"""Moteur unique de génération des échéances depuis les tâches de lot."""
from datetime import date, timedelta

from app_new.extensions import db
from app_new.core.models.planning import Meter, ScheduledTask
from app_new.core.models.maintenance import Intervention, LotTask
from app_new.core.services.planning_service import PlanningService


def _targets(lot):
    result = []
    for root in lot.equipments.filter_by(is_deleted=False):
        if root.tracked_individually:
            result.extend([x for x in root.all_children if not x.is_group and not x.is_deleted])
        elif root.is_group and root.children.count():
            result.extend([x for x in root.children if not x.is_deleted])
        else:
            result.append(root)
    return list({item.id: item for item in result}.values())


def _working_day(candidate):
    for _ in range(370):
        if PlanningService.get_working_hours(candidate):
            return candidate
        candidate += timedelta(days=1)
    raise ValueError("Aucune journée travaillée disponible dans les 12 prochains mois.")


def _last_completion(task, equipment):
    dates = []
    scheduled = ScheduledTask.query.filter(
        ScheduledTask.lot_task_id == task.id,
        ScheduledTask.equipment_id == equipment.id,
        ScheduledTask.status.in_(['completed', 'done']),
    ).order_by(ScheduledTask.completed_at.desc(), ScheduledTask.scheduled_date.desc()).first()
    if scheduled:
        if scheduled.completed_at:
            dates.append(scheduled.completed_at.date())
        elif scheduled.scheduled_date:
            dates.append(scheduled.scheduled_date)
    intervention = Intervention.query.filter(
        Intervention.lot_task_id == task.id,
        Intervention.equipment_id == equipment.id,
        Intervention.status.in_(['terminee', 'cloturee']),
        Intervention.is_deleted.is_(False),
    ).order_by(Intervention.completed_at.desc(), Intervention.completed_date.desc()).first()
    if intervention:
        if intervention.completed_at:
            dates.append(intervention.completed_at.date())
        elif intervention.completed_date:
            dates.append(intervention.completed_date)
        elif intervention.scheduled_date:
            dates.append(intervention.scheduled_date)
    return max(dates) if dates else None


def _calendar_due(task, equipment, today):
    last = _last_completion(task, equipment)
    interval = task.jours_entre_interventions or 0
    return last + timedelta(days=interval) if last and interval else today


def generate_due_tasks(task: LotTask, event=None, today=None, equipment_ids=None, commit=True):
    """Génère les échéances sans doublon et retourne les objets créés."""
    today = today or date.today()
    if not task.is_active:
        return []
    if task.trigger_type in ("event", "weather") and task.trigger_event != event:
        return []
    if task.trigger_type == "season":
        start, end = task.season_start_month or 1, task.season_end_month or 12
        inside = start <= today.month <= end if start <= end else today.month >= start or today.month <= end
        if not inside:
            return []
    created = []
    for equipment in _targets(task.lot):
        if equipment_ids is not None and equipment.id not in set(equipment_ids):
            continue
        if task.trigger_type == "meter":
            meter = Meter.query.filter_by(equipment_id=equipment.id, is_active=True).order_by(Meter.current_value.desc()).first()
            base_value = meter.last_maintenance_value if meter else None
            used_since_maintenance = (meter.current_value - (base_value or meter.initial_value or 0)) if meter else 0
            if not meter or task.meter_threshold is None or used_since_maintenance < task.meter_threshold:
                continue
        existing = ScheduledTask.query.filter(
            ScheduledTask.lot_task_id == task.id,
            ScheduledTask.equipment_id == equipment.id,
            ScheduledTask.status.in_(['planned', 'in_progress']),
        ).first()
        if existing:
            continue
        due = _calendar_due(task, equipment, today) if task.trigger_type == 'calendar' else today
        if task.trigger_type == 'calendar' and due > today + timedelta(days=max(task.advance_days or 0, 0)):
            continue
        if task.trigger_type == 'season':
            completed_this_season = ScheduledTask.query.filter(
                ScheduledTask.lot_task_id == task.id,
                ScheduledTask.equipment_id == equipment.id,
                ScheduledTask.status.in_(['completed', 'done']),
                db.extract('year', ScheduledTask.scheduled_date) == today.year,
            ).first()
            if completed_this_season:
                continue
        due = _working_day(max(due, today))
        item = ScheduledTask(lot_task_id=task.id, equipment_id=equipment.id,
                             room_id=equipment.effective_room.id if equipment.effective_room else None,
                             scheduled_date=due, estimated_duration=task.effective_duration(), status="planned")
        db.session.add(item)
        created.append(item)
    if commit:
        db.session.commit()
    elif created:
        db.session.flush()
    return created


def reconcile_planned_tasks():
    """Déplace les échéances ouvertes placées sur un jour non travaillé."""
    changed = []
    tasks = ScheduledTask.query.filter(ScheduledTask.status.in_(['planned', 'in_progress'])).all()
    for item in tasks:
        if item.scheduled_date and not PlanningService.get_working_hours(item.scheduled_date, user_id=item.assigned_to_id):
            item.scheduled_date = _working_day(item.scheduled_date + timedelta(days=1))
            changed.append(item)
    if changed:
        db.session.commit()
    return changed