"""Contains utils for processing coverage files."""
import pathlib

_RBE_PREFIX = pathlib.Path('/b/f/w')


def rewrite_file_paths_in_lcov(input_path, output_path, workspace_path):
  """Copy the input lcov file to the output, after fixing the paths in it."""
  with open(output_path, 'w') as out_file:
    with open(input_path, 'r') as in_file:
      for line in in_file:
        if line.startswith('SF:'):
          path = pathlib.Path(line.removeprefix('SF:').strip())
          path = _convert_to_workspace_relative_path(path, workspace_path)
          out_file.write(f'SF:{path}\n')
        else:
          out_file.write(line)


def _convert_to_workspace_relative_path(path, workspace_path):
  if not path.is_absolute():
    raise ValueError(f'Expected absolute paths in lcov file, got {path}')
  absolute_workspace_path_or_symlink = _fix_rbe_prefix(path, workspace_path)
  absolute_workspace_path = absolute_workspace_path_or_symlink.resolve()
  return absolute_workspace_path.relative_to(workspace_path)


def _fix_rbe_prefix(path, workspace_path):
  if path.is_relative_to(_RBE_PREFIX):
    return workspace_path / path.relative_to(_RBE_PREFIX)
  return path