import logging

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

from data import model
from data.model import oauth
from app import app
from permissions import QuayDeferredPermissionUser
import scopes

from util.http import abort


logger = logging.getLogger(__name__)


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(':', 1)

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

  elif credentials[0] == '$token':
    # Use as token auth
    try:
      token = model.load_token_data(credentials[1])
      logger.debug('Successfully validated token: %s' % credentials[1])
      ctx = _request_ctx_stack.top
      ctx.validated_token = token

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

    except model.DataModelException:
      logger.debug('Invalid token: %s' % credentials[1])

  elif '+' in credentials[0]:
    logger.debug('Trying robot auth with credentials %s' % str(credentials))
    # Use as robot auth
    try:
      robot = model.verify_robot(credentials[0], credentials[1])
      logger.debug('Successfully validated robot: %s' % credentials[0])
      ctx = _request_ctx_stack.top
      ctx.authenticated_user = robot
      
      deferred_robot = QuayDeferredPermissionUser(robot.username, 'username')
      identity_changed.send(app, identity=deferred_robot)
      return
    except model.InvalidRobotException:
      logger.debug('Invalid robot or password for robot: %s' % credentials[0])

  else:
    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

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

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


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('Not an auth token: %s' % auth)
    return

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

  if len(token_details) != 1:
    logger.warning('Invalid token format: %s' % auth)
    abort(401, message="Invalid token format: %(auth)", issue='invalid-auth-token', auth=auth)

  token_vals = {val[0]: val[1] for val in
                (detail.split('=') for detail in token_details)}
  if 'signature' not in token_vals:
    logger.warning('Token does not contain signature: %s' % auth)
    abort(401, message="Token does not contain a valid signature: %(auth)",
          issue='invalid-auth-token', auth=auth)

  try:
    token_data = model.load_token_data(token_vals['signature'])

  except model.InvalidTokenException:
    logger.warning('Token could not be validated: %s', token_vals['signature'])
    abort(401, message="Token could not be validated: %(auth)", issue='invalid-auth-token',
          auth=auth)

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

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


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

  token = normalized[1]
  validated = oauth.validate_access_token(token)
  if not validated:
    logger.warning('OAuth access token could not be validated: %s', token)
    authenticate_header = {
      'WWW-Authenticate': ('Bearer error="invalid_token", '
                           'error_description="The access token is invalid"'),
    }
    abort(401, message="OAuth access token could not be validated: %(token)",
          issue='invalid-oauth-token', token=token, header=authenticate_header)
  elif validated.expires_at <= datetime.now():
    logger.info('OAuth access with an expired token: %s', token)
    authenticate_header = {
      'WWW-Authenticate': ('Bearer error="invalid_token", '
                           'error_description="The access token expired"'),
    }
    abort(401, message="OAuth access token has expired: %(token)", issue='invalid-oauth-token',
          token=token, headers=authenticate_header)

  # We have a valid token
  scope_set = scopes.scopes_from_scope_string(validated.scope)
  logger.debug('Successfully validated oauth access token: %s with scope: %s', token,
               scope_set)

  ctx = _request_ctx_stack.top
  ctx.authenticated_user = validated.authorized_user

  new_identity = QuayDeferredPermissionUser(validated.authorized_user.username, 'username',
                                            scope_set)
  identity_changed.send(app, identity=new_identity)


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)
      process_oauth(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.error('Unable to load namespace or repository from session: %s' % session)
      abort(400, message="Missing namespace in request")

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