from typing import Optional


class PyTeXError(Exception):
    def __init__(self, msg, explanation: Optional[str] = None):
        self._msg = msg
        self._traceback_explanation = []
        if explanation is not None:
            self._traceback_explanation.append(explanation)
        super().__init__(self._dispstr())

    def _dispstr(self):
        depth = 0
        ret = [self._msg]
        for explanation in self._traceback_explanation:
            ret.append(' ' * 2 * depth + explanation)
            depth += 1
        return '\n'.join(ret)

    def add_explanation(self, explanation: str):
        self._traceback_explanation.append(explanation)

    def __str__(self):
        return self._dispstr()


class PyTeXFormattingError(PyTeXError):
    pass


class PyTeXBuildError(PyTeXError):
    pass


class PyTeXMacroError(PyTeXError):
    pass


class PyTeXInvalidMacroUsageError(PyTeXMacroError):
    pass


class PyTeXInvalidBeginMacroCodeUsageError(PyTeXInvalidMacroUsageError):
    pass


class PyTeXInvalidEndMacroCodeUsageError(PyTeXInvalidMacroUsageError):
    pass