#   -*- coding: utf-8 -*-
#
#   This file is part of PyBuilder
#
#   Copyright 2011-2020 PyBuilder Team
#
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
#   You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#   Unless required by applicable law or agreed to in writing, software
#   distributed under the License is distributed on an "AS IS" BASIS,
#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#   See the License for the specific language governing permissions and
#   limitations under the License.

import sys
from os.path import basename

import pybuilder._vendor


class VendorImporter:
    """
    A PEP 302 meta path importer for finding optionally-vendored
    or otherwise naturally-installed packages from root_name.
    """

    def __init__(self, root_name, vendored_names, vendor_pkg):
        self.root_name = root_name
        self.vendored_names = set(vendored_names)
        self.vendor_pkg = vendor_pkg

    @property
    def search_path(self):
        """
        Search first the vendor package then as a natural package.
        """
        yield self.vendor_pkg + "."
        yield ""

    def find_module(self, fullname, path=None):
        """
        Return self when fullname starts with root_name and the
        target module is one vendored through this importer.
        """
        root, base, target = fullname.partition(self.root_name + ".")
        if root == fullname and not base and not target:
            root = None
            target = fullname
        if root:
            return
        if not any(map(target.startswith, self.vendored_names)):
            return
        return self

    def load_module(self, fullname):
        """
        Iterate over the search path to locate and load fullname.
        """
        root, base, target = fullname.partition(self.root_name + ".")
        if root == fullname and not base and not target:
            root = None
            target = fullname
        for prefix in self.search_path:
            try:
                extant = prefix + target
                __import__(extant)
                mod = sys.modules[extant]
                sys.modules[fullname] = mod
                return mod
            except ImportError:
                pass
        else:
            raise ImportError(
                "The '{target}' package is required; "
                "normally this is bundled with this package so if you get "
                "this warning, consult the packager of your "
                "distribution.".format(**locals())
            )

    def install(self):
        """
        Install this importer into sys.meta_path if not already present.
        """
        if self not in sys.meta_path:
            sys.meta_path.insert(0, self)

        for pkg in self.vendored_names:
            for p in list(sys.modules):
                if p == pkg or p.startswith(pkg + "."):
                    sys.modules.pop(p, None)


# Don't run if we're actually in PDoc
if not (sys.version_info[0] == 2 and basename(sys.argv[0]) == "pdoc"):
    VendorImporter(__name__, pybuilder._vendor.__names__, pybuilder._vendor.__name__).install()
