'use strict'

var escapeHTML = require('./Utils').escapeHTML

var domify = require('min-dom').domify
var domQuery = require('min-dom').query
var domQueryAll = require('min-dom').queryAll
var domRemove = require('min-dom').remove
var domClasses = require('min-dom').classes
var domClosest = require('min-dom').closest
var domAttr = require('min-dom').attr
var domDelegate = require('min-dom').delegate
var domMatches = require('min-dom').matches

var forEach = require('lodash/forEach')
var filter = require('lodash/filter')
var get = require('lodash/get')
var keys = require('lodash/keys')
var isEmpty = require('lodash/isEmpty')
var isArray = require('lodash/isArray')
var xor = require('lodash/xor')
var debounce = require('lodash/debounce')

var updateSelection = require('selection-update')

var scrollTabs = require('scroll-tabs').default

var getBusinessObject = require('bpmn-js/lib/util/ModelUtil').getBusinessObject

var HIDE_CLASS = 'bpp-hidden'
var DEBOUNCE_DELAY = 300

function isToggle(node) {
  return node.type === 'checkbox' || node.type === 'radio'
}

function isSelect(node) {
  return node.type === 'select-one'
}

function isContentEditable(node) {
  return domAttr(node, 'contenteditable')
}

function getPropertyPlaceholders(node) {
  var selector = 'input[name], textarea[name], [data-value], [contenteditable]'
  var placeholders = domQueryAll(selector, node)
  if ((!placeholders || !placeholders.length) && domMatches(node, selector)) {
    placeholders = [node]
  }
  return placeholders
}

/**
 * Return all active form controls.
 * This excludes the invisible controls unless all is true
 *
 * @param {Element} node
 * @param {Boolean} [all=false]
 */
function getFormControls(node, all) {
  var controls = domQueryAll('input[name], textarea[name], select[name], [contenteditable]', node)

  if (!controls || !controls.length) {
    controls = domMatches(node, 'option') ? [node] : controls
  }

  if (!all) {
    controls = filter(controls, function(node) {
      return !domClosest(node, '.' + HIDE_CLASS)
    })
  }

  return controls
}

function getFormControlValuesInScope(entryNode) {
  var values = {}

  var controlNodes = getFormControls(entryNode)

  forEach(controlNodes, function(controlNode) {
    var value = controlNode.value
    // 下拉框多选值设置
    if (controlNode.multiple) {
      let tempValues = ''
      const selectedOptions = controlNode.selectedOptions
      forEach(selectedOptions, function(selectedOption) {
        tempValues += selectedOption.value + ','
      })
      value = tempValues.substring(0, tempValues.length - 1)
    }

    var name = domAttr(controlNode, 'name') || domAttr(controlNode, 'data-name')

    // take toggle state into account for radio / checkboxes
    if (isToggle(controlNode)) {
      if (controlNode.checked) {
        if (!domAttr(controlNode, 'value')) {
          value = true
        } else {
          value = controlNode.value
        }
      } else {
        value = null
      }
    } else if (isContentEditable(controlNode)) {
      value = controlNode.innerText
    }

    if (value !== null) {
      // return the actual value
      // handle serialization in entry provider
      // (ie. if empty string should be serialized or not)
      values[name] = value
    }
  })

  return values
}

/**
 * Extract input values from entry node
 *
 * @param  {DOMElement} entryNode
 * @returns {Object}
 */
function getFormControlValues(entryNode) {
  var values

  var listContainer = domQuery('[data-list-entry-container]', entryNode)
  if (listContainer) {
    values = []
    var listNodes = listContainer.children || []
    forEach(listNodes, function(listNode) {
      values.push(getFormControlValuesInScope(listNode))
    })
  } else {
    values = getFormControlValuesInScope(entryNode)
  }

  return values
}

/**
 * Return true if the given form extracted value equals
 * to an old cached version.
 *
 * @param {Object} value
 * @param {Object} oldValue
 * @return {Boolean}
 */
function valueEqual(value, oldValue) {
  if (value && !oldValue) {
    return false
  }

  var allKeys = keys(value).concat(keys(oldValue))

  return allKeys.every(function(key) {
    return value[key] === oldValue[key]
  })
}

