/**
 * SQL Mode 2 — Aggregate Translator
 *
 * GROUP BY → $group
 * HAVING → $match (after $group)
 * COUNT/SUM/AVG/MIN/MAX/GROUP_CONCAT/ARRAY_AGG/STDDEV → accumulators
 * Window functions → $setWindowFields
 */
import type { AggregateField, WindowSpec } from '../types.js';
/**
 * Check if a SELECT AST has aggregate functions.
 */
export declare function hasAggregates(columns: unknown): boolean;
/**
 * Check if a SELECT AST has window functions.
 */
export declare function hasWindowFunctions(columns: unknown): boolean;
/**
 * Extract aggregate fields from columns.
 */
export declare function extractAggregateFields(columns: unknown, tableAliases?: Map<string, string>): AggregateField[];
/**
 * Extract window function specs from columns.
 */
export declare function extractWindowSpecs(columns: unknown): WindowSpec[];
export interface GroupStageResult {
    groupStage: Record<string, unknown>;
    /** Computed fields that need $addFields BEFORE the $group (for complex GROUP BY expressions) */
    preComputedFields?: Record<string, unknown>;
}
/**
 * Build $group stage from GROUP BY + aggregate functions.
 */
export declare function buildGroupStage(groupBy: unknown, aggregateFields: AggregateField[], columns: unknown, tableAliases: Map<string, string>): GroupStageResult;
/**
 * Build $match stage for HAVING clause (placed after $group).
 * HAVING operates on aggregated values, so aggr_func references must be resolved
 * to their aliases from the $group stage (e.g., AVG(salary) → avg_sal).
 */
export declare function buildHavingStage(having: unknown, aggregateFields?: AggregateField[]): Record<string, unknown> | null;
/**
 * Build $setWindowFields stages for window functions.
 * Specs with different partitionBy/orderBy signatures get separate stages.
 */
export declare function buildWindowStages(specs: WindowSpec[]): Record<string, unknown>[];
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