"""kill_switch.py — Monitor de saúde do treino + kill automático.

Implementa a regra do usuário:
    "monitorar e matar o modelo se não estiver aprendendo"
    "monitorar consumo de RAM, consumo de Armazenamento, a loss e a perplexidade"

Critérios de kill:
1. RAM > 90% da disponível (psutil.virtual_memory)
2. Disco < 1 GB livre (psutil.disk_usage)
3. Loss não diminui em N_steps_patience (default 30) — comparado com
   min_loss_so_far
4. Loss é NaN ou Inf
5. Perplexidade > 1e6 (explosão)

Reaproveita a filosofia do flexnet/oom_guard.py (thread-based) e
flexnet/memory_monitor.py (leak detection), mas unifica em uma classe
síncrona mais simples para o treino de bug-detection.
"""
from __future__ import annotations

import math
import os
import time
from dataclasses import dataclass, field
from pathlib import Path
from typing import Optional

import psutil
import torch


@dataclass
class KillSwitchState:
    """Snapshot do estado do kill-switch em um dado step."""
    step: int
    loss: float
    ppl: float
    ram_pct: float
    ram_used_gb: float
    ram_total_gb: float
    disk_free_gb: float
    disk_total_gb: float
    active_modules: int
    reason: Optional[str] = None  # None = OK, string = motivo do kill


class KillSwitch:
    """Monitor de saúde do treino com kill automático.

    Args:
        ram_threshold_pct: kill se RAM usage > este pct (default 90)
        disk_min_free_gb: kill se disco livre < este valor (default 1.0)
        loss_patience: nº de steps sem melhoria antes de matar (default 30)
        loss_tolerance: loss considerada "melhoria" se cair mais que isto (default 1e-4)
        max_ppl: kill se ppl > este valor (default 1e6)
        log_dir: diretório para salvar logs de monitoramento (default /tmp)

    Uso:
        ks = KillSwitch()
        for step, batch in enumerate(loader):
            loss = train_step(batch)
            state = ks.check(step, loss, active_modules)
            if state.reason:
                logger.error(f"KILL: {state.reason}")
                break
    """

    def __init__(
        self,
        ram_threshold_pct: float = 90.0,
        disk_min_free_gb: float = 1.0,
        loss_patience: int = 30,
        loss_tolerance: float = 1e-4,
        max_ppl: float = 1e6,
        log_dir: Optional[str] = None,
    ):
        self.ram_threshold_pct = ram_threshold_pct
        self.disk_min_free_gb = disk_min_free_gb
        self.loss_patience = loss_patience
        self.loss_tolerance = loss_tolerance
        self.max_ppl = max_ppl
        self.log_dir = Path(log_dir) if log_dir else None

        # Estado interno
        self.min_loss: float = float("inf")
        self.steps_since_improvement: int = 0
        self.history: list[KillSwitchState] = []

        # Snapshot do processo para RAM
        self._process = psutil.Process(os.getpid())

    def _get_ram_usage(self) -> tuple[float, float, float]:
        """Retorna (ram_pct, ram_used_gb, ram_total_gb)."""
        vm = psutil.virtual_memory()
        return vm.percent, vm.used / 1e9, vm.total / 1e9

    def _get_disk_usage(self) -> tuple[float, float]:
        """Retorna (disk_free_gb, disk_total_gb) para o disco do projeto."""
        # Usa o disco onde /home/z/my-project está
        path = "/home/z/my-project"
        try:
            du = psutil.disk_usage(path)
            return du.free / 1e9, du.total / 1e9
        except Exception:
            return float("inf"), float("inf")

    def check(
        self,
        step: int,
        loss: float,
        active_modules: int = 0,
    ) -> KillSwitchState:
        """Verifica saúde do treino e retorna estado.

        Args:
            step: nº do step atual
            loss: loss atual (escalar)
            active_modules: nº de módulos ativos no modelo (para logging)

        Returns:
            KillSwitchState com .reason preenchido se kill recomendado.
        """
        # Calcula ppl (com clipping para evitar overflow)
        if math.isnan(loss) or math.isinf(loss):
            ppl = float("inf")
        else:
            ppl = math.exp(min(20, loss)) if loss < 20 else float("inf")

        ram_pct, ram_used, ram_total = self._get_ram_usage()
        disk_free, disk_total = self._get_disk_usage()

        # Atualiza min_loss e contador de patience
        reason = None
        if math.isnan(loss) or math.isinf(loss):
            reason = f"loss is NaN/Inf at step {step}"
        elif loss < self.min_loss - self.loss_tolerance:
            self.min_loss = loss
            self.steps_since_improvement = 0
        else:
            self.steps_since_improvement += 1
            if self.steps_since_improvement >= self.loss_patience:
                reason = (
                    f"loss not improving for {self.loss_patience} steps "
                    f"(min={self.min_loss:.4f}, current={loss:.4f})"
                )

        # Critério de RAM
        if ram_pct > self.ram_threshold_pct:
            reason = reason or f"RAM {ram_pct:.1f}% > threshold {self.ram_threshold_pct}%"

        # Critério de disco
        if disk_free < self.disk_min_free_gb:
            reason = reason or f"disk free {disk_free:.2f}GB < min {self.disk_min_free_gb}GB"

        # Critério de perplexidade
        if ppl > self.max_ppl:
            reason = reason or f"ppl {ppl:.2e} > max {self.max_ppl:.2e}"

        state = KillSwitchState(
            step=step,
            loss=loss,
            ppl=ppl,
            ram_pct=ram_pct,
            ram_used_gb=ram_used,
            ram_total_gb=ram_total,
            disk_free_gb=disk_free,
            disk_total_gb=disk_total,
            active_modules=active_modules,
            reason=reason,
        )
        self.history.append(state)
        return state

    def summary(self) -> dict:
        """Retorna resumo final do monitoramento."""
        if not self.history:
            return {}
        return {
            "total_steps": len(self.history),
            "min_loss": min(s.loss for s in self.history if not math.isnan(s.loss) and not math.isinf(s.loss)),
            "max_ram_pct": max(s.ram_pct for s in self.history),
            "min_disk_free_gb": min(s.disk_free_gb for s in self.history),
            "max_ppl": max(s.ppl for s in self.history if not math.isinf(s.ppl)),
            "killed": self.history[-1].reason is not None,
            "kill_reason": self.history[-1].reason,
        }