package reward

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"strings"

	"github.com/wangjia/pangolin/server/internal/apierr"
	"github.com/wangjia/pangolin/server/internal/auth"
)

// tgMsgs 是 TG bot 回执文案表(中/英双语)。key 与 ClaimResult / 失效态对应。
type tgMsgSet struct {
	expired, granted, already, notMember, errored string
}

var tgMsgsZH = tgMsgSet{
	expired:   "链接已失效,请回 App 重新点「验证领取」。",
	granted:   "已到账 +3 天 Pro,感谢加入!",
	already:   "你已领取过本奖励(+3 天),无需重复领取。",
	notMember: "未检测到你已加入频道 %s,请先加入频道,再回 App 点「验证领取」。",
	errored:   "验证出错,请稍后重试。",
}

var tgMsgsEN = tgMsgSet{
	expired:   "This link has expired. Please tap \u201cVerify & claim\u201d in the app again.",
	granted:   "+3 days of Pro credited — thanks for joining!",
	already:   "You've already claimed this reward (+3 days) — no need to claim again.",
	notMember: "You don't seem to be a member of %s yet. Please join the channel first, then tap \u201cVerify & claim\u201d in the app.",
	errored:   "Verification failed, please try again later.",
}

// tgMsgSetFor 按 Telegram language_code 选中/英文案表:zh* → 中文,其余(含空)→ 英文。
func tgMsgSetFor(languageCode string) tgMsgSet {
	if strings.HasPrefix(languageCode, "zh") {
		return tgMsgsZH
	}
	return tgMsgsEN
}

const inviteLinkBase = "https://pangolin.yanmeiai.com/i/"

type Handler struct {
	svc       *Service
	st        *Store
	tgEnabled bool
	channel   string
}

func NewHandler(s *Service, st *Store, tgEnabled bool, channel string) *Handler {
	return &Handler{svc: s, st: st, tgEnabled: tgEnabled, channel: channel}
}

func (h *Handler) GetInvite(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	uid, ok := auth.UserIDFromContext(ctx)
	if !ok {
		apierr.WriteJSON(w, http.StatusUnauthorized, apierr.ErrUnauthorized)
		return
	}
	code, err := h.svc.EnsureCode(ctx, uid)
	if err != nil {
		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
		return
	}
	invited, converted, earned, err := h.st.Summary(ctx, uid)
	if err != nil {
		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
		return
	}
	joined, _ := h.st.TelegramClaimed(ctx, uid)
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_ = json.NewEncoder(w).Encode(map[string]any{
		"invite_code": code,
		"invite_link": inviteLinkBase + code,
		"invited":     invited,
		"converted":   converted,
		"earned_days": earned,
		"telegram": map[string]any{
			"enabled": h.tgEnabled,
			"joined":  joined,
			"channel": h.channel,
		},
	})
}

func (h *Handler) TelegramStart(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	uid, ok := auth.UserIDFromContext(ctx)
	if !ok {
		apierr.WriteJSON(w, http.StatusUnauthorized, apierr.ErrUnauthorized)
		return
	}
	if !h.tgEnabled {
		apierr.WriteJSON(w, http.StatusNotFound, apierr.ErrNotFound)
		return
	}
	tok, err := h.svc.IssueTelegramToken(ctx, uid)
	if err != nil {
		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
		return
	}
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	_ = json.NewEncoder(w).Encode(map[string]any{"deep_link": h.svc.TelegramDeepLink(tok)})
}

// TelegramWebhook 处理 Telegram Bot API 回调:校验 secret 头 → 解析 `/start <token>`
// → ConsumeTelegramToken → ClaimTelegram → sendMessage 回执。Telegram 只要求 200 即不重投,
// 业务结果通过 sendMessage 异步告知用户。
func (h *Handler) TelegramWebhook(w http.ResponseWriter, r *http.Request) {
	if !h.tgEnabled || r.Header.Get("X-Telegram-Bot-Api-Secret-Token") != h.svc.WebhookSecret() {
		w.WriteHeader(http.StatusNotFound)
		return
	}
	var upd struct {
		Message struct {
			Text string `json:"text"`
			From struct {
				ID           int64  `json:"id"`
				LanguageCode string `json:"language_code"`
			} `json:"from"`
		} `json:"message"`
	}
	_ = json.NewDecoder(http.MaxBytesReader(w, r.Body, 16<<10)).Decode(&upd)
	w.WriteHeader(http.StatusOK) // Telegram 只要 200;业务异步在下方
	text, fromID := upd.Message.Text, upd.Message.From.ID
	if !strings.HasPrefix(text, "/start ") || fromID == 0 {
		return
	}
	msgs := tgMsgSetFor(upd.Message.From.LanguageCode)
	token := strings.TrimSpace(strings.TrimPrefix(text, "/start "))
	ctx := r.Context()
	uid, ok, _ := h.svc.ConsumeTelegramToken(ctx, token)
	if !ok {
		h.svc.SendTelegram(ctx, fromID, msgs.expired)
		return
	}
	result, err := h.svc.ClaimTelegram(ctx, uid, strconv.FormatInt(fromID, 10))
	switch {
	case err != nil:
		h.svc.SendTelegram(ctx, fromID, msgs.errored)
	case result == ClaimGranted:
		h.svc.SendTelegram(ctx, fromID, msgs.granted)
	case result == ClaimAlready:
		h.svc.SendTelegram(ctx, fromID, msgs.already)
	default: // ClaimNotMember
		h.svc.SendTelegram(ctx, fromID, fmt.Sprintf(msgs.notMember, h.svc.Channel()))
	}
}