/**
 * Return true if the given form extracted value(s)
 * equal an old cached version.
 *
 * @param {Array<Object>|Object} values
 * @param {Array<Object>|Object} oldValues
 * @return {Boolean}
 */
function valuesEqual(values, oldValues) {
  if (isArray(values)) {
    if (values.length !== oldValues.length) {
      return false
    }

    return values.every(function(v, idx) {
      return valueEqual(v, oldValues[idx])
    })
  }

  return valueEqual(values, oldValues)
}

/**
 * Return a mapping of { id: entry } for all entries in the given groups in the given tabs.
 *
 * @param {Object} tabs
 * @return {Object}
 */
function extractEntries(tabs) {
  return keyBy(flattenDeep(map(flattenDeep(map(tabs, 'groups')), 'entries')), 'id')
}

/**
 * Return a mapping of { id: group } for all groups in the given tabs.
 *
 * @param {Object} tabs
 * @return {Object}
 */
function extractGroups(tabs) {
  return keyBy(flattenDeep(map(tabs, 'groups')), 'id')
}

/**
 * A properties panel implementation.
 *
 * To use it provide a `propertiesProvider` component that knows
 * about which properties to display.
 *
 * Properties edit state / visibility can be intercepted
 * via a custom {@link PropertiesActivator}.
 *
 * @class
 * @constructor
 *
 * @param {Object} config
 * @param {EventBus} eventBus
 * @param {Modeling} modeling
 * @param {PropertiesProvider} propertiesProvider
 * @param {Canvas} canvas
 * @param {CommandStack} commandStack
 */
function PropertiesPanel(config, eventBus, modeling, propertiesProvider, commandStack, canvas) {
  this._eventBus = eventBus
  this._modeling = modeling
  this._commandStack = commandStack
  this._canvas = canvas
  this._propertiesProvider = propertiesProvider

  this._init(config)
}

PropertiesPanel.$inject = [
  'config.propertiesPanel',
  'eventBus',
  'modeling',
  'propertiesProvider',
  'commandStack',
  'canvas'
]

module.exports = PropertiesPanel

PropertiesPanel.prototype._init = function(config) {
  var canvas = this._canvas
  var eventBus = this._eventBus

  var self = this

  /**
   * Select the root element once it is added to the canvas
   */
  eventBus.on('root.added', function(e) {
    var element = e.element

    if (isImplicitRoot(element)) {
      return
    }

    self.update(element)
  })

  eventBus.on('selection.changed', function(e) {
    var newElement = e.newSelection[0]

    var rootElement = canvas.getRootElement()

    if (isImplicitRoot(rootElement)) {
      return
    }

    self.update(newElement)
  })

  // add / update tab-bar scrolling
  eventBus.on(['propertiesPanel.changed', 'propertiesPanel.resized'], function(event) {
    var tabBarNode = domQuery('.bpp-properties-tab-bar', self._container)
    if (!tabBarNode) {
      return
    }

    var scroller = scrollTabs.get(tabBarNode)

    if (!scroller) {
      // we did not initialize yet, do that
      // now and make sure we select the active
      // tab on scroll update
      scroller = scrollTabs(tabBarNode, {
        selectors: {
          tabsContainer: '.bpp-properties-tabs-links',
          tab: '.bpp-properties-tabs-links li',
          ignore: '.bpp-hidden',
          active: '.bpp-active'
        }
      })

      scroller.on('scroll', function(newActiveNode, oldActiveNode, direction) {
        var linkNode = domQuery('[data-tab-target]', newActiveNode)

        var tabId = domAttr(linkNode, 'data-tab-target')

        self.activateTab(tabId)
      })
    }

    // react on tab changes and or tabContainer resize
    // and make sure the active tab is shown completely
    scroller.update()
  })

  eventBus.on('elements.changed', function(e) {
    var current = self._current
    var element = current && current.element
    if (element) {
      if (e.elements.indexOf(element) !== -1) {
        self.update(element)
      }
    }
  })

  eventBus.on('elementTemplates.changed', function() {
    var current = self._current
    var element = current && current.element

    if (element) {
      self.update(element)
    }
  })

  eventBus.on('diagram.destroy', function() {
    self.detach()
  })
  // 元素创建时执行
  eventBus.on('commandStack.shape.create.postExecute', function(event) {
    // inspect the event; you'll find the created element
    // you can fiddle around with (i.e. to add additional properties)
  })

  this._container = domify('<div class="bpp-properties-panel"></div>')

  this._bindListeners(this._container)

  if (config && config.parent) {
    this.attachTo(config.parent)
  }
}

PropertiesPanel.prototype.attachTo = function(parentNode) {
  if (!parentNode) {
    throw new Error('parentNode required')
  }

