package cn.iocoder.yudao.module.finance.service.ledger;

import cn.iocoder.yudao.module.finance.controller.admin.ledger.vo.FinLedgerReqVO;
import cn.iocoder.yudao.module.finance.controller.admin.ledger.vo.FinLedgerRespVO;
import cn.iocoder.yudao.module.finance.dal.dataobject.ledger.FinLedgerEntryDO;
import cn.iocoder.yudao.module.finance.dal.dataobject.subject.FinAccountSubjectDO;
import cn.iocoder.yudao.module.finance.dal.mysql.ledger.FinLedgerMapper;
import cn.iocoder.yudao.module.finance.enums.FinBalanceDirectionEnum;
import cn.iocoder.yudao.module.finance.enums.FinLedgerRowTypeEnum;
import cn.iocoder.yudao.module.finance.enums.FinVoucherStatusEnum;
import cn.iocoder.yudao.module.finance.service.subject.FinAccountSubjectService;
import jakarta.annotation.Resource;
import org.springframework.stereotype.Service;
import org.springframework.validation.annotation.Validated;

import java.math.BigDecimal;
import java.time.LocalDate;
import java.time.YearMonth;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;

import static cn.iocoder.yudao.framework.common.exception.util.ServiceExceptionUtil.exception;
import static cn.iocoder.yudao.module.finance.enums.ErrorCodeConstants.LEDGER_MONTH_RANGE_INVALID;
import static cn.iocoder.yudao.module.finance.enums.ErrorCodeConstants.LEDGER_SUBJECT_NOT_EXISTS;

/**
 * 总账 / 明细账 Service 实现类
 *
 * 口径说明：
 * 1. 只统计已过账（posted）的凭证，未过账、已作废的凭证不计入账簿；
 * 2. 余额一律「借方正、贷方负」，期初余额 = 起始月份之前所有已过账分录的借贷净额；
 * 3. 科目的下级科目由 parentId 递归收集（不使用科目编码前缀匹配，避免把形近编码误算进来）。
 *
 * @author 超级管理员
 */
@Service
@Validated
public class FinLedgerServiceImpl implements FinLedgerService {

    @Resource
    private FinLedgerMapper ledgerMapper;
    @Resource
    private FinAccountSubjectService accountSubjectService;

    @Override
    public List<FinLedgerRespVO> getGeneralLedgerList(FinLedgerReqVO reqVO) {
        // 1. 校验科目与期间
        FinAccountSubjectDO subject = validateSubject(reqVO);
        LocalDate startDate = reqVO.getStartMonth().atDay(1);
        LocalDate endDate = reqVO.getEndMonth().atEndOfMonth();
        validateMonthRange(startDate, endDate);
        Set<String> subjectCodes = buildSubjectCodeSet(subject, reqVO.getIncludeChildren());

        // 2. 期初余额
        List<FinLedgerRespVO> rows = new ArrayList<>();
        BigDecimal balance = defaultIfNull(ledgerMapper.selectBalanceBeforeDate(subjectCodes, startDate,
                FinVoucherStatusEnum.POSTED.getStatus()));
        rows.add(buildOpeningRow(subject, startDate, balance));

        // 3. 按月汇总
        List<FinLedgerEntryDO> entries = ledgerMapper.selectEntryList(subjectCodes, startDate, endDate,
                FinVoucherStatusEnum.POSTED.getStatus());
        Map<String, List<FinLedgerEntryDO>> monthMap = entries.stream()
                .collect(Collectors.groupingBy(entry -> YearMonth.from(entry.getVoucherDate()).toString()));
        BigDecimal totalDebit = BigDecimal.ZERO;
        BigDecimal totalCredit = BigDecimal.ZERO;
        YearMonth endMonth = YearMonth.from(endDate);
        for (YearMonth month = YearMonth.from(startDate); !month.isAfter(endMonth); month = month.plusMonths(1)) {
            List<FinLedgerEntryDO> monthEntries = monthMap.getOrDefault(month.toString(), List.of());
            BigDecimal debit = sum(monthEntries, true);
            BigDecimal credit = sum(monthEntries, false);
            balance = balance.add(debit).subtract(credit);
            totalDebit = totalDebit.add(debit);
            totalCredit = totalCredit.add(credit);
            LocalDate monthEndDate = minDate(month.atEndOfMonth(), endDate);
            rows.add(buildRow(FinLedgerRowTypeEnum.MONTHLY_TOTAL, month.toString(), monthEndDate, subject, null,
                    FinLedgerRowTypeEnum.MONTHLY_TOTAL.getName(), debit, credit, balance));
        }

