"""
SLA Endpoints - ServiceManagerWeb

Endpoints para gestión y monitoreo de SLAs
Solo accesible por roles staff internos
"""

from fastapi import APIRouter, Depends, HTTPException, Query, status
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func, and_, or_, desc, case, cast
from sqlalchemy.orm import selectinload
from typing import Optional, List
from datetime import datetime, timedelta, timezone
import uuid
import structlog

from app.core.database import get_db
from app.api.deps import get_current_user, get_current_tenant
from app.models.user import User, UserRole
from app.models.tenant import Tenant
from app.models.ticket import Ticket, TicketStatus, TicketPriority
from app.models.category import Category
from app.api.schemas.sla import (
    SLADashboardResponse,
    SLAComplianceMetrics,
    SLAViolationResponse,
    SLAViolationsListResponse,
    SLAAtRiskListResponse,
    SLATicketAtRisk,
    SLADetailedMetricsResponse,
    SLAMetricsByCategory,
    SLAMetricsByAgent,
    SLAMetricsByPriority,
    SLATrendsResponse,
    SLADailyTrend,
    SLAConfigListResponse,
    SLAConfigByCategoryResponse,
    SLATypeEnum,
    TicketBasicInfo,
    UserBasicInfo,
    CategoryBasicInfo
)

router = APIRouter()
logger = structlog.get_logger(__name__)


def require_staff_role(current_user: User = Depends(get_current_user)) -> User:
    """Requiere roles de staff interno (ADMIN, SUPPORT_MANAGER, AGENT)"""
    allowed_roles = [UserRole.ADMIN, UserRole.SUPPORT_MANAGER, UserRole.AGENT, UserRole.AUDITOR]
    if current_user.role not in allowed_roles:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Solo staff interno puede acceder a métricas de SLA"
        )
    return current_user


def require_manager_role(current_user: User = Depends(get_current_user)) -> User:
    """Requiere roles de gestión (ADMIN, SUPPORT_MANAGER)"""
    if current_user.role not in [UserRole.ADMIN, UserRole.SUPPORT_MANAGER]:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Solo managers pueden acceder a esta funcionalidad"
        )
    return current_user


# ===================================
# DASHBOARD PRINCIPAL
# ===================================

@router.get("/dashboard", response_model=SLADashboardResponse)
async def get_sla_dashboard(
    days: int = Query(default=30, ge=1, le=365, description="Días hacia atrás para el período"),
    current_user: User = Depends(require_staff_role),
    current_tenant: Tenant = Depends(get_current_tenant),
    db: AsyncSession = Depends(get_db)
):
    """
    Dashboard principal de métricas SLA.
    
    **Permisos**: ADMIN, SUPPORT_MANAGER, AGENT, AUDITOR
    
    Retorna métricas agregadas de cumplimiento SLA para el período especificado.
    """
    logger.info(
        "SLA dashboard requested",
        user_id=str(current_user.id),
        tenant_id=str(current_tenant.id),
        days=days
    )
    
    now = datetime.now(timezone.utc).replace(tzinfo=None)
    period_start = now - timedelta(days=days)
    
    # Usar func.now() para comparaciones en SQL (evita timezone issues)
    db_now = func.now()
    
    # Query base para tickets del período
    base_query = select(Ticket).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.created_at >= period_start
        )
    )
    
    # Calcular métricas de Response SLA
    # Para "at risk": ticket pendiente que ha consumido >80% del tiempo disponible
    # Calculamos: (now - created_at) > 0.8 * (sla_response_due - created_at)
    response_query = select(
        func.count().label('total'),
        func.sum(case((Ticket.first_response_at <= Ticket.sla_response_due, 1), else_=0)).label('met'),
        func.sum(case((and_(Ticket.first_response_at > Ticket.sla_response_due, Ticket.first_response_at != None), 1), else_=0)).label('violated'),
        func.sum(case((and_(Ticket.first_response_at == None, Ticket.sla_response_due != None, db_now > Ticket.sla_response_due), 1), else_=0)).label('violated_pending'),
        func.sum(case((
            and_(
                Ticket.first_response_at == None,
                Ticket.sla_response_due != None,
                db_now < Ticket.sla_response_due,
                func.extract('epoch', db_now - Ticket.created_at) > (func.extract('epoch', Ticket.sla_response_due - Ticket.created_at) * 0.8)
            ), 1), else_=0)
        ).label('at_risk'),
        func.avg(
            func.extract('epoch', Ticket.first_response_at - Ticket.created_at) / 3600
        ).label('avg_hours')
    ).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.created_at >= period_start,
            Ticket.sla_response_due != None
        )
    )
    
