import os.path, sys, time, urllib
from time import strftime
import logging

__author__ = 'rhoerbe'

logger = logging.getLogger(__name__)

def fetch_metadata(url, path, maxage=600):
    """
    :param url:  metadata remote location
    :param path: metdata file name
    :param maxage: if max age of existing metadata file (s) is exceeded,
     the file will be fetched from the remote location
    """
    fetch = False
    if not os.path.isfile(path):
        fetch = True
        logger.debug("metadata file %s not found" % path)
    elif (os.path.getmtime(path) + maxage) < time.time():
        fetch = True
        logger.debug("metadata file %s from %s is more than %s s old" %
                     (path,
                      strftime("%Y-%m-%d %H:%M:%S", time.localtime(os.path.getmtime(path))),
                      maxage))
    else:
        logger.debug("metadata file %s is less than %s s old" % (path, maxage))
    if fetch:
        f=urllib.URLopener()
        try:
            f.retrieve(url, path)
            logger.debug("downloaded metadata from %s into %s" % (url, path))
        except:
            logger.debug("downloaded metadata from %s failed: %s" %
                         (url, sys.exc_info()[0]))