<?php

namespace app\api\controller;

use think\Db;

/**
 * 用户端 · 优惠券（Module-COUPON）
 * 路由：
 *   GET  /api/v1/coupon/list     可领取优惠券分页列表（带 received 已领取标记）
 *   POST /api/v1/coupon/receive  领取优惠券
 *
 * 数据表：fa_fc_coupon（券模板）/ fa_fc_user_coupon（领取记录）。
 * 说明：本轮仅做「领取 + 我的资产展示」，**不含下单抵扣**（下单抵扣在后续版本接入）。
 */
class Coupon extends V1
{
    /**
     * 优惠券功能总开关（后台「系统设置」写入 fc_config 的 coupon.enabled，默认开启）
     * 关闭后用户端列表/领取一律拒绝，避免「后台关了前端还能领」。
     */
    protected function assertEnabled()
    {
        if (!(int)$this->cfg('coupon.enabled', 1)) {
            $this->fail('优惠券功能暂未开放');
        }
    }

    /**
     * GET /api/v1/coupon/list  {page,size}
     *   →  分页 {list,page,size,total,hasMore}
     * 列表项：{id,couponId,name,type,amount,minAmount,total,receivedCount,left,days,received,createdAt}
     * 规则：仅 enabled=1（停用券不下发）；received 表示「当前用户是否已领取」；
     *      left = 剩余可领数量（-1 表示不限量）；total=0 表示不限量。
     */
    public function list()
    {
        $this->assertEnabled();
        $user = $this->auth();

        list($rows, $total, $page, $size) = $this->pageQuery(function ($forCount) {
            $q = Db::name('fc_coupon')->where('enabled', 1);
            if ($forCount) {
                return $q;
            }
            return $q->order('sort desc, id desc');
        });

        $list = [];
        foreach ($rows as $row) {
            $received = (bool)Db::name('fc_user_coupon')
                ->where('user_id', $user['id'])
                ->where('coupon_id', $row['id'])
                ->find();
            $list[] = $this->couponItem($row, $received);
        }

        $this->ok($this->paginate($list, $total, $page, $size));
    }

    /**
     * POST /api/v1/coupon/receive  {couponId}
     *   →  {userCouponId}
     * 规则：券必须存在且 enabled=1；领完 → fail('优惠券已领完')；
     *      同一用户同一张券只能领一次 → fail('您已领取过该优惠券')；
     *      days>0 时按「领取时间 + days 天」写过期时间，days=0 表示永久有效。
     */
    public function receive()
    {
        $this->assertEnabled();
        $user = $this->auth();
        $couponId = (int)$this->input('couponId', 0);

        $coupon = $couponId > 0 ? Db::name('fc_coupon')->where('id', $couponId)->find() : null;
        if (!$coupon || (int)$coupon['enabled'] !== 1) {
            $this->fail('优惠券不存在');
        }

        $total = (int)$coupon['total'];
        $receivedCount = (int)$coupon['received'];
        if ($total > 0 && $receivedCount >= $total) {
            $this->fail('优惠券已领完');
        }

        $exist = Db::name('fc_user_coupon')
            ->where('user_id', $user['id'])
            ->where('coupon_id', $couponId)
            ->find();
        if ($exist) {
            $this->fail('您已领取过该优惠券');
        }

        $now = time();
        $days = max(0, (int)$coupon['days']);

        try {
            $userCouponId = Db::name('fc_user_coupon')->insertGetId([
                'user_id'    => $user['id'],
                'coupon_id'  => $couponId,
                'status'     => 'unused',
                'order_no'   => '',
                'usetime'    => null,
                'expiretime' => $days > 0 ? $now + $days * 86400 : null,
                'createtime' => $now,
            ]);
        } catch (\Exception $e) {
            // 并发重复领取兜底
            $this->fail('您已领取过该优惠券');
        }

        // 已领取数 +1（setInc 自增，避免并发覆盖）
        Db::name('fc_coupon')->where('id', $couponId)->setInc('received', 1);

        $this->ok(['userCouponId' => $userCouponId]);
    }

    /**
     * GET /api/v1/coupon/usable?amount=xx
     * 下单可用券列表（按金额计算可抵扣金额）
     */
    public function usable()
    {
        $this->assertEnabled();
        $user = $this->auth();

        $amount = round((float)$this->input('amount', 0), 2);
        if ($amount <= 0) {
            $this->ok([]);
        }

        $now = time();
        $rows = Db::name('fc_user_coupon')->alias('uc')
            ->join('fc_coupon c', 'c.id = uc.coupon_id')
            ->where('uc.user_id', $user['id'])
            ->where('uc.status', 'unused')
            ->where('c.enabled', 1)
            ->where('c.min_amount', '<=', $amount)
            ->where(function ($q) use ($now) {
                $q->whereNull('uc.expiretime')->whereOr('uc.expiretime', '>', $now);
            })
            ->field('uc.id,uc.coupon_id,uc.expiretime,c.name,c.type,c.amount,c.min_amount')
            ->order('c.sort desc, c.id desc')
            ->select();

        $list = [];
        foreach ($rows as $row) {
            try {
                $p = \app\common\library\CouponService::preview($user['id'], (int)$row['id'], $amount);
            } catch (\Throwable $e) {
                continue;
            }
            $list[] = [
                'userCouponId' => (int)$row['id'],
                'couponId'     => (int)$row['coupon_id'],
                'name'         => (string)$row['name'],
                'type'         => (string)$row['type'],
                'amount'       => (float)$row['amount'],
                'minAmount'    => (float)$row['min_amount'],
                'discount'     => $p['discount'],
                'payable'      => $p['payable'],
                'expireAt'     => !empty($row['expiretime']) ? $this->iso($row['expiretime']) : null,
            ];
        }

        $this->ok($list);
    }

    /**
     * 券模板 → 列表项
     * @param array $row      fc_coupon 行
     * @param bool  $received 当前用户是否已领取
     * @return array
     */
    protected function couponItem($row, $received)
    {
        $total = (int)$row['total'];
        $receivedCount = (int)$row['received'];

        return [
            'id'            => (int)$row['id'],
            'couponId'      => (int)$row['id'],
            'name'          => (string)$row['name'],
            'type'          => (string)$row['type'],
            'amount'        => (float)$row['amount'],
            'minAmount'     => (float)$row['min_amount'],
            'total'         => $total,
            'receivedCount' => $receivedCount,
            // -1 表示不限量（total=0）
            'left'          => $total > 0 ? max(0, $total - $receivedCount) : -1,
            'days'          => (int)$row['days'],
            'received'      => (bool)$received,
            'createdAt'     => $this->iso($row['createtime']),
        ];
    }
}