package main

import (
	"bytes"
	"fmt"
	"net/http"
	_ "net/http/pprof"
	"os"
	"path"
	"runtime"
	"strings"

	"encoding/json"
	"github.com/coroot/coroot-node-agent/common"
	"github.com/coroot/coroot-node-agent/config"
	"github.com/coroot/coroot-node-agent/containers"
	"github.com/coroot/coroot-node-agent/flags"
	"github.com/coroot/coroot-node-agent/logs"
	"github.com/coroot/coroot-node-agent/node"
	"github.com/coroot/coroot-node-agent/prom"
	"github.com/coroot/coroot-node-agent/tracing"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	dto "github.com/prometheus/client_model/go"
	"golang.org/x/mod/semver"
	"golang.org/x/sys/unix"
	"golang.org/x/time/rate"
	"k8s.io/klog/v2"
)

var (
	version = "unknown"
)

const minSupportedKernelVersion = "4.16"

func uname() (string, string, error) {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	f, err := os.Open("/proc/1/ns/uts")
	if err != nil {
		return "", "", err
	}
	defer f.Close()

	self, err := os.Open("/proc/self/ns/uts")
	if err != nil {
		return "", "", err
	}
	defer self.Close()

	defer func() {
		unix.Setns(int(self.Fd()), unix.CLONE_NEWUTS)
	}()

	err = unix.Setns(int(f.Fd()), unix.CLONE_NEWUTS)
	if err != nil {
		return "", "", err
	}
	var utsname unix.Utsname
	if err := unix.Uname(&utsname); err != nil {
		return "", "", err
	}
	hostname := string(bytes.Split(utsname.Nodename[:], []byte{0})[0])
	kernelVersion := string(bytes.Split(utsname.Release[:], []byte{0})[0])
	return hostname, kernelVersion, nil
}

func machineID() string {
	for _, p := range []string{"sys/devices/virtual/dmi/id/product_uuid", "etc/machine-id", "var/lib/dbus/machine-id"} {
		payload, err := os.ReadFile(path.Join("/proc/1/root", p))
		if err != nil {
			klog.Warningln("failed to read machine-id:", err)
			continue
		}
		id := strings.TrimSpace(strings.Replace(string(payload), "-", "", -1))
		klog.Infoln("machine-id: ", id)
		return id
	}
	return ""
}

func whitelistNodeExternalNetworks() {
	netdevs, err := node.NetDevices()
	if err != nil {
		klog.Warningln("failed to get network interfaces:", err)
		return
	}
	for _, iface := range netdevs {
		for _, p := range iface.IPPrefixes {
			if p.IP().IsLoopback() || common.IsIpPrivate(p.IP()) {
				continue
			}
			// if the node has an external network IP, whitelist that network  // IK: 如果节点具有外部网络IP，则将该网络列入白名单...
			common.ConnectionFilter.WhitelistPrefix(p)
		}
	}
}

type MetricItemData struct {
	Label map[string]string `json:"metric_tags"`
	Value any               `json:"value"`
}

type MetricData struct {
	MetricKey string           `json:"metric_key"`
	Metric    []MetricItemData `json:"metric"`
}

func main() {
	// IK: 增加配置文件
	agentConfig, err := config.LoadConfig()
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Printf("License=%+v\r\n", agentConfig)

	// IK: 限制资源
	maxProcs := agentConfig.ResourceConfig.ResourceMaxProcs
	if maxProcs <= 0 {
		maxProcs = 1
	}
	runtime.GOMAXPROCS(maxProcs)

	// IK: 初始化日志组件, klog是将日志以http方式发送到server端, 支持配置LogPerSecond等配置.
	klog.LogToStderr(false)
	klog.SetOutput(&RateLimitedLogOutput{limiter: rate.NewLimiter(rate.Limit(*flags.LogPerSecond), *flags.LogBurst)})

	klog.Infoln("agent version:", version)

	hostname, kv, err := uname() // IK: 获取主机名称，内核版本...
	if err != nil {
		klog.Exitln("failed to get uname:", err)
	}
	klog.Infoln("hostname:", hostname)
	klog.Infoln("kernel version:", kv)

	ver := common.KernelMajorMinor(kv)
	if ver == "" {
		klog.Exitln("invalid kernel version:", kv)
	}
	if semver.Compare("v"+ver, "v"+minSupportedKernelVersion) == -1 {
		klog.Exitf("the minimum Linux kernel version required is %s or later", minSupportedKernelVersion)
	}

	whitelistNodeExternalNetworks() // IK:TODO: 将外部网络放到白名单???

