KycTransitions.cs

using System;
using System.Collections.Generic;
using System.Linq;
 
namespace NeuroAccessMaui.Services.Kyc.Domain
{
    internal static class KycTransitions
    {
        public static KycNavigationSnapshot Advance(KycProcessState State, IReadOnlyList<int> VisibleIndices)
        {
            KycNavigationSnapshot nav = State.Navigation;
            if (State.Navigation.State is KycFlowState.Summary or KycFlowState.PendingSummary)
                return nav; // Already at summary; engine will decide apply action.
 
            // Find next visible page after current
            int Current = nav.CurrentPageIndex;
            int Next = -1;
            foreach (int idx in VisibleIndices)
            {
                if (idx > Current) { Next = idx; break; }
            }
            if (Next < 0)
            {
                // No further pages -> transition to summary
                return nav with { State = State.ApplicationSent ? KycFlowState.PendingSummary : KycFlowState.Summary };
            }
            return nav with { CurrentPageIndex = Next };
        }
 
        public static KycNavigationSnapshot Back(KycProcessState state, IReadOnlyList<int> visibleIndices)
        {
            KycNavigationSnapshot Nav = state.Navigation;
            if (Nav.State == KycFlowState.Summary)
            {
                // Leave summary returning to anchor page
                return Nav with { State = KycFlowState.Form, CurrentPageIndex = Nav.AnchorPageIndex >= 0 ? Nav.AnchorPageIndex : Nav.CurrentPageIndex };
            }
            int Current = Nav.CurrentPageIndex;
            int Prev = -1;
            for (int i = visibleIndices.Count - 1; i >= 0; i--)
            {
                int idx = visibleIndices[i];
                if (idx < Current) { Prev = idx; break; }
            }
            if (Prev < 0)
                return Nav; // At first page; caller decides to exit.
            return Nav with { CurrentPageIndex = Prev };
        }
 
        public static KycNavigationSnapshot EnterSummary(KycProcessState state)
        {
            KycNavigationSnapshot Nav = state.Navigation;
            if (Nav.State == KycFlowState.Summary) return Nav;
            return Nav with { State = state.ApplicationSent ? KycFlowState.PendingSummary : KycFlowState.Summary, AnchorPageIndex = Nav.CurrentPageIndex };
        }
 
        public static KycNavigationSnapshot EditFromSummary(KycProcessState state, int targetPageIndex)
        {
            KycNavigationSnapshot Nav = state.Navigation;
            if (Nav.State != KycFlowState.Summary && Nav.State != KycFlowState.RejectedSummary)
                return Nav; // Only allowed from summary flavors
            return new KycNavigationSnapshot(targetPageIndex, Nav.AnchorPageIndex >= 0 ? Nav.AnchorPageIndex : Nav.CurrentPageIndex, KycFlowState.EditingFromSummary);
        }
 
        public static KycNavigationSnapshot ReturnToSummary(KycProcessState state, bool hasInvalid)
        {
            KycNavigationSnapshot Nav = state.Navigation;
            if (Nav.State != KycFlowState.EditingFromSummary) return Nav;
            if (hasInvalid)
                return Nav with { State = KycFlowState.Form }; // Caller may reposition to first invalid
            return Nav with { State = KycFlowState.Summary, CurrentPageIndex = Nav.AnchorPageIndex >= 0 ? Nav.AnchorPageIndex : Nav.CurrentPageIndex };
        }
    }
}