"""
Reports Endpoints - ServiceManagerWeb

Módulo de reportes y estadísticas del sistema.
Accesible por ADMIN y SUPPORT_MANAGER.
"""

from fastapi import APIRouter, Depends, Query, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func, and_, case, text, literal_column
from typing import Optional, List
from datetime import datetime, timedelta, timezone
import uuid

from app.core.database import get_db
from app.api.deps import get_current_user
from app.models.user import User, UserRole
from app.models.ticket import Ticket, TicketStatus, TicketPriority
from app.models.category import Category
from app.models.system import System
from app.models.tenant import Tenant, TenantStatus
from app.api.schemas.reports import (
    ReportSummaryResponse,
    TicketsByStatus,
    TicketsByPriority,
    AgentReportResponse,
    AgentReportRow,
    CategoryReportResponse,
    CategoryReportRow,
    ClientReportResponse,
    ClientReportRow,
    TrendsReportResponse,
    TrendDataPoint,
    CSATReportResponse,
    CSATDistribution,
    SystemReportResponse,
    SystemReportRow,
)

router = APIRouter()

CLOSED_STATUSES = {TicketStatus.RESOLVED, TicketStatus.CLOSED}

# ===================================
# HELPERS
# ===================================

def require_reports_access(current_user: User = Depends(get_current_user)) -> User:
    """ADMIN, SUPPORT_MANAGER y AUDITOR pueden leer reportes."""
    allowed = [UserRole.ADMIN, UserRole.SUPPORT_MANAGER, UserRole.AUDITOR]
    if current_user.role not in allowed:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Solo ADMIN, SUPPORT_MANAGER y AUDITOR pueden acceder a los reportes.",
        )
    return current_user


def require_admin(current_user: User = Depends(get_current_user)) -> User:
    """Solo ADMIN puede ver reportes entre tenants."""
    if current_user.role != UserRole.ADMIN:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Solo ADMIN puede ver reportes de todos los clientes.",
        )
    return current_user


def _period_dates(days: int) -> tuple[datetime, datetime]:
    """Devuelve (inicio, fin) del período solicitado en UTC."""
    end = datetime.now(timezone.utc)
    start = end - timedelta(days=days)
    return start, end


# ===================================
# 1. RESUMEN GENERAL
# ===================================

@router.get("/summary", response_model=ReportSummaryResponse)
async def get_report_summary(
    days: int = Query(default=30, ge=1, le=365, description="Días hacia atrás del período"),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_reports_access),
):
    """
    Resumen ejecutivo del período seleccionado.

    Incluye:
    - Total de tickets creados
    - Tickets abiertos vs resueltos
    - Tiempo promedio de resolución
    - Calificación promedio (CSAT)
    - Desglose por estado y prioridad
    - Comparación con el período anterior
    """
    period_start, period_end = _period_dates(days)
    prev_start = period_start - timedelta(days=days)

    tenant_filter = Ticket.tenant_id == current_user.tenant_id

    # ── Conteos por estado ──
    status_rows = (await db.execute(
        select(Ticket.status, func.count(Ticket.id).label("cnt"))
        .where(and_(tenant_filter, Ticket.created_at >= period_start))
        .group_by(Ticket.status)
    )).all()

    by_status = TicketsByStatus()
    for row in status_rows:
        s = row.status.value if hasattr(row.status, "value") else str(row.status)
        setattr(by_status, s.lower(), row.cnt)
    by_status.total = sum(
        [by_status.new, by_status.triage, by_status.in_progress,
         by_status.waiting_customer, by_status.resolved, by_status.closed, by_status.reopened]
    )

    # ── Conteos por prioridad ──
    priority_rows = (await db.execute(
        select(Ticket.priority, func.count(Ticket.id).label("cnt"))
        .where(and_(tenant_filter, Ticket.created_at >= period_start))
        .group_by(Ticket.priority)
    )).all()

    by_priority = TicketsByPriority()
    for row in priority_rows:
        p = row.priority.value if hasattr(row.priority, "value") else str(row.priority)
        setattr(by_priority, p.lower(), row.cnt)
    by_priority.total = sum([by_priority.low, by_priority.medium, by_priority.high, by_priority.urgent])

    total_tickets = by_status.total
    resolved_tickets = by_status.resolved + by_status.closed
    open_tickets = total_tickets - resolved_tickets

