from __future__ import annotations

import datetime
from typing import Any, Dict, List

from django.db.models import Count
from django.db.models.functions import TruncDate
from django.http import HttpRequest, HttpResponse
from django.utils import timezone
from django.views import View
from inertia import render

from labs.models import EventVoucher, LabInstance, User

from .base import AdminBaseViewMixin


class DashboardView(AdminBaseViewMixin, View):
    """Admin dashboard view with basic stats and charts."""

    def get_chart_data(self, model_class, days: int) -> Dict[str, List[Any]]:
        end_date = timezone.now().date()
        start_date = end_date - datetime.timedelta(days=days - 1)

        # Query and aggregate
        data = (
            model_class.objects.filter(date_joined__date__gte=start_date)
            if model_class == User
            else model_class.objects.filter(created_at__date__gte=start_date)
        )

        date_field = "date_joined" if model_class == User else "created_at"

        qs = (
            data.annotate(date=TruncDate(date_field))
            .values("date")
            .annotate(count=Count("id"))
            .order_by("date")
        )

        # Convert to dict for easy lookup
        counts_map = {item["date"]: item["count"] for item in qs}

        # Fill missing dates
        dates = []
        counts = []
        current = start_date
        while current <= end_date:
            dates.append(current.isoformat())
            counts.append(counts_map.get(current, 0))
            current += datetime.timedelta(days=1)

        return {"dates": dates, "counts": counts}

    def serialize_voucher(self, voucher: EventVoucher) -> Dict[str, Any]:
        return {
            "id": str(voucher.id),
            "unique_code": voucher.unique_code,
            "event_name": voucher.event_name,
            "start_begin_date": voucher.start_begin_date.isoformat()
            if voucher.start_begin_date
            else None,
            "start_end_date": voucher.start_end_date.isoformat()
            if voucher.start_end_date
            else None,
        }

    def get(self, request: HttpRequest) -> HttpResponse:
        try:
            days = int(request.GET.get("days", 30))
        except ValueError:
            days = 30

        if days not in [30, 90, 365]:
            days = 30

        # Basic stats
        total_users = User.objects.count()
        staff_users = User.objects.filter(is_staff=True).count()
        total_instances = LabInstance.objects.count()
        active_instances = LabInstance.objects.filter(
            status__in=[
                LabInstance.LabInstanceStatus.RUNNING,
                LabInstance.LabInstanceStatus.CREATING,
            ],
        ).count()

        # Workshop stats
        now = timezone.now().date()
        next_week = now + datetime.timedelta(days=7)

        happening_vouchers = EventVoucher.objects.filter(
            start_begin_date__lte=now, start_end_date__gte=now
        ).order_by("start_end_date")[:5]

        upcoming_vouchers = EventVoucher.objects.filter(
            start_begin_date__gt=now, start_begin_date__lte=next_week
        ).order_by("start_begin_date")[:5]

        # Chart data
        user_chart = self.get_chart_data(User, days)
        instance_chart = self.get_chart_data(LabInstance, days)

        return render(
            request,
            "Dashboard",
            {
                "stats": {
                    "total_users": total_users,
                    "staff_users": staff_users,
                    "total_instances": total_instances,
                    "active_instances": active_instances,
                },
                "workshops": {
                    "happening": [
                        self.serialize_voucher(v) for v in happening_vouchers
                    ],
                    "upcoming": [self.serialize_voucher(v) for v in upcoming_vouchers],
                },
                "charts": {
                    "user_growth": user_chart,
                    "instance_creation": instance_chart,
                },
                "filters": {"days": days},
            },
        )