<?php

namespace app\common\Service\Lottery;

use app\common\model\lottery\LotteryActivity;
use app\common\model\lottery\LotteryPrize;
use app\common\Enum\LotteryEnum;
use app\common\exception\BusinessException;
use app\common\Enum\ErrorCodeEnum;
use think\Db;
use think\Exception;
use think\Cache;

/**
 * 抽奖服务类
 * 核心抽奖逻辑处理
 */
class LotteryService
{
    // TODO: 分布式锁相关功能（暂时移除，后续实现）
    /**
     * 当前进程持有的锁信息
     * @var array
     */
    // private static $locks = [];
    /**
     * 执行抽奖
     * @param int $activityId 活动ID
     * @param int $userId 用户ID
     * @param int $triggerType 触发类型
     * @param int $triggerOrderId 触发订单ID
     * @param float $triggerAmount 触发金额
     * @return array 抽奖结果
     * @throws Exception
     */
    public static function drawLottery($activityId, $userId, $triggerType = 1, $triggerOrderId = null, $triggerAmount = null)
    {
        // 1. 验证活动有效性
        $activity = LotteryActivity::find($activityId);
        if (!$activity || !self::isActivityRunning($activity)) {
            throw new BusinessException('活动不存在或未开始', ErrorCodeEnum::LOTTERY_ACTIVITY_NOT_FOUND);
        }

        // 2. 验证开奖时间（仅对按时间开奖有效）
        if ($activity->lottery_type == LotteryEnum::LOTTERY_TYPE_TIME) {
            $now = time();
            if ($activity->lottery_time && $now >= $activity->lottery_time) {
                throw new BusinessException('开奖时间已过，无法参与', ErrorCodeEnum::LOTTERY_NOT_IN_TIME);
            }
        }

        // 3. 验证参与人数限制（仅对按人数开奖有效）
        if ($activity->lottery_type == LotteryEnum::LOTTERY_TYPE_PEOPLE) {
            $drawStats = LotteryRecordService::getActivityDrawStats($activityId);
            if ($drawStats['total_draw'] >= $activity->lottery_people_num) {
                throw new BusinessException('参与人数已满，无法参与', ErrorCodeEnum::LOTTERY_REACH_LIMIT);
            }
        }
        // 4. 验证用户资格
        if (!static::validateUserQualification($activity, $userId)) {
            throw new BusinessException('用户不符合参与条件', ErrorCodeEnum::LOTTERY_USER_NOT_QUALIFIED);
        }

        // 5. 检查用户抽奖机会
        $userChance = LotteryChanceService::getUserChance($activityId, $userId);
        if (!$userChance || !LotteryChanceService::hasChance($userChance)) {
            throw new BusinessException('没有抽奖机会', ErrorCodeEnum::LOTTERY_NO_CHANCE);
        }

        // 6. 检查用户参与次数限制
        if (!static::checkUserDrawLimit($activity, $userId)) {
            throw new BusinessException('已达到参与次数上限', ErrorCodeEnum::LOTTERY_REACH_LIMIT);
        }

        // 7. 防重复抽奖检查（基于订单）
        if ($triggerOrderId && static::hasDrawnForOrder($activityId, $userId, $triggerOrderId)) {
            throw new BusinessException('该订单已参与过抽奖', ErrorCodeEnum::LOTTERY_ORDER_ALREADY_DRAWN);
        }

        // TODO: 8. 使用分布式锁防止并发（暂时移除，后续实现）
        // $lockKey = "lottery_lock_{$activityId}_{$userId}";
        // $lockAcquired = static::acquireLock($lockKey, 10);
        // if (!$lockAcquired) {
        //     throw new Exception('操作太频繁，请稍后再试');
        // }

        // try {
            // 8. 根据开奖方式处理抽奖流程
            return static::handleLotteryByType($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount);
        // } finally {
        //     // 释放锁
        //     static::releaseLock($lockKey);
        // }
    }

