/**
 * @fileoverview Latest-period selection behind worldbank_get_data's `mrv` and
 * `mrnev`, shared by both data paths. Upstream's own `mrv`, `mrnev`, and
 * `frequency` are never sent: the Indicators API's response cache does not key
 * on them, so a request carrying one can be answered with the body computed for
 * another. The standard path reads the `date` window {@link latestWindow}
 * computes at the selected period form and, when that falls short, the
 * {@link fullSpan} at that form; both paths reduce what they read with
 * {@link selectLatest}.
 * @module services/worldbank/latest-values
 */
import { type PeriodForm } from './periods.js';
/**
 * Which latest periods to keep: `mrv`, the N most recent periods holding a value
 * for any series in the set, every series at each; `mrnev`, each series' own N
 * most recent periods holding a value.
 */
export type LatestSelection = {
    mode: 'mrv' | 'mrnev';
    count: number;
};
/**
 * Every period a series carries at `form`, as a `date` span. A span's form
 * selects which periods a series publishing several forms returns — Global
 * Economic Monitor answers `1900:2100` with its annual rows only, and
 * `1900M01:2100M12` with its months — while a series with one form answers a
 * span at any other form with its whole series. `1900:2100` returns the same rows
 * as a request without `date`.
 */
export declare function fullSpan(form: PeriodForm): string;
/**
 * The window a latest-value read asks for first, at `form`, open-ended: from
 * {@link WINDOW_YEARS} years before `year`, or far enough back to hold `count`
 * periods when that is further — `2016:2100`, `2016Q1:2100Q4`, or
 * `2024M01:2100M12` in 2026. It holds the answer for nearly every series and
 * country; a series short of `count` values inside it is read again over the
 * {@link fullSpan} at the same form.
 */
export declare function latestWindow(count: number, year: number, form?: PeriodForm): string;
/**
 * The period form a selection is made within when the caller names none: annual
 * whenever the periods include a year, otherwise the first form they carry. A
 * series that publishes an annual value beside monthly or quarterly ones is
 * selected annually; a quarterly-only series keeps its quarters.
 */
export declare function selectionForm(periods: Iterable<string>): PeriodForm | undefined;
/** How to read a row of either data path. */
export type RowReader<T> = {
    /** The series a row belongs to: its country, plus any further dimension value. */
    series: (row: T) => string;
    period: (row: T) => string;
    hasValue: (row: T) => boolean;
};
/** The rows a selection keeps, in input order, and whether the rows held enough to make it. */
export type LatestRows<T> = {
    rows: T[];
    /**
     * True when the rows answered the selection in full: `mrv` found `count` periods
     * holding a value, `mrnev` found `count` values for every series. False on no rows.
     */
    complete: boolean;
    /** For `mrnev`, the series holding fewer than `count` values at the form, in input order. */
    short: string[];
};
/**
 * Keep the latest periods `selection` asks for out of `rows`, counting only rows
 * at `form`: a row at any other form never matches. A series with no value at all
 * keeps no row under `mrnev`, and under `mrv` a series is kept at each selected
 * period, null or not, as the standard endpoint's own `mrv` returns it.
 */
export declare function selectLatest<T>(rows: readonly T[], selection: LatestSelection, form: PeriodForm | undefined, read: RowReader<T>): LatestRows<T>;
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