    response_result = await db.execute(response_query)
    response_row = response_result.one()
    
    response_total = response_row.total or 0
    response_met = (response_row.met or 0)
    response_violated = (response_row.violated or 0) + (response_row.violated_pending or 0)
    response_at_risk = response_row.at_risk or 0
    response_avg = float(response_row.avg_hours) if response_row.avg_hours else 0.0
    response_compliance = (response_met / response_total * 100) if response_total > 0 else 0.0
    
    # Calcular métricas de Resolution SLA
    resolution_query = select(
        func.count().label('total'),
        func.sum(case((Ticket.resolved_at <= Ticket.sla_resolution_due, 1), else_=0)).label('met'),
        func.sum(case((and_(Ticket.resolved_at > Ticket.sla_resolution_due, Ticket.resolved_at != None), 1), else_=0)).label('violated'),
        func.sum(case((and_(Ticket.status.notin_([TicketStatus.RESOLVED, TicketStatus.CLOSED]), Ticket.sla_resolution_due != None, db_now > Ticket.sla_resolution_due), 1), else_=0)).label('violated_pending'),
        func.sum(case((
            and_(
                Ticket.status.notin_([TicketStatus.RESOLVED, TicketStatus.CLOSED]),
                Ticket.sla_resolution_due != None,
                db_now < Ticket.sla_resolution_due,
                func.extract('epoch', db_now - Ticket.created_at) > (func.extract('epoch', Ticket.sla_resolution_due - Ticket.created_at) * 0.8)
            ), 1), else_=0)
        ).label('at_risk'),
        func.avg(
            func.extract('epoch', Ticket.resolved_at - Ticket.created_at) / 3600
        ).label('avg_hours')
    ).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.created_at >= period_start,
            Ticket.sla_resolution_due != None
        )
    )
    
    resolution_result = await db.execute(resolution_query)
    resolution_row = resolution_result.one()
    
    resolution_total = resolution_row.total or 0
    resolution_met = (resolution_row.met or 0)
    resolution_violated = (resolution_row.violated or 0) + (resolution_row.violated_pending or 0)
    resolution_at_risk = resolution_row.at_risk or 0
    resolution_avg = float(resolution_row.avg_hours) if resolution_row.avg_hours else 0.0
    resolution_compliance = (resolution_met / resolution_total * 100) if resolution_total > 0 else 0.0
    
    # Métricas por categoría (top 5)
    category_query = select(
        Category.id,
        Category.name,
        func.count(Ticket.id).label('ticket_count'),
        func.avg(case((Ticket.first_response_at <= Ticket.sla_response_due, 100.0), else_=0.0)).label('response_compliance'),
        func.avg(case((Ticket.resolved_at <= Ticket.sla_resolution_due, 100.0), else_=0.0)).label('resolution_compliance')
    ).select_from(Ticket).join(
        Category, Ticket.category_id == Category.id, isouter=True
    ).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.created_at >= period_start
        )
    ).group_by(Category.id, Category.name).order_by(desc('ticket_count')).limit(5)
    
    category_result = await db.execute(category_query)
    by_category = [
        {
            "category_id": str(row.id) if row.id else None,
            "category_name": row.name or "Sin categoría",
            "ticket_count": row.ticket_count,
            "response_compliance": float(row.response_compliance or 0.0),
            "resolution_compliance": float(row.resolution_compliance or 0.0)
        }
        for row in category_result.all()
    ]
    
