package main

import (
	"os/exec"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/shirou/gopsutil/v4/cpu"
	"github.com/shirou/gopsutil/v4/mem"
	gnet "github.com/shirou/gopsutil/v4/net"
	"view/platform"
)

// HostMetrics 本机总览快照（端口监控页轮询）。
type HostMetrics struct {
	At            string  `json:"at"`
	CPUPercent    float64 `json:"cpu"`
	MemUsedMB     float64 `json:"memUsedMB"`
	MemTotalMB    float64 `json:"memTotalMB"`
	MemPercent    float64 `json:"memPercent"`
	GPUPercent    float64 `json:"gpu"` // -1 表示不可用
	GPUMemUsedMB  float64 `json:"gpuMemUsedMB"`
	GPUMemTotalMB float64 `json:"gpuMemTotalMB"`
	GPUName       string  `json:"gpuName"`
	NetRecvKBs    float64 `json:"netRecvKBs"`
	NetSentKBs    float64 `json:"netSentKBs"`
}

var (
	hostNetMu   sync.Mutex
	hostNetAt   time.Time
	hostNetRecv uint64
	hostNetSent uint64
	hostNetInit bool
)

// GetHostMetrics 采集 CPU / 内存 / 网卡吞吐；GPU 在有 nvidia-smi 时附带利用率。
func (a *App) GetHostMetrics() (HostMetrics, error) {
	out := HostMetrics{At: time.Now().Format(time.RFC3339), GPUPercent: -1}

	if percents, err := cpu.Percent(0, false); err == nil && len(percents) > 0 {
		out.CPUPercent = percents[0]
		if out.CPUPercent < 0 {
			out.CPUPercent = 0
		}
	}

	if vm, err := mem.VirtualMemory(); err == nil && vm != nil {
		out.MemUsedMB = float64(vm.Used) / 1024 / 1024
		out.MemTotalMB = float64(vm.Total) / 1024 / 1024
		out.MemPercent = vm.UsedPercent
	}

	recvKB, sentKB := sampleHostNet()
	out.NetRecvKBs = recvKB
	out.NetSentKBs = sentKB

	fillGPU(&out)
	return out, nil
}

func sampleHostNet() (recvKBs, sentKBs float64) {
	counters, err := gnet.IOCounters(false)
	if err != nil || len(counters) == 0 {
		return 0, 0
	}
	c := counters[0]
	now := time.Now()

	hostNetMu.Lock()
	defer hostNetMu.Unlock()
	if !hostNetInit {
		hostNetInit = true
		hostNetAt = now
		hostNetRecv = c.BytesRecv
		hostNetSent = c.BytesSent
		return 0, 0
	}
	wall := now.Sub(hostNetAt).Seconds()
	if wall <= 0 {
		return 0, 0
	}
	recvKBs = float64(c.BytesRecv-hostNetRecv) / 1024 / wall
	sentKBs = float64(c.BytesSent-hostNetSent) / 1024 / wall
	if recvKBs < 0 {
		recvKBs = 0
	}
	if sentKBs < 0 {
		sentKBs = 0
	}
	hostNetAt = now
	hostNetRecv = c.BytesRecv
	hostNetSent = c.BytesSent
	return recvKBs, sentKBs
}

// fillGPU 优先 nvidia-smi；失败则保持 gpu=-1。无窗口执行，避免端口监控轮询闪 cmd。
func fillGPU(out *HostMetrics) {
	cmd := exec.Command("nvidia-smi",
		"--query-gpu=name,utilization.gpu,memory.used,memory.total",
		"--format=csv,noheader,nounits")
	platform.ConfigureHidden(cmd)
	raw, err := cmd.Output()
	if err != nil {
		return
	}
	line := strings.TrimSpace(strings.Split(string(raw), "\n")[0])
	if line == "" {
		return
	}
	parts := strings.Split(line, ",")
	if len(parts) < 4 {
		return
	}
	out.GPUName = strings.TrimSpace(parts[0])
	if v, e := strconv.ParseFloat(strings.TrimSpace(parts[1]), 64); e == nil {
		out.GPUPercent = v
	}
	if v, e := strconv.ParseFloat(strings.TrimSpace(parts[2]), 64); e == nil {
		out.GPUMemUsedMB = v
	}
	if v, e := strconv.ParseFloat(strings.TrimSpace(parts[3]), 64); e == nil {
		out.GPUMemTotalMB = v
	}
}