    # ── Promedio de tiempo de resolución (segundos → horas) ──
    res_time_row = (await db.execute(
        select(func.avg(
            func.extract("epoch", Ticket.resolved_at - Ticket.created_at)
        ).label("avg_seconds"))
        .where(and_(
            tenant_filter,
            Ticket.created_at >= period_start,
            Ticket.resolved_at.isnot(None),
        ))
    )).scalar_one_or_none()
    avg_resolution_hours = round(res_time_row / 3600, 2) if res_time_row else None

    # ── Promedio de primera respuesta ──
    resp_time_row = (await db.execute(
        select(func.avg(
            func.extract("epoch", Ticket.first_response_at - Ticket.created_at)
        ).label("avg_seconds"))
        .where(and_(
            tenant_filter,
            Ticket.created_at >= period_start,
            Ticket.first_response_at.isnot(None),
        ))
    )).scalar_one_or_none()
    avg_first_response_hours = round(resp_time_row / 3600, 2) if resp_time_row else None

    # ── CSAT ──
    csat_row = (await db.execute(
        select(func.avg(Ticket.rating).label("avg"), func.count(Ticket.rating).label("cnt"))
        .where(and_(tenant_filter, Ticket.created_at >= period_start, Ticket.rating.isnot(None)))
    )).one()
    avg_rating = round(float(csat_row.avg), 2) if csat_row.avg else None
    total_rated = csat_row.cnt or 0

    # ── Comparación con período anterior ──
    prev_total = (await db.execute(
        select(func.count(Ticket.id))
        .where(and_(tenant_filter, Ticket.created_at >= prev_start, Ticket.created_at < period_start))
    )).scalar_one_or_none() or 0

    prev_resolved = (await db.execute(
        select(func.count(Ticket.id))
        .where(and_(
            tenant_filter,
            Ticket.created_at >= prev_start,
            Ticket.created_at < period_start,
            Ticket.status.in_([TicketStatus.RESOLVED, TicketStatus.CLOSED]),
        ))
    )).scalar_one_or_none() or 0

    tickets_change_pct = None
    if prev_total > 0:
        tickets_change_pct = round(((total_tickets - prev_total) / prev_total) * 100, 1)

    resolution_change_pct = None
    if prev_total > 0 and total_tickets > 0:
        cur_rate = resolved_tickets / total_tickets * 100
        prev_rate = prev_resolved / prev_total * 100 if prev_total > 0 else 0
        resolution_change_pct = round(cur_rate - prev_rate, 1)

    return ReportSummaryResponse(
        period_start=period_start,
        period_end=period_end,
        generated_at=datetime.now(timezone.utc),
        total_tickets=total_tickets,
        open_tickets=open_tickets,
        resolved_tickets=resolved_tickets,
        avg_resolution_hours=avg_resolution_hours,
        avg_first_response_hours=avg_first_response_hours,
        avg_rating=avg_rating,
        total_rated=total_rated,
        by_status=by_status,
        by_priority=by_priority,
        tickets_change_pct=tickets_change_pct,
        resolution_change_pct=resolution_change_pct,
    )


# ===================================
# 2. RENDIMIENTO POR AGENTE
# ===================================

@router.get("/by-agent", response_model=AgentReportResponse)
async def get_report_by_agent(
    days: int = Query(default=30, ge=1, le=365),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_reports_access),
):
    """
    Rendimiento de cada agente en el período:
    - Tickets asignados y resueltos
    - Tasa de resolución
    - Tiempo promedio de resolución
    - Calificación promedio (CSAT)
    """
    period_start, period_end = _period_dates(days)
    tenant_filter = and_(
        Ticket.tenant_id == current_user.tenant_id,
        Ticket.created_at >= period_start,
        Ticket.assigned_to.isnot(None),
    )

