package logic

import (
	"context"
	"crypto/aes"
	"crypto/cipher"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"strings"

	"fusenapi/server/feishu-sync/internal/svc"
	"github.com/zeromicro/go-zero/core/logx"
)

type WebhookLogic struct {
	logx.Logger
	ctx    context.Context
	svcCtx *svc.ServiceContext
}

func NewWebhookLogic(ctx context.Context, svcCtx *svc.ServiceContext) *WebhookLogic {
	return &WebhookLogic{
		Logger: logx.WithContext(ctx),
		ctx:    ctx,
		svcCtx: svcCtx,
	}
}

type EncryptWebhookMsg struct {
	Encrypt string `json:"encrypt"` //加密的消息
}
type WebhookMsg struct {
	Type      string                 `json:"type"`
	Challenge string                 `json:"challenge"`
	Header    map[string]interface{} `json:"header"`
	Event     map[string]interface{} `json:"event"`
}

// webhook消息事件header(body参数)基础信息
type BaseWebhookMsgHeaderType struct {
	EventId    string `json:"event_id"`    //事件id(可作为消息唯一性确认)
	EventType  string `json:"event_type"`  //事件类型
	CreateTime string `json:"create_time"` //创建时间
	Token      string `json:"token"`       //事件token
	AppId      string `json:"app_id"`      //app id
	TenantKey  string `json:"tenant_key"`  //租户key
}

func (l *WebhookLogic) Webhook(w http.ResponseWriter, r *http.Request) {
	bodyBytes, err := io.ReadAll(r.Body)
	if err != nil {
		logx.Error("读取请求body失败", err)
		return
	}
	defer r.Body.Close()
	//计算签名
	timestamp := r.Header.Get("X-Lark-Request-Timestamp")
	nonce := r.Header.Get("X-Lark-Request-Nonce")
	encryptKey := "DmiHQ2bHhKiR3KK4tIjLShbs13eErxKA"
	signature := r.Header.Get("X-Lark-Signature")
	sign := l.CalculateFeiShuWebhookSignature(timestamp, nonce, encryptKey, bodyBytes)
	if signature != sign {
		logx.Error("非法的消息，签名验证不通过", sign, "====", signature)
		return
	}
	var encryptMsg EncryptWebhookMsg
	if err = json.Unmarshal(bodyBytes, &encryptMsg); err != nil {
		logx.Error("反序列化body失败", err)
		return
	}
	if encryptMsg.Encrypt == "" {
		logx.Error("消息加密信息是空的")
		return
	}
	//解密
	realMsgBytes, err := l.DecryptFeiShuWebhookMsg(encryptMsg.Encrypt, encryptKey)
	if err != nil {
		logx.Error(err)
		return
	}
	//如果只是验证http连接的消息
	var webhookMsg WebhookMsg
	if err = json.Unmarshal(realMsgBytes, &webhookMsg); err != nil {
		logx.Error("反序列化请求body失败", err)
		return
	}
	//验证连接(直接返回)
	if webhookMsg.Type == "url_verification" {
		challengeRsp := map[string]string{
			"challenge": webhookMsg.Challenge,
		}
		b, _ := json.Marshal(challengeRsp)
		w.Write(b)
		return
	}
	headerByte, err := json.Marshal(webhookMsg.Header)
	if err != nil {
		logx.Error("序列化请求体header失败:", err)
		return
	}
	var msgHeader BaseWebhookMsgHeaderType
	if err = json.Unmarshal(headerByte, &msgHeader); err != nil {
		logx.Error("反序列化请求体中的header失败", err)
		return
	}
	logx.Info("触发webhook:", msgHeader.EventType)
	switch msgHeader.EventType {
	case "contact.custom_attr_event.updated_v3": //成员字段管理属性变更事件
	case "contact.department.created_v3": //部门新建
	case "contact.department.deleted_v3": //部门删除
	case "contact.department.updated_v3": //部门信息变化
	case "contact.employee_type_enum.actived_v3": //启动人员类型事件
	case "contact.employee_type_enum.created_v3": //新建人员类型事件
	case "contact.employee_type_enum.deactivated_v3": //停用人员类型事件
	case "contact.employee_type_enum.deleted_v3": //删除人员类型事件
	case "contact.employee_type_enum.updated_v3": //修改人员类型名称事件
	case "contact.scope.updated_v3": //通讯录范围权限被更新
	case "contact.user.created_v3": //员工入职
	case "contact.user.deleted_v3": //员工离职
	case "contact.user.updated_v3": //员工信息变化

	}
	return
}

// 计算签名
func (l *WebhookLogic) CalculateFeiShuWebhookSignature(timestamp, nonce, encryptKey string, body []byte) string {
	var b strings.Builder
	b.WriteString(timestamp)
	b.WriteString(nonce)
	b.WriteString(encryptKey)
	b.Write(body) //bodystring 指整个请求体，不要在反序列化后再计算
	bs := []byte(b.String())
	h := sha256.New()
	h.Write(bs)
	bs = h.Sum(nil)
	sig := fmt.Sprintf("%x", bs)
	return sig
}

// 解密事件消息
func (l *WebhookLogic) DecryptFeiShuWebhookMsg(encrypt string, encryptKey string) ([]byte, error) {
	h := sha256.New()
	_, err := h.Write([]byte(encryptKey))
	if err != nil {
		return nil, err
	}
	key := hex.EncodeToString(h.Sum(nil))
	buf, err := base64.StdEncoding.DecodeString(encrypt)
	if err != nil {
		return nil, fmt.Errorf("base64StdEncode Error[%v]", err)
	}
	if len(buf) < aes.BlockSize {
		return nil, errors.New("cipher  too short")
	}
	keyBs := sha256.Sum256([]byte(key))
	block, err := aes.NewCipher(keyBs[:sha256.Size])
	if err != nil {
		return nil, fmt.Errorf("AESNewCipher Error[%v]", err)
	}
	iv := buf[:aes.BlockSize]
	buf = buf[aes.BlockSize:]
	// CBC mode always works in whole blocks.
	if len(buf)%aes.BlockSize != 0 {
		return nil, errors.New("ciphertext is not a multiple of the block size")
	}
	mode := cipher.NewCBCDecrypter(block, iv)
	mode.CryptBlocks(buf, buf)
	n := strings.Index(string(buf), "{")
	if n == -1 {
		n = 0
	}
	m := strings.LastIndex(string(buf), "}")
	if m == -1 {
		m = len(buf) - 1
	}
	return buf[n : m+1], nil
}