from dateutil.relativedelta import relativedelta
from django.db.models import Count
from django.db.models.functions import ExtractYear, ExtractMonth
from django.shortcuts import render
from django.urls import reverse
from django.utils import timezone

from apps.transactions.models import Transaction


def toasts(request):
    return render(request, "common/fragments/toasts.html")


def month_year_picker(request):
    field = request.GET.get("field", "reference_date")
    for_ = request.GET.get("for", None)
    url = None

    if for_ == "calendar":
        url = "calendar"
    elif for_ == "monthly_overview":
        url = "monthly_overview"

    # Get current month and year from request or use current date
    current_date = timezone.localdate(timezone.now())
    current_month = int(request.GET.get("month", current_date.month))
    current_year = int(request.GET.get("year", current_date.year))

    # Set start and end dates
    start_date = timezone.datetime(current_year - 1, 1, 1).date()
    end_date = timezone.datetime(current_year + 1, 12, 31).date()

    # Get years from transactions
    transaction_years = Transaction.objects.dates(field, "year", order="ASC")

    # Extend start_date and end_date if necessary
    if transaction_years:
        start_date = min(start_date, transaction_years.first().replace(month=1, day=1))
        end_date = max(end_date, transaction_years.last().replace(month=12, day=31))

    # Generate all months between start_date and end_date
    all_months = []
    current_month_date = start_date
    while current_month_date <= end_date:
        all_months.append(current_month_date)
        current_month_date += relativedelta(months=1)

    # Get transaction counts for each month
    transaction_counts = (
        Transaction.objects.annotate(year=ExtractYear(field), month=ExtractMonth(field))
        .values("year", "month")
        .annotate(transaction_count=Count("id"))
        .order_by("year", "month")
    )

    # Create a dictionary for quick lookup
    count_dict = {
        (item["year"], item["month"]): item["transaction_count"]
        for item in transaction_counts
    }

    # Create the final result
    result = [
        {
            "year": date.year,
            "month": date.month,
            "transaction_count": count_dict.get((date.year, date.month), 0),
            "url": (
                reverse(url, kwargs={"month": date.month, "year": date.year})
                if url
                else ""
            ),
        }
        for date in all_months
    ]

    return render(
        request,
        "common/fragments/month_year_picker.html",
        {
            "month_year_data": result,
            "current_month": current_month,
            "current_year": current_year,
        },
    )