import datetime
from django.contrib.sitemaps import Sitemap
from django.conf import settings
from django.utils import timezone
from apps.article.models import Article


class BaseCanonicalSitemap(Sitemap):
    """
    Base Sitemap class that supports absolute frontend URLs.
    Strips out the django-prepended backend scheme and domain from the final URLs
    if the location returned is already an absolute URL.
    Also ensures all `lastmod` datetimes are rendered in strict W3C / ISO 8601 format with timezone offsets.
    """
    limit = 10000

    def _urls(self, page, protocol, domain):
        urls = super()._urls(page, protocol, domain)
        for url_info in urls:
            # Fix absolute locations
            url_info["location"] = self._fix_absolute_url(url_info["location"])
            if "alternates" in url_info:
                for alt in url_info["alternates"]:
                    alt["location"] = self._fix_absolute_url(alt["location"])
            
            # Format naive/aware lastmod datetime objects to strict ISO 8601 / W3C format
            lastmod_dt = url_info.get("lastmod")
            if isinstance(lastmod_dt, (datetime.datetime, datetime.date)):
                if isinstance(lastmod_dt, datetime.datetime):
                    if timezone.is_naive(lastmod_dt):
                        lastmod_dt = timezone.make_aware(lastmod_dt)
                url_info["lastmod"] = lastmod_dt.isoformat()
        return urls

    def _fix_absolute_url(self, url):
        # Look for a secondary protocol pattern (e.g., http://testserverhttps://domain.com)
        for scheme in ("https://", "http://"):
            idx = url.find(scheme, 7)  # search after the first scheme prefix
            if idx != -1:
                return url[idx:]
        return url


class ArticleSitemap(BaseCanonicalSitemap):
    """
    Sitemap class for Article model.
    Overridden to dynamically build alternate (hreflang) URLs for all supported languages,
    format lastmod to strict W3C / ISO 8601 with timezone offsets, and output directly to XML.
    """
    changefreq = "weekly"
    priority = 0.6

    def items(self):
        # Only include active/published articles, sorted by updated_at
        return Article.objects.filter(status=True).order_by("-updated_at")

    def lastmod(self, obj):
        # Use the article's update timestamp for last modification info
        return obj.updated_at

    def location(self, obj):
        # Use the frontend URL via the share_link property
        return obj.share_link

    def get_urls(self, page=1, site=None, protocol=None):
        urls = []
        paginator_page = self.paginator.page(page)
        
        for item in paginator_page.object_list:
            alternates = []
            
            # Dynamically build alternate URLs for all supported languages
            for lang_code, lang_name in settings.LANGUAGES:
                localized_url = f"{settings.DOVODI_DOMAIN}/{lang_code}/articles/{item.slug}"
                alternates.append({
                    "location": localized_url,
                    "lang_code": lang_code,
                })
            
            # Safely format naive/aware lastmod datetime to strict ISO 8601 / W3C format
            lastmod_dt = item.updated_at
            if lastmod_dt:
                if timezone.is_naive(lastmod_dt):
                    lastmod_dt = timezone.make_aware(lastmod_dt)
                lastmod_str = lastmod_dt.isoformat()
            else:
                lastmod_str = None

            # Construct URL metadata dictionary
            url_info = {
                "item": item,
                "location": item.share_link,
                "lastmod": lastmod_str,
                "changefreq": self.changefreq,
                "priority": str(self.priority),
                "alternates": alternates,
            }
            urls.append(url_info)
            
        return urls