"""
###########################################################################
#   Run a web server using the python flask moduke                        #
#   this is a very simple web app that prints hello world                 #
###########################################################################
"""

import sys 
import os 
from flask import Flask

try:
    ##################################################################################################
    #   Runing a flask web server                                                                    #
    #                                                                                                #                                                                                            
    #   This is a simple web app that prints hello world                                             #                           #
    #                                                                                                #
    #   The web server endpoint cert  file is called webserver_cert.pem                              #
    #                                                                                                #
    #   The certificate chain file is called webserver_cert_chain.pem                                #
    #                                                                                                #
    #   In your terminal make sure that you are in the directory data-protection/usecase-4           #
    #                                                                                                #
    #   We will use the following curl command line statement to verify whether TLS                  #
    #     authentication was successful.                                                             #
    #                                                                                                #
    #     curl --verbose --cacert webserver_cert_chain.pem -X GET https://127.0.0.1:5000/            #
    #                                                                                                #
    #   7.Once you execute the above curl command you will see hello world printed                   #
    ##################################################################################################
    APP = Flask(__name__)

    @APP.route("/")
    def hello():
        """
        ### THis method just returns hello world ###
        """
        return "\nHello World!\n\n"
    
    if __name__ == "__main__":
        #app.run(ssl_context='adhoc')
        CURRENT_DIRECTORY_PATH = os.path.dirname(os.path.realpath(__file__)) + '/'
        webserver_cert_path = CURRENT_DIRECTORY_PATH + 'webserver_cert.pem'
        webserver_key_path = CURRENT_DIRECTORY_PATH + 'webserver_privkey.pem'
        
        ##########################################################################################
        # Since the ssl_context supplied below for the flask webserver requires the private key  #
        # to be a on file webserver_privkey.pem was created                                      #
        # This is only for demonstration purposes, for seucurity private keys should be never be #     
        # stored on disk                                                                         #
        ##########################################################################################
        APP.run(ssl_context=(webserver_cert_path, webserver_key_path))
except:
    print("Unexpected error:", sys.exc_info()[0])
    raise
else:
    exit(0)