#!/usr/bin/env python3

# python standard library
from os import path
import sys
import argparse
import signal

# user installed libraries
from tornado import ioloop, web, httpserver


# ============================================================================
# WebApplication - Tornado Web Server
# ============================================================================
class WebRedirectApplication(web.Application):
    def __init__(self, target='https://localhost'):
        handlers = [
            (r'/*',              RootHandler),           # redirect to https
        ]
        super().__init__(handlers)
        self.target = target

# ============================================================================
# Handlers
# ============================================================================
class RootHandler(web.RequestHandler):
    SUPPORTED_METHODS = ['GET']

    def get(self):
        print('Redirecting...')
        self.redirect(self.application.target)


# -------------------------------------------------------------------------
def signal_handler(signal, frame):
    r = input(' --> Stop webserver? (yes/no) ').lower()
    if r == 'yes':
        ioloop.IOLoop.current().stop()
        print('Webserver stopped.')
        sys.exit(0)


# -------------------------------------------------------------------------
# Tornado web server
# ----------------------------------------------------------------------------
def main():
    # --- Commandline argument parsing
    argparser = argparse.ArgumentParser(
        description='Redirection server. Any request to http will be redirected to a target server provided in the command line argument.')
    argparser.add_argument('target', type=str,
        help='Target https server address, e.g. https://www.example.com.')
    argparser.add_argument('--port', type=int, default=8080,
        help='Port to which this server will listen to, e.g. 8080')
    arg = argparser.parse_args()

    # --- create web redirect application
    try:
        redirectapp = WebRedirectApplication(target=arg.target)
    except Exception as e:
        print('Failed to start web redirect application.')
        raise e

    # --- create webserver
    try:
        http_server = httpserver.HTTPServer(redirectapp)
    except Exception as e:
        print('Failed to create HTTP server.')
        raise e
    else:
        http_server.listen(8080)

    # --- run webserver
    print(f'Redirecting port {arg.port} to {arg.target}  (Ctrl-C to stop)')
    signal.signal(signal.SIGINT, signal_handler)

    try:
        ioloop.IOLoop.current().start()  # running...
    except Exception as e:
        print('Redirection stopped!')
        ioloop.IOLoop.current().stop()
        raise e


# ----------------------------------------------------------------------------
if __name__ == "__main__":
    main()