using BuildFlow.Shared.Domain.Exceptions;
using MediatR;
using BuildFlow.Platform.Application.Roles.DTOs;
using BuildFlow.Platform.Domain.Entities.Role;
using BuildFlow.Platform.Infrastructure.Persistence;
using BuildFlow.Platform.Application.Roles.Commands;

namespace BuildFlow.Platform.Application.Roles.Handlers;

/// <summary>
/// Create角色Command处理器。执行业务校验后持久化。
/// </summary>
public class CreateRoleCommandHandler(PlatformDbContext db) : IRequestHandler<CreateRoleCommand, RoleDto>
{
    public async Task<RoleDto> Handle(CreateRoleCommand request, CancellationToken ct)
    {
        if (await db.Roles.AnyAsync(r => r.Name == request.Name, ct))
            throw new BusinessException("角色名已存在");

        var role = new RoleEntity { Name = request.Name, Description = request.Description };
        await db.Roles.AddAsync(role, ct);
        await db.SaveChangesAsync(ct);

        return new RoleDto(role.Id, role.Name, role.Description, role.CreatedAt, []);
    }
}