# app/modules/messaging/services/admin_notification_service.py
"""
Admin notification service.

Provides functionality for:
- Creating and managing admin notifications
- Managing platform alerts
- Notification statistics and queries
"""

from __future__ import annotations

import logging
from datetime import datetime, timedelta
from typing import Any

from sqlalchemy import and_, case
from sqlalchemy.orm import Session

from app.modules.messaging.models.admin_notification import AdminNotification
from app.modules.tenancy.schemas.admin import (
    AdminNotificationCreate,
    PlatformAlertCreate,
)

logger = logging.getLogger(__name__)


def _get_platform_alert_model():
    """Deferred import for PlatformAlert model (lives in tenancy, consumed by messaging)."""
    from app.modules.tenancy.models import PlatformAlert

    return PlatformAlert


# ============================================================================
# NOTIFICATION TYPES
# ============================================================================

class NotificationType:
    """Notification type constants."""

    SYSTEM_ALERT = "system_alert"
    IMPORT_FAILURE = "import_failure"
    EXPORT_FAILURE = "export_failure"
    ORDER_SYNC_FAILURE = "order_sync_failure"
    STORE_ISSUE = "store_issue"
    CUSTOMER_MESSAGE = "customer_message"
    STORE_MESSAGE = "store_message"
    SECURITY_ALERT = "security_alert"
    PERFORMANCE_ALERT = "performance_alert"
    ORDER_EXCEPTION = "order_exception"
    CRITICAL_ERROR = "critical_error"


class Priority:
    """Priority level constants."""

    LOW = "low"
    NORMAL = "normal"
    HIGH = "high"
    CRITICAL = "critical"


class AlertType:
    """Platform alert type constants."""

    SECURITY = "security"
    PERFORMANCE = "performance"
    CAPACITY = "capacity"
    INTEGRATION = "integration"
    DATABASE = "database"
    SYSTEM = "system"


class Severity:
    """Alert severity constants."""

    INFO = "info"
    WARNING = "warning"
    ERROR = "error"
    CRITICAL = "critical"


# ============================================================================
# ADMIN NOTIFICATION SERVICE
# ============================================================================


class AdminNotificationService:
    """Service for managing admin notifications."""

    def create_notification(
        self,
        db: Session,
        notification_type: str,
        title: str,
        message: str,
        priority: str = Priority.NORMAL,
        action_required: bool = False,
        action_url: str | None = None,
        metadata: dict[str, Any] | None = None,
    ) -> AdminNotification:
        """
        Create a new admin notification.

        Args:
            db: Database session
            notification_type: Type of notification
            title: Notification title
            message: Notification message
            priority: Priority level (low, normal, high, critical)
            action_required: Whether action is required
            action_url: URL to relevant admin page
            metadata: Additional contextual data

        Returns:
            Created AdminNotification
        """
        notification = AdminNotification(
            type=notification_type,
            title=title,
            message=message,
            priority=priority,
            action_required=action_required,
            action_url=action_url,
            notification_metadata=metadata,
        )
        db.add(notification)
        db.flush()

        logger.info(
            f"Created notification: {notification_type} - {title} (priority: {priority})"
        )

        return notification

    def create_from_schema(
        self,
        db: Session,
        data: AdminNotificationCreate,
    ) -> AdminNotification:
        """Create notification from Pydantic schema."""
        return self.create_notification(
            db=db,
            notification_type=data.type,
            title=data.title,
            message=data.message,
            priority=data.priority,
            action_required=data.action_required,
            action_url=data.action_url,
            metadata=data.metadata,
        )

    def get_notifications(
        self,
        db: Session,
        priority: str | None = None,
        is_read: bool | None = None,
        notification_type: str | None = None,
        skip: int = 0,
        limit: int = 50,
    ) -> tuple[list[AdminNotification], int, int]:
        """
        Get paginated admin notifications.

        Returns:
            Tuple of (notifications, total_count, unread_count)
        """
        query = db.query(AdminNotification)

        # Apply filters
        if priority:
            query = query.filter(AdminNotification.priority == priority)

        if is_read is not None:
            query = query.filter(AdminNotification.is_read == is_read)

        if notification_type:
            query = query.filter(AdminNotification.type == notification_type)

        # Get counts
        total = query.count()
        unread_count = (
            db.query(AdminNotification)
            .filter(AdminNotification.is_read == False)  # noqa: E712
            .count()
        )

