import logging
import os
import subprocess
import warnings
##
import jinja2


logger = logging.getLogger()


class RA(object):
    def __init__(self, conf = None, tpl_name = None, tpl_dir = None, *args, **kwargs):
        self.conf = RAConf(conf = conf, tpl_name = tpl_name, tpl_dir = tpl_dir, *args, **kwargs)
        self.svc = RASvc()


class RAConf(object):
    cfgstr = None
    tpl_dir = os.path.join(os.path.dirname(os.path.abspath(os.path.expanduser(__file__))), 'tpl')

    def __init__(self, conf = None, tpl_name = None, tpl_dir = None, *args, **kwargs):
        for k in ('name', 'dir'):
            n = 'tpl_{0}'.format(k)
            v = locals()[n]
            if v:
                setattr(self, n, v)
        if conf:
            self.conf = os.path.abspath(os.path.expanduser(conf))

    def ext_init(self):
        self.tpl_dir = os.path.abspath(os.path.expanduser(self.tpl_dir))
        self.loader = jinja2.FileSystemLoader(self.tpl_dir)
        self.tpl_env = jinja2.Environment(loader = self.loader, extensions = ['jinja2.ext.do'])
        self.tpl = self.tpl_env.get_template(self.tpl_name)
        return(None)

    def generate(self, assignments):
        self.cfgstr = self.tpl.render(assignments = assignments)
        return(None)

    def write(self):
        if not self.cfgstr:
            raise RuntimeError('Must run .generate() first')
        os.makedirs(os.path.dirname(self.conf), exist_ok = True, mode = 0o0700)
        with open(self.conf, 'w') as fh:
            fh.write(self.cfgstr)


class RASvc(object):
    name = None
    is_systemd = False
    cmd_tpl = None
    has_pkill = False
    start_cmd = None
    stop_cmd = None
    restart_cmd = None

    def __init__(self):
        self._get_manager()

    def _exec(self, cmd):
        cmd_exec = subprocess.run(cmd, stdin = subprocess.PIPE, stdout = subprocess.PIPE)
        if cmd_exec.returncode != 0:
            logger.warning('Could not execute {0}; returned status {1}'.format(' '.join(cmd),
                                                                               cmd_exec.returncode))
            for i in ('stdout', 'stderr'):
                s = getattr(cmd_exec, i)
                if s and s.decode('utf-8').strip() != '':
                    logger.warning('{0}: {1}'.format(i.upper(), s.decode('utf-8')))
        return(None)

    def _get_manager(self):
        chkpaths = ('/run/systemd/system',
                    '/dev/.run/systemd',
                    '/dev/.systemd')
        for _ in chkpaths:
            if os.path.exists(_):
                self.is_systemd = True
                break
        if self.is_systemd:
            self.cmd_tpl = 'systemctl {op} {name}'
        else:
            # Systemd haters, if you don't understand the benefits of unified service management across all linux
            # distros, you've obviously never done wide-platform management or scripting.
            # Let this else block be a learning experience for you.
            self.cmd_tpl = None
            self.has_pkill = False
            for p in os.environ.get('PATH', '/usr/bin').split(':'):
                fpath = os.path.abspath(os.path.expanduser(p))
                bins = os.listdir(fpath)
                if 'pkill' in bins:
                    self.has_pkill = True
                if 'service' in bins:  # CentOS/RHEL pre-7.x
                    self.cmd_tpl = 'service {name} {op}'
                    break
                elif 'initctl' in bins:  # older Ubuntu and other Upstart distros
                    self.cmd_tpl = 'initctl {op} {name}'
                    break
                elif 'rc-service' in bins:  # OpenRC
                    self.cmd_tpl = 'rc-service {name} {op}'
                    break
                # That wasn't even all of them.
        if not self.cmd_tpl and not self.has_pkill:
            logger.error('Could not find which service manager this system is using.')
            raise RuntimeError('Could not determine service manager')
        elif self.has_pkill:  # Last-ditch effort.
            self.start_cmd = [self.name]
            self.stop_cmd = ['pkill', self.name]
            self.restart_cmd = ['pkill', '-HUP', self.name]
        else:
            for k in ('start', 'stop', 'restart'):
                setattr(self,
                        '{0}_cmd'.format(k),
                        self.cmd_tpl.format(name = self.name, op = k).split())
        return(None)

    def restart(self):
        cmd = self.restart_cmd
        self._exec(cmd)
        return(None)

    def start(self):
        cmd = self.start_cmd
        self._exec(cmd)
        return(None)

    def stop(self):
        cmd = self.stop_cmd
        self._exec(cmd)
        return(None)


class RADVD(RA):
    name = 'radvd'
    conf = '/etc/radvd.conf'
    tpl_name = 'radvd.conf.j2'

    def __init__(self, conf = None, tpl_name = None, tpl_dir = None):
        if not conf:
            conf = self.conf
        if not tpl_name:
            tpl_name = self.tpl_name
        super().__init__(conf = conf, tpl_name = tpl_name, tpl_dir = tpl_dir)
        self.conf.ext_init()


class DNSMasq(RA):
    name = 'dnsmasq'
    conf = '/etc/dnsmasq.d/ra.conf'
    tpl_name = 'dnsmasq.include.j2'

    def __init__(self, conf = None, tpl_name = None, tpl_dir = None):
        if not conf:
            conf = self.conf
        if not tpl_name:
            tpl_name = self.tpl_name
        super().__init__(conf = conf, tpl_name = tpl_name, tpl_dir = tpl_dir)
        self.conf.ext_init()