package com.ruoyi.account.service.impl.financial;

import com.ruoyi.account.bean.dto.financial.FinDetailLedgerQueryDto;
import com.ruoyi.account.bean.dto.financial.FinLedgerQueryDto;
import com.ruoyi.account.bean.vo.financial.FinLedgerEntryRecordVo;
import com.ruoyi.account.bean.vo.financial.FinLedgerRowVo;
import com.ruoyi.account.mapper.financial.FinVoucherEntryMapper;
import com.ruoyi.account.service.financial.FinLedgerService;
import com.ruoyi.common.exception.ServiceException;
import com.ruoyi.common.utils.StringUtils;
import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.time.LocalDate;
import java.time.YearMonth;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;
import java.util.*;

/**
 * 科目总账/明细账服务实现。
 */
@Service
@RequiredArgsConstructor
public class FinLedgerServiceImpl implements FinLedgerService {

    private static final DateTimeFormatter MONTH_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM");
    private static final BigDecimal ZERO = BigDecimal.ZERO.setScale(2, RoundingMode.HALF_UP);

    private final FinVoucherEntryMapper finVoucherEntryMapper;

    @Override
    public List<FinLedgerRowVo> queryGeneralLedger(FinLedgerQueryDto queryDto) {
        if (queryDto == null || StringUtils.isEmpty(queryDto.getSubjectCode())) {
            return Collections.emptyList();
        }
        YearMonth startMonth = parseMonth(queryDto.getStartMonth(), "开始月份");
        YearMonth endMonth = parseMonth(queryDto.getEndMonth(), "结束月份");
        if (startMonth.isAfter(endMonth)) {
            throw new ServiceException("开始月份不能大于结束月份");
        }
        return buildLedgerRows(queryDto.getSubjectCode(), startMonth, endMonth, null, null);
    }

    @Override
    public List<FinLedgerRowVo> queryDetailLedger(FinDetailLedgerQueryDto queryDto) {
        if (queryDto == null || StringUtils.isEmpty(queryDto.getSubjectCode())) {
            return Collections.emptyList();
        }
        YearMonth startMonth = parseMonth(queryDto.getStartMonth(), "开始月份");
        YearMonth endMonth = parseMonth(queryDto.getEndMonth(), "结束月份");
        if (startMonth.isAfter(endMonth)) {
            throw new ServiceException("开始月份不能大于结束月份");
        }
        return buildLedgerRows(queryDto.getSubjectCode(), startMonth, endMonth, queryDto.getAuxiliaryType(), queryDto.getAuxiliaryId());
    }

    /**
     * 构建账簿行数据，输出期初、分录、本月合计、本年累计。
     */
    private List<FinLedgerRowVo> buildLedgerRows(String subjectCode,
                                                 YearMonth startMonth,
                                                 YearMonth endMonth,
                                                 String auxiliaryType,
                                                 String auxiliaryId) {
        LocalDate startDate = startMonth.atDay(1);
        LocalDate endDate = endMonth.atEndOfMonth();

        List<FinLedgerEntryRecordVo> openingEntries = finVoucherEntryMapper.listPostedEntriesBefore(
                subjectCode, startDate, auxiliaryType, auxiliaryId
        );
        BigDecimal openingBalance = calculateBalance(openingEntries);

        List<FinLedgerEntryRecordVo> currentPeriodEntries = finVoucherEntryMapper.listPostedEntries(
                subjectCode, startDate, endDate, auxiliaryType, auxiliaryId
        );
        Map<YearMonth, List<FinLedgerEntryRecordVo>> monthEntriesMap = groupEntriesByMonth(currentPeriodEntries);

        List<FinLedgerRowVo> rows = new ArrayList<>();
        BigDecimal runningBalance = openingBalance;
        BigDecimal yearDebit = ZERO;
        BigDecimal yearCredit = ZERO;

        for (YearMonth month = startMonth; !month.isAfter(endMonth); month = month.plusMonths(1)) {
            rows.add(buildOpeningRow(month.atDay(1), runningBalance));

            List<FinLedgerEntryRecordVo> monthEntries = monthEntriesMap.getOrDefault(month, Collections.emptyList());
            BigDecimal monthDebit = ZERO;
            BigDecimal monthCredit = ZERO;
            for (FinLedgerEntryRecordVo entry : monthEntries) {
                BigDecimal debit = money(entry.getDebit());
                BigDecimal credit = money(entry.getCredit());
                runningBalance = runningBalance.add(debit).subtract(credit);
                monthDebit = monthDebit.add(debit);
                monthCredit = monthCredit.add(credit);

