import os
from pathlib import Path, WindowsPath, PosixPath

from PyTeX.build.config import GlobalPyTeXConfig
from PyTeX.build.paths import PyTeXRootDirType


class RelativePath(Path):
    """
    Represents a path that knows of its corresponding root directory
    """
    def __new__(cls, pytex_root_dir_type: PyTeXRootDirType, *args, **kwargs):
        if cls is RelativePath:
            cls = RelativeWindowsPath if os.name == 'nt' else RelativePosixPath
        self = cls._from_parts(args, init=False)
        if not self._flavour.is_supported:
            raise NotImplementedError("cannot instantiate %r on your system"
                                      % (cls.__name__,))
        self._init()
        self.__init(pytex_root_dir_type)
        return self

    def __init(self, pytex_root_dir_type: PyTeXRootDirType):
        self._pytex_root_dir_type: PyTeXRootDirType = pytex_root_dir_type
        self._root_dir: Path = {
            PyTeXRootDirType.BUILD: GlobalPyTeXConfig.build_root(),
            PyTeXRootDirType.PYTEX_SOURCE: GlobalPyTeXConfig.source_root(),
            PyTeXRootDirType.DOC: GlobalPyTeXConfig.doc_root(),
            PyTeXRootDirType.TEX_SOURCE: GlobalPyTeXConfig.tex_root()
        }[self._pytex_root_dir_type]
        try:
            self._relative_path = self.relative_to(self._root_dir)
        except ValueError as e:
            raise NotImplementedError

    @property
    def root_dir_type(self) -> PyTeXRootDirType:
        return self._pytex_root_dir_type

    @property
    def root_dir(self) -> Path:
        return self._root_dir

    @property
    def relative_path(self):
        return self._relative_path


class RelativeWindowsPath(RelativePath, WindowsPath):
    pass


class RelativePosixPath(RelativePath, PosixPath):
    pass