feat: version 2 beta

adapters/postgres/providers/snapshot.ts

@@ -0,0 +1,82 @@
+import type { Helper } from "postgres";
+
+import type { Snapshot, SnapshotsProvider } from "../../../types/adapter.ts";
+import type { PostgresDatabase } from "../database.ts";
+
+type PGSnapshot = Omit<Snapshot, "state"> & { state: string };
+
+export class PostgresSnapshotsProvider implements SnapshotsProvider {
+  constructor(
+    readonly db: PostgresDatabase,
+    readonly schema?: string,
+  ) {}
+
+  get table(): Helper<string, []> {
+    if (this.schema !== undefined) {
+      return this.db.sql(`${this.schema}.snapshots`);
+    }
+    return this.db.sql("public.snapshots");
+  }
+
+  /**
+   * Add snapshot state under given reducer stream.
+   *
+   * @param name   - Name of the reducer the snapshot is attached to.
+   * @param stream - Stream the snapshot is attached to.
+   * @param cursor - Cursor timestamp for the last event used in the snapshot.
+   * @param state  - State of the reduced events.
+   */
+  async insert(name: string, stream: string, cursor: string, state: any): Promise<void> {
+    await this.db.sql`
+      INSERT INTO ${this.table} ${this.db.sql(this.#toDriver({ name, stream, cursor, state }))}`.catch((error) => {
+      throw new Error(`EventStore > 'snapshots.insert' failed with postgres error: ${error.message}`);
+    });
+  }
+
+  /**
+   * Get snapshot state by stream.
+   *
+   * @param name   - Name of the reducer which the state was created.
+   * @param stream - Stream the state was reduced for.
+   */
+  async getByStream(name: string, stream: string): Promise<Snapshot | undefined> {
+    return this.db.sql<PGSnapshot[]>`SELECT * FROM ${this.table} WHERE name = ${name} AND stream = ${stream}`
+      .then(this.#fromDriver)
+      .then(([snapshot]) => snapshot)
+      .catch((error) => {
+        throw new Error(`EventStore > 'snapshots.getByStream' failed with postgres error: ${error.message}`);
+      });
+  }
+
+  /**
+   * Removes a snapshot for the given reducer stream.
+   *
+   * @param name   - Name of the reducer the snapshot is attached to.
+   * @param stream - Stream to remove from snapshots.
+   */
+  async remove(name: string, stream: string): Promise<void> {
+    await this.db.sql`DELETE FROM ${this.table} WHERE name = ${name} AND stream = ${stream}`.catch((error) => {
+      throw new Error(`EventStore > 'snapshots.remove' failed with postgres error: ${error.message}`);
+    });
+  }
+
+  /*
+   |--------------------------------------------------------------------------------
+   | Parsers
+   |--------------------------------------------------------------------------------
+   */
+
+  #fromDriver(snapshots: PGSnapshot[]): Snapshot[] {
+    return snapshots.map((snapshot) => {
+      snapshot.state = typeof snapshot.state === "string" ? JSON.parse(snapshot.state) : snapshot.state;
+      return snapshot as unknown as Snapshot;
+    });
+  }
+
+  #toDriver(snapshot: Snapshot): object {
+    return {
+      ...snapshot,
+      state: JSON.stringify(snapshot.state),
+    };
+  }
+}