MyHomepage/backend/Services/CategoryService.cs

using MyHomePage.Api.Common;
using MyHomePage.Api.Models.Dtos;
using MyHomePage.Api.Models.Entities;
using SqlSugar;

namespace MyHomePage.Api.Services;

/// <inheritdoc />
public class CategoryService : ICategoryService
{
    private readonly ISqlSugarClient _db;
    private readonly SyncLogHelper _sync;

    public CategoryService(ISqlSugarClient db, SyncLogHelper sync)
    {
        _db = db;
        _sync = sync;
    }

    /// <inheritdoc />
    public async Task<List<CategoryDto>> GetTreeAsync()
    {
        var all = await _db.Queryable<Category>()
            .OrderBy(c => c.Sort)
            .OrderBy(c => c.Id)
            .ToListAsync();

        return CategoryDto.BuildTree(all);
    }

    /// <inheritdoc />
    public async Task<CategoryDto?> GetByIdAsync(int id)
    {
        var entity = await _db.Queryable<Category>().InSingleAsync(id);
        return entity is null ? null : ToDto(entity);
    }

    /// <inheritdoc />
    public async Task<CategoryDto> CreateAsync(CategoryUpsertRequest request)
    {
        Validate(request);
        var now = DateTime.UtcNow;
        var entity = new Category
        {
            ParentId = request.ParentId,
            Name = request.Name.Trim(),
            Icon = request.Icon,
            Sort = request.Sort,
            CreatedAt = now,
            UpdatedAt = now
        };
        entity.Id = await _db.Insertable(entity).ExecuteReturnIdentityAsync();
        await _sync.WriteAsync("category", entity.Id, "create");
        return ToDto(entity);
    }

    /// <inheritdoc />
    public async Task<CategoryDto> UpdateAsync(int id, CategoryUpsertRequest request)
    {
        Validate(request);
        var entity = await _db.Queryable<Category>().InSingleAsync(id)
            ?? throw new BusinessException("分类不存在", 404);

        entity.ParentId = request.ParentId;
        entity.Name = request.Name.Trim();
        entity.Icon = request.Icon;
        entity.Sort = request.Sort;
        entity.UpdatedAt = DateTime.UtcNow;

        await _db.Updateable(entity).ExecuteCommandAsync();
        await _sync.WriteAsync("category", id, "update");
        return ToDto(entity);
    }

    /// <inheritdoc />
    public async Task DeleteAsync(int id)
    {
        var entity = await _db.Queryable<Category>().InSingleAsync(id)
            ?? throw new BusinessException("分类不存在", 404);

        // 如果是父分类，先检查是否有子分类 / 链接
        if (entity.ParentId == 0)
        {
            var hasChildren = await _db.Queryable<Category>().AnyAsync(c => c.ParentId == id);
            if (hasChildren) throw new BusinessException("请先删除子分类", 400);
        }
        var hasBookmarks = await _db.Queryable<Bookmark>().AnyAsync(b => b.CategoryId == id && !b.IsDeleted);
        if (hasBookmarks) throw new BusinessException("该分类下仍有链接，请先删除链接", 400);

        await _db.Deleteable<Category>(id).ExecuteCommandAsync();
        await _sync.WriteAsync("category", id, "delete");
    }

    /// <summary>校验入参</summary>
    private static void Validate(CategoryUpsertRequest req)
    {
        if (string.IsNullOrWhiteSpace(req.Name)) throw new BusinessException("分类名称不能为空", 400);
        if (req.Name.Length > 64) throw new BusinessException("分类名称不能超过 64 字符", 400);
    }

    private static CategoryDto ToDto(Category c) => new()
    {
        Id = c.Id,
        ParentId = c.ParentId,
        Name = c.Name,
        Icon = c.Icon,
        Sort = c.Sort,
        CreatedAt = c.CreatedAt,
        UpdatedAt = c.UpdatedAt
    };
}