                FinLedgerRowVo row = new FinLedgerRowVo();
                row.setRowType("entry");
                row.setDate(entry.getVoucherDate());
                row.setVoucherNo(entry.getVoucherNo());
                row.setSummary(StringUtils.isNotEmpty(entry.getSummary()) ? entry.getSummary() : "");
                row.setDebit(debit);
                row.setCredit(credit);
                row.setBalance(money(runningBalance));
                row.setDirection(resolveDirection(runningBalance));
                rows.add(row);
            }

            rows.add(buildMonthlyTotalRow(month.atEndOfMonth(), monthDebit, monthCredit, runningBalance));
            yearDebit = yearDebit.add(monthDebit);
            yearCredit = yearCredit.add(monthCredit);
        }

        rows.add(buildYearlyTotalRow(endMonth.atEndOfMonth(), yearDebit, yearCredit, runningBalance));
        return rows;
    }

    private Map<YearMonth, List<FinLedgerEntryRecordVo>> groupEntriesByMonth(List<FinLedgerEntryRecordVo> entries) {
        Map<YearMonth, List<FinLedgerEntryRecordVo>> map = new LinkedHashMap<>();
        for (FinLedgerEntryRecordVo entry : entries) {
            if (entry.getVoucherDate() == null) {
                continue;
            }
            YearMonth month = YearMonth.from(entry.getVoucherDate());
            map.computeIfAbsent(month, key -> new ArrayList<>()).add(entry);
        }
        return map;
    }

    private FinLedgerRowVo buildOpeningRow(LocalDate date, BigDecimal openingBalance) {
        FinLedgerRowVo row = new FinLedgerRowVo();
        row.setRowType("opening");
        row.setDate(date);
        row.setVoucherNo("-");
        row.setSummary("期初余额");
        row.setDebit(ZERO);
        row.setCredit(ZERO);
        row.setBalance(money(openingBalance));
        row.setDirection(resolveDirection(openingBalance));
        return row;
    }

    private FinLedgerRowVo buildMonthlyTotalRow(LocalDate date,
                                                BigDecimal monthDebit,
                                                BigDecimal monthCredit,
                                                BigDecimal monthBalance) {
        FinLedgerRowVo row = new FinLedgerRowVo();
        row.setRowType("monthly_total");
        row.setDate(date);
        row.setVoucherNo("-");
        row.setSummary("本月合计");
        row.setDebit(money(monthDebit));
        row.setCredit(money(monthCredit));
        row.setBalance(money(monthBalance));
        row.setDirection(resolveDirection(monthBalance));
        return row;
    }

    private FinLedgerRowVo buildYearlyTotalRow(LocalDate date,
                                               BigDecimal yearDebit,
                                               BigDecimal yearCredit,
                                               BigDecimal yearBalance) {
        FinLedgerRowVo row = new FinLedgerRowVo();
        row.setRowType("yearly_total");
        row.setDate(date);
        row.setVoucherNo("-");
        row.setSummary("合计");
        row.setDebit(money(yearDebit));
        row.setCredit(money(yearCredit));
        row.setBalance(money(yearBalance));
        row.setDirection(resolveDirection(yearBalance));
        return row;
    }

    private BigDecimal calculateBalance(List<FinLedgerEntryRecordVo> entries) {
        BigDecimal balance = ZERO;
        for (FinLedgerEntryRecordVo entry : entries) {
            balance = balance.add(money(entry.getDebit())).subtract(money(entry.getCredit()));
        }
        return money(balance);
    }

    private String resolveDirection(BigDecimal balance) {
        return money(balance).compareTo(BigDecimal.ZERO) >= 0 ? "借" : "贷";
    }

    private YearMonth parseMonth(String value, String fieldLabel) {
        if (StringUtils.isEmpty(value)) {
            throw new ServiceException(fieldLabel + "不能为空，格式应为YYYY-MM");
        }
        try {
            return YearMonth.parse(value, MONTH_FORMATTER);
        } catch (DateTimeParseException ex) {
            throw new ServiceException(fieldLabel + "格式错误，格式应为YYYY-MM");
        }
    }

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