import { Database } from 'duckdb-async';
import { TempDataManager } from '../../../modules/temp-data-manager';
import { TacoFileParser } from './base-taco-file-parser';
import { ColumnHeader } from '../../../types/column-header';
import { DataRow } from '../../../../shared/types/data-row';
export type ParquetTacoParserType = typeof ParquetTacoParser;
type ParsedDataRow = Record<string, string | null>;
export declare class ParquetTacoParser extends TacoFileParser {
    private tempDataManager;
    private extractorId;
    private filename;
    private filepath;
    private columnHeaderMap;
    private headersFromFile;
    private db;
    constructor(tempDataManager: TempDataManager, extractorId: string, filename: string);
    /**
     * Set columns metadata info to the parser. When columnHeaders are set, getColumnHeaders will
     * respect the given info. Otherwise, all fields are assumed as string type.
     *
     * To prevent the method from being misused, this method can be called once, otherwise,
     * it throws an error.
     */
    setColumnHeaders(columnHeaders: ColumnHeader[]): void;
    /**
     * Get ColumnHeaders for a Parquet file.
     *
     * By default, it returns all column header fields and all columns are typed as string.
     * If columns metadata is set by setColumnHeaders, it will filter the columns with the given columnHeaders,
     * while the column order from the file is still preserved.
     */
    getColumnHeaders(): Promise<ColumnHeader[]>;
    getRowCount(): Promise<number>;
    /**
     * Get the set of data rows from the Parquet file with the specified limit and offset.
     */
    getDataRows(limit: number, offset: number): Promise<{
        data: DataRow[];
        hasMoreRows: boolean;
    }>;
    getDb(): Promise<Database>;
    /**
     * Retrieves the column names from the first row of a parquet file located at the given file path.
     *
     * @param {Database} db - The duckdb database instance to execute the query against.
     * @param {string} filepath - The file path of the parquet file to read from.
     *
     * @returns {Promise<string[]>} - A Promise that resolves with an array of string column names, or an empty array if no column names were found.
     */
    private getColumnNamesFromFile;
}
export declare function stringifyData(datarows: Record<string, unknown>[]): asserts datarows is ParsedDataRow[];
export {};