package com.tourguide.modules.finance.service;

import com.tourguide.common.exception.BusinessException;
import com.tourguide.modules.user.mapper.GuideUserMapper;
import org.springframework.stereotype.Service;

import java.math.BigDecimal;
import java.math.RoundingMode;

/** 统一读取和原子变更导游可提现余额。 */
@Service
public class GuideWithdrawableBalanceService {
    private final GuideUserMapper guideUserMapper;

    public GuideWithdrawableBalanceService(GuideUserMapper guideUserMapper) {
        this.guideUserMapper = guideUserMapper;
    }

    public BigDecimal getAvailableAmount(Long guideId) {
        return money(guideUserMapper.selectBalance(guideId));
    }

    public boolean debit(Long guideId, BigDecimal amount) {
        BigDecimal value = money(amount);
        return value.signum() > 0 && guideUserMapper.decreaseBalance(guideId, value) == 1;
    }

    public void credit(Long guideId, BigDecimal amount) {
        BigDecimal value = money(amount);
        if (value.signum() == 0) return;
        if (value.signum() < 0 || guideUserMapper.increaseBalance(guideId, value) != 1) {
            throw new BusinessException(500, "导游余额更新失败");
        }
    }

    private BigDecimal money(BigDecimal value) {
        return (value == null ? BigDecimal.ZERO : value).setScale(2, RoundingMode.HALF_UP);
    }
}