authentication.py

"""
Spotify Terminal authenticates with Spotify by directing
your browser to the locally hosted authentication link.
"""
import json
import os
import requests
import struct
import urllib
import webbrowser
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
from threading import Thread

import common


logger = common.logging.getLogger(__name__)


class Authenticator(object):
    """Authenticate."""

    port = 12345

    scope = " ".join([
        "playlist-modify-private",
        "playlist-modify-public",
        "playlist-read-collaborative",
        "playlist-read-private",
        "user-read-email",
        "user-read-currently-playing",
        "user-read-playback-state",
        "user-read-private",
        "user-modify-playback-state",
        "user-library-modify",
        "user-library-read"
    ])

    def __init__(self, username):
        self.username = username
        self.token_type = None
        self.access_token = None
        self.refresh_token = None
        self.app_data = []
        self._init()

    def authenticate(self):
        # Try to use local auth file.
        if not self._auth_from_file():
            def start_server():
                http_server = HTTPServer(('localhost', self.port), AuthenticationHandler)
                http_server.handle_request()
                self.data = http_server.data

            logger.debug("Starting auth server")
            web_thread = Thread(target=start_server)
            web_thread.start()

            logger.debug("Opening %s in browser", self._authorize_url())
            webbrowser.open_new_tab(self._authorize_url())

            logger.debug("Waiting for user to complete authentication process")
            web_thread.join()

            self._get_tokens()

    def refresh(self):
        logger.debug("Refreshing token")
        post_body = {
            "grant_type": "refresh_token",
            "refresh_token": self.refresh_token,
            "client_id": self.app_data[0],
            "client_secret": self.app_data[1]
        }

        resp = requests.post(self._token_url(), data=post_body)
        resp.raise_for_status()

        data = json.loads(resp.text)
        data["refresh_token"] = self.refresh_token
        self._save(data)

    def _init(self):
        # Full disclosure -- This is easy to decode.
        # However, this program does not save any of your
        # personal information, so none of your data is compromised.
        filename = os.path.join(
            os.path.dirname(os.path.abspath(__file__)), ".st"
        )
        with open(filename, "rb") as f:
            line = "".join([
                chr(i-1993) for i in struct.unpack("64I", f.readline())
            ])
            self.app_data.append(line[0:32])
            self.app_data.append(line[32::])

    def _auth_from_file(self):
        required_keys = {"access_token",
                         "token_type",
                         "refresh_token"}
        found_keys = set()
        if os.path.isfile(common.get_auth_filename(self.username)):
            with open(common.get_auth_filename(self.username)) as auth_file:
                for line in auth_file:
                    line = line.strip()
                    toks = line.split("=")
                    if toks[0] in required_keys:
                        logger.info("Found %s in auth file", toks[0])
                        setattr(self, toks[0], toks[1])
                        found_keys.add(toks[0])
            return len(required_keys.symmetric_difference(found_keys)) == 0
        else:
            return False

    def _get_tokens(self):
        # First request to get tokens.
        post_body = {
            "grant_type": "authorization_code",
            "code": self.data["code"],
            "redirect_uri": "http://localhost:{}/".format(self.port),
            "client_id": self.app_data[0],
            "client_secret": self.app_data[1]
        }
        resp = requests.post(self._token_url(), data=post_body)
        resp.raise_for_status()
        data = json.loads(resp.text)

        self._save(data)

    def _authorize_url(self):
        params = {
            "client_id": self.app_data[0],
            "redirect_uri": "http://localhost:{}/".format(self.port),
            "scope": self.scope,
            "response_type": "code",
            "show_dialog": True
        }
        return "https://accounts.spotify.com/authorize" + "?" + urllib.urlencode(params)

    def _token_url(self):
        return "https://accounts.spotify.com/api/token"

    def _save(self, data):
        if data:
            for key, value in data.items():
                setattr(self, key, value)

            if not os.path.isdir(common.get_app_dir()):
                os.mkdir(common.get_app_dir())

            with open(common.get_auth_filename(self.username), "w") as auth_file:
                for k, v in data.items():
                    auth_file.write("%s=%s\n" % (k, v))
                logger.debug("%s created", common.get_auth_filename(self.username))
        else:
            try:
                os.remove(common.get_auth_filename(self.username))
                logger.debug("%s deleted", common.get_auth_filename(self.username))
            except OSError:
                pass


class AuthenticationHandler(BaseHTTPRequestHandler):
    HTML = """
        <html>
        You may close this tab, and continue jamming in your terminal!
            <script type="text/javascript">
                    window.close();
            </script>
        </html>
    """

    def do_GET(self):
        if "code=" in self.path:
            self.server.data = self.parse_path(self.path[2::])
            self.send_response(200)
            self.end_headers()
            self.wfile.write(self.HTML)

    def parse_path(self, path):
        data = {}
        items = path.split("&")
        for thing in items:
            toks = thing.split("=")
            data[toks[0]] = toks[1]
        return data

    def log_message(self, format, *args):
        logger.debug(format, *args)