Function cutLinesFromFullFileDiff

git/api/diff.go:96–157

cutLinesFromFullFileDiff reads from r and writes to w headers and between startLine and endLine. if startLine and endLine is equal to 0 then it uses io.Copy warning: changes are possible and param endLine may not exist in the future nolint:gocognit

(w io.Writer, r io.Reader, startLine, endLine int)

//
//nolint:gocognit
func cutLinesFromFullFileDiff(w io.Writer, r io.Reader, startLine, endLine int) error {
	if startLine < 0 {
		startLine = 0
	}

	if endLine < 0 {
		endLine = 0
	}

	if startLine == 0 && endLine > 0 {
		startLine = 1
	}

	if endLine < startLine {
		endLine = 0
	}

	// no need for processing lines just copy the data
	if startLine == 0 && endLine == 0 {
		_, err := io.Copy(w, r)
		return err
	}

	linePos := 0
	start := false
	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		line := scanner.Bytes()

		if start {
			linePos++
		}

		if endLine > 0 && linePos > endLine {
			break
		}

		if linePos > 0 &&
			(startLine > 0 && linePos < startLine) {
			continue
		}

		if len(line) >= 2 && bytes.HasPrefix(line, []byte{'@', '@'}) {
			hunk, ok := parser.ParseDiffHunkHeader(string(line)) // TBD: maybe reader?
			if !ok {
				return fmt.Errorf("failed to extract lines from diff, range [%d,%d] : %w",
					startLine, endLine, ErrParseDiffHunkHeader)
			}
			line = modifyHeader(hunk, startLine, endLine)
			start = true
		}

		if _, err := w.Write(line); err != nil {
			return err
		}

		if _, err := w.Write([]byte{'\n'}); err != nil {
			return err