package bothandler

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"slices"
	"strings"

	"git.pengzhan.dev/aimaren/internal/storage"
	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
)

type BotMode int

const (
	UnsafeMode BotMode = iota
	WhiteListMode
	BlackListMode
)

// BotHandler 处理 Telegram 请求
type BotHandler struct {
	bot   *tgbotapi.BotAPI
	store storage.Storer // 用你的接口而不是具体类型
	mode  BotMode
	list  []int64
}

func NewBotHandler(bot *tgbotapi.BotAPI, store storage.Storer, mode BotMode, list []int64) *BotHandler {
	return &BotHandler{
		bot:   bot,
		store: store,
		mode:  mode,
		list:  list,
	}
}

func (h *BotHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	body, err := io.ReadAll(r.Body)
	if err != nil {
		http.Error(w, "cannot read body", http.StatusBadRequest)
		return
	}

	var update tgbotapi.Update
	if err := json.Unmarshal(body, &update); err != nil {
		http.Error(w, "bad json", http.StatusBadRequest)
		return
	}

	if update.Message == nil {
		w.WriteHeader(http.StatusOK)
		return
	}

	text := strings.TrimSpace(update.Message.Text)
	chatID := update.Message.Chat.ID
	strChatId := fmt.Sprintf("%d", chatID)

	// 模式检查
	switch h.mode {
	case UnsafeMode:
		// nothing
	case WhiteListMode:
		if !slices.Contains(h.list, chatID) {
			log.Printf("❌ Chat ID %d not in whitelist, ignore: %s", chatID, text)
			w.WriteHeader(http.StatusOK)
			return
		}
	case BlackListMode:
		if slices.Contains(h.list, chatID) {
			log.Printf("❌ Chat ID %d in blacklist, ignore: %s", chatID, text)
			w.WriteHeader(http.StatusOK)
			return
		}
	}
	ctx := context.Background()
	userState, err := h.store.FetchUserState(ctx)
	if err != nil {
		log.Printf("❌ FetchUserState error: %v", err)
		http.Error(w, "fetch user state error", http.StatusInternalServerError)
		return
	}
	if userState.Users == nil {
		userState.Users = make(map[string]storage.ChatState)
	}

	cs, ok := userState.Users[strChatId]

	// 判断是否为命令
	if update.Message.IsCommand() {
		switch update.Message.Command() {

		case "start":
			h.send(chatID, helpText())
		case "hello":
			h.send(chatID, escapeMarkdownV2(fmt.Sprintf("👋 你好! 你的 chat id 是 %d", chatID)))
		case "ride":
			if ok && cs.Registered {
				h.send(chatID, "✅ 你已经注册过了！")
				break
			}
			if ok && cs.CurrentOp == "ride_waiting" {
				h.send(chatID, "⏳ 你已经在等待输入邀请码，请直接发送邀请码。")
				break
			}
			userState.Users[strChatId] = storage.ChatState{
				ChatID:    chatID,
				CurrentOp: "ride_waiting",
				Context:   "",
			}
			if err := h.store.UpdateUserState(ctx, userState); err != nil {
				log.Printf("❌ UpdateUserState error: %v", err)
			}
			h.send(chatID, "📩 请输入你的邀请码：")

		case "tea":
			h.send(chatID, "☕ 本项目不盈利，但为了周转，需要你的支持。")

		default:
			h.send(chatID, helpText())
		}

		w.WriteHeader(http.StatusOK)
		return
	}

	// 非命令消息：检查是否在等待邀请码
	if ok && cs.CurrentOp == "ride_waiting" {
		code := text
		if slices.Contains(userState.FreeCode, code) {
			userState.Users[strChatId] = storage.ChatState{
				ChatID:     chatID,
				Registered: true,
				InviteCode: code,
			}
			userState.FreeCode = slices.Delete(userState.FreeCode, slices.Index(userState.FreeCode, code), slices.Index(userState.FreeCode, code)+1)
			if err := h.store.UpdateUserState(ctx, userState); err != nil {
				log.Printf("❌ UpdateUserState error: %v", err)
			}
			log.Printf("✅ Chat ID %d registered with invite code: %s", chatID, code)
			h.store.AddChatID(ctx, chatID)
			log.Printf("💾 Chat ID %d added to app state.", chatID)
			h.send(chatID, "✅ 邀请码校验成功，已注册！")
			h.send(chatID, h.currentStockText(ctx))
		} else {
			userState.Users[strChatId] = storage.ChatState{
				ChatID: chatID,
			}
			if err := h.store.UpdateUserState(ctx, userState); err != nil {
				log.Printf("❌ UpdateUserState error: %v", err)
			}
			h.send(chatID, "❌ 邀请码错误。")
		}
		w.WriteHeader(http.StatusOK)
		return
	}

	w.WriteHeader(http.StatusOK)
}

// send 封装消息发送
func (h *BotHandler) send(chatID int64, text string) {
	msg := tgbotapi.NewMessage(chatID, text)
	msg.ParseMode = "MarkdownV2"
	if _, err := h.bot.Send(msg); err != nil {
		log.Printf("❌ send message error: %v", err)
	}
}

func helpText() string {
	return `🤖 可用命令:
/start 查看帮助
/hello 查看 chat id
/ride 注册
/tea 支持作者`
}

func (h *BotHandler) currentStockText(ctx context.Context) string {
	as, err := h.store.FetchAppState(ctx)
	if err != nil {
		log.Printf("❌ FetchAppState error: %v", err)
		return escapeMarkdownV2("❌ 无法获取当前库存状态")
	}

	if len(as.Bags) == 0 {
		return escapeMarkdownV2("当前没有可用的库存。")
	}

	var sb strings.Builder
	sb.WriteString(escapeMarkdownV2("当前缓存库存：") + "\n")

	for _, bag := range as.Bags {
		if bag.Availability {
			// MarkdownV2 link: [escapedName](escapedURL)
			name := escapeMarkdownV2(bag.Name)
			url := escapeMarkdownV2(bag.URL)
			sb.WriteString(fmt.Sprintf("[%s](%s)\n", name, url))
		}
	}

	return sb.String()
}

func escapeMarkdownV2(text string) string {
	// List of characters that must be escaped in MarkdownV2
	specialChars := []string{"_", "*", "[", "]", "(", ")", "~", "`", ">", "#", "+", "-", "=", "|", "{", "}", ".", "!"}

	escaped := text
	for _, ch := range specialChars {
		escaped = strings.ReplaceAll(escaped, ch, "\\"+ch)
	}
	return escaped
}