import time

import uuid

import threading

class Session:

  def __init__(self, manager, user_id):

    self.manager = manager

    self.server = manager.server

    self.id = uuid.uuid4().hex

    self.user_id = user_id

    self.maxtime = self.server.config['session']['time']

    self.touch()

  def touch(self):

    self.time = time.monotonic()

  def expired(self):

    return self.time + self.maxtime < time.monotonic()

class SessionManager:

  COOKIE='session'

  def __init__(self, server):

    self.server = server

    self.lock = threading.Lock()

    self.sessions = dict()

    self.timer = threading.Timer(server.config['session']['time']*0.1, self.remove_expired)

    self.timer.start()

  def remove_expired(self):

    with self.lock:

      remove = list()

      for id, session in self.sessions.items():

        if session.expired():

          remove.append(id)

      for id in remove:

        del self.sessions[id]

  def delete_by_user_id(self, user_id):

    assert(type(user_id) is int)

    with self.lock:

      remove = list()

      for id, session in self.sessions.items():

        if session.user_id == user_id:

          remove.append(id)

      for id in remove:

        del self.sessions[id]

  def add_cookie_header(self, request):

    remove = list()

    j = 0

    for i in request.answer.headers:

      if i[0] == 'Set-Cookie':

        remove.insert(0, j)

      j += 1

    for i in remove:

      del request.answer.headers[i]

    value = None

    if request.session:

      path = self.server.config['urlprefix'] + '/'

      value = '%s=%s; Path=%s; Max-Age=%d; Secure' \

            % (self.COOKIE, request.session.id, path, request.session.maxtime)

    else:

      value = '%s=; Expires=Thu, 01 Jan 1970 00:00:00 GMT' \

            % (self.COOKIE)

    request.answer.headers.append( ('Set-Cookie', value) )

  def create_session(self, request, user_id):

    assert(type(user_id) is int)

    assert(user_id)

    with self.lock:

      session = Session(self, user_id)

      self.sessions[session.id] = session

      request.session = session

    self.add_cookie_header(request)

  def attach_session(self, request):

    request.session = None

    # parse cookie

    id = None

    for i in request.cookie.split(';'):

      j = i.split('=')

      if len(j) == 2:

        if j[0].strip() == self.COOKIE:

          if not id is None: # double cookie equals no cookie

            id = None

            break

          id = j[1].strip()

    if id:

      with self.lock:

        session = self.sessions.get(id)

        if session:

          if session.expired():

            del self.sessions[id]

          else:

            session.touch()

            request.session = session

    if request.session or request.cookie: # need we add new or delete existant cookie

      self.add_cookie_header(request)

  def close_session(self, request):

    if request.session:

      with self.lock:

        if request.session.id in self.sessions:

          del self.sessions[request.session.id]

      request.session = None

    if request.cookie:

      self.add_cookie_header(request)