    # Obtener todos los agentes del tenant
    agents_result = await db.execute(
        select(User).where(
            and_(
                User.tenant_id == current_user.tenant_id,
                User.role.in_([UserRole.AGENT, UserRole.SUPPORT_MANAGER, UserRole.ADMIN]),
                User.is_active == True,
            )
        )
    )
    agents = agents_result.scalars().all()

    rows: List[AgentReportRow] = []
    for agent in agents:
        agent_filter = and_(tenant_filter, Ticket.assigned_to == agent.id)

        total_assigned = (await db.execute(
            select(func.count(Ticket.id)).where(agent_filter)
        )).scalar_one_or_none() or 0

        if total_assigned == 0:
            continue  # omitir agentes sin tickets en el período

        resolved = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(agent_filter, Ticket.status.in_([TicketStatus.RESOLVED, TicketStatus.CLOSED]))
            )
        )).scalar_one_or_none() or 0

        avg_res_seconds = (await db.execute(
            select(func.avg(func.extract("epoch", Ticket.resolved_at - Ticket.created_at)))
            .where(and_(agent_filter, Ticket.resolved_at.isnot(None)))
        )).scalar_one_or_none()

        csat = (await db.execute(
            select(func.avg(Ticket.rating), func.count(Ticket.rating))
            .where(and_(agent_filter, Ticket.rating.isnot(None)))
        )).one()

        urgent_handled = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(agent_filter, Ticket.priority == TicketPriority.URGENT)
            )
        )).scalar_one_or_none() or 0

        rows.append(AgentReportRow(
            agent_id=str(agent.id),
            agent_name=f"{agent.first_name} {agent.last_name}",
            agent_email=agent.email,
            total_assigned=total_assigned,
            resolved=resolved,
            open=total_assigned - resolved,
            resolution_rate=round((resolved / total_assigned * 100), 1) if total_assigned else 0,
            avg_resolution_hours=round(float(avg_res_seconds) / 3600, 2) if avg_res_seconds else None,
            avg_rating=round(float(csat[0]), 2) if csat[0] else None,
            total_rated=csat[1] or 0,
            urgent_handled=urgent_handled,
        ))

    rows.sort(key=lambda r: r.resolved, reverse=True)

    return AgentReportResponse(
        period_start=period_start,
        period_end=period_end,
        generated_at=datetime.now(timezone.utc),
        agents=rows,
        total_agents=len(rows),
    )


# ===================================
# 3. TICKETS POR CATEGORÍA
# ===================================

@router.get("/by-category", response_model=CategoryReportResponse)
async def get_report_by_category(
    days: int = Query(default=30, ge=1, le=365),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_reports_access),
):
    """
    Tickets agrupados por categoría con tasa de cumplimiento SLA.
    """
    period_start, _ = _period_dates(days)
    period_end = datetime.now(timezone.utc)
    tenant_filter = and_(
        Ticket.tenant_id == current_user.tenant_id,
        Ticket.created_at >= period_start,
    )

    categories_result = await db.execute(
        select(Category).where(
            and_(Category.tenant_id == current_user.tenant_id, Category.is_active == True)
        )
    )
    categories = categories_result.scalars().all()

    rows: List[CategoryReportRow] = []

    for cat in categories:
        cat_filter = and_(tenant_filter, Ticket.category_id == cat.id)

        total = (await db.execute(
            select(func.count(Ticket.id)).where(cat_filter)
        )).scalar_one_or_none() or 0

        if total == 0:
            continue

        resolved = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(cat_filter, Ticket.status.in_([TicketStatus.RESOLVED, TicketStatus.CLOSED]))
            )
        )).scalar_one_or_none() or 0

        avg_res_seconds = (await db.execute(
            select(func.avg(func.extract("epoch", Ticket.resolved_at - Ticket.created_at)))
            .where(and_(cat_filter, Ticket.resolved_at.isnot(None)))
        )).scalar_one_or_none()

        # SLA compliance: tickets resueltos ANTES del deadline
        sla_met = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(
                    cat_filter,
                    Ticket.resolved_at.isnot(None),
                    Ticket.sla_resolution_due.isnot(None),
                    Ticket.resolved_at <= Ticket.sla_resolution_due,
                )
            )
        )).scalar_one_or_none() or 0

        tickets_with_sla = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(cat_filter, Ticket.sla_resolution_due.isnot(None), Ticket.resolved_at.isnot(None))
            )
        )).scalar_one_or_none() or 0

        sla_compliance_pct = round((sla_met / tickets_with_sla * 100), 1) if tickets_with_sla else 0.0

        rows.append(CategoryReportRow(
            category_id=str(cat.id),
            category_name=cat.name,
            total_tickets=total,
            open_tickets=total - resolved,
            resolved_tickets=resolved,
            avg_resolution_hours=round(float(avg_res_seconds) / 3600, 2) if avg_res_seconds else None,
            sla_response_hours=cat.sla_response_hours,
            sla_resolution_hours=cat.sla_resolution_hours,
            sla_compliance_pct=sla_compliance_pct,
        ))

