"""Host resource stats via psutil, with a short cache."""

import time

import psutil

# Cache TTL seconds.
_CACHE_TTL = 2.0


class HostStats:
    """Collects CPU, memory, disk and load stats for the host."""

    def __init__(self, cache_ttl=_CACHE_TTL):
        self.cache_ttl = cache_ttl
        self._cache = None
        self._cached_at = 0.0

    def _fresh(self):
        return time.time() - self._cached_at >= self.cache_ttl

    def refresh(self):
        if not self._fresh():
            return self._cache

        cpu_percent = psutil.cpu_percent(interval=0.3)
        cpu_count = psutil.cpu_count(logical=True)

        mem = psutil.virtual_memory()
        mem = {
            "total_mb": round(mem.total / 1024 / 1024, 0),
            "used_mb": round(mem.used / 1024 / 1024, 0),
            "available_mb": round(mem.available / 1024 / 1024, 0),
            "percent": mem.percent,
        }

        disk = {}
        for part in psutil.disk_partitions(all=False):
            if part.opts.split(",")[0] in ("rw", "") or "rw" in part.opts:
                try:
                    usage = psutil.disk_usage(part.mountpoint)
                    disk[part.mountpoint] = {
                        "total_gb": round(usage.total / 1024 / 1024 / 1024, 1),
                        "used_gb": round(usage.used / 1024 / 1024 / 1024, 1),
                        "percent": usage.percent,
                    }
                except (PermissionError, OSError):
                    continue
        # Always include / at minimum.
        if "/" not in disk:
            try:
                usage = psutil.disk_usage("/")
                disk["/"] = {
                    "total_gb": round(usage.total / 1024 / 1024 / 1024, 1),
                    "used_gb": round(usage.used / 1024 / 1024 / 1024, 1),
                    "percent": usage.percent,
                }
            except (PermissionError, OSError):
                pass

        boot_time = psutil.boot_time()

        load = {}
        try:
            l1, l5, l15 = psutil.getloadavg()
            load = {"1min": round(l1, 2), "5min": round(l5, 2), "15min": round(l15, 2)}
        except (OSError, AttributeError):
            load = {}

        self._cache = {
            "cpu_percent": cpu_percent,
            "cpu_count": cpu_count,
            "cpu_cores": cpu_count,
            "memory": mem,
            "disk": disk,
            "boot_time": boot_time,
            "uptime_seconds": round(time.time() - boot_time, 0),
            "load": load,
            "timestamp": time.time(),
        }
        self._cached_at = time.time()
        return self._cache

    def get(self):
        return self.refresh()