# Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

import os
from collections import defaultdict
from netrc import NetrcParseError
from netrc import netrc as NetrcDb


class Netrc:
    """Fetches username and password from ~/.netrc for logged in user."""

    class NetrcError(Exception):
        """Raised to indicate Netrc errors."""

        def __init__(self, *args, **kwargs):
            super(Netrc.NetrcError, self).__init__(*args, **kwargs)

    def __init__(self):
        self._login = defaultdict(lambda: None)
        self._password = defaultdict(lambda: None)

    def getusername(self, repository):
        self._ensure_loaded()
        return self._login[repository]

    def getpassword(self, repository):
        self._ensure_loaded()
        return self._password[repository]

    def _ensure_loaded(self):
        if not self._login and not self._password:
            db = os.path.expanduser("~/.netrc")
            if not os.path.exists(db):
                raise self.NetrcError("A ~/.netrc file is required to authenticate")
            try:
                db = NetrcDb(db)
                for host, value in db.hosts.items():
                    auth = db.authenticators(host)
                    if auth:
                        login, _, password = auth
                        self._login[host] = login
                        self._password[host] = password
                if len(self._login) == 0:
                    raise self.NetrcError("Found no usable authentication blocks in ~/.netrc")
            except NetrcParseError as e:
                raise self.NetrcError(f"Problem parsing ~/.netrc: {e!r}")