import {isSpreadElement} from '@/astride/types.js';

export default function(node, {evaluate, scope}) {
  const elements = [];
  const asyncSpread = Object.create(null);
  let isAsync = false;
  for (const index in node.elements) {
    const element = node.elements[index];
    if (isSpreadElement(element)) {
      const {async, value} = evaluate(element.argument, {scope});
      isAsync = isAsync || async;
      if (async) {
        elements.push(value);
        asyncSpread[elements.length - 1] = true;
      }
      else {
        elements.push(...value);
      }
    }
    else {
      const {async, value} = evaluate(element, {scope});
      isAsync = isAsync || async;
      elements.push(value);
    }
  }
  return {
    async: !!isAsync,
    value: !isAsync
      ? elements
      : Promise.all(elements).then((elementsAndOrSpreads) => {
        const elements = [];
        for (let i = 0; i < elementsAndOrSpreads.length; ++i) {
          if (asyncSpread[i]) {
            elements.push(...elementsAndOrSpreads[i]);
          }
          else {
            elements.push(elementsAndOrSpreads[i]);
          }
        }
        return elements;
      }),
  };
}