package client

import (
	"bytes"
	"crypto/md5"
	"fmt"
	"math"
	"math/rand"
	"strconv"
	"strings"
	"time"

	"github.com/pkg/errors"

	"github.com/Mrs4s/MiraiGo/binary"
	"github.com/Mrs4s/MiraiGo/client/internal/highway"
	"github.com/Mrs4s/MiraiGo/client/internal/network"
	"github.com/Mrs4s/MiraiGo/client/pb/longmsg"
	"github.com/Mrs4s/MiraiGo/client/pb/msg"
	"github.com/Mrs4s/MiraiGo/client/pb/multimsg"
	"github.com/Mrs4s/MiraiGo/internal/proto"
	"github.com/Mrs4s/MiraiGo/message"
	"github.com/Mrs4s/MiraiGo/utils"
)

func init() {
	decoders["MultiMsg.ApplyUp"] = decodeMultiApplyUpResponse
	decoders["MultiMsg.ApplyDown"] = decodeMultiApplyDownResponse
}

// MultiMsg.ApplyUp
func (c *QQClient) buildMultiApplyUpPacket(data, hash []byte, buType int32, groupUin int64) (uint16, []byte) {
	req := &multimsg.MultiReqBody{
		Subcmd:       1,
		TermType:     5,
		PlatformType: 9,
		NetType:      3,
		BuildVer:     "8.2.0.1296",
		MultimsgApplyupReq: []*multimsg.MultiMsgApplyUpReq{
			{
				DstUin:  groupUin,
				MsgSize: int64(len(data)),
				MsgMd5:  hash,
				MsgType: 3,
			},
		},
		BuType: buType,
	}
	payload, _ := proto.Marshal(req)
	return c.uniPacket("MultiMsg.ApplyUp", payload)
}

// MultiMsg.ApplyUp
func decodeMultiApplyUpResponse(_ *QQClient, _ *network.IncomingPacketInfo, payload []byte) (any, error) {
	body := multimsg.MultiRspBody{}
	if err := proto.Unmarshal(payload, &body); err != nil {
		return nil, errors.Wrap(err, "failed to unmarshal protobuf message")
	}
	if len(body.MultimsgApplyupRsp) == 0 {
		return nil, errors.New("rsp is empty")
	}
	rsp := body.MultimsgApplyupRsp[0]
	switch rsp.Result {
	case 0:
		return rsp, nil
	case 193:
		return nil, errors.New("too large")
	}
	return nil, errors.Errorf("unexpected multimsg apply up response: %d", rsp.Result)
}

// MultiMsg.ApplyDown
func (c *QQClient) buildMultiApplyDownPacket(resID string) (uint16, []byte) {
	req := &multimsg.MultiReqBody{
		Subcmd:       2,
		TermType:     5,
		PlatformType: 9,
		NetType:      3,
		BuildVer:     "8.2.0.1296",
		MultimsgApplydownReq: []*multimsg.MultiMsgApplyDownReq{
			{
				MsgResid: []byte(resID),
				MsgType:  3,
			},
		},
		BuType:         2,
		ReqChannelType: 2,
	}
	payload, _ := proto.Marshal(req)
	return c.uniPacket("MultiMsg.ApplyDown", payload)
}

// MultiMsg.ApplyDown
func decodeMultiApplyDownResponse(_ *QQClient, _ *network.IncomingPacketInfo, payload []byte) (any, error) {
	body := multimsg.MultiRspBody{}
	if err := proto.Unmarshal(payload, &body); err != nil {
		return nil, errors.Wrap(err, "failed to unmarshal protobuf message")
	}
	if len(body.MultimsgApplydownRsp) == 0 {
		return nil, errors.New("not found")
	}
	rsp := body.MultimsgApplydownRsp[0]

