"""
Notification services — point d'entrée pour créer des notifications depuis n'importe quelle app.

Usage depuis une autre app:
    from notifications.services import notify_user, notify_team, notify_users

    # Notification personnelle
    notify_user(
        recipient=user,
        title="Nouvelle intervention assignée",
        content="L'intervention #123 vous a été assignée.",
        notification_type='task',
        action_url='/interventions/123/',
        action_label="Voir l'intervention",
        source_app='interventions',
        sender=request.user,
    )

    # Notification à une équipe
    from notifications.models import Team
    team = Team.objects.get(name='Équipe technique')
    notify_team(
        team=team,
        title="Stock bas",
        content="Le niveau de stock du produit X est critique.",
        notification_type='alert',
        source_app='stock',
    )
"""

from django.contrib.auth.models import User
from django.utils import timezone

import re as _re

# Mention pattern: @[Display Name](u:123) or @[Team Name](t:456)
_MENTION_PATTERN = _re.compile(r'@\[([^\]]+)\]\(([ut]):(\d+)\)')


def _create_notification(
    title,
    content='',
    notification_type='info',
    action_url='',
    action_label='',
    source_app='',
    sender=None,
    expires_at=None,
    is_system=False,
    is_single_claim=False,
):
    from .models import Notification
    return Notification.objects.create(
        title=title,
        content=content,
        notification_type=notification_type,
        action_url=action_url,
        action_label=action_label,
        source_app=source_app,
        sender=sender,
        expires_at=expires_at,
        is_system=is_system,
        is_single_claim=is_single_claim,
    )


def notify_user(
    recipient,
    title,
    content='',
    notification_type='info',
    action_url='',
    action_label='',
    source_app='',
    sender=None,
    expires_at=None,
    is_system=False,
):
    """
    Envoie une notification personnelle à un utilisateur.
    Retourne le NotificationRecipient créé.
    """
    from .models import NotificationRecipient
    notification = _create_notification(
        title=title,
        content=content,
        notification_type=notification_type,
        action_url=action_url,
        action_label=action_label,
        source_app=source_app,
        sender=sender,
        expires_at=expires_at,
        is_system=is_system,
    )
    recipient_obj = NotificationRecipient.objects.create(
        notification=notification,
        user=recipient,
    )
    return recipient_obj


def notify_users(
    recipients,
    title,
    content='',
    notification_type='info',
    action_url='',
    action_label='',
    source_app='',
    sender=None,
    expires_at=None,
    is_system=False,
):
    """
    Envoie une notification à plusieurs utilisateurs (crée un seul objet Notification
    avec plusieurs NotificationRecipient).
    Retourne la Notification créée.
    """
    from .models import Notification, NotificationRecipient
    notification = _create_notification(
        title=title,
        content=content,
        notification_type=notification_type,
        action_url=action_url,
        action_label=action_label,
        source_app=source_app,
        sender=sender,
        expires_at=expires_at,
        is_system=is_system,
    )
    NotificationRecipient.objects.bulk_create([
        NotificationRecipient(notification=notification, user=user)
        for user in recipients
    ], ignore_conflicts=True)
    return notification


def notify_team(
    team,
    title,
    content='',
    notification_type='info',
    action_url='',
    action_label='',
    source_app='',
    sender=None,
    expires_at=None,
    is_system=False,
):
    """
    Envoie une notification à toute une équipe.
    Retourne la TeamNotificationTarget créée.
    """
    from .models import TeamNotificationTarget
    notification = _create_notification(
        title=title,
        content=content,
        notification_type=notification_type,
        action_url=action_url,
        action_label=action_label,
        source_app=source_app,
        sender=sender,
        expires_at=expires_at,
        is_system=is_system,
    )
    target = TeamNotificationTarget.objects.create(
        notification=notification,
        team=team,
    )
    return target


def get_user_notifications(user, include_archived=False):
    """
    Retourne une liste unifiée de notifications pour un utilisateur,
    combinant notifications personnelles et notifications d'équipe.

