1 files changed, 209 insertions, 0 deletions
diff --git a/pkg/commands/patch_parser.go b/pkg/commands/patch_parser.go
new file mode 100644
index 000000000..06781c8cf
--- /dev/null
+++ b/pkg/commands/patch_parser.go
@@ -0,0 +1,209 @@
+package commands
+
+import (
+	"regexp"
+	"strings"
+
+	"github.com/fatih/color"
+	"github.com/jesseduffield/lazygit/pkg/theme"
+	"github.com/jesseduffield/lazygit/pkg/utils"
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	PATCH_HEADER = iota
+	COMMIT_SHA
+	COMMIT_DESCRIPTION
+	HUNK_HEADER
+	ADDITION
+	DELETION
+	CONTEXT
+	NEWLINE_MESSAGE
+)
+
+// the job of this file is to parse a diff, find out where the hunks begin and end, which lines are stageable, and how to find the next hunk from the current position or the next stageable line from the current position.
+
+type PatchLine struct {
+	Kind    int
+	Content string // something like '+ hello' (note the first character is not removed)
+}
+
+type PatchParser struct {
+	Log            *logrus.Entry
+	PatchLines     []*PatchLine
+	PatchHunks     []*PatchHunk
+	HunkStarts     []int
+	StageableLines []int // rename to mention we're talking about indexes
+}
+
+// NewPatchParser builds a new branch list builder
+func NewPatchParser(log *logrus.Entry, patch string) (*PatchParser, error) {
+	hunkStarts, stageableLines, patchLines, err := parsePatch(patch)
+	if err != nil {
+		return nil, err
+	}
+
+	patchHunks := GetHunksFromDiff(patch)
+
+	return &PatchParser{
+		Log:            log,
+		HunkStarts:     hunkStarts, // deprecated
+		StageableLines: stageableLines,
+		PatchLines:     patchLines,
+		PatchHunks:     patchHunks,
+	}, nil
+}
+
+// GetHunkContainingLine takes a line index and an offset and finds the hunk
+// which contains the line index, then returns the hunk considering the offset.
+// e.g. if the offset is 1 it will return the next hunk.
+func (p *PatchParser) GetHunkContainingLine(lineIndex int, offset int) *PatchHunk {
+	if len(p.PatchHunks) == 0 {
+		return nil
+	}
+
+	for index, hunk := range p.PatchHunks {
+		if lineIndex >= hunk.FirstLineIdx && lineIndex <= hunk.LastLineIdx {
+			resultIndex := index + offset
+			if resultIndex < 0 {
+				resultIndex = 0
+			} else if resultIndex > len(p.PatchHunks)-1 {
+				resultIndex = len(p.PatchHunks) - 1
+			}
+			return p.PatchHunks[resultIndex]
+		}
+	}
+
+	// if your cursor is past the last hunk, select the last hunk
+	if lineIndex > p.PatchHunks[len(p.PatchHunks)-1].LastLineIdx {
+		return p.PatchHunks[len(p.PatchHunks)-1]
+	}
+
+	// otherwise select the first
+	return p.PatchHunks[0]
+}
+
+// selected means you've got it highlighted with your cursor
+// included means the line has been included in the patch (only applicable when
+// building a patch)
+func (l *PatchLine) render(selected bool, included bool) string {
+	content := l.Content
+	if len(content) == 0 {
+		content = " " // using the space so that we can still highlight if necessary
+	}
+
+	// for hunk headers we need to start off cyan and then use white for the message
+	if l.Kind == HUNK_HEADER {
+		re := regexp.MustCompile("(@@.*?@@)(.*)")
+		match := re.FindStringSubmatch(content)
+		return coloredString(color.FgCyan, match[1], selected, included) + coloredString(theme.DefaultTextColor, match[2], selected, false)
+	}
+
+	var colorAttr color.Attribute
+	switch l.Kind {
+	case PATCH_HEADER:
+		colorAttr = color.Bold
+	case ADDITION:
+		colorAttr = color.FgGreen
+	case DELETION:
+		colorAttr = color.FgRed
+	case COMMIT_SHA:
+		colorAttr = color.FgYellow
+	default:
+		colorAttr = theme.DefaultTextColor
+	}
+
+	return coloredString(colorAttr, content, selected, included)
+}
+
+func coloredString(colorAttr color.Attribute, str string, selected bool, included bool) string {
+	var cl *color.Color
+	attributes := []color.Attribute{colorAttr}
+	if selected {
+		attributes = append(attributes, color.BgBlue)
+	}
+	cl = color.New(attributes...)
+	var clIncluded *color.Color
+	if included {
+		clIncluded = color.New(append(attributes, color.BgGreen)...)
+	} else {
+		clIncluded = color.New(attributes...)
+	}
+
+	if len(str) < 2 {
+		return utils.ColoredStringDirect(str, clIncluded)
+	}
+
+	return utils.ColoredStringDirect(str[:1], clIncluded) + utils.ColoredStringDirect(str[1:], cl)
+}
+
+func parsePatch(patch string) ([]int, []int, []*PatchLine, error) {
+	lines := strings.Split(patch, "\n")
+	hunkStarts := []int{}
+	stageableLines := []int{}
+	pastFirstHunkHeader := false
+	pastCommitDescription := true
+	patchLines := make([]*PatchLine, len(lines))
+	var lineKind int
+	var firstChar string
+	for index, line := range lines {
+		firstChar = " "
+		if len(line) > 0 {
+			firstChar = line[:1]
+		}
+		if index == 0 && strings.HasPrefix(line, "commit") {
+			lineKind = COMMIT_SHA
+			pastCommitDescription = false
+		} else if !pastCommitDescription {
+			if strings.HasPrefix(line, "diff") || strings.HasPrefix(line, "---") {
+				pastCommitDescription = true
+				lineKind = PATCH_HEADER
+			} else {
+				lineKind = COMMIT_DESCRIPTION
+			}
+		} else if firstChar == "@" {
+			pastFirstHunkHeader = true
+			hunkStarts = append(hunkStarts, index)
+			lineKind = HUNK_HEADER
+		} else if pastFirstHunkHeader {
+			switch firstChar {
+			case "-":
+				lineKind = DELETION
+				stageableLines = append(stageableLines, index)
+			case "+":
+				lineKind = ADDITION
+				stageableLines = append(stageableLines, index)
+			case "\\":
+				lineKind = NEWLINE_MESSAGE
+			case " ":
+				lineKind = CONTEXT
+			}
+		} else {
+			lineKind = PATCH_HEADER
+		}
+		patchLines[index] = &PatchLine{Kind: lineKind, Content: line}
+	}
+	return hunkStarts, stageableLines, patchLines, nil
+}
+
+// Render returns the coloured string of the diff with any selected lines highlighted
+func (p *PatchParser) Render(firstLineIndex int, lastLineIndex int, incLineIndices []int) string {
+	renderedLines := make([]string, len(p.PatchLines))
+	for index, patchLine := range p.PatchLines {
+		selected := index >= firstLineIndex && index <= lastLineIndex
+		included := utils.IncludesInt(incLineIndices, index)
+		renderedLines[index] = patchLine.render(selected, included)
+	}
+	return strings.Join(renderedLines, "\n")
+}
+
+// GetNextStageableLineIndex takes a line index and returns the line index of the next stageable line
+// note this will actually include the current index if it is stageable
+func (p *PatchParser) GetNextStageableLineIndex(currentIndex int) int {
+	for _, lineIndex := range p.StageableLines {
+		if lineIndex >= currentIndex {
+			return lineIndex
+		}
+	}
+	return p.StageableLines[len(p.StageableLines)-1]
+}