# This file is part of Buildbot.  Buildbot is free software: you can
# redistribute it and/or modify it under the terms of the GNU General Public
# License as published by the Free Software Foundation, version 2.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 51
# Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# Copyright Buildbot Team Members


import os
from binascii import hexlify
from hashlib import sha1

from twisted.internet import defer
from twisted.python import log

from buildbot.util import bytes2unicode
from buildbot.util import unicode2bytes

# TODO: fossil comes from a plugin. We should have an API that plugins could use to
# register allowed user types.
srcs = ['git', 'svn', 'hg', 'cvs', 'darcs', 'bzr', 'fossil']
salt_len = 8


def createUserObject(master, author, src=None):
    """
    Take a Change author and source and translate them into a User Object,
    storing the user in master.db, or returning None if the src is not
    specified.

    @param master: link to Buildmaster for database operations
    @type master: master.Buildmaster instance

    @param authors: Change author if string or Authz instance
    @type authors: string or www.authz instance

    @param src: source from which the User Object will be created
    @type src: string
    """

    if not src:
        log.msg("No vcs information found, unable to create User Object")
        return defer.succeed(None)

    if src in srcs:
        usdict = dict(identifier=author, attr_type=src, attr_data=author)
    else:
        log.msg(f"Unrecognized source argument: {src}")
        return defer.succeed(None)

    return master.db.users.findUserByAttr(
        identifier=usdict['identifier'],
        attr_type=usdict['attr_type'],
        attr_data=usdict['attr_data'])


def _extractContact(usdict, contact_types, uid):
    if usdict:
        for type in contact_types:
            contact = usdict.get(type)
            if contact:
                break
    else:
        contact = None
    if contact is None:
        log.msg(format="Unable to find any of %(contact_types)r for uid: %(uid)r",
                contact_types=contact_types, uid=uid)
    return contact


def getUserContact(master, contact_types, uid):
    """
    This is a simple getter function that returns a user attribute
    that matches the contact_types argument, or returns None if no
    uid/match is found.

    @param master: BuildMaster used to query the database
    @type master: BuildMaster instance

    @param contact_types: list of contact attributes to look for in
                         in a given user, such as 'email' or 'nick'
    @type contact_types: list of strings

    @param uid: user that is searched for the contact_types match
    @type uid: integer

    @returns: string of contact information or None via deferred
    """
    d = master.db.users.getUser(uid)
    d.addCallback(_extractContact, contact_types, uid)
    return d


def encrypt(passwd):
    """
    Encrypts the incoming password after adding some salt to store
    it in the database.

    @param passwd: password portion of user credentials
    @type passwd: string

    @returns: encrypted/salted string
    """
    m = sha1()
    salt = hexlify(os.urandom(salt_len))
    m.update(unicode2bytes(passwd) + salt)
    crypted = bytes2unicode(salt) + m.hexdigest()
    return crypted


def check_passwd(guess, passwd):
    """
    Tests to see if the guess, after salting and hashing, matches the
    passwd from the database.

    @param guess: incoming password trying to be used for authentication
    @param passwd: already encrypted password from the database

    @returns: boolean
    """
    m = sha1()
    salt = passwd[:salt_len * 2]  # salt_len * 2 due to encode('hex_codec')
    m.update(unicode2bytes(guess) + unicode2bytes(salt))
    crypted_guess = bytes2unicode(salt) + m.hexdigest()

    return crypted_guess == bytes2unicode(passwd)