from mailu import models, utils
from mailu.internal import internal, nginx
from flask import current_app as app

import flask
import flask_login
import base64

@internal.route("/auth/email")
def nginx_authentication():
    """ Main authentication endpoint for Nginx email server
    """
    client_ip = flask.request.headers["Client-Ip"]
    if utils.limiter.should_rate_limit_ip(client_ip):
        status, code = nginx.get_status(flask.request.headers['Auth-Protocol'], 'ratelimit')
        response = flask.Response()
        response.headers['Auth-Status'] = status
        response.headers['Auth-Error-Code'] = code
        if int(flask.request.headers['Auth-Login-Attempt']) < 10:
            response.headers['Auth-Wait'] = '3'
        return response
    headers = nginx.handle_authentication(flask.request.headers)
    response = flask.Response()
    for key, value in headers.items():
        response.headers[key] = str(value)
    is_valid_user = False
    if "Auth-User-Exists" in response.headers and response.headers["Auth-User-Exists"]:
        username = response.headers["Auth-User"]
        if utils.limiter.should_rate_limit_user(username, client_ip):
            # FIXME could be done before handle_authentication()
            status, code = nginx.get_status(flask.request.headers['Auth-Protocol'], 'ratelimit')
            response = flask.Response()
            response.headers['Auth-Status'] = status
            response.headers['Auth-Error-Code'] = code
            if int(flask.request.headers['Auth-Login-Attempt']) < 10:
                response.headers['Auth-Wait'] = '3'
            return response
        is_valid_user = True
    if ("Auth-Status" not in headers) or (headers["Auth-Status"] != "OK"):
        utils.limiter.rate_limit_user(username, client_ip) if is_valid_user else rate_limit_ip(client_ip)
    elif ("Auth-Status" in headers) and (headers["Auth-Status"] == "OK"):
        utils.limiter.exempt_ip_from_ratelimits(client_ip)
    return response

@internal.route("/auth/admin")
def admin_authentication():
    """ Fails if the user is not an authenticated admin.
    """
    if (not flask_login.current_user.is_anonymous
        and flask_login.current_user.global_admin
        and flask_login.current_user.enabled):
        return ""
    return flask.abort(403)

@internal.route("/auth/user")
def user_authentication():
    """ Fails if the user is not authenticated.
    """
    if (not flask_login.current_user.is_anonymous
        and flask_login.current_user.enabled):
        response = flask.Response()
        response.headers["X-User"] = models.IdnaEmail.process_bind_param(flask_login, flask_login.current_user.get_id(), "")
        response.headers["X-User-Token"] = models.User.get_temp_token(flask_login.current_user.get_id())
        return response
    return flask.abort(403)


@internal.route("/auth/basic")
def basic_authentication():
    """ Tries to authenticate using the Authorization header.
    """
    client_ip = flask.request.headers["X-Real-IP"] if 'X-Real-IP' in flask.request.headers else flask.request.remote_addr
    if utils.limiter.should_rate_limit_ip(client_ip):
        response = flask.Response(status=401)
        response.headers["WWW-Authenticate"] = 'Basic realm="Authentication rate limit from one source exceeded"'
        response.headers['Retry-After'] = '60'
        return response
    authorization = flask.request.headers.get("Authorization")
    if authorization and authorization.startswith("Basic "):
        encoded = authorization.replace("Basic ", "")
        user_email, password = base64.b64decode(encoded).split(b":", 1)
        user_email = user_email.decode("utf8")
        if utils.limiter.should_rate_limit_user(user_email, client_ip):
            response = flask.Response(status=401)
            response.headers["WWW-Authenticate"] = 'Basic realm="Authentication rate limit for this username exceeded"'
            response.headers['Retry-After'] = '60'
            return response
        user = models.User.query.get(user_email)
        if user and nginx.check_credentials(user, password.decode('utf-8'), flask.request.remote_addr, "web"):
            response = flask.Response()
            response.headers["X-User"] = models.IdnaEmail.process_bind_param(flask_login, user.email, "")
            utils.limiter.exempt_ip_from_ratelimits(client_ip)
            return response
        utils.limiter.rate_limit_user(user_email, client_ip) if user else utils.limiter.rate_limit_ip(client_ip)
    response = flask.Response(status=401)
    response.headers["WWW-Authenticate"] = 'Basic realm="Login Required"'
    return response