/*
** Print the "Index:" message that patches wants to see at the top of a diff.
*/
void diff_print_index(const char *zFile, u64 diffFlags, Blob *diffBlob){
  if( (diffFlags & (DIFF_SIDEBYSIDE|DIFF_BRIEF|DIFF_NUMSTAT))==0 ){
    char *z = mprintf("Index: %s\n%.66c\n", zFile, '=');
    if( !diffBlob ){
      fossil_print("%s", z);
    }else{
      blob_appendf(diffBlob, "%s", z);
    }
    fossil_free(z);
  }
}

/*
** Print the +++/--- filename lines for a diff operation.
*/

      z = mprintf("%.*c %.*s %.*c versus %.*c %.*s %.*c\n",
                  (w-n1+10)/2, '=', n1, zLeft, (w-n1+1)/2, '=',
                  (w-n2)/2, '=', n2, zRight, (w-n2+1)/2, '=');
    }
  }else{
    z = mprintf("--- %s\n+++ %s\n", zLeft, zRight);
  }
  if( !diffBlob ){
    fossil_print("%s", z);
  }else{
    blob_appendf(diffBlob, "%s", z);
  }
  fossil_free(z);
}

/*
** Show the difference between two files, one in memory and one on disk.
**
** The difference is the set of edits needed to transform pFile1 into

      if( fSwapDiff ){
        text_diff(&file2, pFile1, &out, 0, diffFlags);
      }else{
        text_diff(pFile1, &file2, &out, 0, diffFlags);
      }
      if( blob_size(&out) ){
        if( diffFlags & DIFF_NUMSTAT ){
          if( !diffBlob ){
            fossil_print("%s %s\n", blob_str(&out), zName);
          }else{
            blob_appendf(diffBlob, "%s %s\n", blob_str(&out), zName);
          }
        }else{
          if( !diffBlob ){
            diff_print_filenames(zName, zName2, diffFlags, 0);
            fossil_print("%s\n", blob_str(&out));
          }else{
            diff_print_filenames(zName, zName2, diffFlags, diffBlob);
            blob_appendf(diffBlob, "%s\n", blob_str(&out));
          }
        }
      }
      blob_reset(&out);
    }