        # Get paginated results ordered by priority and date
        priority_order = case(
            (AdminNotification.priority == "critical", 1),
            (AdminNotification.priority == "high", 2),
            (AdminNotification.priority == "normal", 3),
            (AdminNotification.priority == "low", 4),
            else_=5,
        )

        notifications = (
            query.order_by(
                AdminNotification.is_read,  # Unread first
                priority_order,
                AdminNotification.created_at.desc(),
            )
            .offset(skip)
            .limit(limit)
            .all()
        )

        return notifications, total, unread_count

    def get_unread_count(self, db: Session) -> int:
        """Get count of unread notifications."""
        return (
            db.query(AdminNotification)
            .filter(AdminNotification.is_read == False)  # noqa: E712
            .count()
        )

    def get_recent_notifications(
        self,
        db: Session,
        limit: int = 5,
    ) -> list[AdminNotification]:
        """Get recent unread notifications for header dropdown."""
        priority_order = case(
            (AdminNotification.priority == "critical", 1),
            (AdminNotification.priority == "high", 2),
            (AdminNotification.priority == "normal", 3),
            (AdminNotification.priority == "low", 4),
            else_=5,
        )

        return (
            db.query(AdminNotification)
            .filter(AdminNotification.is_read == False)  # noqa: E712
            .order_by(priority_order, AdminNotification.created_at.desc())
            .limit(limit)
            .all()
        )

    def mark_as_read(
        self,
        db: Session,
        notification_id: int,
        user_id: int,
    ) -> AdminNotification | None:
        """Mark a notification as read."""
        notification = (
            db.query(AdminNotification)
            .filter(AdminNotification.id == notification_id)
            .first()
        )

        if notification and not notification.is_read:
            notification.is_read = True
            notification.read_at = datetime.utcnow()
            notification.read_by_user_id = user_id
            db.flush()

        return notification

    def mark_all_as_read(
        self,
        db: Session,
        user_id: int,
    ) -> int:
        """Mark all unread notifications as read. Returns count of updated."""
        now = datetime.utcnow()
        count = (
            db.query(AdminNotification)
            .filter(AdminNotification.is_read == False)  # noqa: E712
            .update(
                {
                    AdminNotification.is_read: True,
                    AdminNotification.read_at: now,
                    AdminNotification.read_by_user_id: user_id,
                }
            )
        )
        db.flush()
        return count

    def delete_old_notifications(
        self,
        db: Session,
        days: int = 30,
    ) -> int:
        """Delete notifications older than specified days."""
        cutoff = datetime.utcnow() - timedelta(days=days)
        count = (
            db.query(AdminNotification)
            .filter(
                and_(
                    AdminNotification.is_read == True,  # noqa: E712
                    AdminNotification.created_at < cutoff,
                )
            )
            .delete()
        )
        db.flush()
        return count

    def delete_notification(
        self,
        db: Session,
        notification_id: int,
    ) -> bool:
        """
        Delete a notification by ID.

        Returns:
            True if notification was deleted, False if not found.
        """
        notification = (
            db.query(AdminNotification)
            .filter(AdminNotification.id == notification_id)
            .first()
        )

        if notification:
            db.delete(notification)
            db.flush()
            logger.info(f"Deleted notification {notification_id}")
            return True

        return False

    # =========================================================================
    # CONVENIENCE METHODS FOR CREATING SPECIFIC NOTIFICATION TYPES
    # =========================================================================

    def notify_import_failure(
        self,
        db: Session,
        store_name: str,
        job_id: int,
        error_message: str,
        store_id: int | None = None,
    ) -> AdminNotification:
        """Create notification for import job failure."""
        return self.create_notification(
            db=db,
            notification_type=NotificationType.IMPORT_FAILURE,
            title=f"Import Failed: {store_name}",
            message=error_message,
            priority=Priority.HIGH,
            action_required=True,
            action_url=f"/admin/marketplace/letzshop?store_id={store_id}&tab=jobs"
            if store_id
            else "/admin/marketplace",
            metadata={"store_name": store_name, "job_id": job_id, "store_id": store_id},
        )

    def notify_order_sync_failure(
        self,
        db: Session,
        store_name: str,
        error_message: str,
        store_id: int | None = None,
    ) -> AdminNotification:
        """Create notification for order sync failure."""
        return self.create_notification(
            db=db,
            notification_type=NotificationType.ORDER_SYNC_FAILURE,
            title=f"Order Sync Failed: {store_name}",
            message=error_message,
            priority=Priority.HIGH,
            action_required=True,
            action_url=f"/admin/marketplace/letzshop?store_id={store_id}&tab=jobs"
            if store_id
            else "/admin/marketplace/letzshop",
            metadata={"store_name": store_name, "store_id": store_id},
        )

