import hashlib
import json
import re

import requests


BASE_URL = 'https://www.instagram.com'

QUERY_HASH = '42323d64886122307be10013ad2dcc44'

SHARED_DATA = re.compile(r'window\._sharedData = (\{.*\});</script>')


class InstagramError(Exception):
    pass


class Instagram(object):
    def __init__(self, username):
        self.username = username
        shared_data = self._get_shared_data()
        try:
            graphql = shared_data['entry_data']['ProfilePage'][0]['graphql']
            self.user_id = graphql['user']['id']
            self.rhx_gis = shared_data['rhx_gis']
            self.owner = dict(
                name=graphql['user']['username'],
                profile_pic_url=graphql['user']['profile_pic_url'])
        except (IndexError, KeyError, TypeError):
            self.user_id = None
            self.rhx_gis = None

    def _get_shared_data(self):
        r = requests.get('{0}/{1}'.format(BASE_URL, self.username))
        if not r.ok:
            return None
        m = SHARED_DATA.search(r.text)
        if m:
            return json.loads(m.group(1))
        return None

    def _get_media(self):
        def request(count, cursor):
            variables = json.dumps(dict(
                id=self.user_id,
                first=count,
                after=cursor))
            gis = '{0}:{1}'.format(self.rhx_gis, variables)
            gis = hashlib.md5(gis.encode('UTF-8')).hexdigest()
            url = '{0}/graphql/query'.format(BASE_URL)
            params = dict(
                query_hash=QUERY_HASH,
                variables=variables)
            r = requests.get(url, params=params, headers={'X-Instagram-GIS': gis})
            r.raise_for_status()
            return r.json()
        result = []
        try:
            count = 50
            cursor = ''
            while True:
                data = request(count, cursor)
                data = data['data']['user']['edge_owner_to_timeline_media']
                for edge in data['edges']:
                    result.append(dict(
                        type=edge['node']['__typename'].split('Graph')[1],
                        title=edge['node']['edge_media_to_caption']['edges'][0]['node']['text'],
                        url='{0}/p/{1}'.format(BASE_URL, edge['node']['shortcode']),
                        display_url=edge['node']['display_url'],
                        owner=self.owner['name'],
                        owner_url='{0}/{1}'.format(BASE_URL, self.username),
                        owner_pic_url=self.owner['profile_pic_url']))
                cursor = data['page_info']['end_cursor']
                if not cursor:
                    break
        except KeyError:
            return None
        else:
            return result

    def get_media(self):
        if not self.user_id:
            return None
        try:
            result = self._get_media()
        except requests.exceptions.HTTPError as e:
            raise InstagramError('Failed to retrieve media: {0}'.format(e))
        except json.decoder.JSONDecodeError as e:
            raise InstagramError('Failed to retrieve media: {0}'.format(e))
        else:
            return result