    # Sin categoría
    uncategorized = (await db.execute(
        select(func.count(Ticket.id)).where(
            and_(tenant_filter, Ticket.category_id.is_(None))
        )
    )).scalar_one_or_none() or 0

    rows.sort(key=lambda r: r.total_tickets, reverse=True)

    return CategoryReportResponse(
        period_start=period_start,
        period_end=period_end,
        generated_at=datetime.now(timezone.utc),
        categories=rows,
        uncategorized_count=uncategorized,
    )


# ===================================
# 4. TICKETS POR CLIENTE (solo ADMIN)
# ===================================

@router.get("/by-client", response_model=ClientReportResponse)
async def get_report_by_client(
    days: int = Query(default=30, ge=1, le=365),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_admin),
):
    """
    Tickets agrupados por cliente (tenant). Solo accesible por ADMIN.
    Útil para ver qué clientes generan más trabajo.
    """
    period_start, period_end = _period_dates(days)

    tenants_result = await db.execute(select(Tenant).where(Tenant.status == TenantStatus.ACTIVE))
    tenants = tenants_result.scalars().all()

    rows: List[ClientReportRow] = []

    for tenant in tenants:
        t_filter = and_(
            Ticket.tenant_id == tenant.id,
            Ticket.created_at >= period_start,
        )

        total = (await db.execute(
            select(func.count(Ticket.id)).where(t_filter)
        )).scalar_one_or_none() or 0

        if total == 0:
            continue

        resolved = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(t_filter, Ticket.status.in_([TicketStatus.RESOLVED, TicketStatus.CLOSED]))
            )
        )).scalar_one_or_none() or 0

        urgent = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(t_filter, Ticket.priority == TicketPriority.URGENT)
            )
        )).scalar_one_or_none() or 0

        csat_row = (await db.execute(
            select(func.avg(Ticket.rating))
            .where(and_(t_filter, Ticket.rating.isnot(None)))
        )).scalar_one_or_none()

        avg_res_seconds = (await db.execute(
            select(func.avg(func.extract("epoch", Ticket.resolved_at - Ticket.created_at)))
            .where(and_(t_filter, Ticket.resolved_at.isnot(None)))
        )).scalar_one_or_none()

        last_ticket = (await db.execute(
            select(func.max(Ticket.created_at)).where(t_filter)
        )).scalar_one_or_none()

        rows.append(ClientReportRow(
            tenant_id=str(tenant.id),
            tenant_name=tenant.name,
            total_tickets=total,
            open_tickets=total - resolved,
            resolved_tickets=resolved,
            urgent_tickets=urgent,
            avg_resolution_hours=round(float(avg_res_seconds) / 3600, 2) if avg_res_seconds else None,
            avg_rating=round(float(csat_row), 2) if csat_row else None,
            last_ticket_at=last_ticket,
        ))

    rows.sort(key=lambda r: r.total_tickets, reverse=True)

    return ClientReportResponse(
        period_start=period_start,
        period_end=period_end,
        generated_at=datetime.now(timezone.utc),
        clients=rows,
        total_clients=len(rows),
    )


# ===================================
# 5. TENDENCIAS (TICKETS EN EL TIEMPO)
# ===================================

@router.get("/trends", response_model=TrendsReportResponse)
async def get_report_trends(
    days: int = Query(default=30, ge=7, le=90, description="Número de días (7-90)"),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_reports_access),
):
    """
    Evolución diaria de tickets creados y resueltos.
    Útil para detectar picos de trabajo.
    """
    period_start, period_end = _period_dates(days)
    tenant_filter = Ticket.tenant_id == current_user.tenant_id

