<?php

namespace app\common\Service;

use app\common\model\lottery\LotteryActivity;
use app\common\model\lottery\LotteryPrize;
use app\common\model\lottery\LotteryCondition;
use app\common\model\lottery\LotteryDrawRecord;
use app\common\model\lottery\LotteryWinRecord;
use app\common\model\lottery\LotteryUserChance;
use think\Db;
use think\Exception;
use think\Cache;

/**
 * 抽奖服务类
 * 核心抽奖逻辑处理
 */
class LotteryService
{
    /**
     * 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 (!$activity || !$activity->isRunning()) {
            throw new Exception('活动不存在或未开始');
        }

        // 2. 验证抽奖时间
        if (!$activity->isInDrawTime()) {
            throw new Exception('不在抽奖时间内');
        }

        // 3. 验证用户资格
        if (!static::validateUserQualification($activity, $userId)) {
            throw new Exception('用户不符合参与条件');
        }

        // 4. 检查用户抽奖机会
        $userChance = LotteryUserChance::getUserChance($activityId, $userId);
        if (!$userChance || !$userChance->hasChance()) {
            throw new Exception('没有抽奖机会');
        }

        // 5. 检查用户参与次数限制
        if (!static::checkUserDrawLimit($activity, $userId)) {
            throw new Exception('已达到参与次数上限');
        }

        // 6. 防重复抽奖检查（基于订单）
        if ($triggerOrderId && static::hasDrawnForOrder($activityId, $userId, $triggerOrderId)) {
            throw new Exception('该订单已参与过抽奖');
        }

        // 7. 使用Redis锁防止并发
        $lockKey = "lottery_lock_{$activityId}_{$userId}";
        $lock = Cache::store('redis')->handler()->set($lockKey, 1, 'NX', 'EX', 10);
        if (!$lock) {
            throw new Exception('操作太频繁，请稍后再试');
        }

        try {
            // 8. 开始抽奖流程
            return static::processDrawLottery($activity, $userId, $triggerType, $triggerOrderId, $triggerAmount);
        } finally {
            // 释放锁
            Cache::store('redis')->handler()->del($lockKey);
        }
    }

    /**
     * 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 (!$selectedPrize->decreaseStock()) {
                throw new Exception('奖品库存不足');
            }

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

            // 5. 创建抽奖记录
            $isWin = $selectedPrize->type != LotteryPrize::TYPE_NO_PRIZE;
            $winInfo = $isWin ? static::buildWinInfo($selectedPrize) : [];
            
            $drawRecord = LotteryDrawRecord::createRecord(
                $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 = LotteryWinRecord::createWinRecord(
                    $drawRecord->id,
                    $activity->id,
                    $userId,
                    $selectedPrize->id,
                    $selectedPrize->name,
                    $selectedPrize->type,
                    static::buildPrizeValue($selectedPrize)
                );

                // 自动发放奖品
                if ($selectedPrize->deliver_type == LotteryPrize::DELIVER_AUTO) {
                    static::autoDeliverPrize($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;
        }
    }

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

        return $prizes;
    }

    /**
     * 执行抽奖算法（基于概率权重）
     */
    private static function executeLotteryAlgorithm($prizes)
    {
        // 计算总概率
        $totalProbability = $prizes->sum('probability');
        
        // 生成随机数
        $randomNumber = mt_rand(1, $totalProbability * 100) / 100;
        
        // 按概率选择奖品
        $currentProbability = 0;
        foreach ($prizes as $prize) {
            $currentProbability += $prize->probability;
            if ($randomNumber <= $currentProbability) {
                return $prize;
            }
        }
        
        // 保底返回第一个奖品（通常是未中奖）
        return $prizes->first();
    }

    /**
     * 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 LotteryActivity::USER_LIMIT_ALL:
                return true;
            case LotteryActivity::USER_LIMIT_LEVEL:
                return static::checkUserLevel($userId, $activity->user_limit_value);
            case LotteryActivity::USER_LIMIT_TAG:
                return static::checkUserTag($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;
        }
        
        $drawCount = LotteryDrawRecord::getUserDrawCount($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 LotteryDrawRecord::where('activity_id', $activityId)
                               ->where('user_id', $userId)
                               ->where('trigger_order_id', $orderId)
                               ->count() > 0;
    }

    /**
     * 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 LotteryPrize::TYPE_COUPON:
                $prizeValue['coupon_id'] = $prize->coupon_id;
                break;
            case LotteryPrize::TYPE_RED_PACKET:
                $prizeValue['amount'] = $prize->amount;
                break;
            case LotteryPrize::TYPE_GOODS:
                $prizeValue['goods_id'] = $prize->goods_id;
                $prizeValue['goods_sku_id'] = $prize->goods_sku_id;
                break;
            case LotteryPrize::TYPE_EXCHANGE_CODE:
                $prizeValue['exchange_code'] = $prize->getAvailableExchangeCode();
                break;
        }

        return $prizeValue;
    }

    /**
     * 自动发放奖品
     */
    private static function autoDeliverPrize($winRecord, $prize)
    {
        try {
            switch ($prize->type) {
                case LotteryPrize::TYPE_COUPON:
                    static::deliverCoupon($winRecord, $prize);
                    break;
                case LotteryPrize::TYPE_RED_PACKET:
                    static::deliverRedPacket($winRecord, $prize);
                    break;
                case LotteryPrize::TYPE_EXCHANGE_CODE:
                    static::deliverExchangeCode($winRecord, $prize);
                    break;
                case LotteryPrize::TYPE_GOODS:
                    static::deliverGoods($winRecord, $prize);
                    break;
            }
        } catch (Exception $e) {
            $winRecord->markAsFailed($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
        $winRecord->markAsDelivered(['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
        $winRecord->markAsDelivered(['amount' => $prize->amount]);
    }

    /**
     * 发放兑换码
     */
    private static function deliverExchangeCode($winRecord, $prize)
    {
        $code = $prize->getAvailableExchangeCode();
        if ($code) {
            $winRecord->setExchangeCode($code);
            $prize->markExchangeCodeUsed($code);
            $winRecord->markAsDelivered(['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
        $winRecord->markAsDelivered([
            '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;
            $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)
    {
        $userChance = LotteryUserChance::getUserChance($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
        ];
    }
}