sima/lib/simaecho.py

   1 # -*- coding: utf-8 -*-
   2
   3 # Copyright (c) 2014 Jack Kaliko <kaliko@azylum.org>
   4 #
   5 #   This program is free software: you can redistribute it and/or modify
   6 #   it under the terms of the GNU General Public License as published by
   7 #   the Free Software Foundation, either version 3 of the License, or
   8 #   (at your option) any later version.
   9 #
  10 #   This program is distributed in the hope that it will be useful,
  11 #   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 #   GNU General Public License for more details.
  14 #
  15 #   You should have received a copy of the GNU General Public License
  16 #   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 #
  18 #
  19
  20 """
  21 Consume EchoNest web service
  22 """
  23
  24 __version__ = '0.0.1'
  25 __author__ = 'Jack Kaliko'
  26
  27
  28 import logging
  29
  30 from datetime import datetime, timedelta
  31 from time import sleep
  32
  33 from requests import get, Timeout, ConnectionError
  34
  35 from sima import ECH
  36 from sima.lib.meta import Artist
  37 from sima.utils.utils import getws
  38 if len(ECH.get('apikey')) == 23:
  39     getws(ECH)
  40
  41 # Some definitions
  42 WAIT_BETWEEN_REQUESTS = timedelta(0, 1)
  43 SOCKET_TIMEOUT = 4
  44
  45
  46 class EchoError(Exception):
  47     pass
  48
  49 class EchoNotFound(EchoError):
  50     pass
  51
  52 class EchoTimeout(EchoError):
  53     pass
  54
  55 class EchoHTTPError(EchoError):
  56     pass
  57
  58 class Throttle():
  59     def __init__(self, wait):
  60         self.wait = wait
  61         self.last_called = datetime.now()
  62
  63     def __call__(self, func):
  64         def wrapper(*args, **kwargs):
  65             while self.last_called + self.wait > datetime.now():
  66                 sleep(0.1)
  67             result = func(*args, **kwargs)
  68             self.last_called = datetime.now()
  69             return result
  70         return wrapper
  71
  72
  73 class Cache():
  74     def __init__(self, elem, last=None):
  75         self.elem = elem
  76         self.requestdate = last
  77         if not last:
  78             self.requestdate = datetime.utcnow()
  79
  80     def created(self):
  81         return self.requestdate
  82
  83     def get(self):
  84         return self.elem
  85
  86
  87 class SimaEch():
  88     """
  89     """
  90     root_url = 'http://{host}/api/{version}'.format(**ECH)
  91     cache = {}
  92     timestamp = datetime.utcnow()
  93
  94     def __init__(self, cache=True):
  95         self.artist = None
  96         self._ressource = None
  97         self.current_element = None
  98         self.caching = cache
  99         self.purge_cache()
 100
 101     def _fetch(self, payload):
 102         """Use cached elements or proceed http request"""
 103         url = Request('GET', self._ressource, params=payload,).prepare().url
 104         if url in SimaEch.cache:
 105             self.current_element = SimaEch.cache.get(url).elem
 106             return
 107         try:
 108             self._fetch_lfm(payload)
 109         except Timeout:
 110             raise EchoTimeout('Failed to reach server within {0}s'.format(
 111                                SOCKET_TIMEOUT))
 112         except ConnectionError as err:
 113             raise EchoError(err)
 114
 115     @Throttle(WAIT_BETWEEN_REQUESTS)
 116     def _fetch_lfm(self, payload):
 117         """fetch from web service"""
 118         req = get(self._ressource, params=payload,
 119                             timeout=SOCKET_TIMEOUT)
 120         if 'x-ratelimit-remaining' in req.headers:
 121             logging.debug('x-ratelimit-remaining {x-ratelimit-remaining}'.format(**req.headers))
 122         if req.status_code is not 200:
 123             raise EchoHTTPError(req.status_code)
 124         self.current_element = req.json()
 125         self._controls_answer()
 126         if self.caching:
 127             SimaEch.cache.update({req.url:
 128                                  Cache(self.current_element)})
 129
 130     def _controls_answer(self):
 131         """Controls last.fm answer.
 132         """
 133         status = self.current_element.get('response').get('status')
 134         code = status.get('code')
 135         if code is 0:
 136             return True
 137         if code is 5:
 138             raise EchoNotFound('Artist not found: "{0}"'.format(self.artist))
 139         raise EchoError(status.get('message'))
 140
 141     def _forge_payload(self, artist):
 142         """
 143         """
 144         payload = {'api_key': ECH.get('apikey')}
 145         if not isinstance(artist, Artist):
 146             raise TypeError('"{0!r}" not an Artist object'.format(artist))
 147         self.artist = artist
 148         if artist.mbid:
 149             payload.update(
 150                     id='musicbrainz:artist:{0}'.format(artist.mbid))
 151         else:
 152            payload.update(name=artist.name)
 153         payload.update(bucket='id:musicbrainz')
 154         payload.update(results=30)
 155         return payload
 156
 157     def purge_cache(self, age=4):
 158         now = datetime.utcnow()
 159         if now.hour == SimaEch.timestamp.hour:
 160             return
 161         SimaEch.timestamp = datetime.utcnow()
 162         cache = SimaEch.cache
 163         delta = timedelta(hours=age)
 164         for url in list(cache.keys()):
 165             timestamp = cache.get(url).created()
 166             if now - timestamp > delta:
 167                 cache.pop(url)
 168
 169     def get_similar(self, artist=None):
 170         """
 171         """
 172         payload = self._forge_payload(artist)
 173         # Construct URL
 174         self._ressource = '{0}/artist/similar'.format(SimaEch.root_url)
 175         self._fetch(payload)
 176         for art in self.current_element.get('response').get('artists'):
 177             artist = {}
 178             mbid = None
 179             if 'foreign_ids' in art:
 180                for frgnid in art.get('foreign_ids'):
 181                    if frgnid.get('catalog') == 'musicbrainz':
 182                        mbid = frgnid.get('foreign_id').lstrip('musicbrainz:artist:')
 183             yield Artist(mbid=mbid, name=art.get('name'))
 184
 185
 186 # VIM MODLINE
 187 # vim: ai ts=4 sw=4 sts=4 expandtab