import type { Logger } from './types';
export declare const TEXT_LIMIT = 4096;
export declare const CAPTION_LIMIT = 4096;
export interface ValidationOk {
    ok: true;
}
export interface ValidationFail {
    ok: false;
    reason: 'too_large' | 'extension_blocked';
    detail: string;
}
export type ValidationResult = ValidationOk | ValidationFail;
export type CheckTextLengthResult = {
    ok: true;
} | {
    ok: false;
    codePoints: number;
    limit: number;
};
/**
 * Code-point length check (parity with Python `visible_len`).
 * `[...text].length` walks the string by Unicode code points, NOT UTF-16 code units —
 * one astral-plane char (e.g. emoji) counts as 1 here vs 2 with `.length`.
 */
export declare function checkTextLength(text: string, limit?: number): CheckTextLengthResult;
/**
 * Auto-split for outbound text. Order:
 *   1. Paragraph boundaries (`\n\n`)
 *   2. Sentence boundaries (`. `, `! `, `? `, `\n`)
 *   3. Hard cut on a code-point boundary
 *
 * Markdown fenced code blocks (```...```) are kept intact when they fit within `limit`.
 *
 * Always returns at least one chunk; for empty input returns `[""]`.
 */
export declare function splitTextForSending(text: string, limit?: number): string[];
/**
 * Extracts the lowercased extension from a basename.
 *
 * **Pre:** `fileName` MUST be a basename — callers passing a full path must
 * call `path.basename(...)` (Node `node:path`) first. Slashes are not stripped.
 *
 * Examples:
 *   "report.PDF" → "pdf"
 *   "archive.tar.gz" → "gz"
 *   ".dotfile" → "dotfile"
 *   "noext" → ""
 *   "file." → ""
 */
export declare function normalizeExtension(fileName: string): string;
/**
 * Binary-MB ceiling. Parity with Python's `actual_size / (1024 * 1024)` user-display.
 */
export declare function bytesToMB(bytes: number): number;
/**
 * Runtime-mutable per-account file upload limits. Server pushes `getFileUploadLimits`
 * (id matches Python `IncomingUpdateMethod.CHANGED_FILE_UPLOAD_LIMITS`) with payload:
 *   { maxSize: int | null, extensions: { mode: "allow" | "block", list: string[] } | null }
 * `null` means "limit disabled" (Python parity).
 *
 * Static fallback (`staticMaxBytes`) is used only until the first valid server push.
 * After a server push with `maxSize: null`, the limit is treated as unlimited — we do NOT
 * fall back to the static cap.
 */
export declare class FileUploadLimits {
    private maxSizeFromServer;
    private hasServerMaxSize;
    private filterMode;
    private extensionsSet;
    private readonly staticMaxBytes;
    private readonly logger?;
    constructor(staticMaxBytes: number, logger?: Logger);
    /**
     * Validate + apply atomically. Corrupt payload → log warn + no-op (no partial state change).
     */
    updateFromServer(payload: Record<string, unknown>): void;
    /**
     * Effective max-bytes limit:
     *   - server pushed maxSize=null → Number.MAX_SAFE_INTEGER (limit disabled)
     *   - server pushed integer → that integer
     *   - never pushed → staticMaxBytes
     */
    getMaxBytes(): number;
    validateFile(fileName: string, sizeBytes: number): ValidationResult;
}
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