"""中控:读取 PM2 进程 stdout/stderr 日志(系统日志页)."""
from __future__ import annotations

import os
import time
from pathlib import Path
from typing import Any

LOG_TARGETS: dict[str, dict[str, str]] = {
    "binance": {"label": "币安", "pm2_name": "crypto_binance"},
    "gate": {"label": "Gate", "pm2_name": "crypto_gate"},
    "okx": {"label": "OKX", "pm2_name": "crypto_okx"},
    "hub": {"label": "中控", "pm2_name": "manual-trading-hub"},
}

DEFAULT_LINES = 200
MAX_LINES = 500
DEFAULT_TAIL_BYTES = 400_000


def pm2_logs_dir() -> Path:
    raw = (os.getenv("PM2_HOME") or "").strip()
    base = Path(raw) if raw else Path.home() / ".pm2"
    return base / "logs"


def log_file_paths(pm2_name: str) -> tuple[Path, Path]:
    logs_dir = pm2_logs_dir()
    return logs_dir / f"{pm2_name}-out.log", logs_dir / f"{pm2_name}-error.log"


def tail_lines(
    path: Path,
    lines: int = DEFAULT_LINES,
    *,
    max_bytes: int = DEFAULT_TAIL_BYTES,
) -> str:
    if not path.is_file():
        return ""
    try:
        size = path.stat().st_size
        with path.open("rb") as handle:
            if size <= max_bytes:
                data = handle.read()
            else:
                handle.seek(max(0, size - max_bytes))
                data = handle.read()
        text = data.decode("utf-8", errors="replace")
        parts = text.splitlines()
        if len(parts) > lines:
            parts = parts[-lines:]
        return "\n".join(parts)
    except OSError:
        return ""


def system_logs_meta() -> dict[str, Any]:
    return {
        "ok": True,
        "targets": [
            {"key": key, "label": cfg["label"], "pm2_name": cfg["pm2_name"]}
            for key, cfg in LOG_TARGETS.items()
        ],
        "default_lines": DEFAULT_LINES,
        "max_lines": MAX_LINES,
    }


def load_system_logs(target: str, lines: int = DEFAULT_LINES) -> dict[str, Any]:
    key = (target or "").strip().lower()
    if key not in LOG_TARGETS:
        raise KeyError(key)
    cfg = LOG_TARGETS[key]
    line_count = max(20, min(MAX_LINES, int(lines or DEFAULT_LINES)))
    out_path, err_path = log_file_paths(cfg["pm2_name"])
    return {
        "ok": True,
        "key": key,
        "label": cfg["label"],
        "pm2_name": cfg["pm2_name"],
        "lines": line_count,
        "out": tail_lines(out_path, line_count),
        "err": tail_lines(err_path, line_count),
        "out_exists": out_path.is_file(),
        "err_exists": err_path.is_file(),
        "out_path": str(out_path),
        "err_path": str(err_path),
        "updated_at": int(time.time()),
    }