import datetime
from email.message import EmailMessage
import re
import smtplib
from typing import Dict

import jinja2
from zope import component
from zope.interface import implementer

from ceo_common.interfaces import IMailService, IConfig, IUser

smtp_url_re = re.compile(r'^(?P<scheme>smtps?)://(?P<host>[\w.-]+)(:(?P<port>\d+))?$')


@implementer(IMailService)
class MailService:
    def __init__(self):
        cfg = component.getUtility(IConfig)
        smtp_url = cfg.get('mail_smtp_url')
        match = smtp_url_re.match(smtp_url)
        if match is None:
            raise Exception('Invalid SMTP URL: %s' % smtp_url)
        self.smtps = match.group('scheme') == 'smtps'
        self.host = match.group('host')
        self.port = int(match.group('port') or 25)
        self.starttls = cfg.get('mail_smtp_starttls')
        assert not (self.smtps and self.starttls)
        self.base_domain = cfg.get('base_domain')
        self.jinja_env = jinja2.Environment(
            loader=jinja2.PackageLoader('ceod.model'),
        )

    def send(self, _from: str, to: str, headers: Dict[str, str], content: str):
        msg = EmailMessage()
        msg.set_content(content)
        msg['From'] = _from
        msg['To'] = to
        msg['Date'] = datetime.datetime.now().astimezone().strftime('%a, %d %b %Y %H:%M:%S %z')
        for key, val in headers.items():
            msg[key] = val

        if self.smtps:
            client = smtplib.SMTP_SSL(self.host, self.port)
        else:
            client = smtplib.SMTP(self.host, self.port)
        if self.starttls:
            client.starttls()
        client.ehlo()
        client.send_message(msg)
        client.quit()

    def send_welcome_message_to(self, user: IUser):
        template = self.jinja_env.get_template('welcome_message.j2')
        # TODO: store surname and givenName in LDAP
        first_name = user.cn.split(' ', 1)[0]
        body = template.render(name=first_name, user=user.uid)
        self.send(
            f'Computer Science Club <exec@{self.base_domain}>',
            f'{user.cn} <{user.uid}@{self.base_domain}>',
            {'Subject': 'Welcome to the Computer Science Club'},
            body,
        )