Function diffFiles

app/utils/diff.ts:61–76

(fileName: string, oldFileContent: string, newFileContent: string)

 * @see https://www.gnu.org/software/diffutils/manual/html_node/Unified-Format.html
 */
export function diffFiles(fileName: string, oldFileContent: string, newFileContent: string) {
  let unifiedDiff = createTwoFilesPatch(fileName, fileName, oldFileContent, newFileContent);

  const patchHeaderEnd = `--- ${fileName}\n+++ ${fileName}\n`;
  const headerEndIndex = unifiedDiff.indexOf(patchHeaderEnd);

  if (headerEndIndex >= 0) {
    unifiedDiff = unifiedDiff.slice(headerEndIndex + patchHeaderEnd.length);
  }

  if (unifiedDiff === '') {
    return undefined;
  }

  return unifiedDiff;
}

/**
 * Converts the unified diff to HTML.