"""
Complaints analytics service

Provides analytics and metrics for complaints dashboard integration.
"""
from datetime import datetime, timedelta
from typing import Dict, List, Optional

from django.db.models import Count, Q, Avg, F, ExpressionWrapper, DurationField
from django.utils import timezone

from apps.complaints.models import Complaint, ComplaintStatus


class ComplaintAnalytics:
    """Service for complaint analytics and metrics"""
    
    @staticmethod
    def get_complaint_trends(hospital=None, date_range=30):
        """
        Get complaint trends over time.
        
        Args:
            hospital: Optional hospital to filter by
            date_range: Number of days to analyze (default 30)
        
        Returns:
            dict: Trend data with dates and counts
        """
        end_date = timezone.now()
        start_date = end_date - timedelta(days=date_range)
        
        queryset = Complaint.objects.filter(
            created_at__gte=start_date,
            created_at__lte=end_date
        )
        
        if hospital:
            queryset = queryset.filter(hospital=hospital)
        
        # Group by date
        trends = queryset.extra(
            select={'date': 'DATE(created_at)'}
        ).values('date').annotate(
            count=Count('id')
        ).order_by('date')
        
        # Convert dates to strings
        labels = []
        data = []
        for item in trends:
            date_val = item['date']
            # Handle both date objects and strings
            if isinstance(date_val, str):
                labels.append(date_val)
            else:
                labels.append(date_val.strftime('%Y-%m-%d'))
            data.append(item['count'])
        
        return {
            'labels': labels,
            'data': data,
            'total': queryset.count()
        }
    
    @staticmethod
    def get_sla_compliance(hospital=None, date_range=30):
        """
        Calculate SLA compliance metrics.
        
        Args:
            hospital: Optional hospital to filter by
            date_range: Number of days to analyze
        
        Returns:
            dict: SLA compliance data
        """
        end_date = timezone.now()
        start_date = end_date - timedelta(days=date_range)
        
        queryset = Complaint.objects.filter(
            created_at__gte=start_date,
            created_at__lte=end_date
        )
        
        if hospital:
            queryset = queryset.filter(hospital=hospital)
        
        total = queryset.count()
        overdue = queryset.filter(is_overdue=True).count()
        on_time = total - overdue
        
        compliance_rate = (on_time / total * 100) if total > 0 else 0
        
        # Get trend data
        daily_compliance = []
        for i in range(date_range):
            day = start_date + timedelta(days=i)
            day_end = day + timedelta(days=1)
            
            day_total = queryset.filter(
                created_at__gte=day,
                created_at__lt=day_end
            ).count()
            
            day_overdue = queryset.filter(
                created_at__gte=day,
                created_at__lt=day_end,
                is_overdue=True
            ).count()
            
            day_compliance = ((day_total - day_overdue) / day_total * 100) if day_total > 0 else 100
            
            daily_compliance.append({
                'date': day.strftime('%Y-%m-%d'),
                'compliance_rate': round(day_compliance, 2),
                'total': day_total,
                'overdue': day_overdue
            })
        
        return {
            'overall_compliance_rate': round(compliance_rate, 2),
            'total_complaints': total,
            'on_time': on_time,
            'overdue': overdue,
            'daily_compliance': daily_compliance
        }
    
    @staticmethod
    def get_resolution_rate(hospital=None, date_range=30):
        """
        Calculate resolution rate metrics.
        
        Args:
            hospital: Optional hospital to filter by
            date_range: Number of days to analyze
        
        Returns:
            dict: Resolution rate data
        """
        end_date = timezone.now()
        start_date = end_date - timedelta(days=date_range)
        
        queryset = Complaint.objects.filter(
            created_at__gte=start_date,
            created_at__lte=end_date
        )
        
        if hospital:
            queryset = queryset.filter(hospital=hospital)
        
        total = queryset.count()
        resolved = queryset.filter(
            status__in=[ComplaintStatus.RESOLVED, ComplaintStatus.CLOSED]
        ).count()
        
        resolution_rate = (resolved / total * 100) if total > 0 else 0
        
        # Calculate average resolution time
        resolved_complaints = queryset.filter(
            status__in=[ComplaintStatus.RESOLVED, ComplaintStatus.CLOSED],
            resolved_at__isnull=False
        )
        
        avg_resolution_time = None
        if resolved_complaints.exists():
            # Calculate time difference
            time_diffs = []
            for complaint in resolved_complaints:
                if complaint.resolved_at:
                    diff = (complaint.resolved_at - complaint.created_at).total_seconds() / 3600  # hours
                    time_diffs.append(diff)
            
            if time_diffs:
                avg_resolution_time = sum(time_diffs) / len(time_diffs)
        
