import json
import re

from urllib import request as urllib_request
from urllib.error import HTTPError, URLError
from urllib.parse import urlencode
from urllib.request import Request

from wagtail.embeds.exceptions import EmbedException, EmbedNotFoundException

from .base import EmbedFinder


class AccessDeniedInstagramOEmbedException(EmbedException):
    pass


class InstagramOEmbedFinder(EmbedFinder):
    '''
    An embed finder that supports the authenticated Instagram oEmbed Endpoint.
    https://developers.facebook.com/docs/instagram/oembed
    '''
    INSTAGRAM_ENDPOINT = 'https://graph.facebook.com/v9.0/instagram_oembed'
    INSTAGRAM_URL_PATTERNS = [r'^https?://(?:www\.)?instagram\.com/p/.+$',
                              r'^https?://(?:www\.)?instagram\.com/tv/.+$',
                              ]

    def __init__(self, omitscript=False, app_id=None, app_secret=None):
        # {settings.INSTAGRAM_APP_ID}|{settings.INSTAGRAM_APP_SECRET}
        self.app_id = app_id
        self.app_secret = app_secret
        self.omitscript = omitscript

    def accept(self, url):
        for pattern in self.INSTAGRAM_URL_PATTERNS:
            if re.match(pattern, url):
                return True
        return False

    def find_embed(self, url, max_width=None):
        params = {'url': url, 'format': 'json'}
        if max_width:
            params['maxwidth'] = max_width
        if self.omitscript:
            params['omitscript'] = 'true'

        # Configure request
        request = Request(self.INSTAGRAM_ENDPOINT + '?' + urlencode(params))
        request.add_header('Authorization', f'Bearer {self.app_id}|{self.app_secret}')

        # Perform request
        try:
            r = urllib_request.urlopen(request)
        except (HTTPError, URLError) as e:
            if isinstance(e, HTTPError) and e.code == 404:
                raise EmbedNotFoundException
            elif isinstance(e, HTTPError) and e.code in [400, 401, 403]:
                raise AccessDeniedInstagramOEmbedException
            else:
                raise EmbedNotFoundException
        oembed = json.loads(r.read().decode('utf-8'))

        # Convert photos into HTML
        if oembed['type'] == 'photo':
            html = '<img src="%s" alt="">' % (oembed["url"],)
        else:
            html = oembed.get('html')

        # Return embed as a dict
        return {
            'title': oembed['title'] if 'title' in oembed else '',
            'author_name': oembed['author_name'] if 'author_name' in oembed else '',
            'provider_name': oembed['provider_name'] if 'provider_name' in oembed else 'Instagram',
            'type': oembed['type'],
            'thumbnail_url': oembed.get('thumbnail_url'),
            'width': oembed.get('width'),
            'height': oembed.get('height'),
            'html': html,
        }


embed_finder_class = InstagramOEmbedFinder
