import logging
import re
from datetime import timedelta

from django.conf import settings
from django.core.mail import EmailMultiAlternatives
from django.core.management.base import BaseCommand
from django.utils import timezone
from django.utils.translation import gettext as _

from common.models import UserConfig
from notifications.models import NotificationRecipient

logger = logging.getLogger(__name__)


class Command(BaseCommand):
    help = "Envoie un e-mail de rappel aux utilisateurs ayant des notifications non lues depuis un certain délai."

    def add_arguments(self, parser):
        parser.add_argument(
            '--user',
            type=str,
            help="Username spécifique à cibler pour le test.",
        )
        parser.add_argument(
            '--dry-run',
            action='store_true',
            help="Simule l'envoi sans envoyer d'e-mails réels ni mettre à jour la base de données.",
        )

    def handle(self, *args, **options):
        target_username = options.get('user')
        dry_run = options.get('dry-run', False)

        now = timezone.now()
        configs = UserConfig.objects.filter(
            notification_reminder_enabled=True,
            user__is_active=True,
        ).select_related('user')

        if target_username:
            configs = configs.filter(user__username=target_username)

        sent_count = 0
        user_count = 0

        for config in configs:
            user = config.user
            delay_hours = config.notification_reminder_delay_hours or 24
            cutoff_time = now - timedelta(hours=delay_hours)

            # Recueillir les notifications non lues > délai
            recipients = (
                NotificationRecipient.objects.filter(
                    user=user,
                    read_at__isnull=True,
                    archived_at__isnull=True,
                    reminder_sent_at__isnull=True,
                    notification__created_at__lte=cutoff_time,
                )
                .select_related('notification', 'notification__sender')
                .order_by('-notification__created_at')
            )

            # Filtrer les notifications expirées
            valid_recipients = [r for r in recipients if not r.notification.is_expired]

            if not valid_recipients:
                continue

            # Déterminer les adresses e-mail de destination
            email_override = getattr(settings, 'EMAIL_OVERRIDE', None)
            if email_override:
                recipient_emails = [email_override]
            else:
                emails = set()
                raw_emails = config.notification_reminder_emails or user.email or getattr(config, 'generic_email', '')
                if raw_emails:
                    for email in re.split(r'[;,]', str(raw_emails)):
                        e = email.strip()
                        if e:
                            emails.add(e)
                recipient_emails = list(emails)

            if not recipient_emails:
                logger.warning("Aucune adresse e-mail trouvée pour l'utilisateur %s.", user.username)
                continue

            # Construire l'e-mail
            count = len(valid_recipients)
            subject = f"[StreetUp] Rappel : {count} notification(s) non lue(s)"

            # Host URL pour les liens
            domain = getattr(settings, 'SITE_URL', 'http://localhost:8003')

            lines_text = [
                f"Bonjour {user.get_full_name() or user.username},\n",
                f"Vous avez {count} notification(s) non lue(s) reçue(s) il y a plus de {delay_hours} heure(s) :\n",
            ]

            html_items = []
            for r in valid_recipients:
                n = r.notification
                created_str = n.created_at.strftime('%d/%m/%Y à %H:%i')
                sender_str = n.sender.get_full_name() if n.sender else _("Système")
                link = f"{domain}{n.action_url}" if n.action_url else f"{domain}/notifications/"

                lines_text.append(f"- [{n.get_notification_type_display()}] {n.title} (reçue le {created_str} par {sender_str})")
                lines_text.append(f"  Lien: {link}\n")

                html_items.append(
                    f"<li>"
                    f"<strong>{n.title}</strong> ({n.get_notification_type_display()})<br>"
                    f"<small style='color:#6c757d;'>Reçue le {created_str} • {sender_str}</small><br>"
                    f"<a href='{link}' style='color:#2f3e8b; font-weight:bold;'>Consulter</a>"
                    f"</li>"
                )

            lines_text.append(f"\nAccédez à votre boîte de réception : {domain}/notifications/")
            text_body = "\n".join(lines_text)

            html_body = f"""
            <div style="font-family: Arial, sans-serif; max-width: 600px; margin: 0 auto; color: #333;">
                <h2 style="color: #2f3e8b;">Notifications non lues</h2>
                <p>Bonjour {user.get_full_name() or user.username},</p>
                <p>Vous avez <strong>{count}</strong> notification(s) non lue(s) qui attendent votre attention :</p>
                <ul style="line-height: 1.6; padding-left: 20px;">
                    {"".join(html_items)}
                </ul>
                <p style="margin-top: 20px;">
                    <a href="{domain}/notifications/" style="background-color: #2f3e8b; color: #fff; padding: 10px 20px; text-decoration: none; border-radius: 5px; display: inline-block;">
                        Voir mes notifications
                    </a>
                </p>
            </div>
            """

            if dry_run:
                self.stdout.write(f"[DRY-RUN] E-mail simulé pour {user.username} ({recipient_emails}) - {count} notification(s).")
            else:
                try:
                    msg = EmailMultiAlternatives(
                        subject=subject,
                        body=text_body,
                        from_email=getattr(settings, 'DEFAULT_FROM_EMAIL', 'noreply@streetup.be'),
                        to=recipient_emails,
                    )
                    msg.attach_alternative(html_body, "text/html")
                    msg.send()

                    # Marquer le rappel envoyé
                    NotificationRecipient.objects.filter(pk__in=[r.pk for r in valid_recipients]).update(
                        reminder_sent_at=now
                    )
                    sent_count += 1
                    user_count += 1
                    self.stdout.write(self.style.SUCCESS(f"Rappel envoyé avec succès à {user.username} ({recipient_emails})."))
                except Exception as exc:
                    logger.exception("Erreur d'envoi du rappel pour %s: %s", user.username, exc)
                    self.stderr.write(self.style.ERROR(f"Erreur d'envoi pour {user.username}: {exc}"))

        self.stdout.write(self.style.SUCCESS(f"Traitement terminé : {sent_count} e-mail(s) envoyé(s) pour {user_count} utilisateur(s)."))