    def notify_order_exception(
        self,
        db: Session,
        store_name: str,
        order_number: str,
        exception_count: int,
        store_id: int | None = None,
    ) -> AdminNotification:
        """Create notification for order item exceptions."""
        return self.create_notification(
            db=db,
            notification_type=NotificationType.ORDER_EXCEPTION,
            title=f"Order Exception: {order_number}",
            message=f"{exception_count} item(s) need attention for order {order_number} ({store_name})",
            priority=Priority.NORMAL,
            action_required=True,
            action_url=f"/admin/marketplace/letzshop?store_id={store_id}&tab=exceptions"
            if store_id
            else "/admin/marketplace/letzshop",
            metadata={
                "store_name": store_name,
                "order_number": order_number,
                "exception_count": exception_count,
                "store_id": store_id,
            },
        )

    def notify_critical_error(
        self,
        db: Session,
        error_type: str,
        error_message: str,
        details: dict[str, Any] | None = None,
    ) -> AdminNotification:
        """Create notification for critical application errors."""
        return self.create_notification(
            db=db,
            notification_type=NotificationType.CRITICAL_ERROR,
            title=f"Critical Error: {error_type}",
            message=error_message,
            priority=Priority.CRITICAL,
            action_required=True,
            action_url="/admin/logs",
            metadata=details,
        )

    def notify_store_issue(
        self,
        db: Session,
        store_name: str,
        issue_type: str,
        message: str,
        store_id: int | None = None,
    ) -> AdminNotification:
        """Create notification for store-related issues."""
        return self.create_notification(
            db=db,
            notification_type=NotificationType.STORE_ISSUE,
            title=f"Store Issue: {store_name}",
            message=message,
            priority=Priority.HIGH,
            action_required=True,
            action_url=f"/admin/stores/{store_id}" if store_id else "/admin/stores",
            metadata={
                "store_name": store_name,
                "issue_type": issue_type,
                "store_id": store_id,
            },
        )

    def notify_security_alert(
        self,
        db: Session,
        title: str,
        message: str,
        details: dict[str, Any] | None = None,
    ) -> AdminNotification:
        """Create notification for security-related alerts."""
        return self.create_notification(
            db=db,
            notification_type=NotificationType.SECURITY_ALERT,
            title=title,
            message=message,
            priority=Priority.CRITICAL,
            action_required=True,
            action_url="/admin/audit",
            metadata=details,
        )


# ============================================================================
# PLATFORM ALERT SERVICE
# ============================================================================


class PlatformAlertService:
    """Service for managing platform-wide alerts."""

    def create_alert(
        self,
        db: Session,
        alert_type: str,
        severity: str,
        title: str,
        description: str | None = None,
        affected_stores: list[int] | None = None,
        affected_systems: list[str] | None = None,
        auto_generated: bool = True,
    ) -> PlatformAlert:
        """Create a new platform alert."""
        PlatformAlert = _get_platform_alert_model()
        now = datetime.utcnow()

        alert = PlatformAlert(
            alert_type=alert_type,
            severity=severity,
            title=title,
            description=description,
            affected_stores=affected_stores,
            affected_systems=affected_systems,
            auto_generated=auto_generated,
            first_occurred_at=now,
            last_occurred_at=now,
        )
        db.add(alert)
        db.flush()

        logger.info(f"Created platform alert: {alert_type} - {title} ({severity})")

        return alert

    def create_from_schema(
        self,
        db: Session,
        data: PlatformAlertCreate,
    ) -> PlatformAlert:
        """Create alert from Pydantic schema."""
        return self.create_alert(
            db=db,
            alert_type=data.alert_type,
            severity=data.severity,
            title=data.title,
            description=data.description,
            affected_stores=data.affected_stores,
            affected_systems=data.affected_systems,
            auto_generated=data.auto_generated,
        )

    def get_alerts(
        self,
        db: Session,
        severity: str | None = None,
        alert_type: str | None = None,
        is_resolved: bool | None = None,
        skip: int = 0,
        limit: int = 50,
    ) -> tuple[list[PlatformAlert], int, int, int]:
        """
        Get paginated platform alerts.

