/**
 * Channel naming and selection.
 *
 * Two real-world facts drive this module. EDF labels are free text that routinely
 * contain spaces and punctuation ("EEG Fpz-Cz"), and they are not guaranteed to be
 * unique — CHB-MIT recordings ship two channels both labelled "T8-P8", and some
 * carry a channel labelled "-". Labels are therefore preserved verbatim in output,
 * and only disambiguated when the file itself is ambiguous.
 */
import type { EdfSignal } from '../edf/header.js';
/**
 * The name of the column the writer puts in front of the channels, which no channel may take.
 *
 * Exported and used by the writer rather than repeated there, because the whole point of
 * reserving it here is that the two cannot drift apart.
 */
export declare const TIME_COLUMN = "time_s";
export declare class ChannelSelectionError extends Error {
    constructor(message: string);
}
/**
 * Column name for a signal.
 *
 * Names are derived from the whole file, not from the current selection, so a given
 * channel always produces the same column regardless of which channels were asked
 * for. Duplicated labels get a `_ch<index>` suffix pointing at their position in
 * the file, which is the only thing that reliably tells them apart.
 */
export declare function buildColumnNames(signals: readonly EdfSignal[]): Map<number, string>;
/**
 * Channels whose column name was pushed off their own label to keep the header unique.
 *
 * A channel genuinely labelled `T8_ch0` loses that name when another label's disambiguating
 * suffix wants it, and the resulting column is the one thing in the output that no longer
 * matches the file. Silence there is what made the collision hard to see in the first place:
 * the only warning raised was about the *other* label.
 */
export declare function renamedByCollision(signals: readonly EdfSignal[], columnNames: ReadonlyMap<number, string>): EdfSignal[];
export interface ChannelSelection {
    signals: EdfSignal[];
    /** Labels that matched more than one channel, so the user knows why they got extras. */
    ambiguous: {
        term: string;
        matched: EdfSignal[];
    }[];
}
/**
 * Resolve a `--channels` specification against the file's signals.
 *
 * Matching is case-insensitive on the exact label, with `#<index>` available to
 * address a specific channel when labels collide. A term that matches nothing is an
 * error rather than a silent omission: quietly dropping a requested channel would
 * hand the user a CSV that is missing data they explicitly asked for.
 */
export declare function selectChannels(signals: readonly EdfSignal[], terms: readonly string[]): ChannelSelection;
/**
 * The label written so that typing it back selects this channel, or null when nothing does.
 *
 * Double quotes wherever they survive, since they also show where the label begins and ends
 * and every documented example is written that way. They do not survive a label containing a
 * quote of their own, and — less obviously — a shell still expands `$`, a backtick and a
 * backslash inside them, so `EEG $ref` would arrive as `EEG ` with nothing said. Those go in
 * single quotes, the one POSIX form with no escapes inside it, where a single quote in the
 * label closes, escapes and reopens.
 *
 * Two labels have no form at all. `--channels` splits its list on commas after the shell has
 * finished quoting, so no quoting reaches a label with one in it; and a control character
 * cannot be typed. Both take a position instead, which is what NONPRINTABLE_LABEL already
 * says for the same two reasons.
 */
export declare function typeable(label: string): string | null;