import cherrypy
import yaml
import os
from jinja2 import Environment, FileSystemLoader
from cryptography.hazmat.primitives import serialization
from .crypto import generate_and_save_keypair, load_keypair, PRIVATE_KEY_PATH, PUBLIC_KEY_PATH

env = Environment(loader=FileSystemLoader('templates'))


class Disco(object):

    @cherrypy.expose
    @cherrypy.tools.json_out()
    def index(self):
        if not os.path.exists(PRIVATE_KEY_PATH):
            generate_and_save_keypair(PRIVATE_KEY_PATH, PUBLIC_KEY_PATH)
        _, public_key = load_keypair(PRIVATE_KEY_PATH, PUBLIC_KEY_PATH)
        pem_bytes = public_key.public_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PublicFormat.SubjectPublicKeyInfo,
        )

        pem_string = pem_bytes.decode('utf-8')
        baseurl = cherrypy.request.base
        tmpl = env.get_template('discovery.yaml')
        yamldoc = yaml.safe_load(
            tmpl.render(endpoint=baseurl + '/ocm',
                        public_key_id=baseurl + '/ocm#signature',
                        public_key_pem=pem_string))
        return yamldoc