    Chaque élément est un dict avec:
      - notification: Notification
      - is_read: bool
      - is_archived: bool
      - recipient_type: 'personal' | 'team'
      - team_name: str (si team)
      - recipient_id: int (NotificationRecipient.pk ou TeamNotificationTarget.pk)
    """
    from .models import NotificationRecipient, TeamNotificationTarget, TeamNotificationRead

    results = []

    # --- Personal notifications ---
    personal_qs = NotificationRecipient.objects.select_related(
        'notification', 'notification__sender'
    ).prefetch_related('notification__attachments').filter(user=user)
    if not include_archived:
        personal_qs = personal_qs.filter(archived_at__isnull=True)

    for nr in personal_qs:
        if nr.notification.is_expired:
            continue
        results.append({
            'notification': nr.notification,
            'is_read': nr.is_read,
            'is_archived': nr.is_archived,
            'recipient_type': 'personal',
            'team_name': None,
            'recipient_id': nr.pk,
        })

    # --- Team notifications ---
    user_team_ids = user.notification_teams.values_list('id', flat=True)
    team_targets = TeamNotificationTarget.objects.select_related(
        'notification', 'notification__sender', 'team'
    ).prefetch_related('notification__attachments').filter(team_id__in=user_team_ids)

    read_ids = TeamNotificationRead.objects.filter(
        user=user,
        team_notification__in=team_targets,
    ).values_list('team_notification_id', flat=True)

    for tt in team_targets:
        if tt.notification.is_expired:
            continue
        results.append({
            'notification': tt.notification,
            'is_read': tt.pk in read_ids,
            'is_archived': False,
            'recipient_type': 'team',
            'team_name': tt.team.name,
            'recipient_id': tt.pk,
        })

    # Sort by created_at descending
    results.sort(key=lambda x: x['notification'].created_at, reverse=True)
    return results


def get_unread_count(user):
    """Retourne le nombre de notifications non lues pour un utilisateur."""
    from .models import NotificationRecipient, TeamNotificationTarget, TeamNotificationRead

    personal_unread = NotificationRecipient.objects.filter(
        user=user,
        read_at__isnull=True,
        archived_at__isnull=True,
    ).count()

    user_team_ids = user.notification_teams.values_list('id', flat=True)
    team_targets = TeamNotificationTarget.objects.filter(team_id__in=user_team_ids)
    team_read_ids = TeamNotificationRead.objects.filter(
        user=user,
        team_notification__in=team_targets,
    ).values_list('team_notification_id', flat=True)
    team_unread = team_targets.exclude(pk__in=team_read_ids).count()

    return personal_unread + team_unread


# ──────────────────────────────────────────────────────────────────────────────
# Discussion / Messaging services
# ──────────────────────────────────────────────────────────────────────────────

def post_message(discussion, author, content, files=None):
    """
    Poste un message dans une discussion.

    - Crée l'objet Message (+ pièces jointes).
    - Efface les notifications non lues liées à cette discussion pour tous les
      participants (la réponse annule les alertes précédentes).
    - Crée une nouvelle notification pour tous les participants sauf l'auteur.
    - Met à jour discussion.updated_at pour la faire remonter dans les listes.

    Retourne le Message créé.
    """
    from .models import Discussion, Message, MessageAttachment, NotificationRecipient

    message = Message.objects.create(discussion=discussion, author=author, content=content)

    if files:
        for f in files:
            MessageAttachment.objects.create(message=message, file=f, name=f.name)

    # Effacer les anciennes notifications non lues de cette discussion
    NotificationRecipient.objects.filter(
        notification__source_discussion=discussion,
        read_at__isnull=True,
    ).update(read_at=timezone.now())

    # Bump discussion.updated_at sans déclencher auto_now
    Discussion.objects.filter(pk=discussion.pk).update(updated_at=timezone.now())

