import { type Coverage } from "../../layout/structures/coverage.ts";
import { type FeatureList, type ScriptList } from "../../layout/structures/layout-common.ts";
import { SetDigest } from "../../layout/structures/set-digest.ts";
import type { GlyphId, uint16 } from "../../types.ts";
import type { Reader } from "../binary/reader.ts";
import { type ChainingContextSubstSubtable, type ContextSubstSubtable } from "./gsub-contextual.ts";
/** GSUB lookup types */
export declare enum GsubLookupType {
    Single = 1,
    Multiple = 2,
    Alternate = 3,
    Ligature = 4,
    Context = 5,
    ChainingContext = 6,
    Extension = 7,
    ReverseChainingSingle = 8
}
/** Base interface for all GSUB lookups */
export interface GsubLookup {
    type: GsubLookupType;
    flag: uint16;
    markFilteringSet?: uint16;
    /** Bloom filter for fast O(1) glyph rejection */
    digest: SetDigest;
}
/** Single substitution lookup (Type 1) */
export interface SingleSubstLookup extends GsubLookup {
    type: GsubLookupType.Single;
    subtables: SingleSubstSubtable[];
}
export interface SingleSubstSubtable {
    format: 1 | 2;
    coverage: Coverage;
    deltaGlyphId?: number;
    substituteGlyphIds?: GlyphId[];
}
/** Multiple substitution lookup (Type 2) */
export interface MultipleSubstLookup extends GsubLookup {
    type: GsubLookupType.Multiple;
    subtables: MultipleSubstSubtable[];
}
export interface MultipleSubstSubtable {
    coverage: Coverage;
    sequences: GlyphId[][];
}
/** Alternate substitution lookup (Type 3) */
export interface AlternateSubstLookup extends GsubLookup {
    type: GsubLookupType.Alternate;
    subtables: AlternateSubstSubtable[];
}
export interface AlternateSubstSubtable {
    coverage: Coverage;
    alternateSets: GlyphId[][];
}
/** Ligature substitution lookup (Type 4) */
export interface LigatureSubstLookup extends GsubLookup {
    type: GsubLookupType.Ligature;
    subtables: LigatureSubstSubtable[];
}
export interface LigatureSubstSubtable {
    coverage: Coverage;
    ligatureSets: LigatureSet[];
}
export interface LigatureSet {
    ligatures: Ligature[];
}
export interface Ligature {
    ligatureGlyph: GlyphId;
    componentGlyphIds: GlyphId[];
}
/** Context substitution lookup (Type 5) */
export interface ContextSubstLookup extends GsubLookup {
    type: GsubLookupType.Context;
    subtables: ContextSubstSubtable[];
}
/** Chaining context substitution lookup (Type 6) */
export interface ChainingContextSubstLookup extends GsubLookup {
    type: GsubLookupType.ChainingContext;
    subtables: ChainingContextSubstSubtable[];
}
/** Reverse chaining single substitution lookup (Type 8) */
export interface ReverseChainingSingleSubstLookup extends GsubLookup {
    type: GsubLookupType.ReverseChainingSingle;
    subtables: ReverseChainingSingleSubstSubtable[];
}
export interface ReverseChainingSingleSubstSubtable {
    coverage: Coverage;
    backtrackCoverages: Coverage[];
    lookaheadCoverages: Coverage[];
    substituteGlyphIds: GlyphId[];
}
/** Union of all GSUB lookup types */
export type AnyGsubLookup = SingleSubstLookup | MultipleSubstLookup | AlternateSubstLookup | LigatureSubstLookup | ContextSubstLookup | ChainingContextSubstLookup | ReverseChainingSingleSubstLookup;
/** GSUB table */
export interface GsubTable {
    version: {
        major: number;
        minor: number;
    };
    scriptList: ScriptList;
    featureList: FeatureList;
    lookups: AnyGsubLookup[];
}
export type { SequenceLookupRecord } from "./gsub-contextual.ts";
export declare function parseGsub(reader: Reader): GsubTable;
declare function parseGsubLookup(reader: Reader, _lookupListReader: Reader, _lookupOffset: number): AnyGsubLookup | null;
declare function parseExtensionLookup(reader: Reader, subtableOffsets: number[], baseProps: {
    flag: uint16;
    markFilteringSet?: uint16;
}): AnyGsubLookup | null;
export declare function applySingleSubst(lookup: SingleSubstLookup, glyphId: GlyphId): GlyphId | null;
export declare function applyLigatureSubst(lookup: LigatureSubstLookup, glyphIds: GlyphId[], startIndex: number): {
    ligatureGlyph: GlyphId;
    consumed: number;
} | null;
/**
 * Apply ligature substitution using a Uint16Array directly (avoids Array.from allocation).
 * glyphIds is a pre-allocated typed array, matchLen is the valid length to consider.
 */
export declare function applyLigatureSubstDirect(lookup: LigatureSubstLookup, glyphIds: Uint16Array, matchLen: number, startIndex: number): {
    ligatureGlyph: GlyphId;
    consumed: number;
} | null;
export declare const __testing: {
    parseGsubLookup: typeof parseGsubLookup;
    parseExtensionLookup: typeof parseExtensionLookup;
};