    # Tickets creados por día
    # literal_column("'day'") evita que SQLAlchemy genere múltiples parámetros
    # ($1, $4, $5) para 'day', lo que confunde a PostgreSQL en el GROUP BY.
    _day_lit = literal_column("'day'")
    created_rows = (await db.execute(
        select(
            func.date_trunc(_day_lit, Ticket.created_at).label("day"),
            func.count(Ticket.id).label("cnt"),
        )
        .where(and_(tenant_filter, Ticket.created_at >= period_start))
        .group_by(func.date_trunc(_day_lit, Ticket.created_at))
        .order_by(func.date_trunc(_day_lit, Ticket.created_at))
    )).all()

    # Tickets resueltos por día (según resolved_at)
    resolved_rows = (await db.execute(
        select(
            func.date_trunc(_day_lit, Ticket.resolved_at).label("day"),
            func.count(Ticket.id).label("cnt"),
        )
        .where(and_(
            tenant_filter,
            Ticket.resolved_at >= period_start,
            Ticket.resolved_at.isnot(None),
        ))
        .group_by(func.date_trunc(_day_lit, Ticket.resolved_at))
        .order_by(func.date_trunc(_day_lit, Ticket.resolved_at))
    )).all()

    created_map: dict[str, int] = {r.day.strftime("%Y-%m-%d"): r.cnt for r in created_rows}
    resolved_map: dict[str, int] = {r.day.strftime("%Y-%m-%d"): r.cnt for r in resolved_rows}

    # Un punto por cada día del período
    data_points: List[TrendDataPoint] = []
    current = period_start
    while current <= period_end:
        date_str = current.strftime("%Y-%m-%d")
        c = created_map.get(date_str, 0)
        r = resolved_map.get(date_str, 0)
        data_points.append(TrendDataPoint(date=date_str, created=c, resolved=r, net_open=c - r))
        current += timedelta(days=1)

    return TrendsReportResponse(
        period_start=period_start,
        period_end=period_end,
        generated_at=datetime.now(timezone.utc),
        data_points=data_points,
        total_days=len(data_points),
    )


# ===================================
# 6. SATISFACCIÓN DEL CLIENTE (CSAT)
# ===================================

@router.get("/csat", response_model=CSATReportResponse)
async def get_report_csat(
    days: int = Query(default=30, ge=1, le=365),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_reports_access),
):
    """
    Reporte de satisfacción del cliente (calificaciones 1-5).
    Incluye distribución, promedio por categoría y por agente.
    """
    period_start, period_end = _period_dates(days)
    tenant_filter = and_(
        Ticket.tenant_id == current_user.tenant_id,
        Ticket.created_at >= period_start,
    )

    # Total y promedio general
    general = (await db.execute(
        select(func.avg(Ticket.rating).label("avg"), func.count(Ticket.rating).label("rated"))
        .where(and_(tenant_filter, Ticket.rating.isnot(None)))
    )).one()
    total_tickets = (await db.execute(
        select(func.count(Ticket.id)).where(tenant_filter)
    )).scalar_one_or_none() or 0

    # Distribución por estrellas
    dist_rows = (await db.execute(
        select(Ticket.rating, func.count(Ticket.id).label("cnt"))
        .where(and_(tenant_filter, Ticket.rating.isnot(None)))
        .group_by(Ticket.rating)
    )).all()

    dist = CSATDistribution()
    for row in dist_rows:
        setattr(dist, f"rating_{row.rating}", row.cnt)

    # Promedio por categoría
    cat_rows = (await db.execute(
        select(
            Category.name.label("cat_name"),
            func.avg(Ticket.rating).label("avg"),
            func.count(Ticket.rating).label("cnt"),
        )
        .join(Category, Ticket.category_id == Category.id, isouter=True)
        .where(and_(tenant_filter, Ticket.rating.isnot(None)))
        .group_by(Category.name)
        .order_by(func.avg(Ticket.rating).desc())
    )).all()

    by_category = [
        {
            "category": row.cat_name or "Sin categoría",
            "avg_rating": round(float(row.avg), 2) if row.avg else None,
            "total_rated": row.cnt,
        }
        for row in cat_rows
    ]

