<?php
namespace App\Services;

use Db\Database;

class TransactionService {
    private $db;

    public function __construct(Database $db) {
        $this->db = $db;
    }

    /**
     * 用户间转账
     *
     * @param int    $fromUserId  转出用户ID
     * @param string $toUsername   收款用户名
     * @param float  $amount       转账金额
     * @return array ['success' => bool, 'message' => string]
     */
    public function transfer(int $fromUserId, string $toUsername, float $amount): array
    {
        $toUsername = trim($toUsername);

        if ($toUsername === '') {
            return ['success' => false, 'message' => '请输入对方用户名'];
        }
        if ($amount <= 0) {
            return ['success' => false, 'message' => '金额无效'];
        }

        $fromUser = $this->db->get('users', '*', ['id' => $fromUserId]);
        if (!$fromUser) {
            return ['success' => false, 'message' => '用户不存在'];
        }
        if ($fromUser['balance'] < $amount) {
            return ['success' => false, 'message' => '余额不足'];
        }

        // 查找收款用户
        $toUser = $this->db->get('users', '*', ['username' => $toUsername]);
        if (!$toUser) {
            return ['success' => false, 'message' => '收款用户不存在'];
        }
        if ($toUser['id'] === $fromUser['id']) {
            return ['success' => false, 'message' => '不能转给自己'];
        }

        $this->db->medoo->pdo->beginTransaction();
        try {
            $now = date('Y-m-d H:i:s');
            $fromBalanceBefore = floatval($fromUser['balance']);
            $toBalanceBefore = floatval($toUser['balance']);
            $fromBalanceAfter = $fromBalanceBefore - $amount;
            $toBalanceAfter = $toBalanceBefore + $amount;

            // 扣款
            $this->db->update('users', ['balance' => $fromBalanceAfter, 'updated_at' => $now], ['id' => $fromUser['id']]);
            // 加款
            $this->db->update('users', ['balance' => $toBalanceAfter, 'updated_at' => $now], ['id' => $toUser['id']]);

            // 转出流水
            $this->db->insert('transactions', [
                'user_id' => $fromUser['id'],
                'type' => 'transfer_out',
                'amount' => -$amount,
                'balance_before' => $fromBalanceBefore,
                'balance_after' => $fromBalanceAfter,
                'description' => '转账给 ' . $toUser['username'],
                'created_at' => $now,
            ]);
            // 转入流水
            $this->db->insert('transactions', [
                'user_id' => $toUser['id'],
                'type' => 'transfer_in',
                'amount' => $amount,
                'balance_before' => $toBalanceBefore,
                'balance_after' => $toBalanceAfter,
                'description' => '收到 ' . $fromUser['username'] . ' 的转账',
                'created_at' => $now,
            ]);

            $this->db->medoo->pdo->commit();
            return ['success' => true, 'message' => '转账成功'];
        } catch (\Exception $e) {
            $this->db->medoo->pdo->rollBack();
            return ['success' => false, 'message' => '系统错误'];
        }
    }

    /**
     * 充提申请
     *
     * @param int    $userId  用户ID
     * @param string $type    类型: deposit|withdraw
     * @param float  $amount  金额
     * @param string $remark  备注
     * @return array ['success' => bool, 'message' => string]
     */
    public function fundRequest(int $userId, string $type, float $amount, string $remark = ''): array
    {
        if (!in_array($type, ['deposit', 'withdraw'])) {
            return ['success' => false, 'message' => '无效类型'];
        }
        if ($amount <= 0) {
            return ['success' => false, 'message' => '金额无效'];
        }

        $user = $this->db->get('users', '*', ['id' => $userId]);
        if (!$user) {
            return ['success' => false, 'message' => '用户不存在'];
        }

        if ($type === 'withdraw') {
            if ($user['balance'] < $amount) {
                return ['success' => false, 'message' => '余额不足'];
            }
            $this->db->medoo->pdo->beginTransaction();
            try {
                $this->db->update('users', ['balance[-]' => $amount], ['id' => $user['id']]);
                $this->db->insert('fund_requests', [
                    'user_id' => $user['id'],
                    'type' => 'withdraw',
                    'amount' => $amount,
                    'status' => 'pending',
                    'remark' => $remark,
                ]);
                $this->db->medoo->pdo->commit();
                return ['success' => true, 'message' => '提现申请已提交'];
            } catch (\Exception $e) {
                $this->db->medoo->pdo->rollBack();
                return ['success' => false, 'message' => '系统错误'];
            }
        }

        // deposit - 记录申请
        $this->db->insert('fund_requests', [
            'user_id' => $user['id'],
            'type' => 'deposit',
            'amount' => $amount,
            'status' => 'pending',
            'remark' => $remark,
        ]);
        return ['success' => true, 'message' => '充值申请已提交'];
    }
}