	machineId := machineID()
	tracing.Init(machineId, hostname, version) // IK:TODO: 初始化发送???
	logs.Init(machineId, hostname, version)

	registry := prometheus.NewRegistry()
	registerer := prometheus.WrapRegistererWith(prometheus.Labels{"machine_id": machineId}, registry)

	registerer.MustRegister(info("node_agent_info", version))

	if err := registerer.Register(node.NewCollector(hostname, kv)); err != nil {
		klog.Exitln(err)
	}

	//processInfoCh := profiling.Init(machineId, hostname)

	cr, err := containers.NewRegistry(registerer, kv, agentConfig, nil) // IK: 核心代码

	if err != nil {
		klog.Exitln(err)
	}
	defer cr.Close()
	klog.Infoln("START_TRACE")

	//profiling.Start()
	//defer profiling.Stop()
	// 创建一个/metrics路由处理函数
	metricsHandler := func(w http.ResponseWriter, r *http.Request) {
		// 从注册表中获取指标数据
		metrics, err := registry.Gather()
		if err != nil {
			// 错误处理
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		var Data []MetricData
		for _, metric := range metrics {
			if metric.GetName() != "container_net_tcp_successful_connects_total" &&
				metric.GetName() != "container_net_tcp_failed_connects_total" &&
				metric.GetName() != "container_net_tcp_retransmits_total" &&
				metric.GetName() != "container_net_tcp_listen_info" &&
				metric.GetName() != "container_http_requests_total" &&
				metric.GetName() != "container_http_requests_duration_seconds_total" &&
				metric.GetName() != "container_application_type" {
				continue
			}

			var item MetricData
			var itemOther MetricData
			item.MetricKey = metric.GetName()

			for _, m := range metric.GetMetric() {
				metricItem := MetricItemData{}
				label := make(map[string]string)
				for _, l := range m.GetLabel() {
					label[l.GetName()] = l.GetValue()
				}
				metricItem.Label = label
				switch metric.GetType() {
				case dto.MetricType_COUNTER:
					metricItem.Value = m.GetCounter().GetValue()
					item.Metric = append(item.Metric, metricItem)
				case dto.MetricType_GAUGE:
					metricItem.Value = m.GetGauge().GetValue()
					item.Metric = append(item.Metric, metricItem)
				case dto.MetricType_HISTOGRAM:
					item.MetricKey = metric.GetName() + "_sum"
					metricItem.Value = m.GetHistogram().GetSampleSum()
					item.Metric = append(item.Metric, metricItem)
					metricItemOther := MetricItemData{}
					metricItemOther.Label = label

					itemOther.MetricKey = metric.GetName() + "_count"
					metricItemOther.Value = m.GetHistogram().GetSampleCount()
					itemOther.Metric = append(itemOther.Metric, metricItemOther)
				default:
					continue
				}
			}
			Data = append(Data, item)
			if metric.GetType() == dto.MetricType_HISTOGRAM {
				Data = append(Data, itemOther)
			}
		}
		// 将指标数据转换为JSON格式
		jsonData, err := json.Marshal(Data)
		//jsonData, err := json.Marshal(metrics)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		w.Write(jsonData)
	}

	if err := prom.StartAgent(machineId); err != nil {
		klog.Exitln(err)
	}

	http.Handle("/metrics", promhttp.HandlerFor(registry, promhttp.HandlerOpts{ErrorLog: logger{}, Registry: registerer}))
	http.HandleFunc("/metrics2", metricsHandler)
	klog.Infoln("listening on:", *flags.ListenAddress)
	klog.Errorln(http.ListenAndServe(*flags.ListenAddress, nil))
}

func info(name, version string) prometheus.Collector {
	g := prometheus.NewGauge(prometheus.GaugeOpts{
		Name:        name,
		ConstLabels: prometheus.Labels{"version": version},
	})
	g.Set(1)
	return g
}

type logger struct{}

func (l logger) Println(v ...interface{}) {
	klog.Errorln(v...)
}

type RateLimitedLogOutput struct {
	limiter *rate.Limiter
}

func (o *RateLimitedLogOutput) Write(data []byte) (int, error) {
	if !o.limiter.Allow() {
		return len(data), nil
	}
	return os.Stderr.Write(data)
}