fix: filenames with spaces in diff scan

pkg/git/diff.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"regexp"
 	"strconv"
 	"strings"
 
@@ -28,6 +29,8 @@ type FilePatch struct {
 	Chunks Chunks
 }
 
+var pathSplitterRegexp = regexp.MustCompile(`^(([^\.]+)\.([^\s]+))\s(.+)$`)
+
 func Diff(rootDir, baseRef string) ([]FilePatch, error) {
 	var result []FilePatch
 
@@ -113,20 +116,33 @@ func parseDiff(scanner *linescanner.Scanner) ([]FilePatch, error) {
 }
 
 func parseDiffHeader(value string) (string, string, error) {
-	parts := strings.Split(value, " ")
-	fromPath, err := unquoteFilename(parts[2])
+	parts := splitPath(value, 2, 4)
+	fromPath, err := unquoteFilename(parts[0])
 	if err != nil {
 		return "", "", fmt.Errorf("error parsing header 'from' path: %w", err)
 	}
 
-	toPath, err := unquoteFilename(parts[3])
+	toPath, err := unquoteFilename(parts[1])
 	if err != nil {
 		return "", "", fmt.Errorf("error parsing header 'to' path: %w", err)
 	}
 
 	return fromPath, toPath, nil
 }
 
+func splitPath(value string, offset int, expectedLen int) []string {
+	parts := strings.Split(value, " ")
+	if len(parts) == expectedLen {
+		return parts
+	}
+
+	// parts may contain spaces
+	// TODO: how to handle spaces plus multi-fullstop filenames e.g "who would.do.this"?
+	valueWithoutOffset := strings.Join(parts[offset:], " ")
+	matches := pathSplitterRegexp.FindStringSubmatch(valueWithoutOffset)
+	return []string{matches[1], matches[4]}
+}
+
 func parseChunkHeader(value string) (Chunk, error) {
 	parts := strings.Split(value, " ")