/**
 * S3 Snapshot Store - Full database snapshots for faster restore.
 *
 * Stores periodic full snapshots to S3 at:
 *   <prefix><storage_path>/snapshots/<timestamp>_<snapshot_id>.json.gz
 *
 * Snapshots are triggered by:
 * - Time interval (e.g., every 5 minutes)
 * - Change volume threshold (e.g., every 1000 changes)
 */
import { type S3Client } from '@aws-sdk/client-s3';
import { type S3StorageConfig, type StoragePathResolver } from './s3-config.js';
import type { SyncManager, SnapshotChunk } from '@quereus/sync';
/**
 * Snapshot metadata stored alongside the snapshot.
 */
export interface SnapshotMetadata {
    /** Unique snapshot identifier */
    snapshotId: string;
    /** Database ID this snapshot belongs to */
    databaseId: string;
    /** Timestamp when snapshot was created */
    timestamp: string;
    /** Total number of rows in the snapshot */
    totalRows: number;
    /** Total number of tables in the snapshot */
    totalTables: number;
    /** Compressed size in bytes */
    compressedSizeBytes: number;
    /** HLC timestamp of latest change in snapshot */
    hlcTimestamp?: string;
}
/**
 * Configuration for periodic snapshots.
 */
export interface SnapshotScheduleConfig {
    /** Interval in milliseconds between snapshots (default: 5 minutes) */
    intervalMs: number;
    /** Change count threshold to trigger snapshot (default: 1000) */
    changeThreshold: number;
    /** Maximum number of snapshots to retain per database (default: 5) */
    maxRetained: number;
}
/**
 * Tracker for pending snapshot operations.
 */
interface DatabaseSnapshotState {
    lastSnapshotAt: number;
    changesSinceSnapshot: number;
    snapshotInProgress: boolean;
}
/**
 * S3 Snapshot Store for full database snapshots.
 */
export declare class S3SnapshotStore {
    private readonly client;
    private readonly config;
    private readonly scheduleConfig;
    private readonly resolveStoragePath;
    private readonly databaseStates;
    private checkTimer;
    constructor(client: S3Client, config: S3StorageConfig, scheduleConfig?: Partial<SnapshotScheduleConfig>, resolveStoragePath?: StoragePathResolver);
    /**
     * Start periodic snapshot checks.
     */
    start(): void;
    /**
     * Stop periodic snapshot checks.
     */
    stop(): void;
    /**
     * Record that changes have been applied to a database.
     */
    recordChanges(databaseId: string, changeCount: number): void;
    /**
     * Check if a database needs a snapshot based on time or change volume.
     */
    needsSnapshot(databaseId: string): boolean;
    /**
     * Check all tracked databases for scheduled snapshots.
     */
    private checkScheduledSnapshots;
    /**
     * Create and store a full snapshot for a database.
     */
    createSnapshot(databaseId: string, syncManager: SyncManager): Promise<SnapshotMetadata>;
    /**
     * Type guard to check if a chunk is a column-versions chunk.
     */
    private isColumnVersionsChunk;
    /**
     * Check if a snapshot exists for a database.
     */
    hasSnapshot(databaseId: string): Promise<boolean>;
    /**
     * Download and deserialize the latest snapshot for a database.
     * Returns null if no snapshots exist.
     */
    downloadLatestSnapshot(databaseId: string): Promise<{
        chunks: SnapshotChunk[];
        metadata: {
            snapshotId: string;
            timestamp: string;
        };
    } | null>;
    /**
     * Compress data using gzip.
     */
    private compressData;
    /**
     * Decompress gzipped data.
     */
    private decompressData;
    /**
     * Get databases that need snapshots (for external scheduling).
     */
    getDatabasesNeedingSnapshot(): string[];
    /**
     * Force a snapshot for a database (ignoring schedule).
     */
    forceSnapshot(databaseId: string, syncManager: SyncManager): Promise<SnapshotMetadata>;
    /**
     * Get snapshot state for a database.
     */
    getState(databaseId: string): DatabaseSnapshotState | undefined;
}
/**
 * Create an S3 snapshot store from configuration.
 */
export declare function createS3SnapshotStore(client: S3Client, config: S3StorageConfig, scheduleConfig?: Partial<SnapshotScheduleConfig>, resolveStoragePath?: StoragePathResolver): S3SnapshotStore;
export {};
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