package main

import (
	"context"
	"encoding/json"
	"os/exec"
	"sort"
	"sync"
	"time"
)

type GuestMetrics struct {
	VMID        int     `json:"vmid"`
	Name        string  `json:"name"`
	Type        string  `json:"type"`
	Node        string  `json:"node"`
	Status      string  `json:"status"`
	CPU         float64 `json:"cpu"`
	MaxCPU      float64 `json:"maxcpu"`
	MemoryBytes uint64  `json:"mem"`
	MaxMemory   uint64  `json:"maxmem"`
	Uptime      uint64  `json:"uptime"`
	Template    int     `json:"template"`
}

type GuestsMetrics struct {
	Available bool           `json:"available"`
	Guests    []GuestMetrics `json:"guests"`
}

type guestCollector struct {
	mu        sync.Mutex
	cached    GuestsMetrics
	updatedAt time.Time
}

func (c *guestCollector) collect() GuestsMetrics {
	c.mu.Lock()
	defer c.mu.Unlock()
	if time.Since(c.updatedAt) < 3*time.Second {
		return c.cached
	}
	c.cached = readGuests()
	c.updatedAt = time.Now()
	return c.cached
}

func readGuests() GuestsMetrics {
	if _, err := exec.LookPath("pvesh"); err != nil {
		return GuestsMetrics{}
	}
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	output, err := exec.CommandContext(ctx, "pvesh", "get", "/cluster/resources", "--type", "vm", "--output-format", "json").Output()
	result := GuestsMetrics{Available: true}
	if err != nil {
		return result
	}
	if json.Unmarshal(output, &result.Guests) != nil {
		return result
	}
	sort.Slice(result.Guests, func(i, j int) bool {
		return result.Guests[i].VMID < result.Guests[j].VMID
	})
	return result
}