import os

import logging
import logging.handlers

import inspect
import numpy as np


def get_logger(filename, level = logging.DEBUG, logger_name = 'interp', size = 2048, backupCount = 10):
  """
    This is a simple wrapper around a few sane
    defaults using Python's logging functionality.

    An explaination of the optional parameters:
      filename    : the filename
      level       : one of either debug, info, warn, or error
      logger_name : if one needs multiple logfiles, one must name them.
      size        : the size in bytes of the logfile before roll (defaults to 2MB)
      backupCount : number of rolled logs to keep around (defaults to 10)
  """

  logger    = logging.getLogger(logger_name)
  logger.setLevel(level)
  my_format = logging.Formatter('%(asctime)s %(levelname)s (%(process)d) %(filename)s %(funcName)s:%(lineno)d %(message)s')
  handler   = logging.handlers.RotatingFileHandler(
                   filename, maxBytes = size * 1024, backupCount = backupCount)
  handler.setFormatter(my_format)
  logger.addHandler(handler)

  return logger

log = get_logger(filename = '/tmp/interp.log', level = logging.INFO, size = 10240)

def rms(errors):
  """
    root mean square calculation
  """
  r = 0.0
  for i in errors:
    r += np.power(i, 2)
  r = np.sqrt(r / len(errors))
  return r

def exact_func(X):
  """
    the exact function used from baker's article (for testing)
  """
  x ,y = X
  answer = 1.0 + x*x + y*y # np.power((np.sin(x * np.pi) * np.cos(y * np.pi)), 2)
  log.debug(answer)
  return answer

def exact_func_3D(X):
  """
    the exact function (3D) used from baker's article (for testing)
  """
  x = X[0]
  y = X[1]
  z = X[2]
  answer = np.power((np.sin(x * np.pi / 2.0) * np.sin(y * np.pi / 2.0) * np.sin(z * np.pi / 2.0)), 2)
  log.debug(answer)
  return answer

def exact(X):
  x,y,z = X
  return 1 + x*x + y*y + z*z

def improved_answer(answer, exact, verbose=False):
  if not answer['error']:
    return True
  log.debug('qlin:  %s' % answer['qlin'])
  log.debug('error: %s' % answer['error'])
  log.debug('final: %s' % answer['final'])
  log.debug('exact: %s' % exact)

  if np.abs(answer['final'] - exact) <= np.abs(answer['qlin'] - exact):
    log.debug(":) improved result")
    return True
  else:
    log.debug(":( damaged result")
    return False