// main.go — 微信 ClawBot iLink 最小示例（Go，仅标准库）
// 流程: 扫码登录 → 长轮询收消息 → 回声回复
// 运行: go run main.go
package main

import (
	"bytes"
	"crypto/rand"
	"encoding/base64"
	"encoding/binary"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"time"
)

const baseURL = "https://ilinkai.weixin.qq.com"

var stateFile = filepath.Join(func() string { d, _ := os.Executable(); return filepath.Dir(d) }(), "bridge-state.json")

// ---------- 状态持久化: bot_token / 游标 / context_token ----------
type State struct {
	BotToken string            `json:"bot_token"`
	BotID    string            `json:"bot_id,omitempty"`
	Cursor   string            `json:"cursor"`
	Contexts map[string]string `json:"contexts"`
}

var state = State{Contexts: map[string]string{}}

func loadState() {
	if b, err := os.ReadFile(stateFile); err == nil {
		json.Unmarshal(b, &state)
	}
	if state.Contexts == nil {
		state.Contexts = map[string]string{}
	}
}

func saveState() {
	b, _ := json.MarshalIndent(state, "", "  ")
	os.WriteFile(stateFile, b, 0o600)
}

// ---------- 通用请求头: 鉴权 + 防重放 X-WECHAT-UIN ----------
func headers(req *http.Request) {
	var u [4]byte
	rand.Read(u[:])
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("AuthorizationType", "ilink_bot_token")
	req.Header.Set("X-WECHAT-UIN", base64.StdEncoding.EncodeToString(
		[]byte(fmt.Sprint(binary.BigEndian.Uint32(u[:])))))
	if state.BotToken != "" {
		req.Header.Set("Authorization", "Bearer "+state.BotToken)
	}
}

func apiPost(path string, body any, timeout time.Duration) (map[string]any, error) {
	buf, _ := json.Marshal(body)
	req, err := http.NewRequest("POST", baseURL+path, bytes.NewReader(buf))
	if err != nil {
		return nil, err
	}
	headers(req)
	client := &http.Client{Timeout: timeout}
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	var out map[string]any
	return out, json.NewDecoder(resp.Body).Decode(&out)
}

func apiGet(path string, extraHeaders map[string]string) (map[string]any, error) {
	req, err := http.NewRequest("GET", baseURL+path, nil)
	if err != nil {
		return nil, err
	}
	for k, v := range extraHeaders {
		req.Header.Set(k, v)
	}
	resp, err := (&http.Client{Timeout: 15 * time.Second}).Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	var out map[string]any
	return out, json.NewDecoder(resp.Body).Decode(&out)
}

// ---------- 接口1+2: 扫码登录（get_bot_qrcode / get_qrcode_status） ----------
func login() error {
	qr, err := apiGet("/ilink/bot/get_bot_qrcode?bot_type=3", nil)
	if err != nil {
		return err
	}
	fmt.Println("请用微信扫码:", qr["qrcode_img_content"])
	deadline := time.Now().Add(8 * time.Minute)
	for time.Now().Before(deadline) {
		s, err := apiGet("/ilink/bot/get_qrcode_status?qrcode="+url(qr["qrcode"]),
			map[string]string{"iLink-App-ClientVersion": "1"})
		if err == nil && s["status"] == "confirmed" { // wait → scaned → confirmed
			state.BotToken, _ = s["bot_token"].(string)
			state.BotID, _ = s["ilink_bot_id"].(string)
			saveState()
			fmt.Println("登录成功, bot:", state.BotID)
			return nil
		}
		time.Sleep(time.Second)
	}
	return fmt.Errorf("扫码超时")
}

func url(v any) string { // 极简 query 转义（qrcode 内容一般安全，正式代码用 url.QueryEscape）
	s, _ := v.(string)
	return s
}

// ---------- 你的 AI 后端: 替换成自己项目的调用 ----------
func AskYourAI(peerID, text string) string {
	return "你说的是：" + text
}

// ---------- 接口4: POST /ilink/bot/sendmessage ----------
func sendText(toUserID, text, contextToken string) {
	if text == "" {
		text = " "
	}
	for i := 0; i < len(text); i += 1500 { // 长文本分片（按字节切仅适合演示，正式按 rune 切）
		end := i + 1500
		if end > len(text) {
			end = len(text)
		}
		apiPost("/ilink/bot/sendmessage", map[string]any{
			"msg": map[string]any{
				"to_user_id":    toUserID,
				"client_id":     fmt.Sprintf("%d-%d", time.Now().UnixNano(), i),
				"message_type":  2, // bot 消息
				"message_state": 2, // FINISH
				"context_token": contextToken,
				"item_list": []any{map[string]any{
					"type": 1, "text_item": map[string]string{"text": text[i:end]},
				}},
			},
		}, 15*time.Second)
	}
}

// ---------- 接口3: POST /ilink/bot/getupdates 长轮询 ----------
func pollLoop() {
	failures := 0
	for {
		resp, err := apiPost("/ilink/bot/getupdates", map[string]any{
			"get_updates_buf": state.Cursor,
			"base_info":       map[string]string{"channel_version": "1.0.2"},
		}, 45*time.Second)

		if err != nil {
			if os.IsTimeout(err) { // 长轮询正常超时
				continue
			}
			failures++
			wait := 2 * time.Second
			if failures > 3 {
				wait = 30 * time.Second // 退避: 2s ×3 → 30s
			}
			fmt.Printf("轮询异常(%d次)，%v 后重试: %v\n", failures, wait, err)
			time.Sleep(wait)
			continue
		}

		if code, _ := resp["errcode"].(float64); code == -14 { // 会话过期
			fmt.Println("会话过期(errcode=-14)，请删除 bridge-state.json 重新扫码")
			os.Exit(2)
		}

		if buf, ok := resp["get_updates_buf"].(string); ok && buf != "" {
			state.Cursor = buf // 游标立即落盘
			saveState()
		}

		msgs, _ := resp["msgs"].([]any)
		for _, m := range msgs {
			msg, _ := m.(map[string]any)
			if t, _ := msg["message_type"].(float64); t != 1 { // 只处理用户消息
				continue
			}
			text := ""
			for _, it := range msg["item_list"].([]any) {
				item, _ := it.(map[string]any)
				if t, _ := item["type"].(float64); t == 1 {
					if ti, ok := item["text_item"].(map[string]any); ok {
						s, _ := ti["text"].(string)
						text += s + "\n"
					}
				}
			}
			if text == "" {
				continue
			}
			peer, _ := msg["from_user_id"].(string)
			token, _ := msg["context_token"].(string)
			state.Contexts[peer] = token
			saveState()
			sendText(peer, AskYourAI(peer, text), token)
		}
		failures = 0
	}
}

func main() {
	loadState()
	if state.BotToken == "" {
		if err := login(); err != nil {
			fmt.Println(err)
			os.Exit(1)
		}
	}
	pollLoop()
}