"""
Django views for monitoring and metrics endpoints.
"""

import json
from datetime import datetime, timedelta
from typing import Dict, Any, Optional
from django.http import JsonResponse, HttpResponse
from django.views.generic import TemplateView
from django.contrib.auth.mixins import LoginRequiredMixin
from django.db import connection
from django.utils import timezone
from django.conf import settings
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import status
from prometheus_client import generate_latest, REGISTRY, CONTENT_TYPE_LATEST
from prometheus_client.parser import text_string_to_metric_families

from .middleware import MetricsView
from .exporters import metrics_collector
from .alerts import alert_manager, Alert, AlertSeverity, AlertCategory

class MetricsView(APIView):
    """View for Prometheus metrics endpoint."""

    def get(self, request):
        """Get Prometheus metrics."""
        try:
            # Collect current metrics
            metrics_collector.collect_once()

            # Generate Prometheus format
            metrics_data = generate_latest(REGISTRY)
            return HttpResponse(
                metrics_data,
                content_type=CONTENT_TYPE_LATEST
            )
        except Exception as e:
            return JsonResponse(
                {'error': f'Failed to generate metrics: {str(e)}'},
                status=status.HTTP_500_INTERNAL_SERVER_ERROR
            )

class HealthCheckView(APIView):
    """Health check endpoint."""

    def get(self, request):
        """Comprehensive health check."""
        try:
            health_status = {
                'status': 'healthy',
                'timestamp': timezone.now().isoformat(),
                'version': getattr(settings, 'VERSION', '1.0.0'),
                'environment': getattr(settings, 'ENVIRONMENT', 'development'),
                'checks': {}
            }

            # Database health
            try:
                with connection.cursor() as cursor:
                    cursor.execute("SELECT 1")
                    cursor.fetchone()
                health_status['checks']['database'] = {
                    'status': 'healthy',
                    'response_time': self._measure_response_time(self._check_database)
                }
            except Exception as e:
                health_status['checks']['database'] = {
                    'status': 'unhealthy',
                    'error': str(e)
                }
                health_status['status'] = 'degraded'

            # Cache health
            try:
                from django.core.cache import cache
                cache.set('health_check', 'test', 1)
                cache.get('health_check')
                health_status['checks']['cache'] = {
                    'status': 'healthy',
                    'response_time': self._measure_response_time(self._check_cache)
                }
            except Exception as e:
                health_status['checks']['cache'] = {
                    'status': 'unhealthy',
                    'error': str(e)
                }
                health_status['status'] = 'degraded'

            # Storage health
            try:
                storage_health = self._check_storage()
                health_status['checks']['storage'] = storage_health
                if storage_health['status'] != 'healthy':
                    health_status['status'] = 'degraded'
            except Exception as e:
                health_status['checks']['storage'] = {
                    'status': 'unhealthy',
                    'error': str(e)
                }
                health_status['status'] = 'degraded'

            # External services health
            external_services = self._check_external_services()
            health_status['checks']['external_services'] = external_services
            if any(service['status'] != 'healthy' for service in external_services.values()):
                health_status['status'] = 'degraded'

            # Malaysian services health
            malaysian_services = self._check_malaysian_services()
            health_status['checks']['malaysian_services'] = malaysian_services
            if any(service['status'] != 'healthy' for service in malaysian_services.values()):
                health_status['status'] = 'degraded'

            # Determine HTTP status code
            if health_status['status'] == 'healthy':
                http_status = status.HTTP_200_OK
            elif health_status['status'] == 'degraded':
                http_status = status.HTTP_503_SERVICE_UNAVAILABLE
            else:
                http_status = status.HTTP_500_INTERNAL_SERVER_ERROR

            return Response(health_status, status=http_status)

        except Exception as e:
            return Response(
                {'status': 'unhealthy', 'error': str(e)},
                status=status.HTTP_500_INTERNAL_SERVER_ERROR
            )

    def _measure_response_time(self, func) -> float:
        """Measure response time of a function."""
        import time
        start_time = time.time()
        func()
        return time.time() - start_time

    def _check_database(self):
        """Check database connectivity."""
        with connection.cursor() as cursor:
            cursor.execute("SELECT 1")
            cursor.fetchone()

    def _check_cache(self):
        """Check cache functionality."""
        from django.core.cache import cache
        cache.set('health_check', 'test', 1)
        result = cache.get('health_check')
        if result != 'test':
            raise Exception("Cache functionality failed")

    def _check_storage(self) -> Dict[str, Any]:
        """Check storage availability."""
        try:
            import os
            # Check media directory
            media_path = getattr(settings, 'MEDIA_ROOT', '/media')
            if not os.path.exists(media_path):
                return {'status': 'unhealthy', 'error': 'Media directory not found'}

