using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using TMSDAL.DTO.TrainingEnrollment;

namespace TMSBLL.TrainingEnrollment
{
    public interface ITrainingEnrollmentBLL
    {
        // ════════════════════════════════════════════════════════════════════
        // READ
        // ════════════════════════════════════════════════════════════════════

        /// <summary>Fetch full enrollment record by primary key (JSON).</summary>
        Task<string> GetTrainingEnrollment(int enrollmentId, LoginDTO loginDTO);

        /// <summary>All enrollments for a training instance (JSON).</summary>
        Task<string> GetEnrollmentsByInstance(int instanceId, LoginDTO loginDTO);

        /// <summary>All enrollments for an employee (JSON).</summary>
        Task<string> GetEnrollmentsByEmployee(int employeeId, LoginDTO loginDTO);

        /// <summary>Full tenant enrollment list (JSON).</summary>
        Task<string> GetEnrollmentList(LoginDTO loginDTO);

        /// <summary>Paged / filtered dropdown select-list (JSON).</summary>
        Task<string> GetSelectList(CriteriaDTO criteriaDTO, LoginDTO loginDTO, CancellationToken ct);

        // ════════════════════════════════════════════════════════════════════
        // WRITE
        // ════════════════════════════════════════════════════════════════════

        /// <summary>
        /// Create a new enrollment with capacity check, duplicate guard,
        /// and AutoNumber generation. Waitlists when instance is full.
        /// </summary>
        Task<string> SaveTrainingEnrollment(TrainingEnrollmentDTO dto, LoginDTO loginDTO);

        /// <summary>
        /// Approve or reject an enrollment at the Manager or HR tier.
        /// Status transition is validated per tier before actioning.
        /// </summary>
        Task<string> ApproveEnrollment(ApprovalActionDTO dto, LoginDTO loginDTO);

        /// <summary>
        /// Withdraw an enrollment. Only valid from active statuses.
        /// Decrements instance enrolled count when a confirmed seat was held.
        /// </summary>
        Task<string> WithdrawEnrollment(WithdrawEnrollmentDTO dto, LoginDTO loginDTO);

        /// <summary>Soft-delete an enrollment (STATUS = 0).</summary>
        Task<string> DeleteTrainingEnrollment(int enrollmentId, LoginDTO loginDTO);
    }
}