import urllib.parse
from typing import Set, List

from django.core.handlers.wsgi import WSGIRequest
from django.core.paginator import Paginator
from django.db import models
from django.urls import reverse

from bookmarks import queries
from bookmarks.models import BookmarkFilters, User, UserProfile, Tag
from bookmarks.utils import unique

DEFAULT_PAGE_SIZE = 30


class BookmarkListContext:
    def __init__(self, request: WSGIRequest) -> None:
        self.request = request
        self.filters = BookmarkFilters(self.request)

        query_set = self.get_bookmark_query_set()
        page_number = request.GET.get('page')
        paginator = Paginator(query_set, DEFAULT_PAGE_SIZE)
        bookmarks_page = paginator.get_page(page_number)
        # Prefetch related objects, this avoids n+1 queries when accessing fields in templates
        models.prefetch_related_objects(bookmarks_page.object_list, 'owner', 'tags')

        self.is_empty = paginator.count == 0
        self.bookmarks_page = bookmarks_page
        self.return_url = self.generate_return_url(page_number)
        self.link_target = request.user_profile.bookmark_link_target
        self.date_display = request.user_profile.bookmark_date_display
        self.show_url = request.user_profile.display_url
        self.show_favicons = request.user_profile.enable_favicons
        self.show_notes = request.user_profile.permanent_notes

    def generate_return_url(self, page: int):
        base_url = self.get_base_url()
        url_query = {}
        if self.filters.query:
            url_query['q'] = self.filters.query
        if self.filters.user:
            url_query['user'] = self.filters.user
        if page is not None:
            url_query['page'] = page
        url_params = urllib.parse.urlencode(url_query)
        return_url = base_url if url_params == '' else base_url + '?' + url_params
        return urllib.parse.quote_plus(return_url)

    def get_base_url(self):
        raise Exception(f'Must be implemented by subclass')

    def get_bookmark_query_set(self):
        raise Exception(f'Must be implemented by subclass')


class ActiveBookmarkListContext(BookmarkListContext):
    def get_base_url(self):
        return reverse('bookmarks:index')

    def get_bookmark_query_set(self):
        return queries.query_bookmarks(self.request.user,
                                       self.request.user_profile,
                                       self.filters.query)


class ArchivedBookmarkListContext(BookmarkListContext):
    def get_base_url(self):
        return reverse('bookmarks:archived')

    def get_bookmark_query_set(self):
        return queries.query_archived_bookmarks(self.request.user,
                                                self.request.user_profile,
                                                self.filters.query)


class SharedBookmarkListContext(BookmarkListContext):
    def get_base_url(self):
        return reverse('bookmarks:shared')

    def get_bookmark_query_set(self):
        user = User.objects.filter(username=self.filters.user).first()
        public_only = not self.request.user.is_authenticated
        return queries.query_shared_bookmarks(user,
                                              self.request.user_profile,
                                              self.filters.query,
                                              public_only)


class TagGroup:
    def __init__(self, char: str):
        self.tags = []
        self.char = char

    @staticmethod
    def create_tag_groups(tags: Set[Tag]):
        # Ensure groups, as well as tags within groups, are ordered alphabetically
        sorted_tags = sorted(tags, key=lambda x: str.lower(x.name))
        group = None
        groups = []

        # Group tags that start with a different character than the previous one
        for tag in sorted_tags:
            tag_char = tag.name[0].lower()

            if not group or group.char != tag_char:
                group = TagGroup(tag_char)
                groups.append(group)

            group.tags.append(tag)

        return groups


class TagCloudContext:
    def __init__(self, request: WSGIRequest) -> None:
        self.request = request
        self.filters = BookmarkFilters(self.request)

        query_set = self.get_tag_query_set()
        tags = list(query_set)
        selected_tags = self.get_selected_tags(tags)
        unique_tags = unique(tags, key=lambda x: str.lower(x.name))
        unique_selected_tags = unique(selected_tags, key=lambda x: str.lower(x.name))
        has_selected_tags = len(unique_selected_tags) > 0
        unselected_tags = set(unique_tags).symmetric_difference(unique_selected_tags)
        groups = TagGroup.create_tag_groups(unselected_tags)

        self.tags = unique_tags
        self.groups = groups
        self.selected_tags = unique_selected_tags
        self.has_selected_tags = has_selected_tags

    def get_tag_query_set(self):
        raise Exception(f'Must be implemented by subclass')

    def get_selected_tags(self, tags: List[Tag]):
        parsed_query = queries.parse_query_string(self.filters.query)
        tag_names = parsed_query['tag_names']
        if self.request.user_profile.tag_search == UserProfile.TAG_SEARCH_LAX:
            tag_names = tag_names + parsed_query['search_terms']
        tag_names = [tag_name.lower() for tag_name in tag_names]

        return [tag for tag in tags if tag.name.lower() in tag_names]


class ActiveTagCloudContext(TagCloudContext):
    def get_tag_query_set(self):
        return queries.query_bookmark_tags(self.request.user,
                                           self.request.user_profile,
                                           self.filters.query)


class ArchivedTagCloudContext(TagCloudContext):
    def get_tag_query_set(self):
        return queries.query_archived_bookmark_tags(self.request.user,
                                                    self.request.user_profile,
                                                    self.filters.query)


class SharedTagCloudContext(TagCloudContext):
    def get_tag_query_set(self):
        user = User.objects.filter(username=self.filters.user).first()
        public_only = not self.request.user.is_authenticated
        return queries.query_shared_bookmark_tags(user,
                                                  self.request.user_profile,
                                                  self.filters.query,
                                                  public_only)