    # Promedio por agente
    agent_rows = (await db.execute(
        select(
            User.first_name.label("fname"),
            User.last_name.label("lname"),
            func.avg(Ticket.rating).label("avg"),
            func.count(Ticket.rating).label("cnt"),
        )
        .join(User, Ticket.assigned_to == User.id, isouter=True)
        .where(and_(tenant_filter, Ticket.rating.isnot(None)))
        .group_by(User.first_name, User.last_name)
        .order_by(func.avg(Ticket.rating).desc())
    )).all()

    by_agent = [
        {
            "agent": f"{row.fname or ''} {row.lname or ''}".strip() or "Sin asignar",
            "avg_rating": round(float(row.avg), 2) if row.avg else None,
            "total_rated": row.cnt,
        }
        for row in agent_rows
    ]

    # Últimos comentarios de calificación (rating_comment)
    comment_rows = (await db.execute(
        select(Ticket.rating, Ticket.rating_comment, Ticket.rated_at)
        .where(and_(
            tenant_filter,
            Ticket.rating.isnot(None),
            Ticket.rating_comment.isnot(None),
            Ticket.rating_comment != "",
        ))
        .order_by(Ticket.rated_at.desc())
        .limit(10)
    )).all()

    recent_comments = [
        {
            "rating": row.rating,
            "comment": row.rating_comment,
            "rated_at": row.rated_at.isoformat() if row.rated_at else None,
        }
        for row in comment_rows
    ]

    total_rated = general.rated or 0
    response_rate = round((total_rated / total_tickets * 100), 1) if total_tickets else 0.0

    return CSATReportResponse(
        period_start=period_start,
        period_end=period_end,
        generated_at=datetime.now(timezone.utc),
        avg_rating=round(float(general.avg), 2) if general.avg else None,
        total_rated=total_rated,
        total_tickets=total_tickets,
        response_rate=response_rate,
        distribution=dist,
        by_category=by_category,
        by_agent=by_agent,
        recent_comments=recent_comments,
    )


# ===================================
# 7. TICKETS POR SISTEMA AFECTADO
# ===================================

@router.get("/by-system", response_model=SystemReportResponse)
async def get_report_by_system(
    days: int = Query(default=30, ge=1, le=365),
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_reports_access),
):
    """
    Tickets agrupados por sistema afectado.
    Útil para detectar qué sistemas generan más incidentes.
    """
    period_start, period_end = _period_dates(days)
    tenant_filter = and_(
        Ticket.tenant_id == current_user.tenant_id,
        Ticket.created_at >= period_start,
    )

    systems_result = await db.execute(
        select(System).where(
            and_(System.tenant_id == current_user.tenant_id, System.is_active == True)
        )
    )
    systems = systems_result.scalars().all()

    rows: List[SystemReportRow] = []

    for sys in systems:
        sys_filter = and_(tenant_filter, Ticket.affected_system_id == sys.id)

        total = (await db.execute(
            select(func.count(Ticket.id)).where(sys_filter)
        )).scalar_one_or_none() or 0

        if total == 0:
            continue

        resolved = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(sys_filter, Ticket.status.in_([TicketStatus.RESOLVED, TicketStatus.CLOSED]))
            )
        )).scalar_one_or_none() or 0

        urgent = (await db.execute(
            select(func.count(Ticket.id)).where(
                and_(sys_filter, Ticket.priority == TicketPriority.URGENT)
            )
        )).scalar_one_or_none() or 0

        avg_res_seconds = (await db.execute(
            select(func.avg(func.extract("epoch", Ticket.resolved_at - Ticket.created_at)))
            .where(and_(sys_filter, Ticket.resolved_at.isnot(None)))
        )).scalar_one_or_none()

        rows.append(SystemReportRow(
            system_id=str(sys.id),
            system_name=sys.name,
            total_tickets=total,
            open_tickets=total - resolved,
            resolved_tickets=resolved,
            urgent_tickets=urgent,
            avg_resolution_hours=round(float(avg_res_seconds) / 3600, 2) if avg_res_seconds else None,
        ))

    # Sin sistema asignado
    no_system = (await db.execute(
        select(func.count(Ticket.id)).where(
            and_(tenant_filter, Ticket.affected_system_id.is_(None))
        )
    )).scalar_one_or_none() or 0

    rows.sort(key=lambda r: r.total_tickets, reverse=True)

    return SystemReportResponse(
        period_start=period_start,
        period_end=period_end,
        generated_at=datetime.now(timezone.utc),
        systems=rows,
        no_system_count=no_system,
    )