"""Мониторинг: сбор метрик по SSH, снапшоты в БД."""
from __future__ import annotations

from typing import Optional

from sqlmodel import select

from app.core.ssh import SSHClient
from app.db.database import get_session
from app.db.models import MetricSnapshot

# Каждая команда выводит одну строку "KEY value..."; парсер ниже.
# CPU считаем по дельте двух замеров /proc/stat за 1 секунду.
_METRICS_CMD = (
    # CPU: первая строка cpu в /proc/stat (user nice system idle iowait irq softirq steal)
    "read cpu u n s idle iow irq sirq st rest < /proc/stat; "
    "t1=$((u+n+s+idle+iow+irq+sirq+st)); i1=$((idle+iow)); "
    "sleep 1; "
    "read cpu u n s idle iow irq sirq st rest < /proc/stat; "
    "t2=$((u+n+s+idle+iow+irq+sirq+st)); i2=$((idle+iow)); "
    "dt=$((t2-t1)); di=$((i2-i1)); "
    "if [ $dt -gt 0 ]; then awk -v a=$dt -v b=$di 'BEGIN{printf \"CPU %.1f\\n\", (a-b)*100/a}'; else echo 'CPU 0.0'; fi; "
    # RAM: used/total в МБ
    "free -m | awk 'NR==2{printf \"MEM %d %d\\n\", $3, $2}'; "
    # Диск: процент занятого на /
    "df -m / | awk 'NR==2{printf \"DISK %.1f\\n\", $3*100/$2}'; "
    # Load average 1min
    "awk '{printf \"LOAD %s\\n\", $1}' /proc/loadavg; "
    # Сеть: суммарные байты rx/tx всех интерфейсов
    "awk '/: /{rx+=$2; tx+=$10} END{printf \"NET %d %d\\n\", rx, tx}' /proc/net/dev"
)


async def collect(c: SSHClient, server_id: int, prev_net: Optional[tuple] = None) -> MetricSnapshot:
    r = await c.run(_METRICS_CMD, timeout=30)
    cpu = mem_used = mem_total = disk = load = 0.0
    rx = tx = 0
    for line in r.stdout.splitlines():
        p = line.split()
        if len(p) < 2:
            continue
        if p[0] == "CPU":
            cpu = float(p[1])
        elif p[0] == "MEM":
            mem_used, mem_total = int(p[1]), int(p[2])
        elif p[0] == "DISK":
            disk = float(p[1])
        elif p[0] == "LOAD":
            load = float(p[1])
        elif p[0] == "NET":
            rx, tx = int(p[1]), int(p[2])

    rx_kbs = tx_kbs = 0.0
    if prev_net:
        dt = 60.0  # интервал опроса
        rx_kbs = max(0.0, (rx - prev_net[0]) / 1024 / dt)
        tx_kbs = max(0.0, (tx - prev_net[1]) / 1024 / dt)

    snap = MetricSnapshot(
        server_id=server_id,
        cpu_percent=round(cpu, 1),
        mem_percent=round(mem_used * 100 / mem_total, 1) if mem_total else 0,
        mem_used_mb=mem_used,
        mem_total_mb=mem_total,
        disk_percent=disk,
        load1=load,
        net_rx_kbs=round(rx_kbs, 1),
        net_tx_kbs=round(tx_kbs, 1),
    )
    with get_session() as s:
        s.add(snap)
        s.commit()
    return snap


def latest(server_id: int) -> Optional[MetricSnapshot]:
    with get_session() as s:
        return s.exec(
            select(MetricSnapshot)
            .where(MetricSnapshot.server_id == server_id)
            .order_by(MetricSnapshot.id.desc())
            .limit(1)
        ).first()


def history(server_id: int, limit: int = 60) -> list[MetricSnapshot]:
    with get_session() as s:
        rows = s.exec(
            select(MetricSnapshot)
            .where(MetricSnapshot.server_id == server_id)
            .order_by(MetricSnapshot.id.desc())
            .limit(limit)
        ).all()
        return list(reversed(rows))