apitest.py

import urllib.parse
import urllib.request
import base64
import json

class APIMeta(type):
  def __init__(cls, name, bases, nmspc):
    super(APIMeta, cls).__init__(name, bases, nmspc)
  @property
  def URL(cls):
    return f'{cls.__BASE_URL__}{cls.__PATH__}'

class APIClientMeta(APIMeta):
  def __init__(cls, name, bases, nmspc):
    super(APIClientMeta, cls).__init__(name, bases, nmspc)
    if not hasattr(cls, '_apis'):
      cls._apis = dict()
    n = name.lower()
    if n.endswith('api'):
      n = n[:-3]
    cls._apis[n] = cls
    for base in bases:
      bn = base.__name__.lower()
      if bn in cls._apis:
        del cls._apis[bn]

class APIBase(object):
  def _find_path_params(self, url):
    i = url.find('{')
    if i > -1:
      j = url[i:].find('}')
      if j > -1:
        l = self._find_path_params(url[i+j+1:])
        name = url[i+1:i+j]
        l.append(name)
        return l
    else:
      return []
  def _req(self, **params):
    if 'content_type' in params:
      self.content_type = params['content_type']
      del params['content_type']
    if 'method' in params:
      method = params['method']
      if method not in self.__class__.__METHODS__:
        raise RuntimeError()
      del params['method']
    elif len(self.__class__.__METHODS__) == 1:
      method = self.__class__.__METHODS__[0]
    else:
      raise RuntimeError()
    url = self.__class__.URL
    path_params = self._find_path_params(url)
    for path_param in path_params:
      if path_param not in params:
        raise RuntimeError()
      url = url.replace('{' + path_param + '}', str(params[path_param]))
      del params[path_param]
    if method == 'GET':
      qstring = urllib.parse.urlencode(params)
      if qstring:
        url = f'{url}?{qstring}'
      req = urllib.request.Request(url, method=method, headers=self.headers)
    else:
      req = urllib.request.Request(url, data=json.dumps(params), method=method, headers=self.headers)
    return req

class BasicAuthAPIBase(APIBase, metaclass=APIMeta):
  def __init__(self, user, password):
    self.user = user
    self.password = password
    self.content_type = 'application/json'

  @property
  def headers(self):
    encoded = base64.b64encode(f'{self.user}:{self.password}'.encode('ascii')).decode('ascii')
    return {
        'Authorization': f'Basic {encoded}',
        'Accept': 'application/json',
        'Content-Type': self.content_type
    }

  def __call__(self, **params):
    req = self._req(**params)
    with urllib.request.urlopen(req) as res:
      return json.loads(res.read())

class PlainAPIBase(APIBase, metaclass=APIMeta):
  def __init__(self):
    self.content_type = 'application/json'

  @property
  def headers(self):
    return {
        'Accept': 'application/json',
        'Content-Type': self.content_type
    }
  def __call__(self, **params):
    req = self._req(**params)
    with urllib.request.urlopen(req) as res:
      return json.loads(res.read())

class BasicAuthAPIClientBase(object):
  def __init__(self, user, password):
    self.user = user
    self.password = password
  def __getattr__(self, attr):
    if attr in self.__class__._apis:
      return self.__class__._apis[attr](self.user, self.password)
    else:
      return self.__dict__[attr]

class PlainAPIClientBase(object):
  def __getattr__(self, attr):
    if attr in self.__class__._apis:
      return self.__class__._apis[attr]()
    else:
      return self.__dict__[attr]

# 実装するのはここから。
class ExampleAPIBase(BasicAuthAPIBase):
  __BASE_URL__ = 'https://example.com'

class ExampleAPIClient(BasicAuthAPIClientBase, metaclass=APIClientMeta):
  pass

class FooAPI(ExampleAPIBase, ExampleAPIClient):
  __PATH__ = '/foo'
  __METHODS__ = ['GET']

class BarAPI(ExampleAPIBase, ExampleAPIClient):
  __PATH__ = '/bar/{id}/item/{itemid}'
  __METHODS__ = ['GET']

class Example2APIBase(PlainAPIBase):
  __BASE_URL__ = 'https://example2.com'

class Example2APIClient(PlainAPIClientBase, metaclass=APIClientMeta):
  pass

class HogeAPI(Example2APIBase, Example2APIClient):
  __PATH__ = '/hoge'
  __METHODS__ = ['GET', 'POST']

class HugaAPI(Example2APIBase, Example2APIClient):
  __PATH__ = '/huga/{id}'
  __METHODS__ = ['GET', 'POST', 'PUT', 'DELETE']

client = ExampleAPIClient('user', 'password')
print(client.bar(id=1, itemid=2, foo='bar'))
print(client.foo())

client2 = Example2APIClient()
print(client2.hoge(method='GET'))
print(client2.huga(method='POST', id=21, name='Ogawa', email='nekomura@example.com'))