package main

import (
	"context"
	"fmt"
	"log/slog"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/joho/godotenv"
)

const (
	trafficUpdateInterval = 30 * time.Second
	saveTrafficInterval   = 5 * time.Minute
	reportInterval        = 5 * time.Minute
	httpTimeout           = 30 * time.Second
)

type Config struct {
	MasterAddress string
	NodeName      string
	NodeKey       string
	TLSSkipVerify bool
}

func loadConfig() (Config, error) {
	if err := godotenv.Load(); err != nil {
		slog.Warn("加载 .env 文件失败（将使用系统环境变量）", "error", err)
	}

	master := os.Getenv("MASTER_ADDRESS")
	nodeName := os.Getenv("NODE_NAME")
	nodeKey := os.Getenv("NODE_KEY")

	if master == "" || nodeName == "" || nodeKey == "" {
		return Config{}, fmt.Errorf("配置不完整，请检查 .env 文件")
	}

	// TLS_SKIP_VERIFY 默认 false（校验证书）；值为 true 时跳过校验
	tlsSkipVerify := false
	if v, err := strconv.ParseBool(os.Getenv("TLS_SKIP_VERIFY")); err == nil {
		tlsSkipVerify = v
	}

	return Config{
		MasterAddress: strings.TrimRight(strings.TrimSpace(master), "/"),
		NodeName:      nodeName,
		NodeKey:       nodeKey,
		TLSSkipVerify: tlsSkipVerify,
	}, nil
}

func saveTrafficOnExit(tm *TrafficMonitor) {
	month, upload, download := tm.GetSnapshot()
	if err := saveMonthlyTraffic(month, upload, download); err != nil {
		slog.Error("退出前保存流量数据失败", "error", err)
	} else {
		slog.Info("流量数据已保存", "upload_mb", fmt.Sprintf("%.2f", upload), "download_mb", fmt.Sprintf("%.2f", download))
	}
}

func main() {
	slog.Info("探针程序启动")

	config, err := loadConfig()
	if err != nil {
		slog.Error("加载配置失败", "error", err)
		os.Exit(1)
	}

	initHTTPClient(config.TLSSkipVerify)

	trafficMonitor := NewTrafficMonitor()

	if month, upload, download, err := loadMonthlyTraffic(); err == nil {
		trafficMonitor.SetMonthlyTraffic(month, upload, download)
		slog.Info("已加载月流量数据",
			"upload_mb", fmt.Sprintf("%.2f", upload),
			"download_mb", fmt.Sprintf("%.2f", download))
	} else {
		slog.Warn("加载月流量数据失败，将从 0 开始累计", "error", err)
	}

	slog.Info("监控程序运行中", "node", config.NodeName, "master", config.MasterAddress)

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	var wg sync.WaitGroup

	// 启动时立即建立基线：
	//   1) 先采一次流量计数器作为基线，使下一个采样窗口即可算出真实带宽（#10）
	//   2) 同步采一次系统指标填充缓存，保证即将开始的首轮上报有数据可用（#1）
	if err := trafficMonitor.UpdateTraffic(); err != nil {
		slog.Warn("建立流量基线失败，将在下个周期重试", "error", err)
	}
	if err := sampleSystemUsage(); err != nil {
		slog.Warn("首次系统指标采样失败，将在下个周期重试", "error", err)
	}

	wg.Add(1)
	go func() {
		defer wg.Done()
		ticker := time.NewTicker(trafficUpdateInterval)
		defer ticker.Stop()
		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				if err := trafficMonitor.UpdateTraffic(); err != nil {
					slog.Error("更新流量失败", "error", err)
				}
			}
		}
	}()

	// 系统指标(CPU/内存/磁盘)采样协程：与流量采样同周期在后台运行，
	// 把 cpu.Percent 的 1s 阻塞从上报路径剥离到此处（#1）。
	wg.Add(1)
	go func() {
		defer wg.Done()
		ticker := time.NewTicker(trafficUpdateInterval)
		defer ticker.Stop()
		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				if err := sampleSystemUsage(); err != nil {
					slog.Error("系统指标采样失败", "error", err)
				}
			}
		}
	}()

	wg.Add(1)
	go func() {
		defer wg.Done()
		ticker := time.NewTicker(saveTrafficInterval)
		defer ticker.Stop()
		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				month, upload, download := trafficMonitor.GetSnapshot()
				if err := saveMonthlyTraffic(month, upload, download); err != nil {
					slog.Error("保存流量失败", "error", err)
				}
			}
		}
	}()

	wg.Add(1)
	go func() {
		defer wg.Done()
		// 先立即上报一次，再进入周期循环
		if err := submitData(ctx, config, trafficMonitor); err != nil {
			slog.Error("上报失败", "error", err)
		}
		ticker := time.NewTicker(reportInterval)
		defer ticker.Stop()
		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				if err := submitData(ctx, config, trafficMonitor); err != nil {
					slog.Error("上报失败", "error", err)
				}
			}
		}
	}()

	<-ctx.Done()
	slog.Info("收到退出信号，正在等待任务退出...")
	wg.Wait()
	saveTrafficOnExit(trafficMonitor)
	slog.Info("探针程序已退出")
}