"""DiskPanicEnvironment — server-side OpenEnv Environment implementation."""
from __future__ import annotations

import os
from typing import Any, Optional

from openenv.core import Environment, State

from disk_panic.models import DiskPanicAction, DiskPanicObservation
from disk_panic.server.graders import GRADERS
from disk_panic.server.scenarios import SCENARIOS, TASK_ORDER
from disk_panic.server.vfs import VFS, execute

MAX_STEPS = 15


class DiskPanicEnvironment(Environment[DiskPanicAction, DiskPanicObservation, State]):
    """A tiny SRE world where the agent issues bash-lite commands to fix a broken server."""

    SUPPORTS_CONCURRENT_SESSIONS = True

    def __init__(self) -> None:
        super().__init__()
        self._task_index = 0
        self._vfs: VFS = VFS()
        self._targets: dict = {}
        self._task_id: str = TASK_ORDER[0]
        self._step_count: int = 0
        self._state = State(episode_id=None, step_count=0)
        self._last_reward: float = 0.0

    # -- lifecycle ---------------------------------------------------------

    def reset(
        self,
        seed: Optional[int] = None,
        episode_id: Optional[str] = None,
        task_id: Optional[str] = None,
        **kwargs: Any,
    ) -> DiskPanicObservation:
        # Task selection: explicit task_id kwarg > env var > round-robin.
        if task_id and task_id in SCENARIOS:
            chosen = task_id
        else:
            env_task = os.getenv("DISK_PANIC_TASK")
            if env_task and env_task in SCENARIOS:
                chosen = env_task
            else:
                chosen = TASK_ORDER[self._task_index % len(TASK_ORDER)]
                self._task_index += 1

        builder = SCENARIOS[chosen]
        self._vfs, self._targets = builder()
        self._task_id = chosen
        self._step_count = 0
        self._last_reward = 0.0
        self._state = State(episode_id=episode_id or f"ep-{chosen}", step_count=0)

        return DiskPanicObservation(
            done=False,
            reward=None,
            stdout=(
                f"=== DiskPanic task: {chosen} ===\n"
                f"{self._describe_task()}\n"
                f"Current disk usage: {self._vfs.usage_pct():.1f}%"
            ),
            df_output=self._vfs.df_output(),
            service_status=self._vfs.services.get("app", "unknown"),
            task_id=chosen,
            step=0,
            last_error=None,
        )

    def step(
        self,
        action: DiskPanicAction,
        timeout_s: Optional[float] = None,
        **kwargs: Any,
    ) -> DiskPanicObservation:
        self._step_count += 1
        self._state.step_count = self._step_count

        # Execute the command against the VFS.
        result = execute(self._vfs, action.command)
        # Tick the world (runaway writer, etc.)
        self._vfs.tick()

        # Compute current grade — always in [0.0, 1.0].
        grader = GRADERS[self._task_id]
        current_score = grader(self._vfs, self._targets)
        self._last_reward = current_score

        # Episode ends when full score reached OR max steps elapsed.
        done = current_score >= 0.98 or self._step_count >= MAX_STEPS

        # Reward is the ABSOLUTE current grade so the last step reflects the final score.
        reward = round(float(current_score), 4)

        return DiskPanicObservation(
            done=done,
            reward=reward,
            stdout=result.stdout or "",
            df_output=self._vfs.df_output(),
            service_status=self._vfs.services.get("app", "unknown"),
            task_id=self._task_id,
            step=self._step_count,
            last_error=result.error,
        )

    def state(self) -> State:
        return self._state

    def close(self) -> None:
        self._vfs = VFS()
        self._targets = {}

    # -- helpers -----------------------------------------------------------

    def _describe_task(self) -> str:
        if self._task_id == "easy":
            return (
                "Root filesystem is at >95% usage — find and remove the bloated log "
                "under /var/log. DO NOT touch /var/log/audit/."
            )
        if self._task_id == "medium":
            return (
                "Disk is full AND app.service has failed. Free space, restart "
                "app.service, and preserve /var/log/audit/."
            )
        if self._task_id == "hard":
            return (
                "A runaway process keeps growing /var/log/app/runaway.log by ~100M "
                "every tick. Free space, restart app.service, preserve audit logs, "
                "AND drop a logrotate config at /etc/logrotate.d/app (must contain "
                "the words 'rotate' and 'size') to cap the growth."
            )
        return "unknown task"