/*
 * Copyright (C) Sapphirecode - All Rights Reserved
 * This file is part of utilities which is released under MIT.
 * See file 'LICENSE' for full license details.
 * Created by Timo Hocker <timo@scode.ovh>, May 2020
 */

'use strict';

/**
 * truncates a floating point number
 *
 * @param {number} num number to truncate
 * @param {number} len length to truncate to
 * @returns {number} truncated number
 */
function truncate_decimal (num, len) {
  return Math.round (num * (10 ** len)) / (10 ** len);
}

/**
 * parse json and catch invalid strings
 *
 * @param {string} text input
 * @returns {any} parsed
 */
function try_parse_json (text) {
  try {
    return JSON.parse (text);
  }
  catch (e) {
    // noop
  }
  return null;
}


/**
 * copy an object to prevent modification to the original
 *
 * @param {object} obj object to copy
 * @returns {object} copy
 */
function copy_object (obj) {
  return JSON.parse (JSON.stringify (obj));
}

/**
 * run a regular expression and callback for every result
 *
 * @param {any} regex regular expression
 * @param {any} data data to run on
 * @param {any} func function to execute
 */
function run_regex (regex, data, func) {
  if (!regex.global) {
    const result = regex.exec (data);
    if (result)
      func (result);
    return;
  }
  let res = regex.exec (data);
  while (res) {
    func (res);
    res = regex.exec (data);
  }
}

/**
 * check if an object is either undefined, null or NaN
 *
 * @param {any} obj object to check
 * @returns {boolean} true if nil
 */
function is_nil (obj) {
  return typeof obj === 'undefined'
      || obj === null
      || (typeof obj === 'number' && isNaN (obj));
}

function get_element_field (element, carried_data, field) {
  if (typeof carried_data[field] !== 'undefined')
    return carried_data[field];
  return element[field];
}

function check_filter (filter, e, carried_data) {
  if (typeof filter.function !== 'undefined')
    return filter.function ({ ...e, ...carried_data });

  const search_str = Array.isArray (filter.field)
    ? filter.field.map ((f) => get_element_field (e, carried_data, f))
      .filter ((v) => typeof v !== 'undefined')
      .join (' ')
    : get_element_field (e, carried_data, filter.field);

  return filter.filter.test (search_str);
}

function check_filters (filters, e, carried_data, or = false) {
  for (const filter of filters) {
    let res = false;
    if (Array.isArray (filter.or))
      res = check_filters (filter.or, e, carried_data, true);
    else
      res = check_filter (filter, e, carried_data);

    if (or && res)
      return true;
    if (!res && !or)
      return false;
  }
  return !or;
}

/**
 * @typedef Filter
 * @type {object}
 * @property {string|string[]} field - fields to apply filter on
 * @property {RegExp} filter - filter
 */

/**
 * @typedef FilterOrGroup
 * @type {object}
 * @property {(Filter|FilterOrGroup)[]} or - create an OR group of filters
 */

/**
 * filter nested objects
 *
 * @param {Array<object>} input object to filter
 * @param {(Filter|FilterOrGroup)[]} filters filters
 * @param {string[]} carry carry data to children to match
 * @param {object} carried_data internal: carried data
 * @returns {Array<object>} filtered data
 */
function recursive_filter (
  input,
  filters,
  children_key = 'children',
  carry = [],
  carried_data = {}
) {
  const data = [ ...input ];
  const filtered = [];

  for (const c of carry) {
    if (typeof carried_data[c] !== 'string')
      carried_data[c] = '';
  }

  for (let i = 0; i < data.length; i++) {
    const e = { ...data[i] };
    data[i] = e;
    const sub_carry = { ...carried_data };
    for (const c of carry) {
      if (typeof e[c] !== 'undefined')
        sub_carry[c] += `${sub_carry[c].length > 0 ? ' ' : ''}${e[c]}`;
    }
    if (check_filters (filters, e, sub_carry)) {
      filtered.push (e);
    }
    else {
      if (typeof e[children_key] === 'undefined')
        continue;
      e[children_key] = recursive_filter (
        e[children_key],
        filters,
        children_key,
        carry,
        sub_carry
      );
      if (e[children_key].length > 0)
        filtered.push (e);
    }
  }
  return filtered;
}

module.exports = {
  truncate_decimal,
  try_parse_json,
  copy_object,
  run_regex,
  is_nil,
  recursive_filter
};