  // ensure we detach from the
  // previous, old parent
  this.detach()

  // unwrap jQuery if provided
  if (parentNode.get && parentNode.constructor.prototype.jquery) {
    parentNode = parentNode.get(0)
  }

  if (typeof parentNode === 'string') {
    parentNode = domQuery(parentNode)
  }

  var container = this._container

  parentNode.appendChild(container)

  this._emit('attach')
}

PropertiesPanel.prototype.detach = function() {
  var container = this._container
  var parentNode = container.parentNode

  if (!parentNode) {
    return
  }

  this._emit('detach')

  parentNode.removeChild(container)
}

/**
 * Select the given tab within the properties panel.
 *
 * @param {Object|String} tab
 */
PropertiesPanel.prototype.activateTab = function(tab) {
  var tabId = typeof tab === 'string' ? tab : tab.id

  var current = this._current

  var panelNode = current.panel

  var allTabNodes = domQueryAll('.bpp-properties-tab', panelNode)
  var allTabLinkNodes = domQueryAll('.bpp-properties-tab-link', panelNode)

  forEach(allTabNodes, function(tabNode) {
    var currentTabId = domAttr(tabNode, 'data-tab')

    domClasses(tabNode).toggle('bpp-active', tabId === currentTabId)
  })

  forEach(allTabLinkNodes, function(tabLinkNode) {
    var tabLink = domQuery('[data-tab-target]', tabLinkNode)
    var currentTabId = domAttr(tabLink, 'data-tab-target')

    domClasses(tabLinkNode).toggle('bpp-active', tabId === currentTabId)
  })
}

/**
 * Update the DOM representation of the properties panel
 */
PropertiesPanel.prototype.update = function(element) {
  var current = this._current

  // no actual selection change
  var needsCreate = true

  if (typeof element === 'undefined') {
    // use RootElement of BPMN diagram to generate properties panel if no element is selected
    element = this._canvas.getRootElement()
  }

  var newTabs = this._propertiesProvider.getTabs(element)

  if (current && current.element === element) {
    // see if we can reuse the existing panel

    needsCreate = this._entriesChanged(current, newTabs)
  }

  if (needsCreate) {
    if (current) {
      // get active tab from the existing panel before remove it
      var activeTabNode = domQuery('.bpp-properties-tab.bpp-active', current.panel)

      var activeTabId
      if (activeTabNode) {
        activeTabId = domAttr(activeTabNode, 'data-tab')
      }

      // remove old panel
      domRemove(current.panel)
    }
    this._current = this._create(element, newTabs)

    // activate the saved active tab from the remove panel or the first tab
    activeTabId ? this.activateTab(activeTabId) : this.activateTab(this._current.tabs[0])
  }

  if (this._current) {
    // make sure correct tab contents are visible
    this._updateActivation(this._current)
  }

  this._emit('changed')
}

/**
 * Returns true if one of two groups has different entries than the other.
 *
 * @param  {Object} current
 * @param  {Object} newTabs
 * @return {Boolean}
 */
PropertiesPanel.prototype._entriesChanged = function(current, newTabs) {
  var oldEntryIds = keys(current.entries)
  var newEntryIds = keys(extractEntries(newTabs))

  return !isEmpty(xor(oldEntryIds, newEntryIds))
}

PropertiesPanel.prototype._emit = function(event) {
  this._eventBus.fire('propertiesPanel.' + event, { panel: this, current: this._current })
}

PropertiesPanel.prototype._bindListeners = function(container) {
  var self = this

  // handles a change for a given event
  var handleChange = function handleChange(event) {
    // see if we handle a change inside a [data-entry] element.
    // if not, drop out
    var inputNode = event.delegateTarget
    var entryNode = domClosest(inputNode, '[data-entry]')
    var entryId
    var entry

    // change from outside a [data-entry] element, simply ignore
    if (!entryNode) {
      return
    }

    entryId = domAttr(entryNode, 'data-entry')
    entry = self.getEntry(entryId)

    var values = getFormControlValues(entryNode)

    if (event.type === 'change') {
      // - if the "data-on-change" attribute is present and a value is changed,
      //   then the associated action is performed.
      // - if the associated action returns "true" then an update to the business
      //   object is done
      // - if it does not return "true", then only the DOM content is updated
      var onChangeAction = domAttr(inputNode, 'data-on-change')

      if (onChangeAction) {
        var isEntryDirty = self.executeAction(entry, entryNode, onChangeAction, event)

        if (!isEntryDirty) {
          return self.update(self._current.element)
        }
      }
    }
    self.applyChanges(entry, values, entryNode)
    self.updateState(entry, entryNode)
  }

