/**
 * Maps over array passing `isLast` bool to iterator as the second arguemnt
 */
export function mapWithLast<T, P>(array: T[], iteratee: (item: T, isLast: boolean) => P) {
  const res: P[] = [];
  for (let i = 0; i < array.length - 1; i++) {
    res.push(iteratee(array[i], false));
  }
  if (array.length !== 0) {
    res.push(iteratee(array[array.length - 1], true));
  }
  return res;
}

/**
 * Creates an object with the same keys as object and values generated by running each
 * own enumerable string keyed property of object thru iteratee.
 * The iteratee is invoked with three arguments: (value, key, object).
 *
 * @param object the object to iterate over
 * @param iteratee the function invoked per iteration.
 */
export function mapValues<T, P>(
  object: Dict<T>,
  iteratee: (val: T, key: string, obj: Dict<T>) => P,
): Dict<P> {
  const res: { [key: string]: P } = {};
  for (let key in object) {
    if (object.hasOwnProperty(key)) {
      res[key] = iteratee(object[key], key, object);
    }
  }
  return res;
}

/**
 * flattens collection using `prop` field as a children
 * @param items collection items
 * @param prop item property with child elements
 */
export function flattenByProp<T extends object, P extends keyof T>(items: T[], prop: P): T[] {
  const res: T[] = [];
  const iterate = (items: T[]) => {
    for (let i = 0; i < items.length; i++) {
      const item = items[i];
      res.push(item);
      if (item[prop]) {
        iterate(item[prop]);
      }
    }
  };
  iterate(items);
  return res;
}

export function stripTrailingSlash(path: string): string {
  if (path.endsWith('/')) {
    return path.substring(0, path.length - 1);
  }
  return path;
}

export function isAbsolutePath(path: string): boolean {
  return /^(?:[a-z]+:)?/i.test(path);
}

export function isNumeric(n: any): n is Number {
  return !isNaN(parseFloat(n)) && isFinite(n);
}

export function appendToMdHeading(md: string, heading: string, content: string) {
  // if  heading is already in md and append to the end of it
  const testRegex = new RegExp(`(^|\\n)#\\s?${heading}\\s*\\n`, 'i');
  const replaceRegex = new RegExp(`((\\n|^)#\\s*${heading}\\s*(\\n|$)(?:.|\\n)*?)(\\n#|$)`, 'i');
  if (testRegex.test(md)) {
    return md.replace(replaceRegex, `$1\n\n${content}\n$4`);
  } else {
    // else append heading itself
    const br = md === '' || md.endsWith('\n\n') ? '' : md.endsWith('\n') ? '\n' : '\n\n';
    return `${md}${br}# ${heading}\n\n${content}`;
  }
}

// credits https://stackoverflow.com/a/46973278/1749888
export const mergeObjects = <T extends object = object>(target: T, ...sources: T[]): T => {
  if (!sources.length) {
    return target;
  }
  const source = sources.shift();
  if (source === undefined) {
    return target;
  }

  if (isMergebleObject(target) && isMergebleObject(source)) {
    Object.keys(source).forEach(function(key: string) {
      if (isMergebleObject(source[key])) {
        if (!target[key]) {
          target[key] = {};
        }
        mergeObjects(target[key], source[key]);
      } else {
        target[key] = source[key];
      }
    });
  }

  return mergeObjects(target, ...sources);
};

const isObject = (item: any): boolean => {
  return item !== null && typeof item === 'object';
};

const isMergebleObject = (item): boolean => {
  return isObject(item) && !Array.isArray(item);
};