            # Check write permissions
            test_file = os.path.join(media_path, 'health_check_test.tmp')
            try:
                with open(test_file, 'w') as f:
                    f.write('test')
                os.remove(test_file)
            except Exception as e:
                return {'status': 'unhealthy', 'error': f'Write permission error: {str(e)}'}

            # Check disk space
            disk_usage = os.statvfs(media_path)
            free_space_percent = (disk_usage.f_bavail * disk_usage.f_frsize) / (disk_usage.f_blocks * disk_usage.f_frsize) * 100

            if free_space_percent < 10:
                return {
                    'status': 'degraded',
                    'error': f'Low disk space: {free_space_percent:.1f}% free'
                }

            return {'status': 'healthy', 'free_space_percent': free_space_percent}

        except Exception as e:
            return {'status': 'unhealthy', 'error': str(e)}

    def _check_external_services(self) -> Dict[str, Dict[str, Any]]:
        """Check external services health."""
        services = {}

        # Check email service
        try:
            from django.core.mail import get_connection
            connection = get_connection()
            connection.open()
            connection.close()
            services['email'] = {'status': 'healthy'}
        except Exception as e:
            services['email'] = {'status': 'unhealthy', 'error': str(e)}

        # Check Redis (if configured)
        try:
            import redis
            redis_client = redis.from_url(settings.REDIS_URL)
            redis_client.ping()
            services['redis'] = {'status': 'healthy'}
        except Exception as e:
            services['redis'] = {'status': 'unhealthy', 'error': str(e)}

        # Check external APIs (if configured)
        external_apis = getattr(settings, 'EXTERNAL_APIS', {})
        for api_name, api_config in external_apis.items():
            try:
                import requests
                response = requests.get(
                    api_config['health_url'],
                    timeout=api_config.get('timeout', 5)
                )
                if response.status_code == 200:
                    services[api_name] = {'status': 'healthy'}
                else:
                    services[api_name] = {
                        'status': 'unhealthy',
                        'error': f'HTTP {response.status_code}'
                    }
            except Exception as e:
                services[api_name] = {'status': 'unhealthy', 'error': str(e)}

        return services

    def _check_malaysian_services(self) -> Dict[str, Dict[str, Any]]:
        """Check Malaysian-specific services."""
        services = {}

        # Check Malaysian postcode service
        try:
            from core.services.malaysian_services import MalaysianPostcodeService
            postcode_service = MalaysianPostcodeService()
            result = postcode_service.lookup_postcode('50000')
            services['postcode_service'] = {
                'status': 'healthy' if result else 'degraded'
            }
        except Exception as e:
            services['postcode_service'] = {'status': 'unhealthy', 'error': str(e)}

        # Check SST calculation service
        try:
            from core.services.malaysian_services import SSTCalculationService
            sst_service = SSTCalculationService()
            result = sst_service.calculate_sst(100, 'standard', 'Johor')
            services['sst_service'] = {
                'status': 'healthy' if result is not None else 'degraded'
            }
        except Exception as e:
            services['sst_service'] = {'status': 'unhealthy', 'error': str(e)}

        # Check IC validation service
        try:
            from core.services.malaysian_services import ICValidationService
            ic_service = ICValidationService()
            result = ic_service.validate_ic('1234567890')
            services['ic_validation_service'] = {
                'status': 'healthy' if result is not None else 'degraded'
            }
        except Exception as e:
            services['ic_validation_service'] = {'status': 'unhealthy', 'error': str(e)}

        return services

class AlertsView(APIView):
    """Alerts management endpoint."""

    def get(self, request):
        """Get alerts."""
        try:
            # Check for new alerts
            alert_manager.check_rules()

            # Get query parameters
            severity = request.query_params.get('severity')
            category = request.query_params.get('category')
            status = request.query_params.get('status', 'active')
            hours = int(request.query_params.get('hours', 24))

            # Get alerts
            if status == 'active':
                alerts = alert_manager.get_active_alerts(severity=severity, category=category)
            else:
                alerts = alert_manager.get_alert_history(hours=hours)
                if severity:
                    alerts = [a for a in alerts if a.severity == severity]
                if category:
                    alerts = [a for a in alerts if a.category == category]

            # Convert to response format
            response_data = {
                'alerts': [alert.to_dict() for alert in alerts],
                'summary': self._get_alerts_summary(alerts),
                'timestamp': timezone.now().isoformat()
            }

            return Response(response_data)

        except Exception as e:
            return Response(
                {'error': f'Failed to get alerts: {str(e)}'},
                status=status.HTTP_500_INTERNAL_SERVER_ERROR
            )

    def post(self, request):
        """Create manual alert."""
        try:
            data = request.data

            alert = Alert(
                title=data['title'],
                description=data['description'],
                severity=data.get('severity', AlertSeverity.INFO),
                category=data.get('category', AlertCategory.SYSTEM),
                metadata=data.get('metadata', {})
            )

            alert_manager.trigger_alert(alert)

            return Response(
                {'message': 'Alert created successfully', 'alert_id': alert.id},
                status=status.HTTP_201_CREATED
            )

        except Exception as e:
            return Response(
                {'error': f'Failed to create alert: {str(e)}'},
                status=status.HTTP_500_INTERNAL_SERVER_ERROR
            )

    def _get_alerts_summary(self, alerts) -> Dict[str, Any]:
        """Get alerts summary statistics."""
        summary = {
            'total': len(alerts),
            'by_severity': {},
            'by_category': {},
            'by_status': {}
        }

        for alert in alerts:
            # Count by severity
            summary['by_severity'][alert.severity] = summary['by_severity'].get(alert.severity, 0) + 1

