"""Default URL reading functions"""

__all__ = ['_defaultFetcher']

import functools
import urllib.error
import urllib.request

try:
    from importlib import metadata
except ImportError:
    import importlib_metadata as metadata

import encutils

from . import errorhandler

log = errorhandler.ErrorHandler()


@functools.lru_cache
def _get_version():
    try:
        return metadata.version('cssutils')
    except metadata.PackageNotFoundError:
        return 'unknown'


def _defaultFetcher(url):
    """Retrieve data from ``url``. cssutils default implementation of fetch
    URL function.

    Returns ``(encoding, string)`` or ``None``
    """
    try:
        request = urllib.request.Request(url)
        agent = f'cssutils/{_get_version()} (https://pypi.org/project/cssutils)'
        request.add_header('User-agent', agent)
        res = urllib.request.urlopen(request)
    except urllib.error.HTTPError as e:
        # http error, e.g. 404, e can be raised
        log.warn(f'HTTPError opening url={url}: {e.code} {e.msg}', error=e)
    except urllib.error.URLError as e:
        # URLError like mailto: or other IO errors, e can be raised
        log.warn('URLError, %s' % e.reason, error=e)
    except OSError as e:
        # e.g if file URL and not found
        log.warn(e, error=OSError)
    except ValueError as e:
        # invalid url, e.g. "1"
        log.warn('ValueError, %s' % e.args[0], error=ValueError)
    else:
        if res:
            mimeType, encoding = encutils.getHTTPInfo(res)
            if mimeType != 'text/css':
                log.error(
                    'Expected "text/css" mime type for url=%r but found: %r'
                    % (url, mimeType),
                    error=ValueError,
                )
            content = res.read()
            if hasattr(res, 'close'):
                res.close()
            return encoding, content