# Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

import os
from glob import glob1

from pants.base.project_tree import Dir, File, Link, ProjectTree
from pants.util.dirutil import fast_relpath, safe_walk


class FileSystemProjectTree(ProjectTree):
    def _join(self, relpath):
        if relpath.startswith(os.sep):
            raise ValueError('Absolute path "{}" not legal in {}.'.format(relpath, self))
        return os.path.join(self.build_root, relpath)

    def _glob1_raw(self, dir_relpath, glob):
        return glob1(self._join(dir_relpath), glob)

    def _scandir_raw(self, relpath):
        # Sanity check. TODO: this should probably be added to the ProjectTree interface as
        # an optional call, so that we can use it in fs.py rather than applying it by default.
        abspath = os.path.normpath(self._join(relpath))
        if os.path.realpath(abspath) != abspath:
            raise ValueError(
                'scandir for non-canonical path "{}" not supported in {}.'.format(relpath, self)
            )

        for entry in os.scandir(abspath):
            # NB: We don't use `DirEntry.stat`, as the scandir docs indicate that that always requires
            # an additional syscall on Unixes.
            entry_path = os.path.normpath(os.path.join(relpath, entry.name))
            if entry.is_file(follow_symlinks=False):
                yield File(entry_path)
            elif entry.is_dir(follow_symlinks=False):
                yield Dir(entry_path)
            elif entry.is_symlink():
                yield Link(entry_path)
            else:
                raise IOError("Unsupported file type in {}: {}".format(self, entry_path))

    def _isdir_raw(self, relpath):
        return os.path.isdir(self._join(relpath))

    def _isfile_raw(self, relpath):
        return os.path.isfile(self._join(relpath))

    def _exists_raw(self, relpath):
        return os.path.exists(self._join(relpath))

    def _content_raw(self, file_relpath):
        with open(self._join(file_relpath), "rb") as source:
            return source.read()

    def _relative_readlink_raw(self, relpath):
        return os.readlink(self._join(relpath))

    def _walk_raw(self, relpath, topdown=True):
        def onerror(error):
            raise OSError(
                getattr(error, "errno", None), "Failed to walk below {}".format(relpath), error
            )

        for root, dirs, files in safe_walk(self._join(relpath), topdown=topdown, onerror=onerror):
            yield fast_relpath(root, self.build_root), dirs, files

    def __eq__(self, other):
        return other and (type(other) == type(self)) and (self.build_root == other.build_root)

    def __ne__(self, other):
        return not self.__eq__(other)

    def __hash__(self):
        return hash(self.build_root)

    def __repr__(self):
        return "{}({})".format(self.__class__.__name__, self.build_root)