sbeam/src/SuperBeam/__init__.py

import os

from http.server import BaseHTTPRequestHandler
import socketserver
import threading
import pyqrcode
import socket
import struct
import base64

import inspect
from SuperBeam import RequestHandlers


class SuperBeamServer(BaseHTTPRequestHandler):
    """SuperBeam Server

    Handle incoming requests to serve information to the client.

    Class is built on top of :mod:`http.server.BaseHTTPRequestHandler` as
    simple http server.

    During initialization, the RequestHandlers are registered as routable
    paths.

    Call :func:`serve_forever()` to start the HTTP server. The mainloop will
    serve a list of files given as argument to :func:`serve_forever()`.

    Args:
        debug (bool): Enable debug output. Defaults to `False`.
        *args: Variable length argument list.
        **kwargs: Arbitrary keyword arguments.

    Attributes:
        debug (bool): enable debug output.
        files (list): list of files served by the `SuperBeamServer`.
    """

    def __init__(self, request, client_address, server, debug=False):
        self.debug = debug
        self.routes = {}
        for _, cls in inspect.getmembers(RequestHandlers, inspect.isclass):
            if hasattr(cls, 'URI'):
                for route in cls.URI:
                    self.routes[route] = cls
        super(SuperBeamServer, self).__init__(request, client_address, server)

    def do_GET(self):
        """GET request handler

        The :class:`SuperBeamServer` supports specifically defined requests
        URIs. Each requested URI in handled by a different handler class. The
        classes are defined in :mod:`SuperBeam.RequestHandlers` and registered
        in the ``path`` dictionary of this method.

        The requested path is checked against the registered handlers and - if
        exists - forwarded to :func:`respond()`, where the request gets
        answered.
        """
        if self.debug:
            print(threading.current_thread())

        # TODO Add globbing
        if self.path in self.routes:  # TODO startswith key check
            self.respond(self.routes[self.path])

    def respond(self, handler):
        """Respond client with request with registered handler.

        Method is called by :func:`do_GET()`.

        Currently supported handlers are described in
        :mod:`SuperBeam.RequestHandlers`.

        Args:
            class: Handler class implemeting a static ``handle()`` method.
        """
        if self.debug:
            print('='*30 + ' DEBUG ' + '='*30)
            print('CONNECTION:', self.connection)
            print('HEADERS   :', self.headers)
            print('REQUEST   :', self.request)
            print('REQUEST*  :', self.requestline)
            print('PATH      :', self.path)
            print('COMMAND   :', self.command)
            print('HANDLER   :', handler)
            print('='*30 + ' DEBUG ' + '='*30)
        handler.handle(self)


def get_primary_ip() -> str:
    """Get primary IP address.

    Obtain the primary interface IP address. If an error occurs, the default
    loopback adddress '127.0.0.1' is returned.

    Returns:
        str: IP Address
    """
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        # doesn't even have to be reachable
        s.connect(('10.255.255.255', 1))
        IP = s.getsockname()[0]
    except Exception as exc:
        print(exc)
        IP = '127.0.0.1'
    finally:
        s.close()
    return IP


def get_qrcode() -> tuple:
    """Generate QR Code to be scanned by the SuperBeam Client.

    Obtains the IP address of by calling :func:`get_primary_ip()` and creates
    the ``QRCode`` object with :mod:`pyqrcode`.

    Returns:
        tuple(`pyqrcode.QRCode`, str): QRCode object, IP address
    """
    primary_ip = get_primary_ip()
    octets = [1]
    octets.extend([int(_) for _ in primary_ip.split('.')[::-1]])
    url = 'http://superbe.am/q?' + base64.b64encode(
        struct.pack('BBBBB', *octets)
    ).decode('utf-8')
    return pyqrcode.create(url), primary_ip


def show_qrcode():
    """Display QR Code with link for SuperBeam Client.

    The QR code is generated in function :func:`get_qrcode()`. The QR code is
    rendered in the terminal window.
    """
    qrcode, primary_ip = get_qrcode()
    print(qrcode.terminal())
    print(f'SuperBeam Server: http:://{primary_ip}:8080/\n')


def build_filelist(paths, recursive=True) -> list:
    """List of files or directories to be served to SuperBeam clients.

    Args:
        paths (list(str)): list of directories to serve.
        recursive (bool, optional):  serve subdirectories of `paths`. Defaults
            to `True`

    Returns:
        list: list of files with fullpath to be served.
    """
    filelist = []
    for path in paths:
        if os.path.isdir(path) and recursive:
            for root, dirs, files in os.walk(path):
                for file_ in files:
                    filelist.append(os.path.join(root, file_))
        else:
            filelist.append(path)
    return filelist


def serve_forever(files):
    """Start the SuperBeam server and serve `files`.

    Infinite main loop serving `files` via SuperBeam server. Consider calling
    :func:`build_filelist()` to get a list of files to serve.

    The server tries to obtain the primary IP address of the system and binds
    the server to TCP port 8080.

    Args:
        files (list(str)): a list of files with fullpath information to serve.
    """
    Handler = SuperBeamServer
    Handler.files = files
    with socketserver.ThreadingTCPServer(('', 8080), Handler) as httpd:
        show_qrcode()
        httpd.serve_forever()