    /**
     * 根据开奖方式处理抽奖
     */
    private static function handleLotteryByType($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount)
    {
        switch ($activity->lottery_type) {
            case LotteryEnum::LOTTERY_TYPE_INSTANT:
                // 即抽即中：直接执行抽奖
                return static::processDrawLottery($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount);
                
            case LotteryEnum::LOTTERY_TYPE_TIME:
                // 按时间开奖：记录参与，等待定时任务开奖
                return static::recordParticipation($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount);
                
            case LotteryEnum::LOTTERY_TYPE_PEOPLE:
                // 按人数开奖：记录参与，检查是否达到开奖人数
                return static::handlePeopleBasedLottery($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount);
                
            default:
                throw new BusinessException('不支持的开奖方式', ErrorCodeEnum::LOTTERY_ACTIVITY_NOT_FOUND);
        }
    }

    /**
     * 处理抽奖核心逻辑
     */
    private static function processDrawLottery($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount)
    {
        // 开启事务
        Db::startTrans();
        
        try {
            // 1. 获取可用奖品
            $prizes = static::getAvailablePrizes($activity);
        
            if (empty($prizes)) {
                throw new Exception('暂无可抽取的奖品');
            }

            // 2. 执行抽奖算法
            $selectedPrize = static::executeLotteryAlgorithm($prizes);

            // 3. 减少库存
            if (!static::decreasePrizeStock($selectedPrize)) {
                throw new Exception('奖品库存不足');
            }

            // 4. 消耗用户抽奖机会
            $userChance = LotteryChanceService::getUserChance($activity->id, $userId);
            if (!LotteryChanceService::useChance($userChance)) {
                throw new Exception('抽奖机会使用失败');
            }

            // 5. 创建抽奖记录
            $isWin = $selectedPrize->type != LotteryEnum::PRIZE_TYPE_NO_PRIZE;
        
            $winInfo = $isWin ? static::buildWinInfo($selectedPrize) : [];
            
            $drawRecord = LotteryRecordService::createDrawRecord(
                $activity->id,
                $userId,
                $selectedPrize->id,
                $isWin,
                $triggerType,
                $triggerOrderId,
                $triggerAmount,
                $winInfo
            );
          
            // 6. 如果中奖，创建中奖记录
            $winRecord = null;
            if ($isWin) {
                $winRecord = LotteryRecordService::createWinRecord(
                    $drawRecord->id,
                    $activity->id,
                    $userId,
                    $selectedPrize->id,
                    $selectedPrize->name,
                    $selectedPrize->type,
                    static::buildPrizeValue($selectedPrize)
                );

                // 自动发放奖品
                if ($selectedPrize->deliver_type == LotteryEnum::DELIVER_TYPE_AUTO) {
                    LotteryRecordService::autoDeliverPrize($winRecord, $selectedPrize);
                }
            }
        
            // 7. 更新活动统计
            static::updateActivityStats($activity, $isWin);

            // 提交事务
            Db::commit();

            // 8. 返回抽奖结果
            return static::buildDrawResult($drawRecord, $selectedPrize, $winRecord);

        } catch (Exception $e) {
            Db::rollback();
            throw $e;
        }
    }

    /**
     * 记录参与（用于按时间开奖和按人数开奖）
     */
    private static function recordParticipation($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount)
    {
        // 开启事务
        Db::startTrans();
        
        try {
            // 1. 消耗用户抽奖机会
            $userChance = LotteryChanceService::getUserChance($activity->id, $userId);
            if (!LotteryChanceService::useChance($userChance)) {
                throw new Exception('抽奖机会使用失败');
            }

            // 2. 创建参与记录（未开奖状态）
            $drawRecord = LotteryRecordService::createDrawRecord(
                $activity->id,
                $userId,
                0, // 暂时没有奖品ID
                0, // 未开奖
                $triggerType,
                $triggerOrderId,
                $triggerAmount,
                [] // 暂时没有中奖信息
            );

            // 提交事务
            Db::commit();

