package com.ruoyi.account.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.ruoyi.account.bean.dto.AccountSubjectDto;
import com.ruoyi.account.bean.dto.AccountSubjectImportDto;
import com.ruoyi.account.bean.vo.AccountSubjectVo;
import com.ruoyi.account.mapper.AccountSubjectMapper;
import com.ruoyi.account.pojo.AccountSubject;
import com.ruoyi.account.service.AccountSubjectService;
import com.ruoyi.common.exception.ServiceException;
import com.ruoyi.common.utils.StringUtils;
import com.ruoyi.common.utils.poi.ExcelUtil;
import jakarta.servlet.http.HttpServletResponse;
import lombok.RequiredArgsConstructor;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * <p>
 * 总账科目表 服务实现类
 * </p>
 *
 * @author 芯导软件（江苏）有限公司
 * @since 2026-05-07 04:45:30
 */
@Service
@RequiredArgsConstructor
public class AccountSubjectServiceImpl extends ServiceImpl<AccountSubjectMapper, AccountSubject> implements AccountSubjectService {

    private final AccountSubjectMapper accountSubjectMapper;

    @Override
    public IPage<AccountSubjectVo> baseList(Page<AccountSubjectDto> page, AccountSubjectDto accountSubjectDto) {
        Page<AccountSubjectDto> requestPage = page == null ? new Page<>(1, 10) : page;
        List<AccountSubject> allSubjects = list(loadBaseQueryWrapper(accountSubjectDto));
        List<AccountSubject> filteredSubjects = applyTreeFilter(allSubjects, accountSubjectDto);
        List<AccountSubjectVo> fullTree = buildTree(filteredSubjects);

        long current = requestPage.getCurrent() <= 0 ? 1 : requestPage.getCurrent();
        long size = requestPage.getSize() <= 0 ? 10 : requestPage.getSize();
        int fromIndex = (int) Math.min((current - 1) * size, fullTree.size());
        int toIndex = (int) Math.min(fromIndex + size, fullTree.size());
        List<AccountSubjectVo> pagedRoots = fromIndex >= toIndex
                ? Collections.emptyList()
                : fullTree.subList(fromIndex, toIndex);

        Page<AccountSubjectVo> resultPage = new Page<>(current, size, fullTree.size());
        resultPage.setRecords(pagedRoots);
        return resultPage;
    }

    @Override
    public Boolean saveAccountSubject(AccountSubjectDto accountSubjectDto) {
        validateSubjectRequiredFields(accountSubjectDto);
        validateSubjectCodeUnique(accountSubjectDto, false);
        validateParent(accountSubjectDto.getParentId(), null);
        if (accountSubjectDto.getStatus() == null) {
            accountSubjectDto.setStatus(0);
        }
        return save(accountSubjectDto);
    }

    @Override
    public Boolean updateAccountSubject(AccountSubjectDto accountSubjectDto) {
        if (accountSubjectDto == null || accountSubjectDto.getId() == null) {
            throw new ServiceException("修改失败，科目ID不能为空");
        }
        if (getById(accountSubjectDto.getId()) == null) {
            throw new ServiceException("修改失败，未找到对应科目");
        }
        validateParent(accountSubjectDto.getParentId(), accountSubjectDto.getId());
        validateSubjectRequiredFields(accountSubjectDto);
        validateSubjectCodeUnique(accountSubjectDto, true);
        return updateById(accountSubjectDto);
    }

    @Override
    public Boolean removeAccountSubjectByIds(List<Long> ids) {
        if (ids == null || ids.isEmpty()) {
            return true;
        }
        List<AccountSubject> allSubjects = list();
        if (allSubjects == null || allSubjects.isEmpty()) {
            return true;
        }
        Map<Long, List<Long>> childrenIdMap = buildChildrenIdMap(allSubjects);
        Set<Long> removeIds = new LinkedHashSet<>();
        for (Long id : ids) {
            collectDescendantIds(id, childrenIdMap, removeIds);
        }
        if (removeIds.isEmpty()) {
            return true;
        }
        List<String> subjectCodes = allSubjects.stream()
                .filter(subject -> removeIds.contains(subject.getId()))
                .map(AccountSubject::getSubjectCode)
                .filter(StringUtils::isNotEmpty)
                .collect(Collectors.toList());
        if (!subjectCodes.isEmpty()) {
            Long referencedCount = accountSubjectMapper.countReferencedBySubjectCodes(subjectCodes);
            if (referencedCount != null && referencedCount > 0) {
                throw new ServiceException("删除失败，科目已被凭证分录引用");
            }
        }
        return removeByIds(removeIds);
    }

    @Override
    public void exportAccountSubject(HttpServletResponse response) {
        List<AccountSubject> list = accountSubjectMapper.selectList(null);
        List<AccountSubjectImportDto> importDtos = list.stream().map(accountSubject -> {
            AccountSubjectImportDto accountSubjectImportDto = new AccountSubjectImportDto();
            BeanUtils.copyProperties(accountSubject, accountSubjectImportDto);
            return accountSubjectImportDto;
        }).collect(Collectors.toList());
        ExcelUtil<AccountSubjectImportDto> util = new ExcelUtil<>(AccountSubjectImportDto.class);
        util.exportExcel(response, importDtos , "总账科目");
    }

