import os
import shutil
from typing import List

from zope import component
from zope.interface import implementer

from .validators import is_valid_forwarding_address, InvalidForwardingAddressException
from ceo_common.interfaces import IFileService, IConfig, IUser


@implementer(IFileService)
class FileService:
    def __init__(self):
        cfg = component.getUtility(IConfig)
        self.member_home_skel = cfg.get('members_skel')
        self.club_home_skel = cfg.get('clubs_skel')

    def create_home_dir(self, user: IUser):
        if user.is_club():
            skel_dir = self.club_home_skel
        else:
            skel_dir = self.member_home_skel
        home = user.home_directory
        # It's important to NOT use pwd here because if the user was recently
        # deleted (e.g. as part of a rolled back transaction), their old UID
        # and GID numbers will still be in the NSS cache.
        uid = user.uid_number
        gid = user.gid_number
        # recursively copy skel dir to user's home
        shutil.copytree(skel_dir, home)
        # Set ownership and permissions on user's home.
        # The setgid bit ensures that all files created under that
        # directory belong to the owner (useful for clubs).
        os.chmod(home, mode=0o2751)  # rwxr-s--x
        os.chown(home, uid=uid, gid=gid)
        # recursively set file ownership
        for root, dirs, files in os.walk(home):
            for dir in dirs:
                os.chown(os.path.join(root, dir), uid=uid, gid=gid)
            for file in files:
                os.chown(os.path.join(root, file), uid=uid, gid=gid)

    def delete_home_dir(self, user: IUser):
        shutil.rmtree(user.home_directory)

    def get_forwarding_addresses(self, user: IUser) -> List[str]:
        forward_file = os.path.join(user.home_directory, '.forward')
        if not os.path.isfile(forward_file):
            return []
        lines = [
            line.strip() for line in open(forward_file).readlines()
        ]
        return [
            line for line in lines
            if line != '' and line[0] != '#'
        ]

    def set_forwarding_addresses(self, user: IUser, addresses: List[str]):
        for line in addresses:
            if not is_valid_forwarding_address(line):
                raise InvalidForwardingAddressException(line)
        uid = user.uid_number
        gid = user.gid_number
        forward_file = os.path.join(user.home_directory, '.forward')

        if os.path.exists(forward_file):
            # create a backup
            backup_forward_file = forward_file + '.bak'
            shutil.copyfile(forward_file, backup_forward_file)
            os.chown(backup_forward_file, uid=uid, gid=gid)
        else:
            # create a new ~/.forward file
            open(forward_file, 'w')
            os.chown(forward_file, uid=uid, gid=gid)

        with open(forward_file, 'w') as f:
            for line in addresses:
                f.write(line + '\n')