oid or tag
  confirm-checkout     | bool   | true          | Confirm before performing git checkout                                      
  default-view         | string |               | Command to generate a custom default view on start up                       
+ diff-display         | string | fancy         | Diff display format                                                         
  git-binary-file-path | string |               | File path to git binary. Required only when git binary is not in $PATH      
  mouse                | bool   | false         | Mouse support enabled                                                       
  mouse-scroll-rows    | int    | 3             | Number of rows scrolled for each mouse event                                
@@ -596,6 +597,15 @@ DiffView.CommitAuthorDate
 DiffView.CommitCommitter
 DiffView.CommitCommitterDate
 DiffView.CommitMessage
+DiffView.FancyEmptyLineAdded
+DiffView.FancyEmptyLineRemoved
+DiffView.FancyFile
+DiffView.FancyLineAdded
+DiffView.FancyLineAddedChange
+DiffView.FancyLineRemoved
+DiffView.FancyLineRemovedChange
+DiffView.FancySeparator
+DiffView.FancyTrailingWhitespace
 DiffView.Footer
 DiffView.GitDiffExtendedHeader
 DiffView.GitDiffHeader