	var prefix string
	if rsp.MsgExternInfo != nil && rsp.MsgExternInfo.ChannelType == 2 {
		prefix = "https://ssl.htdata.qq.com"
	} else {
		prefix = fmt.Sprintf("http://%s:%d", binary.UInt32ToIPV4Address(uint32(rsp.Uint32DownIp[0])), body.MultimsgApplydownRsp[0].Uint32DownPort[0])
	}
	b, err := utils.HttpGetBytes(fmt.Sprintf("%s%s", prefix, string(rsp.ThumbDownPara)), "")
	if err != nil {
		return nil, errors.Wrap(err, "failed to download by multi apply down")
	}
	if b[0] != 40 {
		return nil, errors.New("unexpected body data")
	}
	tea := binary.NewTeaCipher(body.MultimsgApplydownRsp[0].MsgKey)
	r := binary.NewReader(b[1:])
	i1 := r.ReadInt32()
	i2 := r.ReadInt32()
	if i1 > 0 {
		r.ReadBytes(int(i1)) // im msg head
	}
	data := tea.Decrypt(r.ReadBytes(int(i2)))
	lb := longmsg.LongRspBody{}
	if err = proto.Unmarshal(data, &lb); err != nil {
		return nil, errors.Wrap(err, "failed to unmarshal protobuf message")
	}
	msgContent := lb.MsgDownRsp[0].MsgContent
	if msgContent == nil {
		return nil, errors.New("message content is empty")
	}
	uc := binary.GZipUncompress(msgContent)
	mt := msg.PbMultiMsgTransmit{}
	if err = proto.Unmarshal(uc, &mt); err != nil {
		return nil, errors.Wrap(err, "failed to unmarshal protobuf message")
	}
	return &mt, nil
}

type forwardMsgLinker struct {
	items map[string]*msg.PbMultiMsgItem
}

func (l *forwardMsgLinker) link(name string) *message.ForwardMessage {
	item := l.items[name]
	if item == nil {
		return nil
	}
	nodes := make([]*message.ForwardNode, 0, len(item.Buffer.Msg))
	for _, m := range item.Buffer.Msg {
		name := m.Head.FromNick.Unwrap()
		if m.Head.MsgType.Unwrap() == 82 && m.Head.GroupInfo != nil {
			name = m.Head.GroupInfo.GroupCard.Unwrap()
		}

		msgElems := message.ParseMessageElems(m.Body.RichText.Elems)
		for i, elem := range msgElems {
			if forward, ok := elem.(*message.ForwardElement); ok {
				if forward.FileName != "" {
					msgElems[i] = l.link(forward.FileName) // 递归处理嵌套转发
				}
			}
		}

		gid := int64(0) // 给群号一个缺省值0，防止在读合并转发的私聊内容时候会报错
		if m.Head.GroupInfo != nil {
			gid = m.Head.GroupInfo.GroupCode.Unwrap()
		}
		nodes = append(nodes, &message.ForwardNode{
			GroupId:    gid,
			SenderId:   m.Head.FromUin.Unwrap(),
			SenderName: name,
			Time:       m.Head.MsgTime.Unwrap(),
			Message:    msgElems,
		})
	}
	return &message.ForwardMessage{Nodes: nodes}
}

func (c *QQClient) GetForwardMessage(resID string) *message.ForwardMessage {
	m := c.DownloadForwardMessage(resID)
	if m == nil {
		return nil
	}
	linker := forwardMsgLinker{
		items: make(map[string]*msg.PbMultiMsgItem),
	}
	for _, item := range m.Items {
		linker.items[item.FileName.Unwrap()] = item
	}
	return linker.link("MultiMsg")
}

func (c *QQClient) DownloadForwardMessage(resId string) *message.ForwardElement {
	i, err := c.sendAndWait(c.buildMultiApplyDownPacket(resId))
	if err != nil {
		return nil
	}
	multiMsg := i.(*msg.PbMultiMsgTransmit)
	if multiMsg.PbItemList == nil {
		return nil
	}
	var pv bytes.Buffer
	for i := 0; i < int(math.Min(4, float64(len(multiMsg.Msg)))); i++ {
		m := multiMsg.Msg[i]
		sender := m.Head.FromNick.Unwrap()
		if m.Head.MsgType.Unwrap() == 82 && m.Head.GroupInfo != nil {
			sender = m.Head.GroupInfo.GroupCard.Unwrap()
		}
		brief := message.ToReadableString(message.ParseMessageElems(multiMsg.Msg[i].Body.RichText.Elems))
		fmt.Fprintf(&pv, `<title size="26" color="#777777">%s: %s</title>`, sender, brief)
	}
	return genForwardTemplate(
		resId, pv.String(),
		fmt.Sprintf("查看 %d 条转发消息", len(multiMsg.Msg)),
		time.Now().UnixNano(),
		multiMsg.PbItemList,
	)
}

