Card liquefication

SVSim.EmulatedEntrypoint/Controllers/CardController.cs

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+using Microsoft.AspNetCore.Mvc;
+using SVSim.Database.Repositories.Card;
+using SVSim.EmulatedEntrypoint.Models.Dtos;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Requests.Card;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Responses.Card;
+using System.Text.Json;
+
+namespace SVSim.EmulatedEntrypoint.Controllers;
+
+/// <summary>
+/// /card/* — viewer card-inventory mutations. v1 implements /card/destruct only; reserved
+/// for /card/create, /card/protect, /card/create-foil-card.
+/// </summary>
+[Route("card")]
+public class CardController : SVSimController
+{
+    private readonly ICardInventoryRepository _inventory;
+    private readonly ILogger<CardController> _log;
+
+    public CardController(ICardInventoryRepository inventory, ILogger<CardController> log)
+    {
+        _inventory = inventory;
+        _log = log;
+    }
+
+    [HttpPost("destruct")]
+    public async Task<ActionResult<CardDestructResponse>> Destruct(CardDestructRequest request)
+    {
+        if (!TryGetViewerId(out long viewerId)) return Unauthorized();
+
+        if (!TryParseDestructDict(request.CardIdNumberArray, out var destructCounts, out var snapshots, out var parseError))
+            return BadRequest(new { error = parseError });
+
+        if (destructCounts.Count == 0)
+            return BadRequest(new { error = "malformed_request" });
+
+        var outcome = await _inventory.DestructCards(viewerId, destructCounts);
+        if (!outcome.IsSuccess)
+            return BadRequest(new { error = ErrorKey(outcome.Error!.Value) });
+
+        // Client snapshot mismatch is warn-log only; never blocks the request.
+        foreach (var (cardId, snapshot) in snapshots)
+        {
+            // We don't carry pre-state counts back, but post + destructed = pre.
+            int destructedNum = destructCounts[cardId];
+            int reconstructedPre = outcome.Result!.NewOwnedCounts[cardId] + destructedNum;
+            if (reconstructedPre != snapshot)
+            {
+                _log.LogWarning(
+                    "Destruct possession-snapshot mismatch: card={CardId} client_snapshot={Snapshot} server_pre={ServerPre}",
+                    cardId, snapshot, reconstructedPre);
+            }
+        }
+
+        // Wire spec is int; clamp the ulong total so a hypothetical 2B+ balance can't underflow
+        // to a negative wire value. Realistic balances are well under int.MaxValue.
+        int redEtherWire = outcome.Result!.NewRedEtherTotal > int.MaxValue
+            ? int.MaxValue
+            : (int)outcome.Result!.NewRedEtherTotal;
+        var rewardList = new List<RewardListEntry>
+        {
+            new() { RewardType = 1, RewardId = 0, RewardNum = redEtherWire },
+        };
+        foreach (var (cardId, postCount) in outcome.Result!.NewOwnedCounts)
+        {
+            rewardList.Add(new RewardListEntry { RewardType = 5, RewardId = cardId, RewardNum = postCount });
+        }
+
+        return new CardDestructResponse { RewardList = rewardList };
+    }
+
+    private static string ErrorKey(DestructError error) => error switch
+    {
+        DestructError.UnknownCard       => "unknown_card",
+        DestructError.NotDestructible   => "not_destructible",
+        DestructError.CardProtected     => "card_protected",
+        DestructError.InsufficientCards => "insufficient_cards",
+        _ => "malformed_request",
+    };
+
+    /// <summary>
+    /// Decodes the inner JSON of <c>card_id_number_array</c>. Values are
+    /// <c>"&lt;num_to_destruct&gt;,&lt;client_possession_snapshot&gt;"</c> — both strings.
+    /// Returns false (and sets <paramref name="errorKey"/>) on any structural problem.
+    /// </summary>
+    private static bool TryParseDestructDict(
+        string raw,
+        out Dictionary<long, int> destructCounts,
+        out Dictionary<long, int> clientSnapshots,
+        out string errorKey)
+    {
+        destructCounts = new();
+        clientSnapshots = new();
+        errorKey = "malformed_request";
+
+        if (string.IsNullOrWhiteSpace(raw))
+            return false;
+
+        JsonDocument? doc;
+        try { doc = JsonDocument.Parse(raw); }
+        catch (JsonException) { return false; }
+
+        using (doc)
+        {
+            if (doc.RootElement.ValueKind != JsonValueKind.Object)
+                return false;
+
+            foreach (var prop in doc.RootElement.EnumerateObject())
+            {
+                if (!long.TryParse(prop.Name, out long cardId))
+                    return false;
+                if (prop.Value.ValueKind != JsonValueKind.String)
+                    return false;
+
+                var pair = prop.Value.GetString()!.Split(',');
+                if (pair.Length != 2)
+                    return false;
+                if (!int.TryParse(pair[0], out int num) || num <= 0)
+                    return false;
+                if (!int.TryParse(pair[1], out int snapshot) || snapshot < 0)
+                    return false;
+
+                destructCounts[cardId] = num;
+                clientSnapshots[cardId] = snapshot;
+            }
+        }
+
+        return true;
+    }
+}