        Returns:
            Tuple of (alerts, total_count, active_count, critical_count)
        """
        PlatformAlert = _get_platform_alert_model()
        query = db.query(PlatformAlert)

        # Apply filters
        if severity:
            query = query.filter(PlatformAlert.severity == severity)

        if alert_type:
            query = query.filter(PlatformAlert.alert_type == alert_type)

        if is_resolved is not None:
            query = query.filter(PlatformAlert.is_resolved == is_resolved)

        # Get counts
        total = query.count()
        active_count = (
            db.query(PlatformAlert)
            .filter(PlatformAlert.is_resolved == False)  # noqa: E712
            .count()
        )
        critical_count = (
            db.query(PlatformAlert)
            .filter(
                and_(
                    PlatformAlert.is_resolved == False,  # noqa: E712
                    PlatformAlert.severity == Severity.CRITICAL,
                )
            )
            .count()
        )

        # Get paginated results
        severity_order = case(
            (PlatformAlert.severity == "critical", 1),
            (PlatformAlert.severity == "error", 2),
            (PlatformAlert.severity == "warning", 3),
            (PlatformAlert.severity == "info", 4),
            else_=5,
        )

        alerts = (
            query.order_by(
                PlatformAlert.is_resolved,  # Unresolved first
                severity_order,
                PlatformAlert.last_occurred_at.desc(),
            )
            .offset(skip)
            .limit(limit)
            .all()
        )

        return alerts, total, active_count, critical_count

    def resolve_alert(
        self,
        db: Session,
        alert_id: int,
        user_id: int,
        resolution_notes: str | None = None,
    ) -> PlatformAlert | None:
        """Resolve a platform alert."""
        PlatformAlert = _get_platform_alert_model()
        alert = db.query(PlatformAlert).filter(PlatformAlert.id == alert_id).first()

        if alert and not alert.is_resolved:
            alert.is_resolved = True
            alert.resolved_at = datetime.utcnow()
            alert.resolved_by_user_id = user_id
            alert.resolution_notes = resolution_notes
            db.flush()

            logger.info(f"Resolved platform alert {alert_id}")

        return alert

    def get_statistics(self, db: Session) -> dict[str, int]:
        """Get alert statistics."""
        PlatformAlert = _get_platform_alert_model()
        today_start = datetime.utcnow().replace(hour=0, minute=0, second=0, microsecond=0)

        total = db.query(PlatformAlert).count()
        active = (
            db.query(PlatformAlert)
            .filter(PlatformAlert.is_resolved == False)  # noqa: E712
            .count()
        )
        critical = (
            db.query(PlatformAlert)
            .filter(
                and_(
                    PlatformAlert.is_resolved == False,  # noqa: E712
                    PlatformAlert.severity == Severity.CRITICAL,
                )
            )
            .count()
        )
        resolved_today = (
            db.query(PlatformAlert)
            .filter(
                and_(
                    PlatformAlert.is_resolved == True,  # noqa: E712
                    PlatformAlert.resolved_at >= today_start,
                )
            )
            .count()
        )

        return {
            "total_alerts": total,
            "active_alerts": active,
            "critical_alerts": critical,
            "resolved_today": resolved_today,
        }

    def increment_occurrence(
        self,
        db: Session,
        alert_id: int,
    ) -> PlatformAlert | None:
        """Increment occurrence count for repeated alert."""
        PlatformAlert = _get_platform_alert_model()
        alert = db.query(PlatformAlert).filter(PlatformAlert.id == alert_id).first()

        if alert:
            alert.occurrence_count += 1
            alert.last_occurred_at = datetime.utcnow()
            db.flush()

        return alert

    def find_similar_active_alert(
        self,
        db: Session,
        alert_type: str,
        title: str,
    ) -> PlatformAlert | None:
        """Find an active alert with same type and title."""
        PlatformAlert = _get_platform_alert_model()
        return (
            db.query(PlatformAlert)
            .filter(
                and_(
                    PlatformAlert.alert_type == alert_type,
                    PlatformAlert.title == title,
                    PlatformAlert.is_resolved == False,  # noqa: E712
                )
            )
            .first()
        )

    def create_or_increment_alert(
        self,
        db: Session,
        alert_type: str,
        severity: str,
        title: str,
        description: str | None = None,
        affected_stores: list[int] | None = None,
        affected_systems: list[str] | None = None,
    ) -> PlatformAlert:
        """Create alert or increment occurrence if similar exists."""
        existing = self.find_similar_active_alert(db, alert_type, title)

        if existing:
            self.increment_occurrence(db, existing.id)
            return existing

        return self.create_alert(
            db=db,
            alert_type=alert_type,
            severity=severity,
            title=title,
            description=description,
            affected_stores=affected_stores,
            affected_systems=affected_systems,
        )


# Singleton instances
admin_notification_service = AdminNotificationService()
platform_alert_service = PlatformAlertService()