Add atomic account Boss Card checkpoints and preserve cards in legacy saves (#7)

server/database.mjs

@@ -26,6 +26,7 @@ import { createBiteSizedLayoutRepository } from "./bite-sized-layouts.mjs";
 import { BITE_SIZED_LAYOUT_CATALOG, isLayoutBiteSizedDungeon } from "../shared/bite-sized-layouts.mjs";
 import { createDungeonRaceRepository } from "./dungeon-races.mjs";
 import { createDungeonSimulationRepository } from "./dungeon-simulation.mjs";
+import { mergeBossCardCollections } from "./boss-card-collections.mjs";
 import dungeonLeaderboardCatalog from "../src/game/generated/dungeonLeaderboardCatalog.generated.json" with { type: "json" };
 
 const scrypt = promisify(scryptCallback);
@@ -402,13 +403,78 @@ export function openGameDatabase(options = {}) {
     }
   }
 
+  function cloudSaveDataForWrite(row) {
+    if (!row) return null;
+    try {
+      const data = JSON.parse(row.data_json);
+      if (!data || typeof data !== "object" || Array.isArray(data)) throw new Error("Cloud save data is not an object.");
+      return data;
+    } catch {
+      throw new GameDatabaseError("The cloud save is unreadable.", 500, "cloud_save_corrupt");
+    }
+  }
+
+  function previousCloudSaveForPut(row) {
+    try {
+      return cloudSaveDataForWrite(row);
+    } catch (error) {
+      // Keep legacy PUT's ability to replace an unreadable save document.
+      if (error instanceof GameDatabaseError && error.code === "cloud_save_corrupt") return null;
+      throw error;
+    }
+  }
+
+  function saveCloudData(accountId, data) {
+    const now = Date.now();
+    const row = statements.upsertCloudSave.get(accountId, JSON.stringify(data), now);
+    return { revision: Number(row.revision), updatedAt: Number(row.updated_at), data };
+  }
+
+  function transactCloudSave(operation) {
+    database.exec("BEGIN IMMEDIATE");
+    try {
+      const result = operation();
+      database.exec("COMMIT");
+      return result;
+    } catch (error) {
+      database.exec("ROLLBACK");
+      throw error;
+    }
+  }
+
   function putCloudSave(accountId, data) {
     if (!data || typeof data !== "object" || Array.isArray(data)) {
       throw new GameDatabaseError("Cloud save data must be an object.");
     }
-    const now = Date.now();
-    const row = statements.upsertCloudSave.get(accountId, JSON.stringify(data), now);
-    return { revision: Number(row.revision), updatedAt: Number(row.updated_at), data };
+    return transactCloudSave(() => {
+      const previous = previousCloudSaveForPut(statements.cloudSave.get(accountId));
+      const nextData = { ...data };
+      const hasPreviousCards = previous !== null && Object.hasOwn(previous, "bossCards");
+      const hasIncomingCards = Object.hasOwn(data, "bossCards");
+      if (hasPreviousCards || hasIncomingCards) {
+        nextData.bossCards = mergeBossCardCollections([previous?.bossCards, data.bossCards]);
+      }
+      return saveCloudData(accountId, nextData);
+    });
+  }
+
+  function patchCloudSaveBossCards(accountId, bossCards, expectedRevision) {
+    if (!Number.isSafeInteger(expectedRevision) || expectedRevision < 0) {
+      throw new GameDatabaseError("Expected cloud save revision must be a nonnegative integer.", 400, "invalid_revision");
+    }
+    return transactCloudSave(() => {
+      const row = statements.cloudSave.get(accountId);
+      const currentRevision = row ? Number(row.revision) : 0;
+      if (currentRevision !== expectedRevision) {
+        throw new GameDatabaseError("Cloud save revision changed. Reload before retrying.", 409, "revision_conflict");
+      }
+      const previous = cloudSaveDataForWrite(row) ?? { version: 1, characters: [] };
+      const nextData = {
+        ...previous,
+        bossCards: mergeBossCardCollections([previous.bossCards, bossCards]),
+      };
+      return saveCloudData(accountId, nextData);
+    });
   }
 
   function isGameMaster(account) {
@@ -1213,6 +1279,7 @@ export function openGameDatabase(options = {}) {
     logout: (token) => { if (typeof token === "string" && token) statements.deleteSession.run(tokenHash(token)); },
     getCloudSave,
     putCloudSave,
+    patchCloudSaveBossCards,
     isGameMaster,
     getManastormConfig,
     putManastormConfig,