import { CSSResult } from 'lit';
import { type CssVarSyntax } from './syntax.js';
/**
 * Lower, kebab case requirement for CSS var names.
 *
 * @category Internal
 */
export type CssVarName = `${Lowercase<string>}-${Lowercase<string>}`;
/**
 * The possible values for defining a CSS var's default value.
 *
 * @category Internal
 */
export type CssVarValueInit = string | number | CSSResult;
/**
 * A native CSS property definition.
 *
 * @category Internal
 */
export type CssPropertyDefinition = {
    /** The syntax allowed for this CSS var. This must be set for the var to be animatable. */
    syntax?: CssVarSyntax;
    /**
     * The initial value of this CSS var when it hasn't been applied. This is only used when calling
     * `CSS.registerProperty`. The CSS engine requires this to be computationally independent (it
     * cannot use other CSS vars in its value).
     *
     * If this is not supplied, `default` is used.
     */
    initialValue?: CssVarValueInit;
    /**
     * The fallback for when this CSS var is with `myCssVars['var-name'].value` to interpolate into
     * CSS with `var()`. This can use other CSS vars in calculations.
     */
    default: CssVarValueInit;
};
/**
 * Base type for defineCssVars's input.
 *
 * @category Internal
 */
export type CssVarsSetup = Readonly<Record<CssVarName, CssVarValueInit | CssPropertyDefinition | SingleCssVarDefinition>>;
/**
 * A single CSS var definition.
 *
 * @category Internal
 */
export type SingleCssVarDefinition = {
    name: CSSResult;
    value: CSSResult;
    syntax: string;
    default: string;
};
/**
 * Output for defineCssVars.
 *
 * @category Internal
 */
export type CssVarDefinitions<SpecificSetup extends CssVarsSetup> = {
    [KeyName in keyof SpecificSetup]: SingleCssVarDefinition;
};
/**
 * Creates an easy-to-use-in-lit mapping of the given CSS Var names and defaults. The input
 * determines the CSS var names and their default values. The output is a mapping of the CSS var
 * names to name and value objects that can be easily interpolated into lit's css keyed template
 * strings.
 *
 * @category Main
 * @example
 *
 * ```ts
 * import {defineCssVars} from 'lit-css-vars';
 *
 * // creates a CSS var with name 'my-var' and default value of 50px.
 * const myVars = defineCssVars({'my-var': '50px'});
 * // using the CSS var name: this will be '--my-var'
 * myVars['my-var'].name;
 * // accessing the CSS var value for CSS; this will be: 'var(--my-var, 50px)'
 * myVars['my-var'].value;
 * ```
 */
export declare function defineCssVars<const SpecificVars extends CssVarsSetup>(
/**
 * The CSS var setup input. Keys of this input object become the CSS var names. Values of this
 * input become the default value of the CSS vars.
 */
setup: SpecificVars): CssVarDefinitions<SpecificVars>;
/**
 * Asserts that the given string can be a valid CSS var name (excluding the `--` prefix).
 *
 * @category Internal
 */
export declare function assertValidCssVarName(value: unknown): asserts value is string;
/**
 * Create a CSS engine compatible syntax string.
 *
 * @category Internal
 */
export declare function createSyntaxString(syntax: CssVarSyntax | string | undefined): string;