"""
Metrics management for HA Text AI integration.

@license: CC BY-NC-SA 4.0 International
@author: SMKRV
@github: https://github.com/smkrv/ha-text-ai
@source: https://github.com/smkrv/ha-text-ai
"""
from __future__ import annotations

import json
import logging
import os
import traceback
from typing import Any, Dict

from homeassistant.core import HomeAssistant
from homeassistant.exceptions import HomeAssistantError
from homeassistant.util import dt as dt_util

_LOGGER = logging.getLogger(__name__)

DEFAULT_METRICS: Dict[str, Any] = {
    "total_tokens": 0,
    "prompt_tokens": 0,
    "completion_tokens": 0,
    "successful_requests": 0,
    "failed_requests": 0,
    "total_errors": 0,
    "average_latency": 0,
    "max_latency": 0,
    "min_latency": 0,
}


class MetricsManager:
    """Manages performance metrics for an instance."""

    def __init__(
        self,
        hass: HomeAssistant,
        instance_name: str,
        metrics_file: str,
    ) -> None:
        self.hass = hass
        self.instance_name = instance_name
        self._metrics_file = metrics_file
        self._performance_metrics: Dict[str, Any] = DEFAULT_METRICS.copy()

    @property
    def metrics(self) -> Dict[str, Any]:
        return self._performance_metrics

    async def async_initialize(self) -> None:
        """Load metrics from storage or create defaults."""
        loaded = await self._load_metrics()
        self._performance_metrics = loaded or DEFAULT_METRICS.copy()

    async def _load_metrics(self) -> Dict[str, Any] | None:
        try:
            exists = await self.hass.async_add_executor_job(
                os.path.exists, self._metrics_file
            )
            if exists:
                def read_metrics():
                    with open(self._metrics_file, "r") as f:
                        try:
                            return json.load(f)
                        except json.JSONDecodeError:
                            _LOGGER.warning("Metrics file corrupted, creating new")
                            return None

                return await self.hass.async_add_executor_job(read_metrics)
        except Exception as e:
            _LOGGER.warning("Failed to load metrics: %s", e)
        return None

    async def _save_metrics(self) -> None:
        try:
            def write_metrics():
                with open(self._metrics_file, "w") as f:
                    json.dump(self._performance_metrics, f)

            await self.hass.async_add_executor_job(write_metrics)
        except Exception as e:
            _LOGGER.warning("Failed to save metrics: %s", e)

    async def update_metrics(self, latency: float, response: dict) -> None:
        """Update performance metrics after a successful request."""
        metrics = self._performance_metrics
        tokens = response.get("tokens", {})

        metrics["total_tokens"] += tokens.get("total", 0)
        metrics["prompt_tokens"] += tokens.get("prompt", 0)
        metrics["completion_tokens"] += tokens.get("completion", 0)
        metrics["successful_requests"] += 1

        metrics["average_latency"] = (
            (metrics["average_latency"] * (metrics["successful_requests"] - 1) + latency)
            / metrics["successful_requests"]
        )
        metrics["max_latency"] = max(metrics["max_latency"], latency)
        if metrics["min_latency"] == 0:
            metrics["min_latency"] = latency
        else:
            metrics["min_latency"] = min(metrics["min_latency"], latency)

        await self._save_metrics()

    async def get_current_metrics(self) -> Dict[str, Any]:
        """Get current performance metrics."""
        return self._performance_metrics.copy()

    async def handle_error(
        self,
        error: Exception,
        model: str,
    ) -> Dict[str, Any]:
        """Record an error in metrics and return error details."""
        self._performance_metrics["total_errors"] += 1
        self._performance_metrics["failed_requests"] += 1
        await self._save_metrics()

        error_details: Dict[str, Any] = {
            "timestamp": dt_util.utcnow().isoformat(),
            "model": model,
            "instance": self.instance_name,
            "error_message": str(error),
            "error_type": type(error).__name__,
            "traceback": traceback.format_exc()
            if _LOGGER.isEnabledFor(logging.DEBUG)
            else None,
        }

        error_mapping = {
            HomeAssistantError: {"is_ha_error": True},
            ConnectionError: {"is_connection_error": True},
            TimeoutError: {"is_timeout": True},
            PermissionError: {"is_permission_denied": True},
            ValueError: {"is_validation_error": True},
        }

        for error_type, error_flags in error_mapping.items():
            if isinstance(error, error_type):
                error_details.update(error_flags)
                break

        _LOGGER.error("AI Processing Error: %s", error_details)
        if _LOGGER.isEnabledFor(logging.DEBUG):
            _LOGGER.debug("Full Error Traceback: %s", error_details.get("traceback"))

        return error_details