import re
import subprocess
from shutil import which

#  Originally from https://github.com/opencoff/useful-scripts/blob/master/linktest.py

# mapping fields from ethtool output to simple names
field_map = {
    'Supported ports': 'ports',
    'Supported link modes': 'sup_link_modes',
    'Supports auto-negotiation': 'sup_autoneg',
    'Advertised link modes': 'adv_link_modes',
    'Advertised auto-negotiation': 'adv_autoneg',
    'Speed': 'speed',
    'Duplex': 'duplex',
    'Port': 'port',
    'Auto-negotiation': 'autoneg',
    'Link detected': 'link',
}


def merge_two_dicts(x, y):
    z = x.copy()
    z.update(y)
    return z


class Ethtool():
    """
    This class aims to parse ethtool output
    There is several bindings to have something proper, but it requires
    compilation and other requirements.
    """

    def __init__(self, interface, *args, **kwargs):
        self.interface = interface

    def _parse_ethtool_output(self):
        """
        parse ethtool output
        """

        output = subprocess.getoutput('ethtool {}'.format(self.interface))

        fields = {}
        field = ''
        fields['speed'] = '-'
        fields['link'] = '-'
        fields['duplex'] = '-'
        for line in output.split('\n')[1:]:
            line = line.rstrip()
            r = line.find(':')
            if r > 0:
                field = line[:r].strip()
                if field not in field_map:
                    continue
                field = field_map[field]
                output = line[r + 1:].strip()
                fields[field] = output
            else:
                if len(field) > 0 and \
                   field in field_map:
                    fields[field] += ' ' + line.strip()
        return fields

    def _parse_ethtool_module_output(self):
        status, output = subprocess.getstatusoutput('ethtool -m {}'.format(self.interface))
        if status == 0:
            r = re.search(r'Identifier.*\((\w+)\)', output)
            if r and len(r.groups()) > 0:
                return {'form_factor': r.groups()[0]}
        return {}

    def parse(self):
        if which('ethtool') is None:
            return None
        output = self._parse_ethtool_output()
        output.update(self._parse_ethtool_module_output())
        return output