import { type CSSProperties, type RefObject } from "react";
/** Marks an embed root that resolves the host theme for its subtree. */
export declare const HOST_THEME_ROOT_ATTRIBUTE = "data-og-host-theme";
export type HostThemePreference = "auto" | "light" | "dark";
export type HostSurfacePreference = "host" | "theme";
export type ResolvedHostTheme = "light" | "dark";
/**
 * Stock literal color tokens as `[dark, light]`, mirroring `styles/tokens.css`
 * (a test keeps them in sync). A different value inherited from the host means
 * the host customized that token.
 */
export declare const STOCK_COLOR_TOKENS: Readonly<Record<string, readonly [string, string]>>;
type Rgba = {
    r: number;
    g: number;
    b: number;
    a: number;
};
/** Parse the `rgb()/rgba()` strings that `getComputedStyle` returns. */
export declare function parseComputedColor(value: string | null | undefined): Rgba | null;
/** WCAG relative luminance, 0 (black) to 1 (white). */
export declare function relativeLuminance({ r, g, b }: Pick<Rgba, "r" | "g" | "b">): number;
/** Parse a `#rgb`/`#rrggbb` or `rgb()` token value; null for anything else. */
export declare function parseTokenColor(value: string): Rgba | null;
/**
 * The theme whose text reads better on this background: dark when the stock
 * light text has the higher contrast ratio. Mid-tone and saturated brand
 * backgrounds land on whichever text actually stays legible.
 */
export declare function themeForBackground(color: Pick<Rgba, "r" | "g" | "b">): ResolvedHostTheme;
/**
 * The first opaque background the element sits on (its ancestors only), or
 * null when the page paints none of its own and the browser canvas shows.
 */
export declare function hostBackground(element: Element): Rgba | null;
/**
 * Resolve light or dark for an embedded root from its host page. Pure DOM
 * reads; never consults `prefers-color-scheme` on its own.
 */
export declare function resolveHostTheme(element: Element): ResolvedHostTheme;
/**
 * Canonical text for comparing a token value with the stock one. The
 * published `compiled.css` is minified (`#333`, `oklch(.52 .16 22)`), so the
 * same color must compare equal in short and long form; otherwise every stock
 * token reads as a host customization and dark values leak into light themes.
 */
export declare function normalizeToken(value: string): string;
/**
 * Tokens the host customized on an ancestor, by value. Setting our own
 * `data-og-theme` would otherwise reset them to the theme's stock values.
 */
export declare function hostTokenOverrides(element: Element): Record<`--${string}`, string>;
/** Inline token overrides that blend the stock surfaces into the host background. */
export declare function hostSurfaceStyle(theme: ResolvedHostTheme, background: Pick<Rgba, "r" | "g" | "b"> | null): Record<`--${string}`, string>;
export type HostTheme = {
    /** `data-og-theme` to set on the root, or undefined to inherit. */
    attribute: ResolvedHostTheme | undefined;
    theme: ResolvedHostTheme | undefined;
    style: CSSProperties | undefined;
};
/** Inline style and theme for one embed root. Pure; exported for tests. */
export declare function resolveHostThemeState(element: Element, preference: HostThemePreference, surface: HostSurfacePreference): {
    theme: ResolvedHostTheme;
    inherited: boolean;
    style: Record<string, string> | null;
};
/**
 * Resolve and track the host theme for an embedded root. Re-resolves when the
 * host flips `class`/`data-*`/`style` on <html>, <body> or an ancestor, and
 * when the OS scheme changes (which only matters for hosts that follow it).
 * A root nested inside another embed root inherits its resolution.
 */
export declare function useHostTheme(ref: RefObject<HTMLElement | null>, options: {
    theme?: HostThemePreference | undefined;
    surface?: HostSurfacePreference | undefined;
}): HostTheme;
export {};