    /**
     * 校验科目必填字段，避免脏数据写入。
     */
    private void validateSubjectRequiredFields(AccountSubjectDto accountSubjectDto) {
        if (accountSubjectDto == null) {
            throw new ServiceException("总账科目数据不能为空");
        }
        if (StringUtils.isEmpty(accountSubjectDto.getSubjectCode())) {
            throw new ServiceException("科目编码不能为空");
        }
        if (StringUtils.isEmpty(accountSubjectDto.getSubjectName())) {
            throw new ServiceException("科目名称不能为空");
        }
        if (StringUtils.isEmpty(accountSubjectDto.getSubjectType())) {
            throw new ServiceException("科目类型不能为空");
        }
    }

    /**
     * 校验科目编码唯一，新增和修改都要执行。
     */
    private void validateSubjectCodeUnique(AccountSubjectDto accountSubjectDto, boolean isUpdate) {
        LambdaQueryWrapper<AccountSubject> codeQueryWrapper = new LambdaQueryWrapper<>();
        codeQueryWrapper.eq(AccountSubject::getSubjectCode, accountSubjectDto.getSubjectCode());
        if (isUpdate) {
            codeQueryWrapper.ne(AccountSubject::getId, accountSubjectDto.getId());
        }
        AccountSubject exists = getOne(codeQueryWrapper, false);
        if (Objects.nonNull(exists)) {
            throw new ServiceException("科目编码已存在，请勿重复提交");
        }
    }

    /**
     * 仅按通用过滤条件查询基础数据（树形过滤后续再做）。
     */
    private LambdaQueryWrapper<AccountSubject> loadBaseQueryWrapper(AccountSubjectDto accountSubjectDto) {
        LambdaQueryWrapper<AccountSubject> queryWrapper = new LambdaQueryWrapper<>();
        if (accountSubjectDto != null && accountSubjectDto.getStatus() != null) {
            queryWrapper.eq(AccountSubject::getStatus, accountSubjectDto.getStatus());
        }
        queryWrapper.orderByAsc(AccountSubject::getSubjectCode).orderByAsc(AccountSubject::getId);
        return queryWrapper;
    }

    /**
     * 树形过滤：命中节点后保留其父链与子树，保证递归结构完整。
     */
    private List<AccountSubject> applyTreeFilter(List<AccountSubject> allSubjects, AccountSubjectDto queryDto) {
        if (allSubjects == null || allSubjects.isEmpty()) {
            return Collections.emptyList();
        }
        boolean hasFilter = queryDto != null && (
                StringUtils.isNotEmpty(queryDto.getSubjectCode())
                        || StringUtils.isNotEmpty(queryDto.getSubjectName())
                        || StringUtils.isNotEmpty(queryDto.getSubjectType())
        );
        if (!hasFilter) {
            return allSubjects;
        }

        Map<Long, AccountSubject> subjectMap = allSubjects.stream()
                .filter(item -> item.getId() != null)
                .collect(Collectors.toMap(AccountSubject::getId, item -> item, (a, b) -> a, LinkedHashMap::new));
        Map<Long, List<AccountSubject>> childrenMap = buildChildrenMap(allSubjects);

        Set<Long> matchedIds = new LinkedHashSet<>();
        for (AccountSubject subject : allSubjects) {
            if (subject.getId() == null) {
                continue;
            }
            if (matchesFilter(subject, queryDto)) {
                matchedIds.add(subject.getId());
            }
        }
        if (matchedIds.isEmpty()) {
            return Collections.emptyList();
        }

        Set<Long> resultIds = new LinkedHashSet<>(matchedIds);
        for (Long matchedId : matchedIds) {
            addAncestors(matchedId, subjectMap, resultIds);
            addDescendants(matchedId, childrenMap, resultIds);
        }

        return allSubjects.stream()
                .filter(item -> item.getId() != null && resultIds.contains(item.getId()))
                .collect(Collectors.toList());
    }

    private boolean matchesFilter(AccountSubject subject, AccountSubjectDto queryDto) {
        if (queryDto == null) {
            return true;
        }
        if (StringUtils.isNotEmpty(queryDto.getSubjectCode())
                && (subject.getSubjectCode() == null || !subject.getSubjectCode().contains(queryDto.getSubjectCode()))) {
            return false;
        }
        if (StringUtils.isNotEmpty(queryDto.getSubjectName())
                && (subject.getSubjectName() == null || !subject.getSubjectName().contains(queryDto.getSubjectName()))) {
            return false;
        }
        if (StringUtils.isNotEmpty(queryDto.getSubjectType())
                && !queryDto.getSubjectType().equals(subject.getSubjectType())) {
            return false;
        }
        return true;
    }

    private void addAncestors(Long subjectId, Map<Long, AccountSubject> subjectMap, Set<Long> resultIds) {
        AccountSubject current = subjectMap.get(subjectId);
        if (current == null) {
            return;
        }
        Long parentId = current.getParentId();
        while (parentId != null && parentId > 0) {
            AccountSubject parent = subjectMap.get(parentId);
            if (parent == null) {
                break;
            }
            if (!resultIds.add(parent.getId())) {
                break;
            }
            parentId = parent.getParentId();
        }
    }

