package reward

import (
	"context"
	"crypto/rand"
	"database/sql"
	"encoding/hex"
	"encoding/json"
	"log/slog"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"time"

	"github.com/redis/go-redis/v9"
)

type tgConfig struct {
	botUser, channel, botToken, webhookSecret string
}

// ChatMemberChecker 判定某 telegramID 是否是频道/群成员。默认实现打 Telegram Bot API,
// 测试注入 fake 以避免真实网络调用。
type ChatMemberChecker interface {
	IsMember(ctx context.Context, channel, telegramID string) (bool, error)
}

// SetMemberChecker 注入自定义成员校验器(测试用);生产走 SetTelegram 设置的默认 apiChecker。
func (s *Service) SetMemberChecker(c ChatMemberChecker) { s.checker = c }

// SetTelegram 注入 TG 配置(经 Service.tg)。若尚未注入 checker(测试未 SetMemberChecker),
// 默认设为打 Telegram Bot API 的 apiChecker。
func (s *Service) SetTelegram(botUser, channel, botToken, webhookSecret string) {
	s.tg = tgConfig{botUser: botUser, channel: channel, botToken: botToken, webhookSecret: webhookSecret}
	if s.checker == nil {
		s.checker = apiChecker{botToken: botToken, hc: &http.Client{Timeout: 8 * time.Second}}
	}
}

// WebhookSecret 返回 TG webhook 校验用的 secret token。
func (s *Service) WebhookSecret() string { return s.tg.webhookSecret }

// Channel 返回配置的 TG 频道(@ 形式)。
func (s *Service) Channel() string { return s.tg.channel }

// SetRedis 注入 redis 客户端(经 Service.rdb);为 nil 时 token 走内存兜底(测试/未配 redis)。
func (s *Service) SetRedis(rdb *redis.Client) { s.rdb = rdb }

func randToken() string {
	b := make([]byte, 16)
	_, _ = rand.Read(b)
	return hex.EncodeToString(b)
}

// IssueTelegramToken 生成随机 token,Redis SETEX tg_bind:<token> 600 <userID>;
// Redis 为 nil 时用内存 map 兜底(测试/未配 redis)。
func (s *Service) IssueTelegramToken(ctx context.Context, userID int64) (string, error) {
	tok := randToken()
	if s.rdb != nil {
		return tok, s.rdb.Set(ctx, "tg_bind:"+tok, userID, 10*time.Minute).Err()
	}
	s.memMu.Lock()
	if s.memTok == nil {
		s.memTok = map[string]int64{}
	}
	s.memTok[tok] = userID
	s.memMu.Unlock()
	return tok, nil
}

// ConsumeTelegramToken 一次性消费(GETDEL 语义)。
func (s *Service) ConsumeTelegramToken(ctx context.Context, token string) (int64, bool, error) {
	if s.rdb != nil {
		v, err := s.rdb.GetDel(ctx, "tg_bind:"+token).Result()
		if err == redis.Nil {
			return 0, false, nil
		}
		if err != nil {
			return 0, false, err
		}
		id, _ := strconv.ParseInt(v, 10, 64)
		return id, true, nil
	}
	s.memMu.Lock()
	defer s.memMu.Unlock()
	id, ok := s.memTok[token]
	if ok {
		delete(s.memTok, token)
	}
	return id, ok, nil
}

// ClaimResult 是 ClaimTelegram 的结果三态,供上层(handler)按态回不同文案。
type ClaimResult int

const (
	ClaimGranted   ClaimResult = iota // 发放成功
	ClaimAlready                      // 已领取过(本账户或该 telegram_id)
	ClaimNotMember                    // 不在频道
)

// ClaimTelegram: 真是频道成员则一次性发 TgDays 天(source='task'),唯一守卫防重复领取
// (同 userID 或同 telegramID 只能成功一次)。
func (s *Service) ClaimTelegram(ctx context.Context, userID int64, telegramID string) (ClaimResult, error) {
	member, err := s.checker.IsMember(ctx, s.tg.channel, telegramID)
	if err != nil {
		return ClaimNotMember, err
	}
	if !member {
		return ClaimNotMember, nil
	}
	tx, err := s.db.BeginTx(ctx, &sql.TxOptions{})
	if err != nil {
		return ClaimNotMember, err
	}
	defer func() { _ = tx.Rollback() }()
	now := s.now()
	if err := s.st.InsertClaimTx(ctx, tx, userID, "telegram_join", telegramID, s.cfg.TgDays, now); err != nil {
		if err == ErrClaimExists {
			return ClaimAlready, nil // 已领过(本账户 or 该 tgid)
		}
		return ClaimNotMember, err
	}
	if _, _, err := s.g.GrantRewardTx(ctx, tx, userID, s.cfg.TgDays, "task", "task_telegram_join", "tg:"+telegramID); err != nil {
		return ClaimNotMember, err
	}
	if s.noticer != nil {
		zh, en := rewardNoticeTitles("task_tg", s.cfg.TgDays)
		if err := s.noticer.InsertNoticeTx(ctx, tx, userID, "reward", zh, en, "", "", "", now); err != nil {
			return ClaimNotMember, err
		}
	}
	if err := tx.Commit(); err != nil {
		return ClaimNotMember, err
	}
	return ClaimGranted, nil
}

// apiChecker 是 ChatMemberChecker 的默认生产实现:打 Telegram getChatMember。
type apiChecker struct {
	botToken string
	hc       *http.Client
}

func (c apiChecker) IsMember(ctx context.Context, channel, telegramID string) (bool, error) {
	u := "https://api.telegram.org/bot" + c.botToken + "/getChatMember"
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u, nil)
	if err != nil {
		return false, err
	}
	q := req.URL.Query()
	q.Set("chat_id", channel)
	q.Set("user_id", telegramID)
	req.URL.RawQuery = q.Encode()
	resp, err := c.hc.Do(req)
	if err != nil {
		return false, err
	}
	defer resp.Body.Close()
	var out struct {
		OK     bool `json:"ok"`
		Result struct {
			Status string `json:"status"`
		} `json:"result"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&out); err != nil {
		return false, err
	}
	st := out.Result.Status
	return out.OK && (st == "member" || st == "administrator" || st == "creator"), nil
}

// SendTelegram 打 Bot API sendMessage 给 chatID 发文案;失败只 log,不影响主流程。
func (s *Service) SendTelegram(ctx context.Context, chatID int64, text string) {
	u := "https://api.telegram.org/bot" + s.tg.botToken + "/sendMessage"
	body := url.Values{}
	body.Set("chat_id", strconv.FormatInt(chatID, 10))
	body.Set("text", text)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, u, strings.NewReader(body.Encode()))
	if err != nil {
		slog.Warn("reward: send telegram build request failed", "err", err)
		return
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	hc := &http.Client{Timeout: 8 * time.Second}
	resp, err := hc.Do(req)
	if err != nil {
		slog.Warn("reward: send telegram failed", "err", err)
		return
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 300 {
		slog.Warn("reward: send telegram non-2xx", "status", resp.StatusCode)
	}
}