import re
import requests
from urllib.parse import urlencode

STEAM_OPENID_URL = 'https://steamcommunity.com/openid/login'
STEAM_API_BASE = 'https://api.steampowered.com'


def build_auth_url(return_to, realm):
    params = {
        'openid.ns': 'http://specs.openid.net/auth/2.0',
        'openid.mode': 'checkid_setup',
        'openid.return_to': return_to,
        'openid.realm': realm,
        'openid.identity': 'http://specs.openid.net/auth/2.0/identifier_select',
        'openid.claimed_id': 'http://specs.openid.net/auth/2.0/identifier_select',
    }
    return f"{STEAM_OPENID_URL}?{urlencode(params)}"


def verify_and_get_steam_id(params):
    """Verify OpenID assertion with Steam. Returns steam64 id string or None."""
    verify_params = {k: v for k, v in params.items()}
    verify_params['openid.mode'] = 'check_authentication'
    try:
        resp = requests.post(STEAM_OPENID_URL, data=verify_params, timeout=10)
        resp.raise_for_status()
    except requests.RequestException:
        return None
    if 'is_valid:true' not in resp.text:
        return None
    claimed_id = params.get('openid.claimed_id', '')
    match = re.search(r'/openid/id/(\d+)$', claimed_id)
    return match.group(1) if match else None


def get_owned_games(api_key, steam_id):
    """Return list of games sorted by playtime desc. Raises on API error."""
    url = f"{STEAM_API_BASE}/IPlayerService/GetOwnedGames/v1/"
    params = {
        'key': api_key,
        'steamid': steam_id,
        'include_appinfo': 'true',
        'include_played_free_games': 'true',
        'format': 'json',
    }
    resp = requests.get(url, params=params, timeout=15)
    resp.raise_for_status()
    games = resp.json().get('response', {}).get('games', [])
    return sorted(games, key=lambda g: g.get('playtime_forever', 0), reverse=True)