            // 3. 返回参与结果
            return [
                'draw_id' => $drawRecord->id,
                'is_win' => 0,
                'status' => 'waiting', // 等待开奖
                'lottery_type' => $activity->lottery_type,
                'lottery_time' => $activity->lottery_time ?? 0,
                'message' => $activity->lottery_type == LotteryEnum::LOTTERY_TYPE_TIME ? 
                           '参与成功，等待' . date('Y-m-d H:i:s', $activity->lottery_time) . '开奖' : 
                           '参与成功，等待开奖'
            ];

        } catch (Exception $e) {
            Db::rollback();
            throw $e;
        }
    }

    /**
     * 处理按人数开奖
     */
    private static function handlePeopleBasedLottery($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount)
    {
        // 先记录参与
        $result = static::recordParticipation($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount);
        
        // 检查是否达到开奖人数
        $drawStats = LotteryRecordService::getActivityDrawStats($activity->id);
        $participantCount = $drawStats['total_draw'];
        
        if ($participantCount >= $activity->lottery_people_num) {
            // 达到人数，触发开奖（这里可以异步处理）
            // TODO: 触发按人数开奖的处理逻辑
            $result['message'] = '参与成功，已达到开奖人数，正在开奖中...';
        } else {
            $remainingCount = $activity->lottery_people_num - $participantCount;
            $result['message'] = "参与成功，还需要{$remainingCount}人参与即可开奖";
        }
        
        return $result;
    }

    /**
     * 获取可用奖品列表
     */
    private static function getAvailablePrizes($activity)
    {
        $prizes = static::getValidPrizes($activity->id);
        // 如果开启按人数解锁功能
        if ($activity->unlock_by_people) {
            $currentPeopleCount = LotteryChanceService::getActivityParticipants($activity->id);
            $prizes = $prizes->filter(function($prize) use ($currentPeopleCount) {
                return static::isPrizeUnlocked($prize, $currentPeopleCount);
            });
        }

        return $prizes;
    }

    /**
     * 执行抽奖算法（基于概率权重）
     */
    private static function executeLotteryAlgorithm($prizes)
    {
        // 检查是否有奖品
        if (empty($prizes)) {
            return null;
        }
        
        // 将奖品转换为数组（如果是集合对象）
        $prizeArray = is_array($prizes) ? $prizes : $prizes->toArray();
        
        // 使用BC函数计算总概率
        $totalProbability = '0';
        foreach ($prizeArray as $prize) {
            $totalProbability = bcadd($totalProbability, $prize['probability'] ?? '0', 4);
        }
        
        // 如果总概率为0，返回未中奖奖品
        if (bccomp($totalProbability, '0', 4) == 0) {
            return static::findNoPrizePrize($prizeArray);
        }
        
        // 生成随机数（0-总概率之间）
        $randomNumber = bcdiv(mt_rand(0, bcmul($totalProbability, '10000', 4)), '10000', 4);
        
        // 按概率选择奖品
        $currentProbability = '0';
        foreach ($prizeArray as $prize) {
            $currentProbability = bcadd($currentProbability, $prize['probability'] ?? '0', 4);
            if (bccomp($randomNumber, $currentProbability, 4) <= 0) {
                return $prize;
            }
        }
        
        // 保底返回未中奖类型的奖品
        return static::findNoPrizePrize($prizeArray);
    }

    /**
     * 查找未中奖类型的奖品
     */
    private static function findNoPrizePrize($prizeArray)
    {
        // 优先查找未中奖类型的奖品
        foreach ($prizeArray as $prize) {
            if (($prize['type'] ?? 0) == LotteryEnum::PRIZE_TYPE_NO_PRIZE) {
                return $prize;
            }
        }
        
        // 如果没找到未中奖类型，返回第一个奖品作为兜底
        return isset($prizeArray[0]) ? $prizeArray[0] : null;
    }

    /**
     * 验证用户资格
     */
    private static function validateUserQualification($activity, $userId)
    {
        // 检查用户群体限制
        switch ($activity->user_limit_type) {
            case LotteryEnum::USER_LIMIT_ALL:
                return true;
            case LotteryEnum::USER_LIMIT_LEVEL:
                return static::checkUserLevel($userId, $activity->user_limit_value);
            case LotteryEnum::USER_LIMIT_TAG:
                return static::checkUserTag($userId, $activity->user_limit_value);
            default:
                return false;
        }
    }

