import datetime

from django.template.loader import render_to_string
from django.shortcuts import render
from django.http import HttpResponse


def next_date(year: int, week: int) -> (int, int):
    if week >= 52:
        return (year + 1, 1)
    else:
        return (year, week + 1)


def first_day_of_iso_week(year, week):
    # Create a date object for January 4th of the given year
    # This date is always in the first week of the year according to ISO 8601
    jan4 = datetime.datetime(year, 1, 4)

    # Get the ISO week number and the weekday of January 4th
    start_iso_week, start_iso_day = jan4.isocalendar()[1:3]

    # Calculate the difference in weeks, then adjust for the start of the week
    weeks_diff = week - start_iso_week
    days_to_monday = datetime.timedelta(days=(1 - start_iso_day))

    # Calculate the first day of the given ISO week
    return jan4 + days_to_monday + datetime.timedelta(weeks=weeks_diff)


def get_week_range(p_year, p_week):
    firstdayofweek = datetime.datetime.strptime(
        f"{p_year}-W{int(p_week)}-1", "%Y-W%W-%w"
    ).date()
    lastdayofweek = firstdayofweek + datetime.timedelta(days=6.9)
    return firstdayofweek, lastdayofweek


def is_htmx_request(request) -> bool:
    return request.headers.get("HX-Request") is not None


def title(t):
    return f"""
    <script>
    document.getElementById('page_title').innerHTML = '{t}';
    document.getElementById('page_banner_title').innerHTML = '{t}';
    </script>
    """


def htmx_request(request, content_template, vars, page_title):
    vars["title"] = title(page_title)
    vars["htmx"] = is_htmx_request(request)

    main_content = render_to_string(content_template, vars, request=request)

    if is_htmx_request(request):
        return HttpResponse(main_content, content_type="text/html")
    else:
        return render(
            request,
            "shell.html",
            {
                "title": page_title,
                "main_content": main_content,
            },
        )