    # Métricas por prioridad
    by_priority = {}
    for priority in TicketPriority:
        priority_query = select(
            func.avg(case((Ticket.first_response_at <= Ticket.sla_response_due, 100.0), else_=0.0)).label('response'),
            func.avg(case((Ticket.resolved_at <= Ticket.sla_resolution_due, 100.0), else_=0.0)).label('resolution')
        ).where(
            and_(
                Ticket.tenant_id == current_tenant.id,
                Ticket.created_at >= period_start,
                Ticket.priority == priority
            )
        )
        
        priority_result = await db.execute(priority_query)
        priority_row = priority_result.one()
        
        by_priority[priority.value] = {
            "response_compliance": float(priority_row.response or 0.0),
            "resolution_compliance": float(priority_row.resolution or 0.0)
        }
    
    # Calcular tendencias (comparación con período anterior)
    prev_period_start = period_start - timedelta(days=days)
    prev_response_query = select(
        func.count().label('total'),
        func.sum(case((Ticket.first_response_at <= Ticket.sla_response_due, 1), else_=0)).label('met')
    ).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.created_at >= prev_period_start,
            Ticket.created_at < period_start,
            Ticket.sla_response_due != None
        )
    )
    
    prev_response_result = await db.execute(prev_response_query)
    prev_response_row = prev_response_result.one()
    prev_response_compliance = ((prev_response_row.met or 0) / (prev_response_row.total or 1) * 100) if (prev_response_row.total or 0) > 0 else 0.0
    
    response_trend = response_compliance - prev_response_compliance
    response_trend_str = f"+{response_trend:.1f}%" if response_trend >= 0 else f"{response_trend:.1f}%"
    
    prev_resolution_query = select(
        func.count().label('total'),
        func.sum(case((Ticket.resolved_at <= Ticket.sla_resolution_due, 1), else_=0)).label('met')
    ).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.created_at >= prev_period_start,
            Ticket.created_at < period_start,
            Ticket.sla_resolution_due != None
        )
    )
    
    prev_resolution_result = await db.execute(prev_resolution_query)
    prev_resolution_row = prev_resolution_result.one()
    prev_resolution_compliance = ((prev_resolution_row.met or 0) / (prev_resolution_row.total or 1) * 100) if (prev_resolution_row.total or 0) > 0 else 0.0
    
    resolution_trend = resolution_compliance - prev_resolution_compliance
    resolution_trend_str = f"+{resolution_trend:.1f}%" if resolution_trend >= 0 else f"{resolution_trend:.1f}%"
    
    # Contar violaciones activas
    active_violations_query = select(func.count()).select_from(Ticket).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.status.notin_([TicketStatus.RESOLVED, TicketStatus.CLOSED]),
            or_(
                and_(Ticket.first_response_at == None, Ticket.sla_response_due != None, db_now > Ticket.sla_response_due),
                and_(Ticket.resolved_at == None, Ticket.sla_resolution_due != None, db_now > Ticket.sla_resolution_due)
            )
        )
    )
    
    active_violations_result = await db.execute(active_violations_query)
    active_violations = active_violations_result.scalar() or 0
    
    # Contar total de tickets del período
    total_tickets_query = select(func.count()).select_from(Ticket).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.created_at >= period_start
        )
    )
    
    total_tickets_result = await db.execute(total_tickets_query)
    total_tickets_period = total_tickets_result.scalar() or 0
    
    return SLADashboardResponse(
        tenant_id=current_tenant.id,
        period_start=period_start,
        period_end=now,
        generated_at=now,
        response_sla=SLAComplianceMetrics(
            target_hours=2,  # Promedio, podría calcularse
            met_count=response_met,
            violated_count=response_violated,
            at_risk_count=response_at_risk,
            total_count=response_total,
            compliance_percentage=response_compliance,
            avg_time_hours=response_avg
        ),
        resolution_sla=SLAComplianceMetrics(
            target_hours=24,  # Promedio, podría calcularse
            met_count=resolution_met,
            violated_count=resolution_violated,
            at_risk_count=resolution_at_risk,
            total_count=resolution_total,
            compliance_percentage=resolution_compliance,
            avg_time_hours=resolution_avg
        ),
        active_violations=active_violations,
        at_risk_tickets=response_at_risk + resolution_at_risk,
        total_tickets_period=total_tickets_period,
        by_category=by_category,
        by_priority=by_priority,
        trends={
            "response_sla": response_trend_str,
            "resolution_sla": resolution_trend_str
        }
    )