    /**
     * 检查用户等级
     */
    private static function checkUserLevel($userId, $limitValue)
    {
        if (empty($limitValue)) {
            return true;
        }
        
        $user = \app\common\model\User::find($userId);
        return $user && in_array($user->level, (array)$limitValue);
    }

    /**
     * 检查用户标签
     */
    private static function checkUserTag($userId, $limitValue)
    {
        if (empty($limitValue)) {
            return true;
        }
        
        // 这里需要根据实际的用户标签系统实现
        // 暂时返回true
        return true;
    }

    /**
     * 检查用户抽奖次数限制
     */
    private static function checkUserDrawLimit($activity, $userId)
    {
        if (!$activity->person_limit_num) {
            return true;
        }
        
        $drawCount = LotteryRecordService::getUserDrawCount($activity->id, $userId);
        return $drawCount < $activity->person_limit_num;
    }

    /**
     * 检查订单是否已抽奖
     */
    private static function hasDrawnForOrder($activityId, $userId, $orderId)
    {
        return LotteryRecordService::hasUserDrawnForOrder($activityId, $userId, $orderId);
    }

    /**
     * 构建中奖信息
     */
    private static function buildWinInfo($prize)
    {
        return [
            'prize_id' => $prize->id,
            'prize_name' => $prize->name,
            'prize_type' => $prize->type,
            'prize_image' => $prize->image,
            'win_prompt' => $prize->win_prompt
        ];
    }

    /**
     * 构建奖品价值信息
     */
    private static function buildPrizeValue($prize)
    {
        $prizeValue = [
            'type' => $prize->type,
            'name' => $prize->name,
            'image' => $prize->image
        ];

        switch ($prize->type) {
            case LotteryEnum::PRIZE_TYPE_COUPON:
                $prizeValue['coupon_id'] = $prize->coupon_id;
                break;
            case LotteryEnum::PRIZE_TYPE_REDPACK:
                $prizeValue['amount'] = $prize->amount;
                break;
            case LotteryEnum::PRIZE_TYPE_SHOP_GOODS:
                $prizeValue['goods_id'] = $prize->goods_id;
                $prizeValue['goods_sku_id'] = $prize->goods_sku_id;
                break;
            case LotteryEnum::PRIZE_TYPE_CODE:
                $prizeValue['exchange_code'] = static::getAvailableExchangeCode($prize);
                break;
        }

        return $prizeValue;
    }

    /**
     * 自动发放奖品
     */
    private static function autoDeliverPrize($winRecord, $prize)
    {
        try {
            switch ($prize->type) {
                case LotteryEnum::PRIZE_TYPE_COUPON:
                    static::deliverCoupon($winRecord, $prize);
                    break;
                case LotteryEnum::PRIZE_TYPE_REDPACK:
                    static::deliverRedPacket($winRecord, $prize);
                    break;
                case LotteryEnum::PRIZE_TYPE_CODE:
                    static::deliverExchangeCode($winRecord, $prize);
                    break;
                case LotteryEnum::PRIZE_TYPE_SHOP_GOODS:
                    static::deliverGoods($winRecord, $prize);
                    break;
            }
        } catch (Exception $e) {
            LotteryRecordService::markWinRecordAsFailed($winRecord, $e->getMessage());
        }
    }

    /**
     * 发放优惠券
     */
    private static function deliverCoupon($winRecord, $prize)
    {
        // 这里调用优惠券发放接口
        // 示例代码，需要根据实际优惠券系统实现
        LotteryRecordService::markWinRecordAsDelivered($winRecord, ['coupon_id' => $prize->coupon_id]);
    }

    /**
     * 发放红包
     */
    private static function deliverRedPacket($winRecord, $prize)
    {
        // 这里调用红包发放接口
        // 示例代码，需要根据实际红包系统实现
        LotteryRecordService::markWinRecordAsDelivered($winRecord, ['amount' => $prize->amount]);
    }

