import uuid
from functools import cached_property
from hashlib import sha256
from urllib.parse import urlencode

import feedparser
import requests
from django import forms
from django.conf import settings
from django.contrib.contenttypes.models import ContentType
from django.core.cache import cache
from django.db.models import Q
from django.template.loader import render_to_string
from django.urls import NoReverseMatch, resolve, reverse
from django.utils.translation import gettext as _

from extras.choices import BookmarkOrderingChoices
from extras.utils import FeatureQuery
from utilities.forms import BootstrapMixin
from utilities.permissions import get_permission_for_model
from utilities.templatetags.builtins.filters import render_markdown
from utilities.utils import content_type_identifier, content_type_name, dict_to_querydict, get_viewname
from .utils import register_widget

__all__ = (
    'BookmarksWidget',
    'DashboardWidget',
    'NoteWidget',
    'ObjectCountsWidget',
    'ObjectListWidget',
    'RSSFeedWidget',
    'WidgetConfigForm',
)


def get_content_type_labels():
    return [
        (content_type_identifier(ct), content_type_name(ct))
        for ct in ContentType.objects.filter(
            FeatureQuery('export_templates').get_query() | Q(app_label='extras', model='objectchange') |
            Q(app_label='extras', model='configcontext')
        ).order_by('app_label', 'model')
    ]


def get_models_from_content_types(content_types):
    """
    Return a list of models corresponding to the given content types, identified by natural key.
    """
    models = []
    for content_type_id in content_types:
        app_label, model_name = content_type_id.split('.')
        content_type = ContentType.objects.get_by_natural_key(app_label, model_name)
        models.append(content_type.model_class())
    return models


class WidgetConfigForm(BootstrapMixin, forms.Form):
    pass


class DashboardWidget:
    """
    Base class for custom dashboard widgets.

    Attributes:
        description: A brief, user-friendly description of the widget's function
        default_title: The string to show for the widget's title when none has been specified.
        default_config: Default configuration parameters, as a dictionary mapping
        width: The widget's default width (1 to 12)
        height: The widget's default height; the number of rows it consumes
    """
    description = None
    default_title = None
    default_config = {}
    width = 4
    height = 3

    class ConfigForm(WidgetConfigForm):
        """
        The widget's configuration form.
        """
        pass

    def __init__(self, id=None, title=None, color=None, config=None, width=None, height=None, x=None, y=None):
        self.id = id or str(uuid.uuid4())
        self.config = config or self.default_config
        self.title = title or self.default_title
        self.color = color
        if width:
            self.width = width
        if height:
            self.height = height
        self.x, self.y = x, y

    def __str__(self):
        return self.title or self.__class__.__name__

    def set_layout(self, grid_item):
        self.width = grid_item.get('w', 1)
        self.height = grid_item.get('h', 1)
        self.x = grid_item.get('x')
        self.y = grid_item.get('y')

    def render(self, request):
        """
        This method is called to render the widget's content.

        Params:
            request: The current request
        """
        raise NotImplementedError(f"{self.__class__} must define a render() method.")

    @property
    def name(self):
        return f'{self.__class__.__module__.split(".")[0]}.{self.__class__.__name__}'

    @property
    def form_data(self):
        return {
            'title': self.title,
            'color': self.color,
            'config': self.config,
        }


@register_widget
class NoteWidget(DashboardWidget):
    default_title = _('Note')
    description = _('Display some arbitrary custom content. Markdown is supported.')

    class ConfigForm(WidgetConfigForm):
        content = forms.CharField(
            widget=forms.Textarea()
        )

    def render(self, request):
        return render_markdown(self.config.get('content'))


@register_widget
class ObjectCountsWidget(DashboardWidget):
    default_title = _('Object Counts')
    description = _('Display a set of NetBox models and the number of objects created for each type.')
    template_name = 'extras/dashboard/widgets/objectcounts.html'

    class ConfigForm(WidgetConfigForm):
        models = forms.MultipleChoiceField(
            choices=get_content_type_labels
        )
        filters = forms.JSONField(
            required=False,
            label='Object filters',
            help_text=_("Filters to apply when counting the number of objects")
        )

        def clean_filters(self):
            if data := self.cleaned_data['filters']:
                try:
                    dict(data)
                except TypeError:
                    raise forms.ValidationError("Invalid format. Object filters must be passed as a dictionary.")
            return data

    def render(self, request):
        counts = []
        for model in get_models_from_content_types(self.config['models']):
            permission = get_permission_for_model(model, 'view')
            if request.user.has_perm(permission):
                url = reverse(get_viewname(model, 'list'))
                qs = model.objects.restrict(request.user, 'view')
                # Apply any specified filters
                if filters := self.config.get('filters'):
                    params = dict_to_querydict(filters)
                    filterset = getattr(resolve(url).func.view_class, 'filterset', None)
                    qs = filterset(params, qs).qs
                    url = f'{url}?{params.urlencode()}'
                object_count = qs.count
                counts.append((model, object_count, url))
            else:
                counts.append((model, None, None))

        return render_to_string(self.template_name, {
            'counts': counts,
        })