    # Notifier les utilisateurs et équipes mentionnés dans le message
    _notify_mentions(discussion, author, content)

    return message


def _notify_mentions(discussion, author, content):
    """
    Parse les mentions @[Name](u:id) et @[Name](t:id) dans le contenu d'un message
    et envoie des notifications ciblées aux personnes/équipes mentionnées.
    Ajoute également les utilisateurs mentionnés comme participants de la discussion.
    """
    from .models import Notification, NotificationRecipient, TeamNotificationTarget, Team

    mentioned_user_ids = set()
    mentioned_team_ids = set()

    for m in _MENTION_PATTERN.finditer(content):
        kind = m.group(2)
        obj_id = int(m.group(3))
        if kind == 'u':
            mentioned_user_ids.add(obj_id)
        else:
            mentioned_team_ids.add(obj_id)

    if not mentioned_user_ids and not mentioned_team_ids:
        return

    action_url = discussion.object_url or discussion.get_absolute_url()
    action_label = discussion.object_label or str(discussion)
    author_name = author.get_full_name().strip() or author.username if author else "Système"
    exclude_pk = author.pk if author else -1

    title = f"{author_name} vous a mentionné — {discussion.title or str(discussion)}"
    msg_preview = content[:200]

    # Mentions d'utilisateurs individuels
    users_to_notify = list(
        User.objects.filter(pk__in=mentioned_user_ids).exclude(pk=exclude_pk)
    )
    if users_to_notify:
        notif = Notification.objects.create(
            title=title,
            content=msg_preview,
            notification_type=Notification.TYPE_MESSAGE,
            sender=author,
            action_url=action_url,
            action_label=action_label,
            source_app='discussions',
            source_discussion=discussion,
        )
        NotificationRecipient.objects.bulk_create([
            NotificationRecipient(notification=notif, user=u)
            for u in users_to_notify
        ], ignore_conflicts=True)
        # Ajouter les utilisateurs mentionnés comme participants
        discussion.participants.add(*users_to_notify)

    # Mentions d'équipes
    if mentioned_team_ids:
        teams = Team.objects.filter(pk__in=mentioned_team_ids).prefetch_related('members')
        for team in teams:
            notif = Notification.objects.create(
                title=title,
                content=msg_preview,
                notification_type=Notification.TYPE_MESSAGE,
                sender=author,
                action_url=action_url,
                action_label=action_label,
                source_app='discussions',
                source_discussion=discussion,
            )
            TeamNotificationTarget.objects.create(notification=notif, team=team)
            # Ajouter les membres de l'équipe comme participants
            discussion.participants.add(*team.members.all())


def mark_discussion_seen(discussion, user=None):
    """
    Marque comme lues les notifications non lues liées à cette discussion.
    Si `user` est fourni, seules les notifications de cet utilisateur sont marquées.
    """
    from .models import NotificationRecipient
    qs = NotificationRecipient.objects.filter(
        notification__source_discussion=discussion,
        read_at__isnull=True,
    )
    if user is not None:
        qs = qs.filter(user=user)
    qs.update(read_at=timezone.now())


# ──────────────────────────────────────────────────────────────────────────────
# Règles de notification automatiques
# ──────────────────────────────────────────────────────────────────────────────

def process_notification_rules(event, context, source_app=''):
    """
    Déclenche les règles de notification actives correspondant à *event*.

    Arguments
    ---------
    event : str
        Identifiant de l'événement, ex. ``'intervention_canceled'``.
    context : dict
        Données contextuelles utilisées pour :
          - filtrer les règles (ex. ``cancellation_type``) ;
          - interpoler les modèles de titre/contenu (format Python ``{var}``) ;
          - fournir ``action_url`` et ``action_label`` pour le lien.
    source_app : str
        Application source enregistrée sur les notifications créées.

