package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/http/httputil"
	"net/url"
	"os"
	"os/exec"
	"strconv"
	"strings"
	"sync"
	"time"

	"gitee.com/aurawing/surguard-go/device"
	"github.com/labstack/echo"
	"github.com/labstack/echo/middleware"
	"github.com/shirou/gopsutil/v3/net"
	"golang.org/x/net/http2"
	"golang.org/x/net/http2/h2c"
)

type StatResp struct {
	Code int                    `json:"code"`
	Msg  string                 `json:"msg"`
	Data map[string]interface{} `json:"data"`
}

var statSrv http.Server
var statWg sync.WaitGroup
var statInterfaceName string
var statGroupName string
var statDev *device.Device

func startStatServer(interfaceName, portStr string, logger *device.Logger, dev *device.Device) error {
	statWg.Add(1)
	statDev = dev
	groupNameStr := os.Getenv(device.ENV_SG_GROUP_NAME)
	if groupNameStr == "" {
		statGroupName = device.DEFAULT_GROUP_NAME
	} else {
		statGroupName = groupNameStr
	}
	if strings.TrimSpace(interfaceName) == "" {
		logger.Errorf("interface name is empty")
		return errors.New("interface name is empty")
	}
	statInterfaceName = interfaceName
	port := int64(device.DEFAULT_LISTEN_PORT)
	if strings.TrimSpace(portStr) != "" {
		var err error
		port, err = strconv.ParseInt(strings.TrimSpace(portStr), 10, 64)
		if err != nil {
			logger.Errorf("parse stat server port failed %v", err)
			return err
		}
	}
	server := echo.New()
	server.Use(middleware.Logger())
	server.Use(middleware.Recover())
	server.Use(middleware.GzipWithConfig(middleware.GzipConfig{
		Level: 5,
	}))
	server.GET("/surguard/netstat", sgNetStat)
	server.POST("/surguard/bypass", bypass)
	server.POST("/surguard/disableBypass", disableBypass)

	apiStatPort := port + 1
	apiStatPortStr := os.Getenv("SG_STAT_PORT")
	if apiStatPortStr != "" {
		var err error
		apiStatPort, err = strconv.ParseInt(strings.TrimSpace(apiStatPortStr), 10, 64)
		if err != nil {
			logger.Errorf("parse API stat server port failed %v", err)
			return err
		}
	}
	proxy := httputil.NewSingleHostReverseProxy(&url.URL{
		Scheme: "http",
		Host:   fmt.Sprintf("localhost:%d", apiStatPort),
	})
	server.Any("/surwall/*", echo.WrapHandler(proxy))

	h2s := &http2.Server{}
	statSrv = http.Server{
		Addr:    fmt.Sprintf(":%d", port),
		Handler: h2c.NewHandler(server, h2s),
		//ReadTimeout: 30 * time.Second, // customize http.Server timeouts
	}
	go func() {
		if err := statSrv.ListenAndServe(); err != http.ErrServerClosed {
			logger.Errorf("stat server error: %v", err)
		}
		statWg.Done()
	}()
	return nil
}

func getNetStats(interfaceName string) (*net.IOCountersStat, error) {
	netStats, err := net.IOCounters(true)
	if err != nil {
		return nil, err
	}

	for _, stats := range netStats {
		if stats.Name == interfaceName {
			return &stats, nil
		}
	}

	return nil, fmt.Errorf("interface '%s' not found", interfaceName)
}

func sgNetStat(c echo.Context) error {
	resp := new(StatResp)
	stats, err := getNetStats(statInterfaceName)
	if err != nil {
		resp.Code = -1
		resp.Msg = err.Error()
		resp.Data = map[string]interface{}{}
	} else {
		resp.Code = 0
		resp.Msg = "ok"
		resp.Data = map[string]interface{}{
			"InterfaceName":   stats.Name,
			"BytesSent":       stats.BytesSent,
			"BytesReceived":   stats.BytesRecv,
			"PacketsSent":     stats.PacketsSent,
			"PacketsReceived": stats.PacketsRecv,
			"ErrorsSent":      stats.Errout,
			"ErrorsReceived":  stats.Errin,
			"DropsSent":       stats.Dropout,
			"DropReceived":    stats.Dropin,
		}
	}
	b, err := json.Marshal(resp)
	if err != nil {
		resp.Code = -2
		resp.Msg = err.Error()
		resp.Data = map[string]interface{}{}
	}
	return c.JSONBlob(http.StatusOK, b)
}

func bypass(c echo.Context) error {
	resp := new(StatResp)
	if !device.IfBindInterface() {
		err := runCmd("ip", "route", "flush", "table", statGroupName)
		if err != nil {
			resp.Code = -3
			resp.Msg = err.Error()
			resp.Data = map[string]interface{}{}
		}
	} else {
		statDev.IterPeerEndpoint(func(s string) {
			runCmd("route", "delete", s)
		})
	}
	b, err := json.Marshal(resp)
	if err != nil {
		resp.Code = -2
		resp.Msg = err.Error()
		resp.Data = map[string]interface{}{}
	}
	return c.JSONBlob(http.StatusOK, b)
}

func disableBypass(c echo.Context) error {
	resp := new(StatResp)
	if !device.IfBindInterface() {
		err := runCmd("ip", "route", "add", "default", "dev", statInterfaceName, "table", statGroupName)
		if err != nil {
			resp.Code = -4
			resp.Msg = err.Error()
			resp.Data = map[string]interface{}{}
		}
	} else {
		statDev.IterPeerEndpoint(func(s string) {
			runCmd("route", "add", s, "mask", "255.255.255.255", "0.0.0.0", "IF", strconv.Itoa(device.GetDeviceIndex()))
		})
	}
	b, err := json.Marshal(resp)
	if err != nil {
		resp.Code = -2
		resp.Msg = err.Error()
		resp.Data = map[string]interface{}{}
	}
	return c.JSONBlob(http.StatusOK, b)
}

func stopStatServer(logger *device.Logger) {
	timeoutCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	defer statWg.Wait()
	// 关闭 HTTP 服务器
	if err := statSrv.Shutdown(timeoutCtx); err != nil {
		logger.Errorf("Stat server shutdown error: %v", err)
	}
}

func runCmd(args ...string) error {
	cmd := exec.Command(args[0], args[1:]...)
	cmd.Stderr = os.Stderr
	cmd.Stdout = os.Stdout
	cmd.Stdin = os.Stdin
	err := cmd.Run()
	return err
}