package main

import (
	"Spark/modules"
	"Spark/server/common"
	"Spark/server/config"
	"Spark/server/handler"
	"bytes"
	"net"
	"strings"
	"time"

	"github.com/rakyll/statik/fs"

	_ "Spark/server/embed/built"
	_ "Spark/server/embed/web"
	"Spark/utils"
	"Spark/utils/melody"
	"encoding/hex"
	"io/ioutil"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/kataras/golog"
)

func main() {
	golog.SetTimeFormat(`2006/01/02 15:04:05`)
	gin.SetMode(`release`)

	data, err := ioutil.ReadFile(`./Config.json`)
	if err != nil {
		golog.Fatal(`读取配置文件失败：`, err)
		return
	}
	err = utils.JSON.Unmarshal(data, &config.Config)
	if err != nil {
		golog.Fatal(`解析配置文件失败：`, err)
		return
	}
	if len(config.Config.Salt) > 24 {
		golog.Fatal(`Salt的长度不能超过24位`)
		return
	}
	config.Config.StdSalt = []byte(config.Config.Salt)
	config.Config.StdSalt = append(config.Config.StdSalt, bytes.Repeat([]byte{25}, 24)...)
	config.Config.StdSalt = config.Config.StdSalt[:24]

	webFS, err := fs.NewWithNamespace(`web`)
	if err != nil {
		golog.Fatal(`加载静态资源失败：`, err)
		return
	}
	common.BuiltFS, err = fs.NewWithNamespace(`built`)
	if err != nil {
		golog.Fatal(`加载预编译客户端失败：`, err)
		return
	}
	app := gin.New()
	auth := gin.BasicAuth(config.Config.Auth)
	app.NoRoute(auth, func(ctx *gin.Context) {
		http.FileServer(webFS).ServeHTTP(ctx.Writer, ctx.Request)
	})
	handler.APIRouter(app.Group(`/api`), auth)
	app.Any(`/ws`, wsHandshake)

	common.Melody.Config.MaxMessageSize = 1024
	common.Melody.HandleConnect(wsOnConnect)
	common.Melody.HandleMessage(wsOnMessage)
	common.Melody.HandleMessageBinary(wsOnMessageBinary)
	common.Melody.HandleDisconnect(wsOnDisconnect)
	go common.WSHealthCheck(common.Melody)

	app.Run(config.Config.Listen)
}

func wsHandshake(ctx *gin.Context) {
	if ctx.IsWebsocket() {
		clientUUID, _ := hex.DecodeString(ctx.GetHeader(`UUID`))
		clientKey, _ := hex.DecodeString(ctx.GetHeader(`Key`))
		if len(clientUUID) != 16 || len(clientKey) != 32 {
			ctx.Status(http.StatusUnauthorized)
			return
		}
		decrypted, err := common.DecAES(clientKey, config.Config.StdSalt)
		if err != nil || !bytes.Equal(decrypted, clientUUID) {
			ctx.Status(http.StatusUnauthorized)
			return
		}
		secret := append(utils.GetUUID(), utils.GetUUID()...)
		err = common.Melody.HandleRequestWithKeys(ctx.Writer, ctx.Request, http.Header{
			`Secret`: []string{hex.EncodeToString(secret)},
		}, gin.H{
			`Secret`:   secret,
			`LastPack`: time.Now().Unix(),
			`Address`:  getRemoteAddr(ctx),
		})
		if err != nil {
			golog.Error(err)
			ctx.Status(http.StatusUpgradeRequired)
			return
		}
	} else {
		// When message is too large to transport via websocket,
		// client will try to send these data via http.
		// Here is the data validator.
		const MaxBufferSize = 2 << 18 //524288 512KB
		secret, err := hex.DecodeString(ctx.GetHeader(`Secret`))
		if err != nil || len(secret) != 32 {
			return
		}
		body, err := ctx.GetRawData()
		if err != nil {
			return
		}
		common.Melody.IterSessions(func(uuid string, s *melody.Session) bool {
			if val, ok := s.Get(`Secret`); ok {
				// Check if there's the connection with the secret.
				if b, ok := val.([]byte); ok && bytes.Equal(b, secret) {
					wsOnMessageBinary(s, body)
					return false
				}
			}
			return true
		})
	}
}

func wsOnConnect(session *melody.Session) {
}

func wsOnMessage(session *melody.Session, bytes []byte) {
	session.Close()
}

func wsOnMessageBinary(session *melody.Session, data []byte) {
	var pack modules.Packet
	data, ok := common.Decrypt(data, session)
	if !(ok && utils.JSON.Unmarshal(data, &pack) == nil) {
		common.SendPack(modules.Packet{Code: -1}, session)
		session.Close()
		return
	}
	if pack.Act == `report` || pack.Act == `setDevice` {
		session.Set(`LastPack`, time.Now().Unix())
		handler.WSDevice(data, session)
		return
	}
	if !common.Devices.Has(session.UUID) {
		session.Close()
		return
	}
	handler.WSRouter(pack, session)
	session.Set(`LastPack`, time.Now().Unix())
}

func wsOnDisconnect(session *melody.Session) {
	common.Devices.Remove(session.UUID)
}

func getRemoteAddr(ctx *gin.Context) string {
	if remote, ok := ctx.RemoteIP(); ok {
		if remote.IsLoopback() {
			forwarded := ctx.GetHeader(`X-Forwarded-For`)
			if len(forwarded) > 0 {
				return forwarded
			}
			realIP := ctx.GetHeader(`X-Real-IP`)
			if len(realIP) > 0 {
				return realIP
			}
		} else {
			if ip := remote.To4(); ip != nil {
				return ip.String()
			}
			if ip := remote.To16(); ip != nil {
				return ip.String()
			}
		}
	}

	remote := net.ParseIP(ctx.Request.RemoteAddr)
	if remote != nil {
		if remote.IsLoopback() {
			forwarded := ctx.GetHeader(`X-Forwarded-For`)
			if len(forwarded) > 0 {
				return forwarded
			}
			realIP := ctx.GetHeader(`X-Real-IP`)
			if len(realIP) > 0 {
				return realIP
			}
		} else {
			if ip := remote.To4(); ip != nil {
				return ip.String()
			}
			if ip := remote.To16(); ip != nil {
				return ip.String()
			}
		}
	}
	addr := ctx.Request.RemoteAddr
	if pos := strings.LastIndex(addr, `:`); pos > -1 {
		return strings.Trim(addr[:pos], `[]`)
	}
	return addr
}