# PyMod-Milter is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# PyMod-Milter is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with PyMod-Milter.  If not, see <http://www.gnu.org/licenses/>.
#

import logging
import re

from netaddr import IPAddress, IPNetwork, AddrFormatError


class Conditions:
    """Conditions to implement conditions for rules and actions."""

    def __init__(self, local_addrs, args, logger=None):
        if logger is None:
            logger = logging.getLogger(__name__)

        self._local_addrs = []
        self.logger = logger
        self._args = {}

        try:
            for addr in local_addrs:
                self._local_addrs.append(IPNetwork(addr))
        except AddrFormatError as e:
            raise RuntimeError(f"invalid address in local_addrs: {e}")

        try:
            if "local" in args:
                logger.debug(f"condition: local = {args['local']}")
                self._args["local"] = args["local"]

            if "hosts" in args:
                logger.debug(f"condition: hosts = {args['hosts']}")
                self._args["hosts"] = []
                try:
                    for host in args["hosts"]:
                        self._args["hosts"].append(IPNetwork(host))
                except AddrFormatError as e:
                    raise RuntimeError(f"invalid address in hosts: {e}")

            if "envfrom" in args:
                logger.debug(f"condition: envfrom = {args['envfrom']}")
                try:
                    self._args["envfrom"] = re.compile(
                        args["envfrom"], re.IGNORECASE)
                except re.error as e:
                    raise RuntimeError(f"unable to parse envfrom regex: {e}")

            if "envto" in args:
                logger.debug(f"condition: envto = {args['envto']}")
                try:
                    self._args["envto"] = re.compile(
                        args["envto"], re.IGNORECASE)
                except re.error as e:
                    raise RuntimeError(f"unable to parse envto regex: {e}")

        except KeyError as e:
            raise RuntimeError(
                f"mandatory argument not found: {e}")

    def match(self, args):
        if "host" in args:
            ip = IPAddress(args["host"])

            if "local" in self._args:
                is_local = False
                for addr in self._local_addrs:
                    if ip in addr:
                        is_local = True
                        break

                if is_local != self._args["local"]:
                    self.logger.debug(
                        f"ignore host {args['host']}, "
                        f"condition local does not match")
                    return False

                self.logger.debug(
                    f"condition local matches for host {args['host']}")

            if "hosts" in self._args:
                found = False
                for addr in self._args["hosts"]:
                    if ip in addr:
                        found = True
                        break

                if not found:
                    self.logger.debug(
                        f"ignore host {args['host']}, "
                        f"condition hosts does not match")
                    return False

                self.logger.debug(
                    f"condition hosts matches for host {args['host']}")

        if "envfrom" in args and "envfrom" in self._args:
            if not self._args["envfrom"].match(args["envfrom"]):
                self.logger.debug(
                    f"ignore envelope-from address {args['envfrom']}, "
                    f"condition envfrom does not match")
                return False

            self.logger.debug(
                f"condition envfrom matches for "
                f"envelope-from address {args['envfrom']}")

        if "envto" in args and "envto" in self._args:
            if not isinstance(args["envto"], list):
                args["envto"] = [args["envto"]]

            for envto in args["envto"]:
                if not self._args["envto"].match(envto):
                    self.logger.debug(
                        f"ignore envelope-to address {args['envto']}, "
                        f"condition envto does not match")
                    return False

            self.logger.debug(
                f"condition envto matches for "
                f"envelope-to address {args['envto']}")

        return True