package main

import (
	"encoding/binary"
	"encoding/hex"
	"fmt"
	"math/rand"
	"time"

	wxproto "github.com/yincongcyincong/weixin-macos/onebot/proto"
	"google.golang.org/protobuf/proto"
)

// BuildTextMsgProto 构建发送文本消息的protobuf并返回hex编码的字符串
func BuildTextMsgProto(receiver, content, atUser string) (string, error) {
	// 构建 msgsource XML
	xmlStr := "<msgsource>"
	if atUser != "" {
		xmlStr += "<atuserlist>" + atUser + "</atuserlist>"
	}
	xmlStr += "<alnode><fr>1</fr></alnode></msgsource>"

	// 生成随机消息ID
	msgId := rand.Int63n(1<<34) | (1 << 34)

	msg := &wxproto.WxSendTextMsg{
		Type: 1,
		Body: &wxproto.WxSendTextBody{
			Receiver:  &wxproto.WxString{Value: receiver},
			Content:   []byte(content),
			Flag:      1,
			Timestamp: time.Now().Unix(),
			MsgId:     msgId,
			Xml:       []byte(xmlStr),
		},
	}

	data, err := proto.Marshal(msg)
	if err != nil {
		return "", fmt.Errorf("marshal text proto failed: %w", err)
	}

	//fmt.Printf("[text-proto] final protobuf hex dump:\n%s\n", HexDump(data, 0))

	return hex.EncodeToString(data), nil
}

// BuildSendPayload 构建MMStartTask的完整payload (0x1A0字节)，返回hex编码字符串
// msgType: "text", "img", "video"
// 布局: [taskId(4字节)] + [payloadData(412字节)]，总长固定0x1A0字节
// JS中的writePointer使用绝对偏移(0x18, 0xb8, 0x190)进行patch
func BuildSendPayload(taskId int64, msgType string) string {
	// 公共模板 (412字节，与JS原始img/video payloadData完全一致)
	// 差异字节通过下方switch设置: [0],[1],[16],[28],[92],[93]
	payloadData := []byte{
		0x00, 0x00, 0x00, 0x00, // [0]-[3] 由msgType决定         abs 0x04
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x08
		0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // [16]  abs 0x10
		0x40, 0xEC, 0x0E, 0x12, 0x01, 0x00, 0x00, 0x00, //       abs 0x18 (被cgiAddr覆盖)
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // [28]  abs 0x20
		0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, //       abs 0x28
		0x00, 0x01, 0x01, 0x01, 0x00, 0xAA, 0xAA, 0xAA, //       abs 0x30
		0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, //       abs 0x38
		0x01, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, //       abs 0x40
		0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0xAA, 0xAA, 0xAA, //       abs 0x48
		0xFF, 0xFF, 0xFF, 0xFF, 0xAA, 0xAA, 0xAA, 0xAA, //       abs 0x50
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x58
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // [92]  abs 0x60
		0x64, 0x65, 0x66, 0x61, 0x75, 0x6C, 0x74, 0x2D, //       abs 0x68 "default-"
		0x6C, 0x6F, 0x6E, 0x67, 0x6C, 0x69, 0x6E, 0x6B, //       abs 0x70 "longlink"
		0x00, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0x10, //       abs 0x78
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x80
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x88
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x90
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x98
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xA0
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xA8
		0x00, 0x00, 0x00, 0x00, 0xAA, 0xAA, 0xAA, 0xAA, //       abs 0xB0
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xB8 (被指针patch覆盖)
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xC0
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xC8
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xD0
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xD8
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xE0
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xE8
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xF0
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0xF8
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x100
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x108
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x110
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x118
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x120
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x128
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x130
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x138
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x140
		0x01, 0x00, 0x00, 0x00, 0xAA, 0xAA, 0xAA, 0xAA, //       abs 0x148
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x150
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x158
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x160
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x168
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x170
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x178
		0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x180
		0x00, 0x00, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, //       abs 0x188
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x190 (被指针patch覆盖)
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, //       abs 0x198
	}

	// 根据msgType设置差异字节
	switch msgType {
	case "text":
		payloadData[0] = 0x0A
		payloadData[1] = 0x02
		payloadData[16] = 0x01
		payloadData[28] = 0x20
		payloadData[92] = 0x0A
		payloadData[93] = 0x02
	case "img":
		payloadData[0] = 0x6E
		payloadData[16] = 0x10
		payloadData[28] = 0x22
		payloadData[92] = 0x6E
	case "video":
		payloadData[0] = 0x6E
		payloadData[16] = 0x10
		payloadData[28] = 0x21
		payloadData[92] = 0x6E
	case "reply":
		payloadData[0] = 0x6E
		payloadData[16] = 0x10
		payloadData[28] = 0x20
		payloadData[92] = 0x6E
	case "file":
		payloadData[0] = 0x6E
		payloadData[16] = 0x10
		payloadData[28] = 0x20
		payloadData[92] = 0x6E
	case "fileupload":
		payloadData[0] = 0x6E
		payloadData[16] = 0x10
		payloadData[28] = 0x27
		payloadData[92] = 0x6E
	case "appattach":
		payloadData[0] = 0x6E
		payloadData[16] = 0x10
		payloadData[28] = 0x25
		payloadData[92] = 0x6E
	case "voice":
		payloadData[0] = 0x6E
		payloadData[16] = 0x10
		payloadData[28] = 0x21
		payloadData[92] = 0x6E
	}

	// 构建完整buffer: taskId(4字节) + payloadData(412字节) = 0x1A0字节
	payload := make([]byte, 0x1A0)
	binary.LittleEndian.PutUint32(payload[0:4], uint32(taskId))
	copy(payload[4:], payloadData)

	return hex.EncodeToString(payload)
}