Feature/persist watermelondb

package.json

@@ -68,6 +68,7 @@
         "@evilmartians/lefthook": "^1.6.13",
         "@happy-dom/global-registrator": "^14.12.0",
         "@jest/globals": "^29.7.0",
+        "@nozbe/watermelondb": "^0.28.0",
         "@react-native-async-storage/async-storage": "^1.23.1",
         "@release-it/conventional-changelog": "^8.0.1",
         "@supabase/supabase-js": "^2.43.4",

src/persist-plugins/watermelondb.ts

@@ -0,0 +1,90 @@
+import { applyChanges, internal } from '@legendapp/state';
+
+import type { ObservablePersistPlugin, PersistMetadata, PersistOptions } from '@legendapp/state/sync';
+import type { Change } from '@legendapp/state';
+import type LocalStorage from '@nozbe/watermelondb/Database/LocalStorage';
+
+const MetadataSuffix = '__m';
+
+const { safeParse, safeStringify } = internal;
+
+class ObservablePersistWatermelonDB implements ObservablePersistPlugin {
+    private readonly storage: LocalStorage;
+    private data: Record<string, unknown> = {};
+
+    constructor(storage: LocalStorage) {
+        if (!storage) {
+            throw new Error(
+                '[legend-state] ObservablePersistWatermelonDB failed to initialize. You need to pass the WatermelonDB localStorage instance.',
+            );
+        }
+
+        this.storage = storage;
+    }
+
+    getTable<T = any>(table: string, init: any): T {
+        if (this.data[table] === undefined) {
+            try {
+                this.storage._getSync(table, (val) => {
+                    this.data[table] = val ? safeParse(val) : init;
+                });
+            } catch (e) {
+                console.error('[legend-state] ObservablePersistWatermelonDB parse failed', table, e);
+            }
+        }
+
+        return this.data[table] as T;
+    }
+
+    deleteTable(table: string): Promise<void> | void {
+        if (!this.storage) return undefined;
+
+        delete this.data[table];
+
+        return this.storage.remove(table);
+    }
+
+    set(table: string, changes: Change[]): Promise<void> | void {
+        const current = this.data[table] ?? {};
+        const updated = applyChanges(current, changes);
+        this.data[table] = updated;
+
+        return this.storage.set(table, safeStringify(updated));
+    }
+
+    getMetadata(table: string, _config: PersistOptions): PersistMetadata {
+        return this.getTable(table + MetadataSuffix, {});
+    }
+
+    setMetadata(table: string, metadata: PersistMetadata): Promise<void> | void {
+        const key = table + MetadataSuffix;
+        this.data[key] = metadata;
+
+        return this.storage.set(key, metadata);
+    }
+
+    deleteMetadata(table: string): Promise<void> | void {
+        const key = table + MetadataSuffix;
+        delete this.data[key];
+
+        return this.storage.remove(key);
+    }
+}
+
+/**
+ * Usage:
+ * ```ts
+ * import { observablePersistWatermelonDB } from '@legendapp/state/sync-plugins/ObservablePersistWatermelonDB'
+ * import { database } from '@/lib/db'
+ *
+ * syncObservable(settings$, {
+ *   persist: {
+ *     name: 'settings',
+ *     plugin: observablePersistWatermelonDB(database.localStorage),
+ *   },
+ * })
+ * ```
+ */
+export function observablePersistWatermelonDB(localStorage: LocalStorage) {
+    return new ObservablePersistWatermelonDB(localStorage);
+}