using System.Data.Common;
using System.Threading.Tasks;
using GB5Shared.DTO.Framework.Login;
using GoodBooks.PAY.PAYDAL.DTO.Loyalty;

namespace GoodBooks.PAY.PAYDAL.CustomCode.Loyalty
{
    /// <summary>
    /// Data-access contract for MCUSTLOYALTYENROLLMENT.
    /// </summary>
    public interface ICustomerLoyaltyEnrollmentDAL
    {
        /// <summary>
        /// Fetches a single enrollment by ID with program and tier names.
        /// Returns serialised JSON string.
        /// </summary>
        Task<string> GetEnrollment(int enrollmentId, LoginDTO login);

        /// <summary>
        /// Fetches a single enrollment for a customer+program combination.
        /// Returns null when the customer is not enrolled.
        /// </summary>
        Task<CustomerLoyaltyEnrollmentDTO?> GetEnrollmentByCustomerProgram(int customerId, int programId, LoginDTO login);

        /// <summary>
        /// Returns the count of existing enrollments for a customer+program combination.
        /// Used as an idempotency guard — BLL rejects enroll when count > 0.
        /// </summary>
        Task<int> CountEnrollment(int customerId, int programId, LoginDTO login);

        /// <summary>
        /// Inserts a new enrollment row. Returns rows affected.
        /// </summary>
        Task<int> InsertEnrollment(CustomerLoyaltyEnrollmentDTO dto, LoginDTO login, DbTransaction? tx);

        /// <summary>
        /// Updates the running point totals on an enrollment.
        /// Called after every ledger transaction. Returns rows affected.
        /// </summary>
        Task<int> UpdateEnrollmentPoints(int enrollmentId, decimal currentPoints, decimal lifetimePoints, LoginDTO login, DbTransaction? tx);

        /// <summary>
        /// Updates the tier assignment after a tier-upgrade evaluation.
        /// Returns rows affected.
        /// </summary>
        Task<int> UpdateEnrollmentTier(int enrollmentId, int loyaltyTierId, LoginDTO login, DbTransaction? tx);
    }
}