From 56274835899891d0dc0376b18d79039c4aba452f Mon Sep 17 00:00:00 2001
From: TekH <h.tek@digitaldata.works>
Date: Mon, 5 Oct 2026 16:43:34 +0200
Subject: [PATCH] Make RecentReceiverSuggestionDto immutable; refactor query

Updated RecentReceiverSuggestionDto to use `init` properties,
adding immutability and a new `LastUsedAt` field. Refactored
ReadRecentReceiverSuggestionsQueryHandler to simplify query
logic, remove `IMapper` dependency, and improve determinism
in results. Introduced tie-breaking for duplicate timestamps
and optimized ordering by `LastUsedAt` and `EmailAddress`.
Removed redundant `Include` and mapping steps for clarity.
---
 .../Receiver/RecentReceiverSuggestionDto.cs   |  6 ++-
 .../ReadRecentReceiverSuggestionsQuery.cs     | 50 ++++++++++++++-----
 2 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/EnvelopeGenerator.Application/Common/Dto/Receiver/RecentReceiverSuggestionDto.cs b/EnvelopeGenerator.Application/Common/Dto/Receiver/RecentReceiverSuggestionDto.cs
index 1928f56e..37a167e0 100644
--- a/EnvelopeGenerator.Application/Common/Dto/Receiver/RecentReceiverSuggestionDto.cs
+++ b/EnvelopeGenerator.Application/Common/Dto/Receiver/RecentReceiverSuggestionDto.cs
@@ -2,7 +2,9 @@ namespace EnvelopeGenerator.Application.Common.Dto.Receiver;
 
 public class RecentReceiverSuggestionDto
 {
-    public required string FullName { get; set; }
+    public required string FullName { get; init; }
 
-    public required string EmailAddress { get; set; }
+    public required string EmailAddress { get; init; }
+
+    public required DateTime LastUsedAt { get; init; }
 }
diff --git a/EnvelopeGenerator.Application/EnvelopeReceivers/Queries/ReadRecentReceiverSuggestionsQuery.cs b/EnvelopeGenerator.Application/EnvelopeReceivers/Queries/ReadRecentReceiverSuggestionsQuery.cs
index c9017cd6..f6cef12f 100644
--- a/EnvelopeGenerator.Application/EnvelopeReceivers/Queries/ReadRecentReceiverSuggestionsQuery.cs
+++ b/EnvelopeGenerator.Application/EnvelopeReceivers/Queries/ReadRecentReceiverSuggestionsQuery.cs
@@ -1,4 +1,3 @@
-using AutoMapper;
 using DigitalData.Core.Abstraction.Application.Repository;
 using EnvelopeGenerator.Application.Common.Dto.Receiver;
 using EnvelopeGenerator.Domain.Entities;
@@ -21,7 +20,7 @@ public record ReadRecentReceiverSuggestionsQuery : IRequest<IReadOnlyList<Recent
     internal string? Username { get; private init; }
 
     /// <summary>
-    /// Desired number of results. Effective range is clamped to 3..5.
+    /// Desired number of results. Default value is 5.
     /// </summary>
     public int Take { get; init; } = 5;
 
@@ -39,7 +38,7 @@ public record ReadRecentReceiverSuggestionsQuery : IRequest<IReadOnlyList<Recent
 /// <summary>
 /// Handles <see cref="ReadRecentReceiverSuggestionsQuery"/>.
 /// </summary>
-public class ReadRecentReceiverSuggestionsQueryHandler(IRepository<EnvelopeReceiver> repository, IMapper mapper)
+public class ReadRecentReceiverSuggestionsQueryHandler(IRepository<EnvelopeReceiver> repository)
     : IRequestHandler<ReadRecentReceiverSuggestionsQuery, IReadOnlyList<RecentReceiverSuggestionDto>>
 {
     /// <summary>
@@ -50,23 +49,50 @@ public class ReadRecentReceiverSuggestionsQueryHandler(IRepository<EnvelopeRecei
     /// <returns>Ordered list of recent receiver suggestions.</returns>
     public async Task<IReadOnlyList<RecentReceiverSuggestionDto>> Handle(ReadRecentReceiverSuggestionsQuery request, CancellationToken cancellationToken)
     {
-        var take = Math.Clamp(request.Take, 3, 5);
-
         var query = repository.Query
             .AsNoTracking()
-            .Include(er => er.Receiver)
             .Where(er => er.Receiver != null);
 
         if (request.Username is not null)
             query = query.Where(er => er.Envelope != null && er.Envelope.User.Username == request.Username);
 
-        var rows = await query
-            .GroupBy(er => er.Receiver!.EmailAddress.ToUpperInvariant())
-            .Select(g => g.OrderByDescending(er => er.ChangedWhen ?? er.AddedWhen).First())
-            .OrderByDescending(er => er.ChangedWhen ?? er.AddedWhen)
-            .Take(take)
+        // 1) For each email, compute the latest usage timestamp.
+        var latestPerEmail = query
+            .GroupBy(er => er.Receiver!.EmailAddress)
+            .Select(g => new
+            {
+                EmailAddress = g.Key,
+                LastUsedAt = g.Max(er => er.AddedWhen),
+            });
+
+        // 2) Join back to rows that match the latest timestamp per email.
+        var latestRows =
+            from er in query
+            join latest in latestPerEmail
+                on new { EmailAddress = er.Receiver!.EmailAddress, LastUsedAt = er.AddedWhen }
+                equals new { latest.EmailAddress, latest.LastUsedAt }
+            select new
+            {
+                EmailAddress = er.Receiver!.EmailAddress,
+                FullName = er.Name,
+                LastUsedAt = er.AddedWhen,
+            };
+
+        // 3) Tie-break: if multiple rows share the same latest timestamp for an email,
+        // pick a deterministic name via Max(FullName), then order by most recent usage.
+        var suggestions = await latestRows
+            .GroupBy(x => new { x.EmailAddress, x.LastUsedAt })
+            .Select(g => new RecentReceiverSuggestionDto
+            {
+                EmailAddress = g.Key.EmailAddress,
+                FullName = g.Max(x => x.FullName) ?? string.Empty,
+                LastUsedAt = g.Key.LastUsedAt,
+            })
+            .OrderByDescending(x => x.LastUsedAt)
+            .ThenBy(x => x.EmailAddress)
+            .Take(request.Take)
             .ToListAsync(cancellationToken);
 
-        return mapper.Map<List<RecentReceiverSuggestionDto>>(rows);
+        return suggestions;
     }
 }