using PayRollDAL.DTO.SAP;
using System.Collections.Generic;

namespace PayRollBLL.SAP.Builders
{
    /// <summary>
    /// One SAP POST target produced by a builder.
    /// Most infotypes produce a single sub-type per declaration; infotype 584 produces two
    /// (Housing Loan and Other Income Sources), each targeting a separate OData endpoint.
    /// </summary>
    /// <param name="Infotype">SAP infotype number this sub-payload belongs to.</param>
    /// <param name="Description">Human-readable sub-type label, e.g. "Housing Loan".</param>
    /// <param name="EndpointPath">OData entity-set path to POST to.</param>
    /// <param name="MsgNavProperty">Response navigation property carrying SAP messages.</param>
    /// <param name="Json">Serialized JSON body to POST.</param>
    public record SapSubtypePayload(
        int    Infotype,
        string Description,
        string EndpointPath,
        string MsgNavProperty,
        string Json);

    /// <summary>
    /// Contract for a builder that transforms flat declaration rows into one or more
    /// SAP OData POST payloads.  Each implementation handles exactly one SAP infotype (580–586).
    /// </summary>
    public interface ISapInfotypeBuilder
    {
        /// <summary>SAP infotype number (580–586).</summary>
        int Infotype { get; }

        /// <summary>Human-readable name used in messages and audit logs, e.g. "HRA / Rent Paid".</summary>
        string DisplayName { get; }

        /// <summary>
        /// Primary OData entity-set endpoint path.
        /// For infotypes with multiple sub-types (e.g. 584) this is the first sub-type's path.
        /// </summary>
        string EndpointPath { get; }

        /// <summary>
        /// Navigation property name carrying SAP messages in the primary sub-type response.
        /// </summary>
        string MsgNavProperty { get; }

        /// <summary>
        /// Builds the primary JSON payload for this infotype.
        /// Returns an empty string when <paramref name="rows"/> contains no relevant data.
        /// Used by preview / download endpoints; push logic uses <see cref="BuildAll"/> instead.
        /// </summary>
        string Build(IEnumerable<ITDeclarationSapDTO> rows, string date, string remarks);

        /// <summary>
        /// Returns all sub-type payloads to POST for this infotype.
        /// The default implementation wraps <see cref="Build"/> in a single-item result.
        /// Infotypes with multiple sub-types (e.g. 584) override this to yield additional items.
        /// </summary>
        IEnumerable<SapSubtypePayload> BuildAll(
            IEnumerable<ITDeclarationSapDTO> rows, string date, string remarks)
        {
            string json = Build(rows, date, remarks);
            if (!string.IsNullOrEmpty(json))
                yield return new SapSubtypePayload(Infotype, string.Empty, EndpointPath, MsgNavProperty, json);
        }
    }
}