using BuildFlow.Shared.Domain.Exceptions;
using MediatR;
using BuildFlow.Application.Roles.DTOs;
using BuildFlow.Infrastructure.Persistence;
using BuildFlow.Application.Roles.Queries;

namespace BuildFlow.Application.Roles.Handlers;

/// <summary>
/// Get角色ById查询处理器。执行业务校验后持久化。
/// </summary>
public class GetRoleByIdQueryHandler(RagDbContext db) : IRequestHandler<GetRoleByIdQuery, RoleDto>
{
    public async Task<RoleDto> Handle(GetRoleByIdQuery request, CancellationToken ct)
    {
        var role = await db.Roles
            .Include(r => r.RolePermissions).ThenInclude(rp => rp.Permission)
            .FirstOrDefaultAsync(r => r.Id == request.Id, ct)
            ?? throw new NotFoundException("角色不存在");

        return new RoleDto(role.Id, role.Name, role.Description, role.CreatedAt,
            role.RolePermissions.Select(rp => rp.Permission.Code).ToList());
    }
}