/**
 * Internal shape of pretext's PreparedTextWithSegments — only `segments` is in
 * pretext's public TS type; the numeric arrays exist at runtime but are not in
 * the published signature. Verified against node_modules/@chenglou/pretext/src/layout.ts.
 */
interface PretextInternals {
    /**
     * Per-segment text.
     */
    segments: string[];
    /**
     * Per-segment full width in pixels.
     */
    widths: number[];
    /**
     * Per-segment per-grapheme advance widths, or null when the segment is a single grapheme.
     */
    breakableFitAdvances: (number[] | null)[];
    /**
     * Per-segment line-end fit advance.
     */
    lineEndFitAdvances: number[];
    /**
     * Per-segment line-end paint advance.
     */
    lineEndPaintAdvances: number[];
}

/**
 * Per-grapheme data computed during dual-font layout. Internal to the engine;
 * consumed by computeLineRenderModel to derive the per-frame render model.
 */
export interface ComparisonChar {
    /**
     * Grapheme cluster (may be >1 code unit for emoji, combining marks).
     */
    char: string;
    /**
     * X offset from line start in fontA, pixels.
     */
    xA: number;
    /**
     * Advance width of this grapheme in fontA, pixels.
     */
    widthA: number;
    /**
     * X offset from line start in fontB, pixels.
     */
    xB: number;
    /**
     * Advance width of this grapheme in fontB, pixels.
     */
    widthB: number;
}

/**
 * A single laid-out line. `chars` carries the per-grapheme data needed by
 * computeLineRenderModel. Consumers should not iterate it directly.
 */
export interface ComparisonLine {
    /**
     * Full text of this line as returned by pretext.
     */
    text: string;
    /**
     * Rendered width in pixels — maximum across fontA and fontB.
     */
    width: number;
    /**
     * Per-grapheme metadata for both fonts.
     */
    chars: ComparisonChar[];
}

/**
 * Aggregated output of a dual-font layout pass.
 */
export interface ComparisonResult {
    /**
     * Per-line grapheme data. Empty when input text is empty.
     */
    lines: ComparisonLine[];
    /**
     * Total height in pixels.
     */
    totalHeight: number;
}