# ===================================
# VIOLACIONES
# ===================================

@router.get("/violations", response_model=SLAViolationsListResponse)
async def get_sla_violations(
    skip: int = Query(default=0, ge=0),
    limit: int = Query(default=50, ge=1, le=100),
    sla_type: Optional[str] = Query(default=None, regex="^(response|resolution)$"),
    category_id: Optional[uuid.UUID] = None,
    priority: Optional[str] = None,
    current_user: User = Depends(require_staff_role),
    current_tenant: Tenant = Depends(get_current_tenant),
    db: AsyncSession = Depends(get_db)
):
    """
    Listar violaciones SLA activas.
    
    **Permisos**: ADMIN, SUPPORT_MANAGER, AGENT (solo sus tickets), AUDITOR
    
    Retorna tickets que han violado sus SLAs de respuesta o resolución.
    """
    logger.info(
        "SLA violations requested",
        user_id=str(current_user.id),
        tenant_id=str(current_tenant.id),
        sla_type=sla_type
    )
    
    now = datetime.now(timezone.utc).replace(tzinfo=None)
    db_now = func.now()
    
    # Base query con carga de relaciones
    query = select(Ticket).options(
        selectinload(Ticket.created_by_user),
        selectinload(Ticket.assigned_to_user),
        selectinload(Ticket.category)
    ).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.status.notin_([TicketStatus.RESOLVED, TicketStatus.CLOSED])
        )
    )
    
    # Filtrar por tipo de SLA
    if sla_type == "response":
        query = query.where(
            and_(
                Ticket.first_response_at == None,
                Ticket.sla_response_due != None,
                db_now > Ticket.sla_response_due
            )
        )
    elif sla_type == "resolution":
        query = query.where(
            and_(
                Ticket.sla_resolution_due != None,
                db_now > Ticket.sla_resolution_due
            )
        )
    else:
        # Ambos tipos
        query = query.where(
            or_(
                and_(Ticket.first_response_at == None, Ticket.sla_response_due != None, db_now > Ticket.sla_response_due),
                and_(Ticket.sla_resolution_due != None, db_now > Ticket.sla_resolution_due)
            )
        )
    
    # Filtros adicionales
    if category_id:
        query = query.where(Ticket.category_id == category_id)
    
    if priority:
        try:
            priority_enum = TicketPriority(priority.upper())
            query = query.where(Ticket.priority == priority_enum)
        except ValueError:
            pass
    
    # AGENTS solo ven sus tickets
    if current_user.role == UserRole.AGENT:
        query = query.where(Ticket.assigned_to == current_user.id)
    
    # Contar total
    count_query = select(func.count()).select_from(query.subquery())
    total_result = await db.execute(count_query)
    total = total_result.scalar() or 0
    
    # Obtener todos los tickets sin paginación primero (los ordenaremos por tiempo vencido después)
    result = await db.execute(query)
    tickets = result.scalars().all()
    
    # Formatear response
    violations = []
    for ticket in tickets:
        # Todos los campos son timezone-naive (TIMESTAMP WITHOUT TIME ZONE)
        sla_response_due = ticket.sla_response_due
        sla_resolution_due = ticket.sla_resolution_due
        
        # Determinar tipo de violación
        response_violated = ticket.first_response_at is None and sla_response_due and now > sla_response_due
        resolution_violated = sla_resolution_due and now > sla_resolution_due
        
