import type { RuntimeHost } from 'mathjslab/runtime';

/** Calculator effects supported without coupling the Worker to the browser DOM. */
export const calculatorRuntimeHost: RuntimeHost = {
    async request(effect, context) {
        if (effect.type === 'clock-now') return { value: Date.now() };
        if (effect.type !== 'delay') throw new Error('Unsupported calculator effect: ' + effect.type);
        await new Promise<void>((resolve, reject) => {
            const signal = context.signal;
            if (signal?.aborted) {
                reject(signal.reason);
                return;
            }
            const finish = (): void => {
                signal?.removeEventListener('abort', abort);
                resolve();
            };
            const timer = setTimeout(finish, effect.milliseconds);
            const abort = (): void => {
                clearTimeout(timer);
                signal?.removeEventListener('abort', abort);
                reject(signal?.reason);
            };
            signal?.addEventListener('abort', abort, { once: true });
        });
        return {};
    },
};