    Exemple d'appel (depuis interventions) ::

        from notifications.services import process_notification_rules

        process_notification_rules(
            event='intervention_canceled',
            context={
                'intervention_code': intervention.code,
                'intervention_title': intervention.title,
                'cancellation_type': 'to_redirect',
                'cancellation_type_label': 'A rediriger',
                'cancellation_reason': reason_text,
                'action_url': '/interventions/42/',
                'action_label': "Voir l'intervention",
            },
            source_app='interventions',
        )
    """
    from .models import NotificationRule, NotificationRecipient

    rules = NotificationRule.objects.filter(
        is_active=True, trigger_event=event
    ).prefetch_related('recipient_teams', 'recipient_users')

    cancellation_type = context.get('cancellation_type', '')

    for rule in rules:
        # Filtre conditionnel : si la règle précise un type d'annulation,
        # on ne déclenche que si ça correspond.
        if rule.trigger_cancellation_type and rule.trigger_cancellation_type != cancellation_type:
            continue

        # Préparer les variables sécurisées pour l'interpolation
        safe_ctx = {k: (v or '') for k, v in context.items()}

        try:
            title = rule.title_template.format(**safe_ctx)
        except (KeyError, ValueError):
            title = rule.title_template

        try:
            content = rule.content_template.format(**safe_ctx) if rule.content_template else ''
        except (KeyError, ValueError):
            content = rule.content_template

        notification = _create_notification(
            title=title,
            content=content,
            notification_type=rule.notification_type,
            action_url=safe_ctx.get('action_url', ''),
            action_label=safe_ctx.get('action_label', ''),
            source_app=source_app,
            is_system=True,
            is_single_claim=rule.single_claim,
        )

        # Collecter tous les utilisateurs destinataires :
        # - membres (CompanyMember.user) des équipes CompanyTeam configurées
        # - utilisateurs individuels configurés
        from contracts.models import CompanyMember
        recipient_user_ids = set()
        for team in rule.recipient_teams.all():
            team_user_ids = CompanyMember.objects.filter(
                teams=team, user__isnull=False
            ).values_list('user_id', flat=True)
            recipient_user_ids.update(team_user_ids)
        for u in rule.recipient_users.all():
            recipient_user_ids.add(u.pk)

        if recipient_user_ids:
            NotificationRecipient.objects.bulk_create(
                [NotificationRecipient(notification=notification, user_id=uid)
                 for uid in recipient_user_ids],
                ignore_conflicts=True,
            )


def can_post_observation_message(user, observation):
    """
    Retourne True si l'utilisateur peut poster un message dans la discussion
    d'une observation. Critères :
      - C'est le créateur de l'observation, OU
      - Il est admin/superuser/operator, OU
      - Il peut traiter l'observation (process_thematic_ids), OU
      - Il est membre d'une équipe gestionnaire d'assets (is_assets_manager=True)
        qui gère la catégorie de l'observation.
    Cohérence : tout utilisateur disposant des actions peut aussi poster un message.
    """
    if not user or not user.is_authenticated:
        return False
    if user.is_superuser:
        return True
    user_config = getattr(user, 'config', None)
    if user_config and hasattr(user_config, 'has_role'):
        if user_config.has_role('admin') or user_config.has_role('operator'):
            return True
    if observation.created_by_id and observation.created_by_id == user.pk:
        return True
    # Check if user can process this observation via process_thematic_ids
    try:
        from observations.permissions import get_observation_access_context
        access_context = get_observation_access_context(user, user_config=user_config)
        if access_context and access_context.can_process_observation(observation):
            return True
    except Exception:
        pass
    if observation.category_id:
        try:
            from contracts.models import CompanyMember
            return CompanyMember.objects.filter(
                user=user,
                teams__is_assets_manager=True,
                teams__asset_categories=observation.category,
            ).exists()
        except Exception:
            pass
    return False


def get_or_create_observation_discussion(observation):
    """
    Trouve ou crée la discussion associée à une observation.

