"""
Persistent, JSON-serialized sessions.

"""
import os
import re

from http.cookies import SimpleCookie
from pathlib import Path
from typing import Iterable, Optional, Union
from urllib.parse import urlsplit

from requests.auth import AuthBase
from requests.cookies import RequestsCookieJar, create_cookie

from .cli.dicts import RequestHeadersDict
from .config import BaseConfigDict, DEFAULT_CONFIG_DIR
from .plugins.registry import plugin_manager


SESSIONS_DIR_NAME = 'sessions'
DEFAULT_SESSIONS_DIR = DEFAULT_CONFIG_DIR / SESSIONS_DIR_NAME
VALID_SESSION_NAME_PATTERN = re.compile('^[a-zA-Z0-9_.-]+$')
# Request headers starting with these prefixes won't be stored in sessions.
# They are specific to each request.
# <https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Requests>
SESSION_IGNORED_HEADER_PREFIXES = ['Content-', 'If-']


def get_httpie_session(
    config_dir: Path,
    session_name: str,
    host: Optional[str],
    url: str,
) -> 'Session':
    if os.path.sep in session_name:
        path = os.path.expanduser(session_name)
    else:
        hostname = host or urlsplit(url).netloc.split('@')[-1]
        if not hostname:
            # HACK/FIXME: httpie-unixsocket's URLs have no hostname.
            hostname = 'localhost'

        # host:port => host_port
        hostname = hostname.replace(':', '_')
        path = (
            config_dir / SESSIONS_DIR_NAME / hostname / f'{session_name}.json'
        )
    session = Session(path)
    session.load()
    return session


class Session(BaseConfigDict):
    helpurl = 'https://httpie.org/doc#sessions'
    about = 'HTTPie session file'

    def __init__(self, path: Union[str, Path]):
        super().__init__(path=Path(path))
        self['headers'] = {}
        self['cookies'] = {}
        self['auth'] = {
            'type': None,
            'username': None,
            'password': None
        }

    def update_headers(self, request_headers: RequestHeadersDict):
        """
        Update the session headers with the request ones while ignoring
        certain name prefixes.

        """
        headers = self.headers
        for name, value in request_headers.items():

            if value is None:
                continue  # Ignore explicitly unset headers

            if type(value) is not str:
                value = value.decode('utf8')

            if name.lower() == 'user-agent' and value.startswith('HTTPie/'):
                continue

            if name.lower() == 'cookie':
                for cookie_name, morsel in SimpleCookie(value).items():
                    self['cookies'][cookie_name] = {'value': morsel.value}
                del request_headers[name]
                continue

            for prefix in SESSION_IGNORED_HEADER_PREFIXES:
                if name.lower().startswith(prefix.lower()):
                    break
            else:
                headers[name] = value

        self['headers'] = dict(headers)

    @property
    def headers(self) -> RequestHeadersDict:
        return RequestHeadersDict(self['headers'])

    @property
    def cookies(self) -> RequestsCookieJar:
        jar = RequestsCookieJar()
        for name, cookie_dict in self['cookies'].items():
            jar.set_cookie(create_cookie(
                name, cookie_dict.pop('value'), **cookie_dict))
        jar.clear_expired_cookies()
        return jar

    @cookies.setter
    def cookies(self, jar: RequestsCookieJar):
        # <https://docs.python.org/2/library/cookielib.html#cookie-objects>
        stored_attrs = ['value', 'path', 'secure', 'expires']
        self['cookies'] = {}
        for cookie in jar:
            self['cookies'][cookie.name] = {
                attname: getattr(cookie, attname)
                for attname in stored_attrs
            }

    @property
    def auth(self) -> Optional[AuthBase]:
        auth = self.get('auth', None)
        if not auth or not auth['type']:
            return

        plugin = plugin_manager.get_auth_plugin(auth['type'])()

        credentials = {'username': None, 'password': None}
        try:
            # New style
            plugin.raw_auth = auth['raw_auth']
        except KeyError:
            # Old style
            credentials = {
                'username': auth['username'],
                'password': auth['password'],
            }
        else:
            if plugin.auth_parse:
                from .cli.argtypes import parse_auth
                parsed = parse_auth(plugin.raw_auth)
                credentials = {
                    'username': parsed.key,
                    'password': parsed.value,
                }

        return plugin.get_auth(**credentials)

    @auth.setter
    def auth(self, auth: dict):
        assert {'type', 'raw_auth'} == auth.keys()
        self['auth'] = auth

    def remove_cookies(self, names: Iterable[str]):
        for name in names:
            if name in self['cookies']:
                del self['cookies'][name]