import type { DatasetSchema } from '../entities/dataset-schema.js';
/**
* Service for computing effective row limits for query results.
*
* Handles the logic for determining the actual number of rows to return
* based on dataset limits and user requests.
*/
export class LimitService {
/**
* Compute the effective limit for a query.
*
* Logic:
* - If no limit requested, use dataset's defaultLimit
* - If limit requested, use min(requested, maxLimit)
* - Always enforce maxLimit as upper bound
*
* @param schema - The dataset schema containing limit configuration
* @param requestedLimit - The limit requested by the client (optional)
* @returns The effective limit to apply
*/
computeEffectiveLimit(schema: DatasetSchema, requestedLimit?: number): number {
const { defaultLimit, maxLimit } = schema.limits;
// If no limit requested, use default
if (requestedLimit === undefined || requestedLimit === null) {
return defaultLimit;
}
// If limit is <= 0, use default
if (requestedLimit <= 0) {
return defaultLimit;
}
// Return the minimum of requested and max limit
return Math.min(requestedLimit, maxLimit);
}
/**
* Check if the result set was truncated due to limit.
*
* @param totalRows - The total number of rows available
* @param effectiveLimit - The limit that was applied
* @returns true if more rows exist beyond the limit
*/
wasTruncated(totalRows: number, effectiveLimit: number): boolean {
return totalRows > effectiveLimit;
}
}