  // debounce update only elements that are target of key events,
  // i.e. INPUT and TEXTAREA. SELECTs will trigger an immediate update anyway.
  domDelegate.bind(
    container,
    'input, textarea, [contenteditable]',
    'input',
    debounce(handleChange, DEBOUNCE_DELAY),
  )
  domDelegate.bind(container, 'input, textarea, select, [contenteditable]', 'change', handleChange)

  // paste as plain text only
  domDelegate.bind(container, '[contenteditable]', 'paste', handlePaste)

  function handlePaste(event) {
    var text = (event.clipboardData || window.clipboardData).getData('text')
    document.execCommand('insertText', false, text)

    event.preventDefault()
  }

  // handle key events
  domDelegate.bind(container, 'select', 'keydown', function(e) {
    // DEL
    if (e.keyCode === 46) {
      e.stopPropagation()
      e.preventDefault()
    }
  })

  domDelegate.bind(container, '[data-action]', 'click', function onClick(event) {
    // triggers on all inputs
    var inputNode = event.delegateTarget
    var entryNode = domClosest(inputNode, '[data-entry]')

    var actionId = domAttr(inputNode, 'data-action')
    var entryId = domAttr(entryNode, 'data-entry')

    var entry = self.getEntry(entryId)

    var isEntryDirty = self.executeAction(entry, entryNode, actionId, event)

    if (isEntryDirty) {
      var values = getFormControlValues(entryNode)

      self.applyChanges(entry, values, entryNode)
    }

    self.updateState(entry, entryNode)
  })

  function handleInput(event, element) {
    // triggers on all inputs
    var inputNode = event.delegateTarget

    var entryNode = domClosest(inputNode, '[data-entry]')

    // only work on data entries
    if (!entryNode) {
      return
    }

    var eventHandlerId = domAttr(inputNode, 'data-blur')
    var entryId = domAttr(entryNode, 'data-entry')

    var entry = self.getEntry(entryId)

    var isEntryDirty = self.executeAction(entry, entryNode, eventHandlerId, event)

    if (isEntryDirty) {
      var values = getFormControlValues(entryNode)

      self.applyChanges(entry, values, entryNode)
    }

    self.updateState(entry, entryNode)
  }

  domDelegate.bind(container, '[data-blur]', 'blur', handleInput, true)

  // make tab links interactive
  domDelegate.bind(container, '.bpp-properties-tabs-links [data-tab-target]', 'click', function(
    event,
  ) {
    event.preventDefault()

    var delegateTarget = event.delegateTarget

    var tabId = domAttr(delegateTarget, 'data-tab-target')

    // activate tab on link click
    self.activateTab(tabId)
  })
}

PropertiesPanel.prototype.updateState = function(entry, entryNode) {
  this.updateShow(entry, entryNode)
  this.updateDisable(entry, entryNode)
}

/**
 * Update the visibility of the entry node in the DOM
 */
PropertiesPanel.prototype.updateShow = function(entry, node) {
  var current = this._current

  if (!current) {
    return
  }

  var showNodes = domQueryAll('[data-show]', node) || []

  forEach(showNodes, function(showNode) {
    var expr = domAttr(showNode, 'data-show')
    var fn = get(entry, expr)
    if (fn) {
      var scope = domClosest(showNode, '[data-scope]') || node
      var shouldShow = fn(current.element, node, showNode, scope) || false
      if (shouldShow) {
        domClasses(showNode).remove(HIDE_CLASS)
      } else {
        domClasses(showNode).add(HIDE_CLASS)
      }
    }
  })
}

/**
 * Evaluates a given function. If it returns true, then the
 * node is marked as "disabled".
 */
PropertiesPanel.prototype.updateDisable = function(entry, node) {
  var current = this._current

  if (!current) {
    return
  }

  var nodes = domQueryAll('[data-disable]', node) || []

  forEach(nodes, function(currentNode) {
    var expr = domAttr(currentNode, 'data-disable')
    var fn = get(entry, expr)
    if (fn) {
      var scope = domClosest(currentNode, '[data-scope]') || node
      var shouldDisable = fn(current.element, node, currentNode, scope) || false
      domAttr(currentNode, 'disabled', shouldDisable ? '' : null)
    }
  })
}

