# -*- coding: utf-8 -*-
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

from napalm.base.exceptions import (
    CommandErrorException,
    MergeConfigException,
    ReplaceConfigException,
)
from napalm_device_types import ConfigLifecycleMixin


class OpenWrtConfigMixin(ConfigLifecycleMixin):
    """Mixin providing configuration-management NAPALM methods for OpenWrt.

    Reuses the standard lifecycle (load/compare/discard) from
    :class:`ConfigLifecycleMixin` and adds OpenWrt-specific
    ``commit_config`` and ``rollback``.
    """

    _comment_chars = ("#",)

    def _get_running_config(self) -> str:
        return self._send_command("uci export")

    def commit_config(self, message: str = "", revert_in: int | None = None) -> None:
        """Apply the staged candidate configuration and commit it.

        **Merge mode**: each UCI command line is sent to the device shell, then
        ``uci commit`` is called to persist the changes.

        **Replace mode**: the candidate is piped through ``uci import`` and
        then ``uci commit`` is called for every affected package.

        :raises MergeConfigException: if no candidate is staged or if
            commands are rejected.
        :raises ReplaceConfigException: same, for replace candidates.
        """
        if self._candidate_config is None:
            raise MergeConfigException("No candidate configuration is staged.")

        ex_cls = ReplaceConfigException if self._candidate_mode == "replace" else MergeConfigException

        self._backup_config = self._send_command("uci export")

        errors: list[str] = []
        try:
            if self._candidate_mode == "merge":
                for line in self._candidate_config.splitlines():
                    stripped = line.strip()
                    if not stripped or stripped.startswith("#"):
                        continue
                    out = self._send_command(stripped)
                    if out and ("uci: " in out.lower() or "error" in out.lower()):
                        errors.append(f"  {stripped!r}: {out}")
                self._send_command("uci commit")
            else:
                escaped = self._candidate_config.replace("'", "'\\''")
                self._send_command(f"printf '%s' '{escaped}' > /tmp/napalm_candidate.uci")
                out = self._send_command("uci import < /tmp/napalm_candidate.uci && uci commit")
                self._send_command("rm -f /tmp/napalm_candidate.uci")
                if out and "error" in out.lower():
                    errors.append(out)
        except Exception as exc:
            raise ex_cls(str(exc)) from exc

        if errors:
            raise ex_cls("The following commands were rejected:\n" + "\n".join(errors))

        self._candidate_config = None
        self._candidate_mode = None

    def rollback(self) -> None:
        """Restore the UCI configuration to the state before the last :meth:`commit_config`.

        Pipes the saved backup through ``uci import`` and then commits.

        :raises CommandErrorException: if no backup is available.
        """
        if self._backup_config is None:
            raise CommandErrorException(
                "No backup configuration available – commit_config has not been called in this session."
            )

        escaped = self._backup_config.replace("'", "'\\''")
        self._send_command(f"printf '%s' '{escaped}' > /tmp/napalm_rollback.uci")
        self._send_command("uci import < /tmp/napalm_rollback.uci && uci commit")
        self._send_command("rm -f /tmp/napalm_rollback.uci")

        self._backup_config = None