/**
 * Which dialect the file claims to be.
 *
 * Layer 2. Sole owner of the version-block and reserved-field grammars — the two fields that
 * decide sample width, EDF+ dialect and continuity, and therefore every byte offset and every
 * time value computed downstream.
 *
 * Two rules deserve stating because they look wrong:
 *
 * - The 8-byte version block is the ONLY reliable EDF-vs-BDF discriminator. EDF+ deliberately
 *   keeps `'0       '` so legacy readers still open the file, so nothing in the reserved field
 *   can be trusted to identify the family.
 * - BDF's version block is not ASCII: byte 0 is 0xFF, then `'BIOSEMI'`.
 */
import { type DiagnosticSink } from '../diagnostics/collector.js';
import type { EdfVariant } from '../types.js';
/**
 * The half of a variant that decides byte layout: EDF stores 16-bit samples, BDF 24-bit. It is
 * detected from the version byte rather than the reserved marker, because a file can be BDF
 * without ever claiming `BDF+`, and every offset in the record depends on getting this right.
 */
export type EdfFamily = 'EDF' | 'BDF';
/** The recognised reserved-field prefixes. Matched on the first five bytes, never trimmed. */
export type EdfReservedMarker = 'EDF+C' | 'EDF+D' | 'BDF+C' | 'BDF+D' | '24BIT';
/**
 * Everything the two identifying fields yield, kept apart rather than collapsed into `variant`.
 * The parts disagree on real files — a 24-bit file whose reserved field says nothing is BDF with
 * no marker — and each consumer needs a different one, so none of them is derived twice.
 */
export interface EdfVariantInfo {
    readonly variant: EdfVariant;
    /** From the version block alone. Sample width follows from this and nothing else. */
    readonly family: EdfFamily;
    readonly bytesPerSample: 2 | 3;
    readonly continuity: 'continuous' | 'discontinuous';
    /** True for EDF+C/EDF+D/BDF+C/BDF+D: the file claims the EDF+ dialect, so the subfield
     *  grammars in `identification.ts` apply and an annotation signal is mandatory. */
    readonly isPlus: boolean;
    /** The five-byte prefix that actually matched, or `undefined` when the field is blank or
     *  unrecognised. */
    readonly reservedMarker: EdfReservedMarker | undefined;
    /** Trimmed, case-sensitive annotation label for this family. */
    readonly annotationsLabel: string;
    /** What the sample width can represent. Drives `DIGITAL_RANGE_EXCEEDS_FORMAT`. */
    readonly digitalMinimumLimit: number;
    readonly digitalMaximumLimit: number;
}
/**
 * EDF's version block: ASCII `'0'` then seven spaces.
 *
 * NUL is accepted as padding alongside space. The spec says space, but a writer that pads with
 * NUL has produced the same value, and `NOT_AN_EDF_FILE` — the only alternative here — would
 * refuse a file whose every other byte is fine.
 */
export declare function isEdfVersionBlock(versionBytes: Uint8Array): boolean;
/** BDF's version block: byte 0 = 0xFF, bytes 1..7 = `'BIOSEMI'`. Exact, no padding tolerance. */
export declare function isBdfVersionBlock(versionBytes: Uint8Array): boolean;
/**
 * The dialect marker carried by the reserved field, matched on its five-byte PREFIX.
 *
 * The prefix rule is what makes `'EDF+D v2.1'` an EDF+D file rather than an unrecognised one.
 */
export declare function reservedMarkerOf(reserved: string): EdfReservedMarker | undefined;
/** The container these bytes begin with, or `undefined` — which is most files. */
export declare function containerAt(bytes: Uint8Array): string | undefined;
/**
 * Read the version block and the reserved field, and decide the variant.
 *
 * `headerBytes` must cover at least the 256-byte fixed header; the caller has already refused
 * anything shorter with `SOURCE_TOO_SMALL`.
 *
 * When the reserved marker names a different family than the version block does — `'BDF+C'` on
 * a file whose version block is EDF — the version block wins for the family, but the marker is
 * still honoured for continuity and EDF+ dialect, and the disagreement is reported. Dropping
 * the `D` would silently turn a discontinuous recording into one whose every timestamp is
 * wrong; keeping the wrong sample width would make every sample wrong instead.
 */
export declare function detectVariant(headerBytes: Uint8Array, sink: DiagnosticSink): EdfVariantInfo;
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