        // 4. 本期累计
        rows.add(buildRow(FinLedgerRowTypeEnum.YEARLY_TOTAL, null, endDate, subject, null,
                FinLedgerRowTypeEnum.YEARLY_TOTAL.getName(), totalDebit, totalCredit, balance));
        return rows;
    }

    @Override
    public List<FinLedgerRespVO> getDetailLedgerList(FinLedgerReqVO reqVO) {
        // 1. 校验科目与期间
        FinAccountSubjectDO subject = validateSubject(reqVO);
        LocalDate startDate = reqVO.getStartMonth().atDay(1);
        LocalDate endDate = reqVO.getEndMonth().atEndOfMonth();
        validateMonthRange(startDate, endDate);
        Set<String> subjectCodes = buildSubjectCodeSet(subject, reqVO.getIncludeChildren());

        // 2. 期初余额
        List<FinLedgerRespVO> rows = new ArrayList<>();
        BigDecimal balance = defaultIfNull(ledgerMapper.selectBalanceBeforeDate(subjectCodes, startDate,
                FinVoucherStatusEnum.POSTED.getStatus()));
        rows.add(buildOpeningRow(subject, startDate, balance));

        // 3. 逐条明细，并对每条分录结转余额；每逢月末补一行「本月合计」
        List<FinLedgerEntryDO> entries = ledgerMapper.selectEntryList(subjectCodes, startDate, endDate,
                FinVoucherStatusEnum.POSTED.getStatus());
        BigDecimal totalDebit = BigDecimal.ZERO;
        BigDecimal totalCredit = BigDecimal.ZERO;
        BigDecimal monthDebit = BigDecimal.ZERO;
        BigDecimal monthCredit = BigDecimal.ZERO;
        YearMonth currentMonth = null;
        for (FinLedgerEntryDO entry : entries) {
            YearMonth month = YearMonth.from(entry.getVoucherDate());
            // 3.1 跨月：先补上个月的本月合计
            if (currentMonth != null && !currentMonth.equals(month)) {
                rows.add(buildRow(FinLedgerRowTypeEnum.MONTHLY_TOTAL, currentMonth.toString(),
                        currentMonth.atEndOfMonth(), subject, null, FinLedgerRowTypeEnum.MONTHLY_TOTAL.getName(),
                        monthDebit, monthCredit, balance));
                monthDebit = BigDecimal.ZERO;
                monthCredit = BigDecimal.ZERO;
            }
            currentMonth = month;
            // 3.2 明细行
            BigDecimal debit = defaultIfNull(entry.getDebit());
            BigDecimal credit = defaultIfNull(entry.getCredit());
            balance = balance.add(debit).subtract(credit);
            monthDebit = monthDebit.add(debit);
            monthCredit = monthCredit.add(credit);
            totalDebit = totalDebit.add(debit);
            totalCredit = totalCredit.add(credit);
            rows.add(buildRow(FinLedgerRowTypeEnum.ENTRY, month.toString(), entry.getVoucherDate(), subject,
                    entry.getVoucherNo(), entry.getSummary(), debit, credit, balance)
                    .setSubjectCode(entry.getSubjectCode()).setSubjectName(entry.getSubjectName()));
        }

