import { themeContractTree, themeVarName } from './contract.js';

/**
 * Recursively walks the contract tree and builds a same-shape object where each leaf holds its
 * stable `var(--luke-*)` reference. This keeps the public `vars` shape fully source-owned and free
 * of styling-engine types: no `@vanilla-extract/css` import contributes to its declarations.
 */
function buildVars(
	node: Record<string, unknown>,
	segments: Array<string> = [],
): Record<string, unknown> {
	const result: Record<string, unknown> = {};
	for (const [key, value] of Object.entries(node)) {
		const path = [...segments, key];
		result[key] =
			value === null
				? `var(${themeVarName(path)})`
				: buildVars(value as Record<string, unknown>, path);
	}
	return result;
}

type ContractVars<T> = {
	[K in keyof T]: T[K] extends null
		? string
		: T[K] extends Record<string, unknown>
			? ContractVars<T[K]>
			: never;
};

/**
 * Typed access to the semantic theme custom properties. Each path resolves to a stable global
 * `--luke-*` variable reference, for example `vars.color.background.danger.solid.hover` is
 * `var(--luke-color-background-danger-solid-hover)`. Emits no CSS; values are supplied by a
 * theme stylesheet built with `buildTheme`.
 */
export const vars = buildVars(themeContractTree) as ContractVars<typeof themeContractTree>;