import {
	resolveMotion,
	MOTIONS_INTENT,
	type MotionEffective,
	type MotionIntent
} from '$libs/motion';
import type { PrefsDimension } from '$libs/prefs';

export interface MotionDimensionOptions {
	readonly intents?: readonly MotionIntent[];
	readonly default?: MotionEffective;
}

/**
 * Built-in motion dimension. Like theme, intent includes `'system'`
 * but effective is narrower (`'allow' | 'reduce'`); the dimension's
 * `resolve` folds intent + `env.reducedMotion` into the effective
 * value.
 */
export function motionDimension(
	options: MotionDimensionOptions = {}
): PrefsDimension<MotionIntent, MotionEffective> {
	const intents = options.intents ?? MOTIONS_INTENT;
	const fallback = options.default ?? 'allow';
	return {
		defaultValue: fallback,
		validate(value) {
			if (typeof value !== 'string') return { ok: false, reason: 'unsupported_motion' };
			if (!intents.includes(value as MotionIntent)) {
				return { ok: false, reason: 'unsupported_motion' };
			}
			return { ok: true, value: value as MotionIntent };
		},
		resolve(intent, env) {
			return resolveMotion(intent, env.reducedMotion, fallback);
		},
		catalog: () => intents
	};
}