        // 4. 最后一个月的本月合计
        if (currentMonth != null) {
            rows.add(buildRow(FinLedgerRowTypeEnum.MONTHLY_TOTAL, currentMonth.toString(),
                    minDate(currentMonth.atEndOfMonth(), endDate), subject, null,
                    FinLedgerRowTypeEnum.MONTHLY_TOTAL.getName(), monthDebit, monthCredit, balance));
        }
        // 5. 本期累计
        rows.add(buildRow(FinLedgerRowTypeEnum.YEARLY_TOTAL, null, endDate, subject, null,
                FinLedgerRowTypeEnum.YEARLY_TOTAL.getName(), totalDebit, totalCredit, balance));
        return rows;
    }

    private FinAccountSubjectDO validateSubject(FinLedgerReqVO reqVO) {
        FinAccountSubjectDO subject = accountSubjectService.getAccountSubjectByCode(reqVO.getSubjectCode());
        if (subject == null) {
            throw exception(LEDGER_SUBJECT_NOT_EXISTS, reqVO.getSubjectCode());
        }
        return subject;
    }

    private void validateMonthRange(LocalDate startDate, LocalDate endDate) {
        if (startDate.isAfter(endDate)) {
            throw exception(LEDGER_MONTH_RANGE_INVALID, YearMonth.from(startDate), YearMonth.from(endDate));
        }
    }

    /**
     * 收集查询用的科目编码集合：默认包含所有下级科目
     */
    private Set<String> buildSubjectCodeSet(FinAccountSubjectDO subject, Boolean includeChildren) {
        Set<String> subjectCodes = new HashSet<>();
        subjectCodes.add(subject.getSubjectCode());
        if (!Boolean.TRUE.equals(includeChildren)) {
            return subjectCodes;
        }
        // 用 parentId 递归收集下级，visited 由 subjectCodes 的 add 结果兼作防护，避免脏数据成环时死循环
        Map<Long, List<FinAccountSubjectDO>> childrenMap = accountSubjectService.getAccountSubjectList().stream()
                .filter(item -> item.getParentId() != null)
                .collect(Collectors.groupingBy(FinAccountSubjectDO::getParentId));
        Deque<Long> queue = new ArrayDeque<>();
        queue.add(subject.getId());
        while (!queue.isEmpty()) {
            for (FinAccountSubjectDO child : childrenMap.getOrDefault(queue.poll(), List.of())) {
                if (subjectCodes.add(child.getSubjectCode())) {
                    queue.add(child.getId());
                }
            }
        }
        return subjectCodes;
    }

    private FinLedgerRespVO buildOpeningRow(FinAccountSubjectDO subject, LocalDate date, BigDecimal balance) {
        return buildRow(FinLedgerRowTypeEnum.OPENING, YearMonth.from(date).toString(), date, subject, null,
                FinLedgerRowTypeEnum.OPENING.getName(), null, null, balance);
    }

    private FinLedgerRespVO buildRow(FinLedgerRowTypeEnum rowType, String period, LocalDate date,
                                     FinAccountSubjectDO subject, String voucherNo, String summary,
                                     BigDecimal debit, BigDecimal credit, BigDecimal balance) {
        return new FinLedgerRespVO()
                .setRowType(rowType.getType())
                .setRowTypeName(rowType.getName())
                .setPeriod(period)
                .setDate(date)
                .setVoucherNo(voucherNo)
                .setSubjectCode(subject.getSubjectCode())
                .setSubjectName(subject.getSubjectName())
                .setSummary(summary)
                .setDebit(debit)
                .setCredit(credit)
                .setDirection(FinBalanceDirectionEnum.getByBalance(balance))
                .setBalance(balance);
    }

    private static BigDecimal sum(List<FinLedgerEntryDO> entries, boolean debit) {
        return entries.stream()
                .map(entry -> debit ? defaultIfNull(entry.getDebit()) : defaultIfNull(entry.getCredit()))
                .reduce(BigDecimal.ZERO, BigDecimal::add);
    }

    private static BigDecimal defaultIfNull(BigDecimal amount) {
        return amount == null ? BigDecimal.ZERO : amount;
    }

    private static LocalDate minDate(LocalDate date, LocalDate maxDate) {
        return date.isAfter(maxDate) ? maxDate : date;
    }

}