import type { Collection } from "@valkyr/db";

import type { Snapshot, SnapshotsProvider } from "../../../types/adapter.ts";

export class BrowserSnapshotsProvider implements SnapshotsProvider {
  constructor(readonly snapshots: Collection<Snapshot>) {}

  /**
   * 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: Record<string, unknown>): Promise<void> {
    await this.snapshots.insertOne({ name, stream, cursor, state });
  }

  /**
   * 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.snapshots.findOne({ name, stream });
  }

  /**
   * 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.snapshots.remove({ name, stream });
  }
}