"""Log file management — session paths, listing, tail."""

import json
from datetime import datetime
from pathlib import Path
from typing import Optional

from espmon.config import LOGS_DIR, DEPLOY_JSON


class LogManager:
    """Manage serial monitor log files in tools/logs/."""

    @staticmethod
    def ensure_dirs():
        """Create the logs root directory if needed."""
        LOGS_DIR.mkdir(exist_ok=True)

    @staticmethod
    def session_path(port: str) -> Path:
        """Create a new log file path for a monitor session.

        Format: tools/logs/<port_name>/YYYY-MM-DD_HHhMM.log
        """
        port_name = port.replace("/dev/", "").replace("/", "_")
        port_dir = LOGS_DIR / port_name
        port_dir.mkdir(parents=True, exist_ok=True)

        timestamp = datetime.now().strftime("%Y-%m-%d_%Hh%M")
        path = port_dir / f"{timestamp}.log"

        # Avoid collision if multiple sessions in same minute
        if path.exists():
            secs = datetime.now().strftime("%S")
            path = port_dir / f"{timestamp}_{secs}.log"

        return path

    @staticmethod
    def latest_log(port: str = None, device: str = None) -> Optional[Path]:
        """Find the most recent log file.

        Args:
            port: Filter by serial port (e.g. /dev/ttyUSB0)
            device: Filter by device ID (looks up port in deploy.json)
        """
        if device:
            mapped = LogManager._device_to_port(device)
            if mapped:
                port = mapped

        if port:
            port_name = port.replace("/dev/", "").replace("/", "_")
            port_dir = LOGS_DIR / port_name
            if not port_dir.exists():
                return None
            logs = sorted(port_dir.glob("*.log"), key=lambda p: p.stat().st_mtime)
            return logs[-1] if logs else None

        # No filter: most recent across all ports
        if not LOGS_DIR.exists():
            return None
        all_logs = sorted(LOGS_DIR.rglob("*.log"), key=lambda p: p.stat().st_mtime)
        return all_logs[-1] if all_logs else None

    @staticmethod
    def list_all() -> list:
        """List all log files with metadata.

        Returns list of dicts with: path, relative, size, mtime
        """
        if not LOGS_DIR.exists():
            return []

        entries = []
        for log_file in sorted(
            LOGS_DIR.rglob("*.log"),
            key=lambda p: p.stat().st_mtime,
            reverse=True,
        ):
            stat = log_file.stat()
            entries.append({
                "path": log_file,
                "relative": log_file.relative_to(LOGS_DIR),
                "size": stat.st_size,
                "mtime": datetime.fromtimestamp(stat.st_mtime),
            })
        return entries

    @staticmethod
    def _device_to_port(device_id: str) -> Optional[str]:
        """Look up serial port for a device ID from deploy.json."""
        if not DEPLOY_JSON.exists():
            return None
        try:
            with open(DEPLOY_JSON) as f:
                data = json.load(f)
            for dev in data.get("devices", []):
                if dev.get("device_id") == device_id:
                    return dev.get("port")
        except (json.JSONDecodeError, KeyError, OSError):
            pass
        return None