    /**
     * 发放兑换码
     */
    private static function deliverExchangeCode($winRecord, $prize)
    {
        $code = static::getAvailableExchangeCode($prize);
        if ($code) {
            LotteryRecordService::setWinRecordExchangeCode($winRecord, $code);
            static::markExchangeCodeUsed($prize, $code);
            LotteryRecordService::markWinRecordAsDelivered($winRecord, ['exchange_code' => $code]);
        } else {
            throw new Exception('兑换码已用完');
        }
    }

    /**
     * 发放商城商品
     */
    private static function deliverGoods($winRecord, $prize)
    {
        // 这里可以自动加入购物车或创建订单
        // 示例代码，需要根据实际商城系统实现
        LotteryRecordService::markWinRecordAsDelivered($winRecord, [
            'goods_id' => $prize->goods_id,
            'goods_sku_id' => $prize->goods_sku_id
        ]);
    }

    /**
     * 更新活动统计
     */
    private static function updateActivityStats($activity, $isWin)
    {
        $activity->total_draw_count += 1;
        if ($isWin) {
            $activity->total_win_count += 1;
        }
        $activity->save();
    }

    /**
     * 构建抽奖结果
     */
    private static function buildDrawResult($drawRecord, $prize, $winRecord = null)
    {
        $result = [
            'draw_id' => $drawRecord->id,
            'is_win' => $drawRecord->is_win,
            'prize' => [
                'id' => $prize->id,
                'name' => $prize->name,
                'type' => $prize->type,
                'type_text' => $prize->type_text,
                'image' => $prize->image,
                'win_prompt' => $prize->win_prompt
            ],
            'draw_time' => $drawRecord->draw_time
        ];

        if ($winRecord) {
            $result['win_record_id'] = $winRecord->id;
            $result['deliver_status'] = $winRecord->deliver_status;
            
            // 只有兑换码类型的奖品才记录兑换码信息
            if ($prize->type == LotteryEnum::PRIZE_TYPE_CODE) {
                $result['exchange_code'] = $winRecord->exchange_code;
            }
        }

        return $result;
    }

    /**
     * 获取用户抽奖机会
     * @param int $activityId 活动ID
     * @param int $userId 用户ID
     * @return array
     */
    public static function getUserChances($activityId, $userId)
    {
        $userChance = LotteryChanceService::getUserChance($activityId, $userId);
        
        if (!$userChance) {
            return [
                'total_chances' => 0,
                'used_chances' => 0,
                'remain_chances' => 0
            ];
        }

        return [
            'total_chances' => $userChance->total_chances,
            'used_chances' => $userChance->used_chances,
            'remain_chances' => $userChance->remain_chances,
            'last_get_time' => $userChance->last_get_time,
            'last_use_time' => $userChance->last_use_time
        ];
    }

    // ============ 从LotteryPrize模型移过来的业务逻辑方法 ============

    /**
     * 检查奖品库存是否充足
     */
    public static function hasPrizeStock(LotteryPrize $prize, $quantity = 1)
    {
        return $prize->remain_stock >= $quantity;
    }

    /**
     * 减少奖品库存
     */
    public static function decreasePrizeStock(LotteryPrize $prize, $quantity = 1)
    {
        if (!static::hasPrizeStock($prize, $quantity)) {
            return false;
        }
        
        $prize->remain_stock -= $quantity;
        $prize->win_count += $quantity;
        return $prize->save();
    }

    /**
     * 获取可用的兑换码
     */
    public static function getAvailableExchangeCode(LotteryPrize $prize)
    {
        if ($prize->type != LotteryEnum::PRIZE_TYPE_CODE) {
            return null;
        }
        
        $allCodes = $prize->exchange_codes_list;
        $usedCodes = $prize->used_codes_list;
        
        $availableCodes = array_diff($allCodes, $usedCodes);
        
        if (empty($availableCodes)) {
            return null;
        }
        
        return array_shift($availableCodes);
    }

    /**
     * 标记兑换码为已使用
     */
    public static function markExchangeCodeUsed(LotteryPrize $prize, $code)
    {
        $usedCodes = $prize->used_codes_list;
        if (!in_array($code, $usedCodes)) {
            $usedCodes[] = $code;
            $prize->used_codes = json_encode($usedCodes);
            return $prize->save();
        }
        return true;
    }