func forwardDisplay(resID, fileName, preview, summary string) string {
	sb := strings.Builder{}
	sb.WriteString(`<?xml version='1.0' encoding='UTF-8'?><msg serviceID="35" templateID="1" action="viewMultiMsg" brief="[聊天记录]" `)
	if resID != "" {
		sb.WriteString(`m_resid="`)
		sb.WriteString(resID)
		sb.WriteString("\" ")
	}
	sb.WriteString(`m_fileName="`)
	sb.WriteString(fileName)
	sb.WriteString(`" tSum="3" sourceMsgId="0" url="" flag="3" adverSign="0" multiMsgFlag="0"><item layout="1"><title color="#000000" size="34">群聊的聊天记录</title> `)
	sb.WriteString(preview)
	sb.WriteString(`<hr></hr><summary size="26" color="#808080">`)
	sb.WriteString(summary)
	// todo: 私聊的聊天记录？
	sb.WriteString(`</summary></item><source name="聊天记录"></source></msg>`)
	return sb.String()
}

func (c *QQClient) NewForwardMessageBuilder(groupCode int64) *ForwardMessageBuilder {
	return &ForwardMessageBuilder{
		c:         c,
		groupCode: groupCode,
	}
}

type ForwardMessageBuilder struct {
	c         *QQClient
	groupCode int64
	objs      []*msg.PbMultiMsgItem
}

// NestedNode 返回一个嵌套转发节点，其内容将会被 Builder 重定位
func (builder *ForwardMessageBuilder) NestedNode() *message.ForwardElement {
	filename := strconv.FormatInt(time.Now().UnixNano(), 10) // 大概率不会重复
	return &message.ForwardElement{FileName: filename}
}

// Link 将真实的消息内容填充 reloc
func (builder *ForwardMessageBuilder) Link(reloc *message.ForwardElement, fmsg *message.ForwardMessage) {
	seq := builder.c.nextGroupSeq()
	m := fmsg.PackForwardMessage(seq, rand.Int31(), builder.groupCode)
	builder.objs = append(builder.objs, &msg.PbMultiMsgItem{
		FileName: proto.String(reloc.FileName),
		Buffer: &msg.PbMultiMsgNew{
			Msg: m,
		},
	})
	reloc.Content = forwardDisplay("", reloc.FileName, fmsg.Preview(), fmt.Sprintf("查看 %d 条转发消息", fmsg.Length()))
}

// Main 最外层的转发消息, 调用该方法后即上传消息
func (builder *ForwardMessageBuilder) Main(m *message.ForwardMessage) *message.ForwardElement {
	if m.Length() > 200 {
		return nil
	}
	c := builder.c
	seq := c.nextGroupSeq()
	fm := m.PackForwardMessage(seq, rand.Int31(), builder.groupCode)
	const filename = "MultiMsg"
	builder.objs = append(builder.objs, &msg.PbMultiMsgItem{
		FileName: proto.String(filename),
		Buffer: &msg.PbMultiMsgNew{
			Msg: fm,
		},
	})
	trans := &msg.PbMultiMsgTransmit{
		Msg:        fm,
		PbItemList: builder.objs,
	}
	b, _ := proto.Marshal(trans)
	data := binary.GZipCompress(b)
	hash := md5.Sum(data)
	rsp, body, err := c.multiMsgApplyUp(builder.groupCode, data, hash[:], 2)
	if err != nil {
		return nil
	}
	content := forwardDisplay(rsp.MsgResid, utils.RandomString(32), m.Preview(), fmt.Sprintf("查看 %d 条转发消息", m.Length()))
	bodyHash := md5.Sum(body)
	input := highway.Transaction{
		CommandID: 27,
		Ticket:    rsp.MsgSig,
		Body:      bytes.NewReader(body),
		Sum:       bodyHash[:],
		Size:      int64(len(body)),
	}
	for i, ip := range rsp.Uint32UpIp {
		addr := highway.Addr{IP: uint32(ip), Port: int(rsp.Uint32UpPort[i])}
		err := c.highwaySession.Upload(addr, input)
		if err != nil {
			continue
		}
		return &message.ForwardElement{
			FileName: filename,
			Content:  content,
			ResId:    rsp.MsgResid,
		}
	}
	return nil
}