            # Count by category
            summary['by_category'][alert.category] = summary['by_category'].get(alert.category, 0) + 1

            # Count by status
            status = alert.get_status()
            summary['by_status'][status] = summary['by_status'].get(status, 0) + 1

        return summary

class AlertActionView(APIView):
    """Alert management actions."""

    def post(self, request, alert_id: str, action: str):
        """Perform alert actions."""
        try:
            if action == 'acknowledge':
                user = request.user.username if request.user.is_authenticated else 'api_user'
                alert_manager.acknowledge_alert(alert_id, user)
                return Response({'message': f'Alert {alert_id} acknowledged'})

            elif action == 'resolve':
                user = request.user.username if request.user.is_authenticated else 'api_user'
                alert_manager.resolve_alert(alert_id, user)
                return Response({'message': f'Alert {alert_id} resolved'})

            else:
                return Response(
                    {'error': f'Unknown action: {action}'},
                    status=status.HTTP_400_BAD_REQUEST
                )

        except Exception as e:
            return Response(
                {'error': f'Failed to perform action {action} on alert {alert_id}: {str(e)}'},
                status=status.HTTP_500_INTERNAL_SERVER_ERROR
            )

class MonitoringDashboardView(LoginRequiredMixin, TemplateView):
    """Monitoring dashboard template view."""

    template_name = 'monitoring/dashboard.html'

    def get_context_data(self, **kwargs):
        """Get dashboard context data."""
        context = super().get_context_data(**kwargs)

        # Get current alerts
        context['active_alerts'] = alert_manager.get_active_alerts()
        context['alert_summary'] = self._get_alerts_summary(context['active_alerts'])

        # Get system metrics
        context['system_metrics'] = self._get_system_metrics()

        # Get business metrics
        context['business_metrics'] = self._get_business_metrics()

        # Malaysian-specific metrics
        context['malaysian_metrics'] = self._get_malaysian_metrics()

        return context

    def _get_alerts_summary(self, alerts) -> Dict[str, Any]:
        """Get alerts summary."""
        summary = {
            'total': len(alerts),
            'critical': len([a for a in alerts if a.severity == AlertSeverity.CRITICAL]),
            'error': len([a for a in alerts if a.severity == AlertSeverity.ERROR]),
            'warning': len([a for a in alerts if a.severity == AlertSeverity.WARNING]),
            'info': len([a for a in alerts if a.severity == AlertSeverity.INFO]),
        }
        return summary

    def _get_system_metrics(self) -> Dict[str, Any]:
        """Get system metrics."""
        try:
            import psutil

            return {
                'cpu_usage': psutil.cpu_percent(interval=1),
                'memory_usage': psutil.virtual_memory().percent,
                'disk_usage': psutil.disk_usage('/').percent,
                'load_average': psutil.getloadavg()[0],
                'uptime': datetime.now() - datetime.fromtimestamp(psutil.boot_time()),
            }
        except Exception:
            return {}

    def _get_business_metrics(self) -> Dict[str, Any]:
        """Get business metrics."""
        try:
            from django.contrib.auth import get_user_model
            from core.models import Transaction

            User = get_user_model()

            # Active users
            active_users = User.objects.filter(
                is_active=True,
                last_login__gte=timezone.now() - timedelta(minutes=30)
            ).count()

            # Today's transactions
            today_transactions = Transaction.objects.filter(
                created_at__date=timezone.now().date(),
                status='completed'
            ).count()

            return {
                'active_users': active_users,
                'today_transactions': today_transactions,
            }
        except Exception:
            return {}

    def _get_malaysian_metrics(self) -> Dict[str, Any]:
        """Get Malaysian-specific metrics."""
        try:
            from core.models import MalaysianICValidation, SSTCalculation

            return {
                'ic_validations_today': MalaysianICValidation.objects.filter(
                    created_at__date=timezone.now().date()
                ).count(),
                'sst_calculations_today': SSTCalculation.objects.filter(
                    created_at__date=timezone.now().date()
                ).count(),
            }
        except Exception:
            return {}

class MetricsDashboardView(LoginRequiredMixin, TemplateView):
    """Metrics dashboard template view."""

    template_name = 'monitoring/metrics_dashboard.html'