/**
 * Compressor Module
 *
 * Phase 3: Reduce token usage by extracting only essential fields
 * from search results based on compression level.
 *
 * Token targets:
 * - minimal: ~20 tokens per record (id, url, source)
 * - standard: ~50 tokens per record (+ title, year)
 * - full: ~80 tokens per record (+ type, creator)
 */
import type { CompressionLevel, CompressedRecord, CompressionOptions, CompressionResult } from './types.js';
/**
 * Estimate the number of tokens for a data structure
 *
 * Uses a simple heuristic: ~4 characters per token for English text,
 * plus JSON structure overhead.
 *
 * @param data - Any data structure (will be JSON stringified)
 * @returns Estimated token count
 */
export declare function estimateTokens(data: unknown): number;
/**
 * Truncate a title at a word boundary
 *
 * Preserves word boundaries to avoid cutting mid-word.
 * Adds ellipsis if truncated.
 *
 * @param title - Original title
 * @param maxLength - Maximum length (default: 50)
 * @returns Truncated title
 */
export declare function truncateTitle(title: string, maxLength?: number): string;
/**
 * Extract year from various date formats in a record
 *
 * Handles:
 * - Direct year field: { year: 1920 }
 * - ISO date: { date: "1920-05-12" }
 * - Year string: { dateCreated: "1920" }
 * - Decade: { period: "1920s" }
 * - In title: { title: "Report 1920" }
 *
 * @param record - Record with potential date fields
 * @returns Extracted year or undefined
 */
export declare function extractYear(record: Record<string, unknown>): number | undefined;
/**
 * Compress a single record to the specified level
 *
 * @param record - Original record with any structure
 * @param source - Source data provider name
 * @param level - Compression level
 * @param maxTitleLength - Maximum title length for truncation
 * @returns Compressed record
 */
export declare function compressRecord(record: Record<string, unknown>, source: string, level: CompressionLevel, maxTitleLength?: number): CompressedRecord;
/**
 * Compress multiple records with statistics
 *
 * @param records - Array of records to compress
 * @param options - Compression options
 * @returns Compression result with statistics
 */
export declare function compressRecords(records: Array<{
    record: Record<string, unknown>;
    source: string;
}>, options?: Partial<CompressionOptions>): CompressionResult;
/**
 * Convenience function to compress an array of records with inferred source
 *
 * @param records - Array of records (must have source field)
 * @param options - Compression options
 * @returns Compression result
 */
export declare function compressRecordArray(records: Record<string, unknown>[], options?: Partial<CompressionOptions>): CompressionResult;
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