    private void addDescendants(Long subjectId, Map<Long, List<AccountSubject>> childrenMap, Set<Long> resultIds) {
        List<AccountSubject> children = childrenMap.getOrDefault(subjectId, Collections.emptyList());
        for (AccountSubject child : children) {
            if (child.getId() == null) {
                continue;
            }
            if (resultIds.add(child.getId())) {
                addDescendants(child.getId(), childrenMap, resultIds);
            }
        }
    }

    private Map<Long, List<AccountSubject>> buildChildrenMap(List<AccountSubject> subjects) {
        Map<Long, List<AccountSubject>> childrenMap = new HashMap<>();
        for (AccountSubject subject : subjects) {
            if (subject.getId() == null) {
                continue;
            }
            Long parentId = subject.getParentId();
            if (parentId == null || parentId <= 0) {
                continue;
            }
            childrenMap.computeIfAbsent(parentId, key -> new ArrayList<>()).add(subject);
        }
        return childrenMap;
    }

    /**
     * 基于 parentId 递归构建科目树。
     */
    private List<AccountSubjectVo> buildTree(List<AccountSubject> subjects) {
        if (subjects == null || subjects.isEmpty()) {
            return Collections.emptyList();
        }
        List<AccountSubject> sortedSubjects = new ArrayList<>(subjects);
        sortedSubjects.sort(Comparator
                .comparing(AccountSubject::getSubjectCode, Comparator.nullsLast(String::compareTo))
                .thenComparing(AccountSubject::getId, Comparator.nullsLast(Long::compareTo)));

        Map<Long, AccountSubjectVo> subjectVoMap = new LinkedHashMap<>();
        for (AccountSubject subject : sortedSubjects) {
            if (subject.getId() == null) {
                continue;
            }
            AccountSubjectVo vo = new AccountSubjectVo();
            BeanUtils.copyProperties(subject, vo);
            subjectVoMap.put(subject.getId(), vo);
        }

        List<AccountSubjectVo> roots = new ArrayList<>();
        for (AccountSubject subject : sortedSubjects) {
            if (subject.getId() == null) {
                continue;
            }
            AccountSubjectVo current = subjectVoMap.get(subject.getId());
            Long parentId = subject.getParentId();
            if (parentId != null && parentId > 0 && subjectVoMap.containsKey(parentId)) {
                subjectVoMap.get(parentId).getChildren().add(current);
            } else {
                roots.add(current);
            }
        }

        markLeafRecursively(roots);
        return roots;
    }

    private void markLeafRecursively(List<AccountSubjectVo> nodes) {
        for (AccountSubjectVo node : nodes) {
            List<AccountSubjectVo> children = node.getChildren();
            node.setLeaf(children == null || children.isEmpty());
            if (children != null && !children.isEmpty()) {
                markLeafRecursively(children);
            }
        }
    }

    /**
     * 校验父子关系：父节点必须存在，且不能形成循环引用。
     */
    private void validateParent(Long parentId, Long currentId) {
        if (parentId == null || parentId <= 0) {
            return;
        }
        if (currentId != null && parentId.equals(currentId)) {
            throw new ServiceException("父科目不能选择自身");
        }
        AccountSubject parent = getById(parentId);
        if (parent == null) {
            throw new ServiceException("父科目不存在，请重新选择");
        }
        // 防止形成环：更新时，父节点不能是当前节点的任意子孙节点。
        if (currentId != null) {
            Set<Long> visited = new HashSet<>();
            Long traceParentId = parentId;
            while (traceParentId != null && traceParentId > 0) {
                if (!visited.add(traceParentId)) {
                    throw new ServiceException("科目层级存在循环引用，请检查父科目设置");
                }
                if (traceParentId.equals(currentId)) {
                    throw new ServiceException("父科目不能是当前科目或其子科目");
                }
                AccountSubject traceNode = getById(traceParentId);
                if (traceNode == null) {
                    break;
                }
                traceParentId = traceNode.getParentId();
            }
        }
    }

    private Map<Long, List<Long>> buildChildrenIdMap(List<AccountSubject> subjects) {
        Map<Long, List<Long>> map = new HashMap<>();
        for (AccountSubject subject : subjects) {
            if (subject.getId() == null || subject.getParentId() == null || subject.getParentId() <= 0) {
                continue;
            }
            map.computeIfAbsent(subject.getParentId(), key -> new ArrayList<>()).add(subject.getId());
        }
        return map;
    }

    /**
     * 收集待删除节点及其所有子孙节点。
     */
    private void collectDescendantIds(Long id, Map<Long, List<Long>> childrenIdMap, Set<Long> result) {
        if (id == null || !result.add(id)) {
            return;
        }
        List<Long> children = childrenIdMap.getOrDefault(id, Collections.emptyList());
        for (Long childId : children) {
            collectDescendantIds(childId, childrenIdMap, result);
        }
    }
}