        # Priorizar resolution si ambos están violados
        if resolution_violated:
            violation_type = SLATypeEnum.RESOLUTION
            due_at = sla_resolution_due
        else:
            violation_type = SLATypeEnum.RESPONSE
            due_at = sla_response_due
        
        hours_overdue = (now - due_at).total_seconds() / 3600 if due_at else 0
        
        # Las relaciones ya están cargadas por selectinload
        violations.append(SLAViolationResponse(
            ticket=TicketBasicInfo(
                id=ticket.id,
                ticket_number=ticket.ticket_number,
                subject=ticket.subject,
                priority=ticket.priority.value,
                status=ticket.status.value
            ),
            category=CategoryBasicInfo(
                id=ticket.category.id,
                name=ticket.category.name,
                sla_response_hours=ticket.category.sla_response_hours,
                sla_resolution_hours=ticket.category.sla_resolution_hours
            ) if ticket.category else None,
            created_by=UserBasicInfo(
                id=ticket.created_by_user.id,
                first_name=ticket.created_by_user.first_name,
                last_name=ticket.created_by_user.last_name,
                email=ticket.created_by_user.email
            ),
            assigned_to=UserBasicInfo(
                id=ticket.assigned_to_user.id,
                first_name=ticket.assigned_to_user.first_name,
                last_name=ticket.assigned_to_user.last_name,
                email=ticket.assigned_to_user.email
            ) if ticket.assigned_to_user else None,
            sla_type=violation_type,
            sla_due_at=due_at,
            violated_at=due_at,  # Se violó en el momento del due
            hours_overdue=hours_overdue,
            first_response_at=ticket.first_response_at,
            resolved_at=ticket.resolved_at
        ))
    
    # Ordenar por tiempo vencido (de mayor a menor)
    violations.sort(key=lambda v: v.hours_overdue, reverse=True)
    
    # Aplicar paginación en Python
    paginated_violations = violations[skip:skip + limit]
    
    total_pages = (total + limit - 1) // limit
    
    return SLAViolationsListResponse(
        violations=paginated_violations,
        total=total,
        page=(skip // limit) + 1,
        per_page=limit,
        total_pages=total_pages
    )


# ===================================
# TICKETS EN RIESGO
# ===================================

@router.get("/at-risk", response_model=SLAAtRiskListResponse)
async def get_tickets_at_risk(
    threshold: int = Query(default=80, ge=50, le=95, description="% de tiempo consumido para considerar en riesgo"),
    current_user: User = Depends(require_staff_role),
    current_tenant: Tenant = Depends(get_current_tenant),
    db: AsyncSession = Depends(get_db)
):
    """
    Listar tickets que están en riesgo de violar SLA.
    
    **Permisos**: ADMIN, SUPPORT_MANAGER, AGENT (solo sus tickets), AUDITOR
    
    Retorna tickets que están cerca de vencer su SLA (por defecto, 80% del tiempo consumido).
    """
    logger.info(
        "SLA at-risk tickets requested",
        user_id=str(current_user.id),
        tenant_id=str(current_tenant.id),
        threshold=threshold
    )
    
    now = datetime.now(timezone.utc).replace(tzinfo=None)
    db_now = func.now()
    threshold_decimal = threshold / 100.0
    
    # Query para tickets en riesgo con relaciones precargadas
    # Un ticket está en riesgo si: (now - created_at) / (due_at - created_at) >= threshold
    query = select(Ticket).options(
        selectinload(Ticket.assigned_to_user),
        selectinload(Ticket.category)
    ).where(
        and_(
            Ticket.tenant_id == current_tenant.id,
            Ticket.status.notin_([TicketStatus.RESOLVED, TicketStatus.CLOSED]),
            or_(
                # Response SLA en riesgo
                and_(
                    Ticket.first_response_at == None,
                    Ticket.sla_response_due != None,
                    db_now < Ticket.sla_response_due,
                    # Calcular si está en zona de riesgo
                    func.extract('epoch', db_now - Ticket.created_at) >= (func.extract('epoch', Ticket.sla_response_due - Ticket.created_at) * threshold_decimal)
                ),
                # Resolution SLA en riesgo
                and_(
                    Ticket.sla_resolution_due != None,
                    db_now < Ticket.sla_resolution_due,
                    func.extract('epoch', db_now - Ticket.created_at) >= (func.extract('epoch', Ticket.sla_resolution_due - Ticket.created_at) * threshold_decimal)
                )
            )
        )
    ).order_by(desc(Ticket.sla_response_due if Ticket.sla_response_due else Ticket.sla_resolution_due))
    
