package common

import (
	"Spark/modules"
	"Spark/utils"
	"Spark/utils/cmap"
	"Spark/utils/melody"
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"net/http"
	"time"
)

var Melody = melody.New()
var Devices = cmap.New()
var BuiltFS http.FileSystem

func SendPackUUID(pack modules.Packet, uuid string) bool {
	session, ok := Melody.GetSessionByUUID(uuid)
	if !ok {
		return false
	}
	return SendPack(pack, session)
}

func SendPack(pack modules.Packet, session *melody.Session) bool {
	if session == nil {
		return false
	}
	data, err := utils.JSON.Marshal(pack)
	if err != nil {
		return false
	}
	data, ok := Encrypt(data, session)
	if !ok {
		return false
	}
	err = session.WriteBinary(data)
	return err == nil
}

func Encrypt(data []byte, session *melody.Session) ([]byte, bool) {
	temp, ok := session.Get(`Secret`)
	if !ok {
		return nil, false
	}
	secret := temp.([]byte)
	dec, err := utils.Encrypt(data, secret)
	if err != nil {
		return nil, false
	}
	return dec, true
}

func Decrypt(data []byte, session *melody.Session) ([]byte, bool) {
	temp, ok := session.Get(`Secret`)
	if !ok {
		return nil, false
	}
	secret := temp.([]byte)
	dec, err := utils.Decrypt(data, secret)
	if err != nil {
		return nil, false
	}
	return dec, true
}

func WSHealthCheck(container *melody.Melody) {
	const MaxInterval = 90
	for now := range time.NewTicker(30 * time.Second).C {
		timestamp := now.Unix()
		// stores sessions to be disconnected
		queue := make([]*melody.Session, 0)
		container.IterSessions(func(uuid string, s *melody.Session) bool {
			val, ok := s.Get(`LastPack`)
			if !ok {
				queue = append(queue, s)
				return true
			}
			lastPack, ok := val.(int64)
			if !ok {
				queue = append(queue, s)
				return true
			}
			if timestamp-lastPack > MaxInterval {
				queue = append(queue, s)
			}
			return true
		})
		for i := 0; i < len(queue); i++ {
			queue[i].Close()
		}
	}
}

func CheckDevice(deviceID string) (string, bool) {
	connUUID := ``
	Devices.IterCb(func(uuid string, v interface{}) bool {
		device := v.(*modules.Device)
		if device.ID == deviceID {
			connUUID = uuid
			return false
		}
		return true
	})
	return connUUID, len(connUUID) > 0
}

func EncAES(data []byte, key []byte) ([]byte, error) {
	hash, _ := utils.GetMD5(data)
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	stream := cipher.NewCTR(block, hash)
	encBuffer := make([]byte, len(data))
	stream.XORKeyStream(encBuffer, data)
	return append(hash, encBuffer...), nil
}

func DecAES(data []byte, key []byte) ([]byte, error) {
	// MD5[16 bytes] + Data[n bytes]
	dataLen := len(data)
	if dataLen <= 16 {
		return nil, utils.ErrEntityInvalid
	}
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}
	stream := cipher.NewCTR(block, data[:16])
	decBuffer := make([]byte, dataLen-16)
	stream.XORKeyStream(decBuffer, data[16:])
	hash, _ := utils.GetMD5(decBuffer)
	if !bytes.Equal(hash, data[:16]) {
		return nil, utils.ErrFailedVerification
	}
	return decBuffer[:dataLen-16], nil
}