/**
 * MongoDB Connection Management
 *
 * Singleton pool, connect/close, default db accessor.
 * Extracted from mongo.ts — pure code movement.
 */
import { type Collection, type Db, type Document, MongoClient } from 'mongodb';
type PoolPreset = 'high' | 'standard' | 'low';
interface PoolConfig {
    maxPoolSize: number;
    minPoolSize: number;
}
export interface ConnectOptions {
    /** Pool size preset or custom config */
    pool?: PoolPreset | PoolConfig;
    /** Database name (defaults to DATABASE_NAME env or 'app') */
    dbName?: string;
    /** Label for logging */
    label?: string;
    /** Enable Next.js hot-reload persistence via globalThis */
    nextjs?: boolean;
}
/**
 * Connect to MongoDB. Returns the same client/db for the same URI (singleton).
 * Safe to call multiple times — only connects once per URI.
 */
export declare function connect(uri?: string, options?: ConnectOptions): Promise<{
    client: MongoClient;
    db: Db;
}>;
/** Close all connection pools. Call on graceful shutdown. */
export declare function closePool(): Promise<void>;
/** Get the default database instance. Connects automatically if needed. */
export declare function getDb(options?: ConnectOptions): Promise<Db>;
/** Get a typed collection from the default database */
export declare function getCollection<T extends Document>(name: string): Promise<Collection<T>>;
/**
 * Gracefully close all MongoDB pools and exit the process.
 * Safe to call multiple times — only runs once.
 *
 * Wire this to ALL process exit events in your entry point:
 *
 * ```typescript
 * import { gracefulShutdown } from '@/core/db/index.js';
 *
 * process.on('SIGTERM', gracefulShutdown);
 * process.on('SIGINT', gracefulShutdown);
 * process.on('uncaughtException', (err) => {
 *   console.error('Uncaught Exception:', err);
 *   gracefulShutdown(1);
 * });
 * process.on('unhandledRejection', (reason) => {
 *   console.error('Unhandled Rejection:', reason);
 *   gracefulShutdown(1);
 * });
 * ```
 */
export declare function gracefulShutdown(exitCode?: number | unknown): Promise<void>;
export {};
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