PropertiesPanel.prototype.executeAction = function(entry, entryNode, actionId, event) {
  var current = this._current

  if (!current) {
    return
  }

  var fn = get(entry, actionId)
  if (fn) {
    var scopeNode = domClosest(event.target, '[data-scope]') || entryNode
    return fn.apply(entry, [current.element, entryNode, event, scopeNode])
  }
}

/**
 * Apply changes to the business object by executing a command
 */
PropertiesPanel.prototype.applyChanges = function(entry, values, containerElement) {
  var element = this._current.element

  // ensure we only update the model if we got dirty changes
  if (valuesEqual(values, entry.oldValues)) {
    return
  }

  var command = entry.set(element, values, containerElement)

  var commandToExecute

  if (isArray(command)) {
    if (command.length) {
      commandToExecute = {
        cmd: 'properties-panel.multi-command-executor',
        context: flattenDeep(command)
      }
    }
  } else {
    commandToExecute = command
  }
  // 解决validate验证不通过，但依然将属性值插入xml中的问题
  // var current = this._current;
  // const entryNode = domQuery('[data-entry="' + entry.id + '"]', current.panel);
  // const validateResult = this.validate(entry, values, entryNode);
  // if(validateResult) {
  //   if (commandToExecute) {
  //     this._commandStack.execute(commandToExecute.cmd, commandToExecute.context || { element : element });
  //   } else {
  //     this.update(element);
  //   }
  // }
  if (commandToExecute) {
    this._commandStack.execute(
      commandToExecute.cmd,
      commandToExecute.context || { element: element },
    )
  } else {
    this.update(element)
  }
}

/**
 * apply validation errors in the DOM and show or remove an error message near the entry node.
 */
PropertiesPanel.prototype.applyValidationErrors = function(validationErrors, entryNode) {
  var valid = true

  var controlNodes = getFormControls(entryNode, true)

  forEach(controlNodes, function(controlNode) {
    var name = domAttr(controlNode, 'name') || domAttr(controlNode, 'data-name')

    var error = validationErrors && validationErrors[name]

    var errorMessageNode = domQuery('.bpp-error-message', controlNode.parentNode)

    if (error) {
      valid = false

      if (!errorMessageNode) {
        errorMessageNode = domify('<div></div>')

        domClasses(errorMessageNode).add('bpp-error-message')

        // insert errorMessageNode after controlNode
        controlNode.parentNode.insertBefore(errorMessageNode, controlNode.nextSibling)
      }

      errorMessageNode.textContent = error

      domClasses(controlNode).add('invalid')
    } else {
      domClasses(controlNode).remove('invalid')

      if (errorMessageNode) {
        controlNode.parentNode.removeChild(errorMessageNode)
      }
    }
  })

  return valid
}

/**
 * Check if the entry contains valid input
 */
PropertiesPanel.prototype.validate = function(entry, values, entryNode) {
  var self = this

  var current = this._current

  var valid = true

  entryNode = entryNode || domQuery('[data-entry="' + entry.id + '"]', current.panel)

  if (values instanceof Array) {
    var listContainer = domQuery('[data-list-entry-container]', entryNode)
    var listEntryNodes = listContainer.children || []

    // create new elements
    for (var i = 0; i < values.length; i++) {
      var listValue = values[i]

      if (entry.validateListItem) {
        var validationErrors = entry.validateListItem(current.element, listValue, entryNode, i)
        var listEntryNode = listEntryNodes[i]

        valid = self.applyValidationErrors(validationErrors, listEntryNode) && valid
      }
    }
  } else {
    if (entry.validate) {
      this.validationErrors = entry.validate(current.element, values, entryNode)

      valid = self.applyValidationErrors(this.validationErrors, entryNode) && valid
    }
  }

  return valid
}

PropertiesPanel.prototype.getEntry = function(id) {
  return this._current && this._current.entries[id]
}

var flattenDeep = require('lodash/flattenDeep')
var keyBy = require('lodash/keyBy')
var map = require('lodash/map')

