/**
 * The `Pick` kind: several options from a list that narrows as a person types.
 *
 * Every option carries a mark saying whether it is picked, and `space` toggles
 * the one under the caret. Options that name a group sit one step in beneath
 * the group's header, whose mark says whether all, some, or none of them are
 * picked and which toggles them together. Typing narrows the list to the
 * options whose titles contain what was typed, and a group with none of them
 * goes. The list shows as much as the height it is given allows, names what it
 * left out above and below, and keeps the header of the caret's group pinned
 * above it once the header has scrolled away. Neither the reducer nor the view
 * touches the terminal.
 */
import type { Doc } from "../doc.js";
import { type AskKey, type AskKind, type AskReducerAction, type PickAsk } from "./ask.js";
/** Where the caret stands, what is picked, what narrows the list, and what was refused. */
export interface PickState {
    /** The caret's row among the rows the filter leaves. */
    readonly cursor: number;
    /** The positions in the question's options of those picked. */
    readonly picked: ReadonlySet<number>;
    readonly filter: string;
    /** Why the last key was refused, until the next key that changes something. */
    readonly problem?: string;
}
export type PickAction = AskReducerAction<PickState, ReadonlyArray<number>>;
/**
 * One line of the list: a group's header with every option in the group and
 * those the filter leaves, or one option by its position in the question.
 */
export type PickRow = {
    readonly _tag: "Group";
    readonly label: string;
    readonly members: ReadonlyArray<number>;
    readonly shown: ReadonlyArray<number>;
} | {
    readonly _tag: "Option";
    readonly index: number;
    readonly grouped: boolean;
};
/** The question opens on its first row, with the options it marks as selected picked. */
export declare const initialPickState: <A>(ask: PickAsk<A>) => PickState;
/**
 * The rows the filter leaves, in order: options without a group first, then
 * each group in the order it first appears, its header before its options. A
 * group none of whose options match is left out, header and all.
 */
export declare const pickRows: <A>(ask: PickAsk<A>, filter: string) => ReadonlyArray<PickRow>;
/**
 * One key against one list. The arrows move the caret and stop at either end;
 * `space` toggles the row under it, a group's header toggling the options of
 * the group that show; `ctrl`+`a` toggles every option that shows; `enter`
 * submits what is picked once it is within the question's bounds. Typed text
 * narrows the list, `backspace` takes back a character, and `ctrl`+`u` or
 * escape clears the filter. Escape with nothing typed, and an interrupt,
 * cancel.
 */
export declare const reducePick: <A>(ask: PickAsk<A>, state: PickState, key: AskKey) => PickAction;
/** The question as the live scene shows it in `rows` lines while it stands open. */
export declare const pickDoc: <A>(ask: PickAsk<A>, state: PickState, rows: number) => Doc;
/**
 * The one transcript line an answered list leaves behind: the titles picked,
 * the first few by name and the rest as a count.
 */
export declare const pickAnswer: <A>(ask: PickAsk<A>, picked: ReadonlyArray<number>) => Doc;
/** A `Pick` as the `Screen` runs it. */
export declare const pickKind: <A>(ask: PickAsk<A>) => AskKind<PickState, A>;
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