'use strict';

const xml2js = require('xml2js');
const stripNS = xml2js.processors.stripPrefix;
const parser = new xml2js.Parser({
  tagNameProcessors: [stripNS],
  // xmlns: true,
  explicitChildren: true,
});

const parseXML = input => parser.parseStringPromise(input);

function childAttr(obj, key, errorCode = 452) {
  const value = obj[key];
  if (value === undefined || value.length === 0) {
    return undefined;
  }

  if (value.length !== 1) {
    const error = new Error(`Invalid attribute: ${key}`);
    error.errorCode = errorCode;
    throw error;
  }

  if (value[0]['$'] && value[0]['_']) {
    return value[0]['_'];
  }

  return value[0];
}

function boolean(input, errorCode = 452) {
  const trimmed = (input || '').toLowerCase().trim();

  if (trimmed === '') {
    return undefined;
  } else if (trimmed === 'true' || trimmed === '1') {
    return true;
  } else if (trimmed === 'false' || trimmed === '0') {
    return false;
  }

  const error = new Error(`Not a boolean: ${input}`);
  error.errorCode = errorCode;
  throw error;
}

function dateTime(input, key, errorCode = 452) {
  if (input) {
    if (input['$$']) {
      return childAttr(input['$$'], key, errorCode);
    }
    throw new Error(`unknown dateTime: ${input}`);
  }
}

function duration(input, key, errorCode = 452) {
  if (input) {
    if (input['$$']) {
      return childAttr(input['$$'], key, errorCode);
    }
    throw new Error(`unknown duration: ${input}`);
  }
}

function number(input, errorCode = 452) {
  const trimmed = (input || '').toLowerCase().trim();
  const parsed = Number(trimmed);

  if (trimmed === '') {
    return undefined;
  } else if (isNaN(parsed)) {
    const error = new Error(`Not a number: ${input}`);
    error.errorCode = errorCode;
    throw error;
  } else {
    return parsed;
  }
}

function required(input, key, errorCode = 452) {
  if (input == null) {
    const error = new Error(`Missing required value: ${key}`);
    error.errorCode = errorCode;
    throw error;
  }
  return input;
}

module.exports = {
  parseXML,
  childAttr,
  dateTime,
  duration,
  boolean,
  required,
  number,
};