import { LitElement } from 'lit';
type Constructor<T = object> = new (...args: any[]) => T;
/**
 * Interface that components using FormAssociatedMixin must satisfy.
 */
export interface FormAssociated {
    error: boolean;
    errorText: string;
    required: boolean;
    readonly validationMessage: string;
    readonly validity: ValidityState;
    checkValidity(): boolean;
    reportValidity(focus?: boolean): boolean;
    setCustomValidity(message: string): void;
}
/**
 * Base class for the mixin — named so TypeScript can expose its shape.
 * Do not use directly; use FormAssociatedMixin() instead.
 * @internal
 */
export declare class FormAssociatedBase {
    error: boolean;
    required: boolean;
    get errorText(): string;
    set errorText(value: string);
    protected _errorText: string;
    protected _validationMessage: string;
    protected _parentForm: HTMLFormElement | undefined;
    protected _errorSetByValidation: boolean;
    protected _isValid(): boolean;
    protected _getValidationMessage(): string;
    protected _getNativeInput(): HTMLInputElement | HTMLTextAreaElement | undefined;
    checkValidity(): boolean;
    reportValidity(focus?: boolean): boolean;
    setCustomValidity(message: string): void;
    get validationMessage(): string;
    get validity(): ValidityState;
    connectedCallback(): void;
    disconnectedCallback(): void;
    protected _updateValidationState(): void;
    protected _clearErrorStateIfValid(): void;
    protected _setErrorTextByValidation(message: string): void;
    protected _handleInvalid(e: Event): void;
}
/**
 * FormAssociatedMixin
 *
 * A Lit mixin that provides HTML form validation scaffolding for CTT
 * Design System components. Eliminates duplicated validation code across
 * Checkbox, RadioButton, TextareaInput, and similar form-field components.
 *
 * Components must implement the abstract methods:
 *   - `_isValid(): boolean`
 *   - `_getValidationMessage(): string`
 *
 * Optionally override `_getNativeInput()` to return the native element
 * used for focus-on-error and setCustomValidity() delegation.
 *
 * @example
 * ```ts
 * class CttMyInput extends FormAssociatedMixin(LitElement) {
 *   protected _isValid(): boolean {
 *     return !this.required || this._value.trim() !== '';
 *   }
 *   protected _getValidationMessage(): string {
 *     return this._isValid() ? '' : 'This field is required.';
 *   }
 * }
 * ```
 */
export declare const FormAssociatedMixin: <TBase extends Constructor<LitElement>>(Base: TBase) => Constructor<FormAssociatedBase> & TBase;
export {};