import logging

from functools import wraps
from flask import request, make_response, _request_ctx_stack, abort, session
from flask.ext.principal import identity_changed, Identity
from base64 import b64decode

from data import model
from app import app

from util.names import parse_namespace_repository


logger = logging.getLogger(__name__)


def get_authenticated_user():
  return getattr(_request_ctx_stack.top, 'authenticated_user', None)


def get_validated_token():
  return getattr(_request_ctx_stack.top, 'validated_token', None)


def process_basic_auth(auth):
  normalized = [part.strip() for part in auth.split(' ') if part]
  if normalized[0].lower() != 'basic' or len(normalized) != 2:
    logger.debug('Invalid basic auth format.')
    return

  credentials = b64decode(normalized[1]).split(':')

  if len(credentials) != 2:
    logger.debug('Invalid basic auth credential formet.')

  authenticated = model.verify_user(credentials[0], credentials[1])

  if authenticated:
    logger.debug('Successfully validated user: %s' % authenticated.username)
    ctx = _request_ctx_stack.top
    ctx.authenticated_user = authenticated

    identity_changed.send(app, identity=Identity(authenticated.username,
                                                 'username'))
    return

  # We weren't able to authenticate via basic auth.
  logger.debug('Basic auth present but could not be validated.')
  abort(401)


def process_token(auth):
  normalized = [part.strip() for part in auth.split(' ') if part]
  if normalized[0].lower() != 'token' or len(normalized) != 2:
    logger.debug('Invalid token format.')
    return

  token_details = normalized[1].split(',')

  if len(token_details) != 2:
    logger.debug('Invalid token format.')
    return

  token_vals = {val[0]: val[1] for val in
                (detail.split('=') for detail in token_details)}
  if ('signature' not in token_vals or 'repository' not in token_vals):
    logger.debug('Invalid token components.')
    return

  unquoted = token_vals['repository'][1:-1]
  namespace, repository = parse_namespace_repository(unquoted)
  logger.debug('Validing signature: %s' % token_vals['signature'])
  validated = model.verify_token(token_vals['signature'], namespace,
                                 repository)

  if validated:
    session['repository'] = repository
    session['namespace'] = namespace

    logger.debug('Successfully validated token: %s' % validated.code)
    ctx = _request_ctx_stack.top
    ctx.validated_token = validated

    identity_changed.send(app, identity=Identity(validated.code, 'token'))

    return

  # WE weren't able to authenticate the token
  logger.debug('Token present but could not be validated.')
  abort(401)


def process_auth(f):
  @wraps(f)
  def wrapper(*args, **kwargs):
    auth = request.headers.get('authorization', '')

    if auth:
      logger.debug('Validating auth header: %s' % auth)
      process_token(auth)
      process_basic_auth(auth)
    else:
      logger.debug('No auth header.')

    return f(*args, **kwargs)
  return wrapper


def extract_namespace_repo_from_session(f):
  @wraps(f)
  def wrapper(*args, **kwargs):
    if 'namespace' not in session or 'repository' not in session:
      logger.debug('Unable to load namespace or repository from session.')
      abort(400)

    return f(session['namespace'], session['repository'], *args, **kwargs)
  return wrapper