    # AGENTS solo ven sus tickets
    if current_user.role == UserRole.AGENT:
        query = query.where(Ticket.assigned_to == current_user.id)
    
    result = await db.execute(query)
    tickets = result.scalars().all()
    
    # Formatear response
    at_risk_tickets = []
    for ticket in tickets:
        # Determinar cuál SLA está en riesgo
        response_at_risk = (
            ticket.first_response_at is None and 
            ticket.sla_response_due and 
            now < ticket.sla_response_due
        )
        
        resolution_at_risk = (
            ticket.sla_resolution_due and 
            now < ticket.sla_resolution_due
        )
        
        # Priorizar response si ambos están en riesgo
        if response_at_risk:
            sla_type = SLATypeEnum.RESPONSE
            due_at = ticket.sla_response_due
        elif resolution_at_risk:
            sla_type = SLATypeEnum.RESOLUTION
            due_at = ticket.sla_resolution_due
        else:
            continue
        
        # Normalizar created_at a timezone-naive para evitar errores de comparación
        created_at = ticket.created_at.replace(tzinfo=None) if ticket.created_at.tzinfo else ticket.created_at
        
        time_remaining = (due_at - now).total_seconds() / 3600
        total_time = (due_at - created_at).total_seconds() / 3600
        elapsed_time = total_time - time_remaining
        risk_percentage = (elapsed_time / total_time * 100) if total_time > 0 else 0
        
        # Las relaciones ya están cargadas por selectinload
        at_risk_tickets.append(SLATicketAtRisk(
            ticket=TicketBasicInfo(
                id=ticket.id,
                ticket_number=ticket.ticket_number,
                subject=ticket.subject,
                priority=ticket.priority.value,
                status=ticket.status.value
            ),
            category=CategoryBasicInfo(
                id=ticket.category.id,
                name=ticket.category.name,
                sla_response_hours=ticket.category.sla_response_hours,
                sla_resolution_hours=ticket.category.sla_resolution_hours
            ) if ticket.category else None,
            assigned_to=UserBasicInfo(
                id=ticket.assigned_to_user.id,
                first_name=ticket.assigned_to_user.first_name,
                last_name=ticket.assigned_to_user.last_name,
                email=ticket.assigned_to_user.email
            ) if ticket.assigned_to_user else None,
            sla_type=sla_type,
            sla_due_at=due_at,
            time_remaining_hours=time_remaining,
            risk_percentage=risk_percentage
        ))
    
    return SLAAtRiskListResponse(
        tickets=at_risk_tickets,
        total=len(at_risk_tickets)
    )


# ===================================
# CONFIGURACIÓN
# ===================================

@router.get("/config", response_model=SLAConfigListResponse)
async def get_sla_config(
    current_user: User = Depends(require_manager_role),
    current_tenant: Tenant = Depends(get_current_tenant),
    db: AsyncSession = Depends(get_db)
):
    """
    Obtener configuración de SLAs por categoría.
    
    **Permisos**: ADMIN, SUPPORT_MANAGER
    
    Retorna la configuración de tiempos SLA para todas las categorías del tenant.
    """
    query = select(Category).where(
        Category.tenant_id == current_tenant.id
    ).order_by(Category.name)
    
    result = await db.execute(query)
    categories = result.scalars().all()
    
    return SLAConfigListResponse(
        tenant_id=current_tenant.id,
        categories=[
            SLAConfigByCategoryResponse(
                category_id=cat.id,
                category_name=cat.name,
                sla_response_hours=cat.sla_response_hours,
                sla_resolution_hours=cat.sla_resolution_hours,
                warning_threshold_percentage=80,  # Por ahora hardcoded
                is_active=cat.is_active
            )
            for cat in categories
        ]
    )