from rest_framework import generics, permissions, status
from rest_framework.response import Response
from rest_framework.views import APIView
from django.db.models import Count
from django.db.models.functions import TruncDate
from django.utils.dateparse import parse_date
from .models import ActivityLog, AuditLog
from .serializers import ActivityLogSerializer, AuditLogSerializer
from accounts.permissions import IsTenantUser, IsAdmin
from projects.models import Project, Task

class ActivityLogListView(generics.ListAPIView):
    serializer_class = ActivityLogSerializer
    permission_classes = [permissions.IsAuthenticated, IsTenantUser]

    def get_queryset(self):
        return ActivityLog.objects.filter(tenant=self.request.tenant)

class ReportView(APIView):
    """
    Returns aggregated stats for a date range with daily breakdown
    Query params: start_date (YYYY-MM-DD), end_date (YYYY-MM-DD)
    """
    permission_classes = [permissions.IsAuthenticated, IsTenantUser, IsAdmin] # Only admins can see reports usually

    def get(self, request):
        tenant = request.tenant
        start_date_str = request.query_params.get('start_date')
        end_date_str = request.query_params.get('end_date')

        project_qs = Project.objects.filter(tenant=tenant)
        task_qs = Task.objects.filter(tenant=tenant)

        if start_date_str:
            start_date = parse_date(start_date_str)
            if start_date:
                project_qs = project_qs.filter(created_at__date__gte=start_date)
                task_qs = task_qs.filter(created_at__date__gte=start_date)
        
        if end_date_str:
            end_date = parse_date(end_date_str)
            if end_date:
                project_qs = project_qs.filter(created_at__date__lte=end_date)
                task_qs = task_qs.filter(created_at__date__lte=end_date)

        # Total counts
        projects_created = project_qs.count()
        tasks_created = task_qs.count()
        tasks_completed = task_qs.filter(status='done').count()

        # Daily metrics: group by date
        from django.db.models.functions import TruncDate
        
        daily_projects = project_qs.annotate(day=TruncDate('created_at')).values('day').annotate(count=Count('id')).order_by('day')
        daily_tasks_completed = task_qs.filter(status='done').annotate(day=TruncDate('created_at')).values('day').annotate(count=Count('id')).order_by('day')
        daily_tasks_created = task_qs.annotate(day=TruncDate('created_at')).values('day').annotate(count=Count('id')).order_by('day')
        
        # Build daily metrics array
        daily_metrics = []
        # Collect all unique dates from both projects and tasks
        all_dates = set()
        for item in daily_projects:
            all_dates.add(item['day'])
        for item in daily_tasks_completed:
            all_dates.add(item['day'])
        for item in daily_tasks_created:
            all_dates.add(item['day'])
        
        # Sort dates
        sorted_dates = sorted(all_dates)
        
        for date_obj in sorted_dates:
            date_str = date_obj.strftime('%Y-%m-%d')
            # Find counts for this date
            proj_count = next((item['count'] for item in daily_projects if item['day'] == date_obj), 0)
            tasks_comp = next((item['count'] for item in daily_tasks_completed if item['day'] == date_obj), 0)
            tasks_created_count = next((item['count'] for item in daily_tasks_created if item['day'] == date_obj), 0)
            
            daily_metrics.append({
                'date': date_str,
                'projects_created': proj_count,
                'tasks_completed': tasks_comp,
                'tasks_created': tasks_created_count,
            })

        return Response({
            'period': {
                'start': start_date_str,
                'end': end_date_str
            },
            'total_projects': projects_created,
            'total_tasks': tasks_created,
            'tasks_completed': tasks_completed,
            'daily_metrics': daily_metrics
        })