    Les participants sont : le créateur de l'observation + les membres des
    équipes gestionnaires d'assets (is_assets_manager=True) pour la catégorie
    concernée.
    Retourne (discussion, created).
    """
    from .models import Discussion
    from django.contrib.contenttypes.models import ContentType as CT
    from django.urls import reverse

    ct = CT.objects.get_for_model(observation)
    discussion = Discussion.objects.filter(
        content_type=ct, object_id=observation.pk
    ).first()

    if discussion:
        return discussion, False

    try:
        obj_url = reverse('observations:observation_detail', args=[observation.pk])
    except Exception:
        obj_url = ''

    obj_label = f"Observation {observation.code}"

    discussion = Discussion.objects.create(
        title=obj_label,
        created_by=observation.created_by,
        content_type=ct,
        object_id=observation.pk,
        object_url=obj_url,
        object_label=obj_label,
    )

    participants = set()
    if observation.created_by_id:
        participants.add(observation.created_by)

    if observation.category_id:
        try:
            from contracts.models import CompanyMember
            from django.contrib.auth.models import User as AuthUser
            manager_users = AuthUser.objects.filter(
                companymember__teams__is_assets_manager=True,
                companymember__teams__asset_categories=observation.category,
            ).distinct()
            participants.update(manager_users)
        except Exception:
            pass

    discussion.participants.set(participants)
    return discussion, True


def can_post_intervention_message(user, intervention):
    """
    Retourne True si l'utilisateur peut poster un message dans la discussion
    d'une intervention. Critères :
      - Il est superuser, OU
      - Il est admin/operator, OU
      - Il peut voir l'intervention (can_view_intervention).
    """
    if not user or not user.is_authenticated:
        return False
    if user.is_superuser:
        return True
    user_config = getattr(user, 'config', None)
    if user_config and hasattr(user_config, 'has_role'):
        if user_config.has_role('admin') or user_config.has_role('operator'):
            return True
    try:
        from interventions.permissions import can_view_intervention
        return can_view_intervention(user, intervention)
    except Exception:
        return False


def get_or_create_intervention_discussion(intervention):
    """
    Trouve ou crée la discussion associée à une intervention.

    Les participants sont : les utilisateurs ayant un accès contrat à cette
    intervention + les membres de l'équipe assignée (si présente).
    Retourne (discussion, created).
    """
    from .models import Discussion
    from django.contrib.contenttypes.models import ContentType as CT
    from django.urls import reverse

    ct = CT.objects.get_for_model(intervention)
    discussion = Discussion.objects.filter(
        content_type=ct, object_id=intervention.pk
    ).first()

    if discussion:
        return discussion, False

    try:
        obj_url = reverse('interventions:intervention_detail', args=[intervention.pk])
    except Exception:
        obj_url = ''

    obj_label = f"Intervention {intervention.code}"

    discussion = Discussion.objects.create(
        title=obj_label,
        created_by=intervention.created_by,
        content_type=ct,
        object_id=intervention.pk,
        object_url=obj_url,
        object_label=obj_label,
    )

    participants = set()

    # Membres de l'équipe assignée
    if intervention.assigned_team:
        try:
            from contracts.models import CompanyMember
            from django.contrib.auth.models import User as AuthUser
            team_users = AuthUser.objects.filter(
                companymember__teams=intervention.assigned_team,
            ).distinct()
            participants.update(team_users)
        except Exception:
            pass

    # Utilisateurs avec accès contrat
    if intervention.contract:
        try:
            from common.models import UserContractAccess
            from django.contrib.auth.models import User as AuthUser
            contract_users = AuthUser.objects.filter(
                config__usercontractaccess__contract=intervention.contract,
                config__usercontractaccess__can_view_interventions=True,
            ).distinct()
            participants.update(contract_users)
        except Exception:
            pass

    if participants:
        discussion.participants.set(participants)
    return discussion, True