"""IMAP ophalen en SMTP versturen, alleen met de standaardbibliotheek."""
import email
import html
import imaplib
import re
import smtplib
from datetime import datetime, timedelta
from email.message import EmailMessage
from email.policy import default as policy
from email.utils import formatdate, make_msgid, parseaddr, parsedate_to_datetime

MONTHS = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']


def _text(msg):
    part = msg.get_body(preferencelist=('plain', 'html'))
    if part is None:
        return ''
    try:
        content = part.get_content()
    except Exception:
        content = (part.get_payload(decode=True) or b'').decode('utf-8', 'replace')
    if part.get_content_type() == 'text/html':
        content = re.sub(r'(?is)<(script|style|head).*?</\1>', '', content)
        content = re.sub(r'(?i)<br\s*/?>|</p>|</div>|</tr>|</h\d>|</li>', '\n', content)
        content = html.unescape(re.sub(r'<[^>]+>', '', content))
    content = re.sub(r'[ \t]+\n', '\n', content)
    return re.sub(r'\n{3,}', '\n\n', content).strip()


def _connect_imap(cfg):
    host, port = cfg['imap_host'], int(cfg.get('imap_port') or 993)
    if port == 993:
        conn = imaplib.IMAP4_SSL(host, port, timeout=30)
    else:
        conn = imaplib.IMAP4(host, port, timeout=30)
        conn.starttls()
    conn.login(cfg['imap_user'], cfg.get('imap_pass', ''))
    return conn


def fetch(cfg, known, limit=200):
    """Haal berichten van de laatste `imap_days` dagen op die nog niet in `known` staan."""
    folder = cfg.get('imap_folder') or 'INBOX'
    days = int(cfg.get('imap_days') or 30)
    since = datetime.now() - timedelta(days=days)
    since_str = f'{since.day:02d}-{MONTHS[since.month - 1]}-{since.year}'

    conn = _connect_imap(cfg)
    try:
        typ, _ = conn.select(f'"{folder}"', readonly=True)
        if typ != 'OK':
            raise RuntimeError(f'Map "{folder}" niet gevonden')
        _, data = conn.uid('search', None, 'SINCE', since_str)
        uids = data[0].split()[-limit:]
        out = []
        for uid in uids:
            key = f'{folder}:{uid.decode()}'
            if key in known:
                continue
            _, msgdata = conn.uid('fetch', uid, '(BODY.PEEK[])')
            if not msgdata or not isinstance(msgdata[0], tuple):
                continue
            msg = email.message_from_bytes(msgdata[0][1], policy=policy)
            name, addr = parseaddr(str(msg.get('From', '')))
            try:
                date = parsedate_to_datetime(msg['Date']).astimezone().strftime('%Y-%m-%d %H:%M:%S')
            except Exception:
                date = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
            out.append({
                'uid': key,
                'message_id': str(msg.get('Message-ID', '')),
                'from_name': name,
                'from_addr': addr.lower(),
                'to_addr': str(msg.get('To', '')),
                'subject': str(msg.get('Subject', '')) or '(geen onderwerp)',
                'body': _text(msg),
                'date': date,
            })
        return out
    finally:
        try:
            conn.logout()
        except Exception:
            pass


def send(cfg, to, subject, body, in_reply_to=None):
    host = cfg.get('smtp_host')
    if not host:
        raise RuntimeError('Geen SMTP-server ingesteld')
    user = cfg.get('smtp_user') or cfg.get('imap_user', '')
    password = cfg.get('smtp_pass') or cfg.get('imap_pass', '')
    port = int(cfg.get('smtp_port') or 587)

    msg = EmailMessage()
    msg['From'] = cfg.get('smtp_from') or user
    msg['To'] = to
    msg['Subject'] = subject
    msg['Date'] = formatdate(localtime=True)
    msg['Message-ID'] = make_msgid()
    if in_reply_to:
        msg['In-Reply-To'] = in_reply_to
        msg['References'] = in_reply_to
    msg.set_content(body)

    if port == 465:
        server = smtplib.SMTP_SSL(host, port, timeout=30)
    else:
        server = smtplib.SMTP(host, port, timeout=30)
        server.starttls()
    with server:
        if user:
            server.login(user, password)
        server.send_message(msg)
    return msg['Message-ID']