"""Which stream addresses the server may open for track titles (/radio/sse/, docs/radio.md).

- Never an address inside a private network (loopback, 10.x, 172.16-31.x, 192.168.x,
  link-local, the Docker network …): the server would otherwise reach what only it can see.
- Without an account only the directory's stations: the page's curated lists, the featured
  ones, and those radio-browser.info lists (by its station id, or by the address). Bringing an address of
  one's own is for saving it, and saving needs an account.
"""
import functools
import hashlib
import ipaddress
import re
import socket
from pathlib import Path
from urllib.parse import urlparse

import requests
from django.core.cache import cache

from .models import FeaturedStation

DIRECTORY = 'https://de1.api.radio-browser.info/json/stations'
# The page's curated lists (SomaFM, SWR2 …) are part of the directory too; their addresses
# are read from where the page has them, so they stand in one place only.
CURATED_JS = Path(__file__).resolve().parent.parent / 'static' / 'js' / 'app' / '16-stations.js'
DIRECTORY_TIMEOUT = 6
DIRECTORY_CACHE = 24 * 3600


def public_address(url):
    """True when url is http(s) and every address its host resolves to is a public one."""
    try:
        parsed = urlparse(url)
    except ValueError:
        return False
    if parsed.scheme not in ('http', 'https') or not parsed.hostname:
        return False
    try:
        infos = socket.getaddrinfo(parsed.hostname, parsed.port or (443 if parsed.scheme == 'https' else 80),
                                   proto=socket.IPPROTO_TCP)
    except (OSError, UnicodeError, ValueError):
        return False
    addresses = {info[4][0] for info in infos}
    return bool(addresses) and all(ipaddress.ip_address(a.split('%')[0]).is_global for a in addresses)


def _directory_lists(url, uuid):
    if uuid:
        try:
            r = requests.get(f'{DIRECTORY}/byuuid/{uuid}', timeout=DIRECTORY_TIMEOUT,
                             headers={'User-Agent': 'diora/1.0'})
            if r.ok and any(url in (s.get('url'), s.get('url_resolved')) for s in r.json()):
                return True
        except (requests.RequestException, ValueError):
            pass
    try:
        r = requests.get(f'{DIRECTORY}/byurl', params={'url': url}, timeout=DIRECTORY_TIMEOUT,
                         headers={'User-Agent': 'diora/1.0'})
        return bool(r.ok and r.json())
    except (requests.RequestException, ValueError):
        return False


@functools.lru_cache(maxsize=1)
def curated():
    try:
        return frozenset(re.findall(r"url: '([^']+)'", CURATED_JS.read_text(encoding='utf-8')))
    except OSError:
        return frozenset()


def in_directory(url, uuid='', own_host=''):
    """A station of the directory: curated on the page, featured, ours (the creamfresh stream
    through this server), or listed by radio-browser.info. Answers are kept a day."""
    if url in curated() or FeaturedStation.objects.filter(url=url, active=True).exists():
        return True
    if own_host and urlparse(url).netloc == own_host:
        return True
    key = 'radio:dir:' + hashlib.sha1(f'{url} {uuid}'.encode()).hexdigest()
    known = cache.get(key)
    if known is None:
        known = _directory_lists(url, uuid)
        cache.set(key, known, DIRECTORY_CACHE)
    return known