"""
modules/app_watchdog.py — Phase 4: Auto-restart crashed apps + excessive resource detection.

This is real:
- Watch a configured set of process names and relaunch commands.
- Detect "excessive resource" processes and report top offenders.

Configuration is stored in data/app_watchdog.json.
"""

from __future__ import annotations

import json
import subprocess
import time
from dataclasses import dataclass
from pathlib import Path

import psutil


DATA_DIR = Path(__file__).resolve().parents[1] / "data"
CFG_PATH = DATA_DIR / "app_watchdog.json"


@dataclass(frozen=True, slots=True)
class WatchResult:
    ok: bool
    message: str


def _load_cfg() -> dict:
    if CFG_PATH.exists():
        try:
            return json.loads(CFG_PATH.read_text(encoding="utf-8"))
        except Exception:
            return {}
    return {}


def add_watch(process_name: str, launch_cmd: str) -> WatchResult:
    pn = (process_name or "").strip()
    cmd = (launch_cmd or "").strip()
    if not pn or not cmd:
        return WatchResult(False, "Usage: watch app <process.exe> <launch command>")
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    cfg = _load_cfg()
    cfg.setdefault("apps", {})[pn.lower()] = cmd
    CFG_PATH.write_text(json.dumps(cfg, ensure_ascii=False), encoding="utf-8")
    return WatchResult(True, f"Watching {pn}.")


def remove_watch(process_name: str) -> WatchResult:
    pn = (process_name or "").strip().lower()
    cfg = _load_cfg()
    apps = cfg.get("apps") or {}
    if pn in apps:
        apps.pop(pn, None)
        cfg["apps"] = apps
        CFG_PATH.write_text(json.dumps(cfg, ensure_ascii=False), encoding="utf-8")
        return WatchResult(True, f"Removed watch: {pn}.")
    return WatchResult(False, "Not watched.")


def list_watch() -> WatchResult:
    cfg = _load_cfg()
    apps = cfg.get("apps") or {}
    if not apps:
        return WatchResult(True, "No watched apps.")
    rows = [f"{k} -> {v}" for k, v in list(apps.items())[:10]]
    return WatchResult(True, " | ".join(rows)[:240])


def excessive_resources(cpu_threshold: float = 35.0, limit: int = 5) -> WatchResult:
    try:
        # Snapshot CPU usage over a short window
        procs = list(psutil.process_iter(["name"]))
        for p in procs:
            try:
                p.cpu_percent(None)
            except Exception:
                pass
        time.sleep(0.4)
        rows = []
        for p in procs:
            try:
                c = p.cpu_percent(None)
                if c >= cpu_threshold:
                    rows.append((c, p.pid, p.info.get("name") or ""))
            except Exception:
                continue
        rows.sort(reverse=True)
        if not rows:
            return WatchResult(True, "No heavy processes right now.")
        msg = " | ".join(f"{n}({pid}) {c:.0f}%" for c, pid, n in rows[:limit])
        return WatchResult(True, msg[:240])
    except Exception as e:
        return WatchResult(False, f"Resource scan failed: {e}")


def run_loop(interval_s: float = 2.5) -> None:
    cfg = _load_cfg()
    apps: dict[str, str] = cfg.get("apps") or {}
    if not apps:
        return
    interval = max(1.0, float(interval_s))
    while True:
        try:
            alive = { (p.info.get("name") or "").lower() for p in psutil.process_iter(["name"]) }
            for pn, cmd in apps.items():
                if pn not in alive:
                    try:
                        subprocess.Popen(cmd, shell=True)
                    except Exception:
                        pass
        except Exception:
            pass
        time.sleep(interval)