def context(conf, retry = None, fake_error = None):
  """
  Examples:
    - Do not fail unless the third try goes also wrong: retries = 3
    - wait delay_ms between eacht try
    - Succeed on the 3rd try: fails=2

  retry = dict(retries=2, delay_ms=1)
  fake_error = dict(fails=3)
  ctx = swapi.context(conf)
  """
  res = dict(
    conf=conf,
    retry = dict(
      retries=3,
      delay_ms=2000,
      ),
    fake_error = dict(), # fake_error = dict(fails=2)
  )
  if retry is not None:
    res["retry"].update(retry)
  if fake_error is not None:
    res["fake_error"].update(fake_error)
  return res


class SwapiFakeIOError(OSError): 
  pass
  """
  This is our Simulated IO Error Exception for Unit Testing.
  From Python 3.3 on this is the relevant IO Exception hierarchy:
  +-- OSError
        |    +-- BlockingIOError
        |    +-- ChildProcessError
        |    +-- ConnectionError
        |    |    +-- BrokenPipeError
        |    |    +-- ConnectionAbortedError
        |    |    +-- ConnectionRefusedError
        |    |    +-- ConnectionResetError
        |    +-- FileExistsError
        |    +-- FileNotFoundError
        |    +-- InterruptedError
        |    +-- IsADirectoryError
        |    +-- NotADirectoryError
        |    +-- PermissionError
        |    +-- ProcessLookupError
        |    +-- TimeoutError
  """

def rest_call(method, url, auth, data = None, fake_error = {}):
  fails_left = fake_error.get("fail_times", 0)
  if fails_left > 0:
    msg = "%s %s fails, %s fake errors left." % (
      method, url, fails_left - 1)
    LOG.debug(msg)
    raise SwapiFakeIOError(msg)

  import requests
  if method == "GET":
    r = requests.get(
      url = url,
      auth = auth,
      )
  if method == "POST":
    r = requests.delete(
      url = url,
      auth = auth,
      )
  if method == "PUT":
    r = requests.delete(
      url = url,
      auth = auth,
      )
  if method == "DELETE":
    r = requests.delete(
      url = url,
      auth = auth,
      )
  return r

def construct_auth(conf):
  proto, server, basepath, user, key = conf
  import requests.auth
  auth=requests.auth.HTTPDigestAuth(user, key)
  return auth

def construct_url(conf, coll):
  """
  >>> conf = ("http","example.com", "/subshop/", "api", "key123key")
  >>> construct_url(conf,"articles")
  'http://example.com/subshop/api/articles'

  >>> conf = ("https","example.com", "/", "api", "key123key")
  >>> construct_url(conf,"orders")
  'https://example.com/api/orders'

  """
  proto, server, basepath, user, key = conf
  url = '%s://%s%sapi/%s' % (proto,server,basepath, coll)
  import swapi
  swapi.LOG.debug("Url constructed: %s", url)
  return url

def get(ctx, coll, suffix = ""):
  #next_action, exception, message, result = handle_context(ctx)
  #if next_action == "return"
  #  return result
  #if next_action == "exception"
  #  raise
  conf = ctx["conf"]
  url = "%s%s" % (construct_url(conf,coll), suffix)
  global LOG # use LOG from the module namespace
  import swapi
  swapi.LOG.debug("Auth user: %s", conf[3])
  auth = construct_auth(conf)
  import requests
  
  
  last_i = ctx["retry"]["retries"]+1
  assert last_i > 0
  for i in range(0,last_i):
    try:
      r = rest_call(
        method = "GET",
        url = url,
        auth = auth,
        fake_error = ctx["fake_error"],
        )
    except OSError as e: # all IO Errors are catched here
      import traceback
      tb = traceback.format_exc()      
      LOG.error("OSError exception: %s" % tb)
      # are we out of retries?
      if i >= ctx["retry"]["retries"]:
        # then re-raise it!
        raise
    except:
      import traceback
      tb = traceback.format_exc()      
      LOG.error("Unexpected exception: %s" % tb)
    else: # no exception
      break # if it worked, exit the loop now

  rdict = r.json()
  if str(r) == "<Response [200]>":
    swapi.LOG.debug("Response of GET request: %s" % str(r))
    data = rdict.get("data",{})
    info = data
    return True, r, info
  else:
    swapi.LOG.warning("Response of GET request: %s" % str(r))
    message = rdict.get("message",None)
    info = message
    return False, r , info