using System.Linq.Expressions;
using Data.SeaHavenIndustries;

namespace SeaHaven.DataServices.Helpers
{
    /// <summary>
    /// The single definition of an uplift's amount: the NTE increase being requested.
    /// The two creation paths store different meanings in RequestedNTE. Vendor-portal
    /// requests store the requested new NTE total, so the amount is RequestedNTE minus
    /// the NTE at request time. Work-order requests store the increase itself. Vendor
    /// sessions have no identity user, so createdby is null only on vendor-portal rows.
    /// </summary>
    public static class UpliftAmount
    {
        /// <summary>Translatable form for EF queries and aggregates.</summary>
        public static readonly Expression<Func<DispatchUpliftRequest, decimal>> ForQuery =
            u => u.createdby == null
                ? u.RequestedNTE - (u.CurrentNTE ?? 0m)
                : u.RequestedNTE;

        private static readonly Func<DispatchUpliftRequest, decimal> Compiled = ForQuery.Compile();

        public static decimal Of(DispatchUpliftRequest request) => Compiled(request);

        public static decimal Of(string? createdBy, decimal requestedNte, decimal? currentNte) =>
            Compiled(new DispatchUpliftRequest
            {
                createdby = createdBy,
                RequestedNTE = requestedNte,
                CurrentNTE = currentNte,
            });
    }
}