@register_widget
class ObjectListWidget(DashboardWidget):
    default_title = _('Object List')
    description = _('Display an arbitrary list of objects.')
    template_name = 'extras/dashboard/widgets/objectlist.html'
    width = 12
    height = 4

    class ConfigForm(WidgetConfigForm):
        model = forms.ChoiceField(
            choices=get_content_type_labels
        )
        page_size = forms.IntegerField(
            required=False,
            min_value=1,
            max_value=100,
            help_text=_('The default number of objects to display')
        )
        url_params = forms.JSONField(
            required=False,
            label='URL parameters'
        )

        def clean_url_params(self):
            if data := self.cleaned_data['url_params']:
                try:
                    urlencode(data)
                except (TypeError, ValueError):
                    raise forms.ValidationError("Invalid format. URL parameters must be passed as a dictionary.")
            return data

    def render(self, request):
        app_label, model_name = self.config['model'].split('.')
        model = ContentType.objects.get_by_natural_key(app_label, model_name).model_class()
        viewname = get_viewname(model, action='list')

        # Evaluate user's permission. Note that this controls only whether the HTMX element is
        # embedded on the page: The view itself will also evaluate permissions separately.
        permission = get_permission_for_model(model, 'view')
        has_permission = request.user.has_perm(permission)

        try:
            htmx_url = reverse(viewname)
        except NoReverseMatch:
            htmx_url = None
        parameters = self.config.get('url_params') or {}
        if page_size := self.config.get('page_size'):
            parameters['per_page'] = page_size

        if parameters:
            try:
                htmx_url = f'{htmx_url}?{urlencode(parameters, doseq=True)}'
            except ValueError:
                pass
        return render_to_string(self.template_name, {
            'viewname': viewname,
            'has_permission': has_permission,
            'htmx_url': htmx_url,
        })


@register_widget
class RSSFeedWidget(DashboardWidget):
    default_title = _('RSS Feed')
    default_config = {
        'max_entries': 10,
        'cache_timeout': 3600,  # seconds
    }
    description = _('Embed an RSS feed from an external website.')
    template_name = 'extras/dashboard/widgets/rssfeed.html'
    width = 6
    height = 4

    class ConfigForm(WidgetConfigForm):
        feed_url = forms.URLField(
            label=_('Feed URL')
        )
        max_entries = forms.IntegerField(
            min_value=1,
            max_value=1000,
            help_text=_('The maximum number of objects to display')
        )
        cache_timeout = forms.IntegerField(
            min_value=600,  # 10 minutes
            max_value=86400,  # 24 hours
            help_text=_('How long to stored the cached content (in seconds)')
        )

    def render(self, request):
        return render_to_string(self.template_name, {
            'url': self.config['feed_url'],
            **self.get_feed()
        })

    @cached_property
    def cache_key(self):
        url = self.config['feed_url']
        url_checksum = sha256(url.encode('utf-8')).hexdigest()
        return f'dashboard_rss_{url_checksum}'

    def get_feed(self):
        # Fetch RSS content from cache if available
        if feed_content := cache.get(self.cache_key):
            return {
                'feed': feedparser.FeedParserDict(feed_content),
            }

        # Fetch feed content from remote server
        try:
            response = requests.get(
                url=self.config['feed_url'],
                headers={'User-Agent': f'NetBox/{settings.VERSION}'},
                proxies=settings.HTTP_PROXIES,
                timeout=3
            )
            response.raise_for_status()
        except requests.exceptions.RequestException as e:
            return {
                'error': e,
            }

        # Parse feed content
        feed = feedparser.parse(response.content)
        if not feed.bozo:
            # Cap number of entries
            max_entries = self.config.get('max_entries')
            feed['entries'] = feed['entries'][:max_entries]
            # Cache the feed content
            cache.set(self.cache_key, dict(feed), self.config.get('cache_timeout'))

        return {
            'feed': feed,
        }


@register_widget
class BookmarksWidget(DashboardWidget):
    default_title = _('Bookmarks')
    default_config = {
        'order_by': BookmarkOrderingChoices.ORDERING_NEWEST,
    }
    description = _('Show your personal bookmarks')
    template_name = 'extras/dashboard/widgets/bookmarks.html'

    class ConfigForm(WidgetConfigForm):
        object_types = forms.MultipleChoiceField(
            # TODO: Restrict the choices by FeatureQuery('bookmarks')
            choices=get_content_type_labels,
            required=False
        )
        order_by = forms.ChoiceField(
            choices=BookmarkOrderingChoices
        )
        max_items = forms.IntegerField(
            min_value=1,
            required=False
        )

    def render(self, request):
        from extras.models import Bookmark

        if request.user.is_anonymous:
            bookmarks = list()
        else:
            bookmarks = Bookmark.objects.filter(user=request.user).order_by(self.config['order_by'])
            if object_types := self.config.get('object_types'):
                models = get_models_from_content_types(object_types)
                conent_types = ContentType.objects.get_for_models(*models).values()
                bookmarks = bookmarks.filter(object_type__in=conent_types)
            if max_items := self.config.get('max_items'):
                bookmarks = bookmarks[:max_items]

        return render_to_string(self.template_name, {
            'bookmarks': bookmarks,
        })