/*
 * JavaScript Templates Demo
 * https://github.com/blueimp/JavaScript-Templates
 *
 * Copyright 2013, Sebastian Tschan
 * https://blueimp.net
 *
 * Licensed under the MIT license:
 * https://opensource.org/licenses/MIT
 */

/* global tmpl */

/* eslint-disable strict */

;(function () {
  'use strict'

  var templateInput = document.getElementById('template')
  var dataInput = document.getElementById('data')
  var resultNode = document.getElementById('result')
  var templateDemoNode = document.getElementById('tmpl-demo')
  var templateDataNode = document.getElementById('tmpl-data')

  /**
   * Renders error messages
   *
   * @param {string} title Error title
   * @param {Error} error Error object
   */
  function renderError(title, error) {
    resultNode.innerHTML = tmpl('tmpl-error', { title: title, error: error })
  }

  /**
   * Renders the templating result
   *
   * @param {event} event Click event
   */
  function render(event) {
    event.preventDefault()
    var data
    try {
      data = JSON.parse(dataInput.value)
    } catch (e) {
      renderError('JSON parsing failed', e)
      return
    }
    try {
      resultNode.innerHTML = tmpl(templateInput.value, data)
    } catch (e) {
      renderError('Template rendering failed', e)
    }
  }

  /**
   * Removes all child elements from a Node
   *
   * @param {HTMLElement} node HTML element node
   */
  function empty(node) {
    while (node.lastChild) {
      node.removeChild(node.lastChild)
    }
  }

  /**
   * Initialization function
   *
   * @param {event} [event] Initialixation event
   */
  function init(event) {
    if (event) {
      event.preventDefault()
    }
    templateInput.value = templateDemoNode.innerHTML.replace(
      // Replace unnecessary whitespace:
      /^\n|\s+$| {6}/g,
      ''
    )
    dataInput.value = JSON.stringify(
      JSON.parse(templateDataNode.innerHTML),
      null,
      2
    )
    empty(resultNode)
  }

  document.getElementById('render').addEventListener('click', render)
  document.getElementById('reset').addEventListener('click', init)

  init()
})()