    /**
     * 获取有效奖品（库存大于0且状态正常）
     */
    public static function getValidPrizes($activityId)
    {
        return LotteryPrize::where('activity_id', $activityId)
                           ->where('status', 1)
                           ->where('remain_stock', '>', 0)
                           ->order('sort_order', 'asc')
                           ->select();
    }

    /**
     * 检查奖品是否已解锁（按人数解锁功能）
     */
    public static function isPrizeUnlocked(LotteryPrize $prize, $currentPeopleCount)
    {
        if (empty($prize->unlock_people_num)) {
            return true;
        }
        
        return $currentPeopleCount >= $prize->unlock_people_num;
    }

    /**
     * 检查活动是否正在进行
     */
    public static function isActivityRunning(LotteryActivity $activity)
    {
        $now = time();
        return $activity->status == LotteryEnum::STATUS_ONGOING 
               && $activity->start_time <= $now 
               && $activity->end_time >= $now;
    }

    /**
     * 检查活动是否已结束
     */
    public static function isActivityEnded(LotteryActivity $activity)
    {
        $now = time();
        return $activity->status == LotteryEnum::STATUS_ENDED 
               || $activity->end_time < $now;
    }

    /**
     * 检查活动是否未开始
     */
    public static function isActivityNotStarted(LotteryActivity $activity)
    {
        $now = time();
        return $activity->status == LotteryEnum::STATUS_NOT_STARTED 
               && $activity->start_time > $now;
    }

    /**
     * 检查活动是否已暂停
     */
    public static function isActivitySuspended(LotteryActivity $activity)
    {
        return $activity->status == LotteryEnum::STATUS_SUSPENDED;
    }

    /**
     * 检查活动是否已取消
     */
    public static function isActivityCancelled(LotteryActivity $activity)
    {
        return $activity->status == LotteryEnum::STATUS_CANCELLED;
    }
    // TODO: 分布式锁相关方法（暂时移除，后续实现）
    /*
    private static function acquireLock($lockKey, $expireTime = 10)
    {
        // Redis锁获取逻辑
    }

    private static function releaseLock($lockKey)
    {
        // Redis锁释放逻辑
    }

    private static function acquireFileLock($lockKey, $expireTime = 10)
    {
        // 文件锁获取逻辑
    }

    private static function releaseFileLock($lockKey)
    {
        // 文件锁释放逻辑
    }
    */

    /**
     * 获取正在进行的活动
     */
    public static function getRunningActivities()
    {
        $now = time();
        return LotteryActivity::where('status', LotteryEnum::STATUS_ONGOING)
                             ->where('start_time', '<=', $now)
                             ->where('end_time', '>=', $now)
                             ->select();
    }

    /**
     * 获取未开始的活动
     */
    public static function getNotStartedActivities()
    {
        $now = time();
        return LotteryActivity::where('status', LotteryEnum::STATUS_NOT_STARTED)
                             ->where('start_time', '>', $now)
                             ->select();
    }

    /**
     * 获取已结束的活动
     */
    public static function getEndedActivities()
    {
        $now = time();
        return LotteryActivity::where('status', LotteryEnum::STATUS_ENDED)
                             ->orWhere('end_time', '<', $now)
                             ->select();
    }

    /**
     * 获取可显示的活动（排除逻辑状态）
     */
    public static function getDisplayableActivities()
    {
        $displayableStatuses = array_keys(LotteryEnum::getActivityStatusMap());
        return LotteryActivity::whereIn('status', $displayableStatuses)->select();
    }

    /**
     * 验证活动状态是否有效
     */
    public static function isValidActivityStatus(LotteryActivity $activity)
    {
        return LotteryEnum::isValidActivityStatus($activity->status);
    }

    /**
     * 验证开奖方式是否有效
     */
    public static function isValidLotteryType(LotteryActivity $activity)
    {
        return LotteryEnum::isValidLotteryType($activity->lottery_type);
    }


}