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 def purge_cache(self, age=4):
  88     now = datetime.utcnow()
  89     if now.hour == SimaEch.timestamp.hour:
  90         return
  91     SimaEch.timestamp = datetime.utcnow()
  92     cache = SimaEch.cache
  93     delta = timedelta(hours=age)
  94     for url in list(cache.keys()):
  95         timestamp = cache.get(url).created()
  96         if now - timestamp > delta:
  97             cache.pop(url)
  98
  99
 100 class SimaEch():
 101     """
 102     """
 103     root_url = 'http://{host}/api/{version}'.format(**ECH)
 104     cache = {}
 105     timestamp = datetime.utcnow()
 106
 107     def __init__(self, cache=True):
 108         self.artist = None
 109         self._ressource = None
 110         self.current_element = None
 111         self.caching = cache
 112         self.purge_cache()
 113
 114     def _fetch(self, payload):
 115         """Use cached elements or proceed http request"""
 116         url = Request('GET', self._ressource, params=payload,).prepare().url
 117         if url in SimaEch.cache:
 118             self.current_element = SimaEch.cache.get(url).elem
 119             return
 120         try:
 121             self._fetch_lfm(payload)
 122         except Timeout:
 123             raise EchoTimeout('Failed to reach server within {0}s'.format(
 124                                SOCKET_TIMEOUT))
 125         except ConnectionError as err:
 126             raise EchoError(err)
 127
 128     @Throttle(WAIT_BETWEEN_REQUESTS)
 129     def _fetch_lfm(self, payload):
 130         """fetch from web service"""
 131         req = get(self._ressource, params=payload,
 132                             timeout=SOCKET_TIMEOUT)
 133         if 'x-ratelimit-remaining' in req.headers:
 134             logging.debug('x-ratelimit-remaining {x-ratelimit-remaining}'.format(**req.headers))
 135         if req.status_code is not 200:
 136             raise EchoHTTPError(req.status_code)
 137         self.current_element = req.json()
 138         self._controls_answer()
 139         if self.caching:
 140             SimaEch.cache.update({req.url:
 141                                  Cache(self.current_element)})
 142
 143     def _controls_answer(self):
 144         """Controls last.fm answer.
 145         """
 146         status = self.current_element.get('response').get('status')
 147         code = status.get('code')
 148         if code is 0:
 149             return True
 150         if code is 5:
 151             raise EchoNotFound('Artist not found: "{0}"'.format(self.artist))
 152         raise EchoError(status.get('message'))
 153
 154     def _forge_payload(self, artist):
 155         """
 156         """
 157         payload = {'api_key': ECH.get('apikey')}
 158         if not isinstance(artist, Artist):
 159             raise TypeError('"{0!r}" not an Artist object'.format(artist))
 160         self.artist = artist
 161         if artist.mbid:
 162             payload.update(
 163                     id='musicbrainz:artist:{0}'.format(artist.mbid))
 164         else:
 165            payload.update(name=artist.name)
 166         payload.update(bucket='id:musicbrainz')
 167         payload.update(results=30)
 168         return payload
 169
 170     def get_similar(self, artist=None):
 171         """
 172         """
 173         payload = self._forge_payload(artist)
 174         # Construct URL
 175         self._ressource = '{0}/artist/similar'.format(SimaEch.root_url)
 176         self._fetch(payload)
 177         for art in self.current_element.get('response').get('artists'):
 178             artist = {}
 179             mbid = None
 180             if 'foreign_ids' in art:
 181                 for frgnid in art.get('foreign_ids'):
 182                     if frgnid.get('catalog') == 'musicbrainz':
 183                         mbid = frgnid.get('foreign_id'
 184                                           ).lstrip('musicbrainz:artist:')
 185             yield Artist(mbid=mbid, name=art.get('name'))
 186
 187
 188 # VIM MODLINE
 189 # vim: ai ts=4 sw=4 sts=4 expandtab