        # Resolution by department
        by_department = queryset.filter(
            status__in=[ComplaintStatus.RESOLVED, ComplaintStatus.CLOSED],
            department__isnull=False
        ).values(
            'department__name'
        ).annotate(
            count=Count('id')
        ).order_by('-count')[:10]
        
        return {
            'resolution_rate': round(resolution_rate, 2),
            'total_complaints': total,
            'resolved': resolved,
            'pending': total - resolved,
            'avg_resolution_time_hours': round(avg_resolution_time, 2) if avg_resolution_time else None,
            'by_department': list(by_department)
        }
    
    @staticmethod
    def get_top_categories(hospital=None, date_range=30, limit=10):
        """
        Get top complaint categories.
        
        Args:
            hospital: Optional hospital to filter by
            date_range: Number of days to analyze
            limit: Number of top categories to return
        
        Returns:
            dict: Top categories data
        """
        end_date = timezone.now()
        start_date = end_date - timedelta(days=date_range)
        
        queryset = Complaint.objects.filter(
            created_at__gte=start_date,
            created_at__lte=end_date
        )
        
        if hospital:
            queryset = queryset.filter(hospital=hospital)
        
        categories = queryset.values('category').annotate(
            count=Count('id')
        ).order_by('-count')[:limit]
        
        return {
            'categories': [
                {
                    'category': item['category'],
                    'count': item['count']
                }
                for item in categories
            ]
        }
    
    @staticmethod
    def get_overdue_complaints(hospital=None, limit=10):
        """
        Get list of overdue complaints.
        
        Args:
            hospital: Optional hospital to filter by
            limit: Number of complaints to return
        
        Returns:
            QuerySet: Overdue complaints
        """
        queryset = Complaint.objects.filter(
            is_overdue=True,
            status__in=[ComplaintStatus.OPEN, ComplaintStatus.IN_PROGRESS]
        ).select_related(
            'patient', 'hospital', 'department', 'assigned_to'
        ).order_by('due_at')
        
        if hospital:
            queryset = queryset.filter(hospital=hospital)
        
        return queryset[:limit]
    
    @staticmethod
    def get_dashboard_summary(hospital=None):
        """
        Get comprehensive dashboard summary.
        
        Args:
            hospital: Optional hospital to filter by
        
        Returns:
            dict: Dashboard summary data
        """
        queryset = Complaint.objects.all()
        
        if hospital:
            queryset = queryset.filter(hospital=hospital)
        
        # Current status counts
        status_counts = {
            'total': queryset.count(),
            'open': queryset.filter(status=ComplaintStatus.OPEN).count(),
            'in_progress': queryset.filter(status=ComplaintStatus.IN_PROGRESS).count(),
            'resolved': queryset.filter(status=ComplaintStatus.RESOLVED).count(),
            'closed': queryset.filter(status=ComplaintStatus.CLOSED).count(),
            'overdue': queryset.filter(is_overdue=True).count(),
        }
        
        # Severity breakdown
        severity_counts = queryset.values('severity').annotate(
            count=Count('id')
        )
        
        # Recent high severity
        recent_high_severity = queryset.filter(
            severity__in=['high', 'critical'],
            created_at__gte=timezone.now() - timedelta(days=7)
        ).count()
        
        # Trends (last 7 days vs previous 7 days)
        last_7_days = queryset.filter(
            created_at__gte=timezone.now() - timedelta(days=7)
        ).count()
        
        previous_7_days = queryset.filter(
            created_at__gte=timezone.now() - timedelta(days=14),
            created_at__lt=timezone.now() - timedelta(days=7)
        ).count()
        
        trend_percentage = 0
        if previous_7_days > 0:
            trend_percentage = ((last_7_days - previous_7_days) / previous_7_days) * 100
        
        return {
            'status_counts': status_counts,
            'severity_counts': list(severity_counts),
            'recent_high_severity': recent_high_severity,
            'trend': {
                'last_7_days': last_7_days,
                'previous_7_days': previous_7_days,
                'percentage_change': round(trend_percentage, 2)
            }
        }