PropertiesPanel.prototype._create = function(element, tabs) {
  if (!element) {
    return null
  }

  var containerNode = this._container

  var panelNode = this._createPanel(element, tabs)
  // 将所有的tab以及tab里的内容添加到页面上
  containerNode.appendChild(panelNode)
  var entries = extractEntries(tabs)
  var groups = extractGroups(tabs)

  return {
    tabs: tabs,
    groups: groups,
    entries: entries,
    element: element,
    panel: panelNode
  }
}

/**
 * Update variable parts of the entry node on element changes.
 *
 * @param {djs.model.Base} element
 * @param {EntryDescriptor} entry
 * @param {Object} values
 * @param {HTMLElement} entryNode
 * @param {Number} idx
 */
PropertiesPanel.prototype._bindTemplate = function(element, entry, values, entryNode, idx) {
  var eventBus = this._eventBus

  function isPropertyEditable(entry, propertyName) {
    return eventBus.fire('propertiesPanel.isPropertyEditable', {
      entry: entry,
      propertyName: propertyName,
      element: element
    })
  }

  var inputNodes = getPropertyPlaceholders(entryNode)

  forEach(inputNodes, function(node) {
    var name, newValue, editable

    // we deal with an input element
    if ('value' in node || isContentEditable(node) === 'true') {
      name = domAttr(node, 'name') || domAttr(node, 'data-name')
      newValue = values[name]

      editable = isPropertyEditable(entry, name)
      if (editable && entry.editable) {
        editable = entry.editable(element, entryNode, node, name, newValue, idx)
      }

      domAttr(node, 'readonly', editable ? null : '')
      domAttr(node, 'disabled', editable ? null : '')

      // take full control over setting the value
      // and possibly updating the input in entry#setControlValue
      if (entry.setControlValue) {
        entry.setControlValue(element, entryNode, node, name, newValue, idx)
      } else if (isToggle(node)) {
        setToggleValue(node, newValue)
      } else if (isSelect(node)) {
        setSelectValue(node, newValue)
      } else {
        setInputValue(node, newValue)
      }
    }

    // we deal with some non-editable html element
    else {
      name = domAttr(node, 'data-value')
      newValue = values[name]
      if (entry.setControlValue) {
        entry.setControlValue(element, entryNode, node, name, newValue, idx)
      } else {
        setTextValue(node, newValue)
      }
    }
  })
}

// TODO(nikku): WTF freaking name? Change / clarify.
// 在这里设置哪个element显示那些tab
PropertiesPanel.prototype._updateActivation = function(current) {
  var self = this

  var eventBus = this._eventBus

  var element = current.element

  function isEntryVisible(entry) {
    return eventBus.fire('propertiesPanel.isEntryVisible', {
      entry: entry,
      element: element
    })
  }

  function isGroupVisible(group, element, groupNode) {
    if (typeof group.enabled === 'function') {
      return group.enabled(element, groupNode)
    } else {
      return true
    }
  }

  function isTabVisible(tab, element) {
    if (typeof tab.enabled === 'function') {
      return tab.enabled(element)
    } else {
      return true
    }
  }

  function toggleVisible(node, visible) {
    domClasses(node).toggle(HIDE_CLASS, !visible)
  }

  // check whether the active tab is visible
  // if not: set the first tab as active tab
  function checkActiveTabVisibility(node, visible) {
    var isActive = domClasses(node).has('bpp-active')
    if (!visible && isActive) {
      self.activateTab(current.tabs[0])
    }
  }

  function updateLabel(element, selector, text) {
    var labelNode = domQuery(selector, element)

    if (!labelNode) {
      return
    }

    labelNode.textContent = text
  }

  var panelNode = current.panel

  forEach(current.tabs, function(tab) {
    var tabNode = domQuery('[data-tab=' + tab.id + ']', panelNode)
    var tabLinkNode = domQuery('[data-tab-target=' + tab.id + ']', panelNode).parentNode

    var tabVisible = false

    forEach(tab.groups, function(group) {
      var groupVisible = false

      var groupNode = domQuery('[data-group=' + group.id + ']', tabNode)

      forEach(group.entries, function(entry) {
        var entryNode = domQuery('[data-entry="' + entry.id + '"]', groupNode)

        var entryVisible = isEntryVisible(entry)

        groupVisible = groupVisible || entryVisible

        toggleVisible(entryNode, entryVisible)

        var values = 'get' in entry ? entry.get(element, entryNode) : {}

        if (values instanceof Array) {
          var listEntryContainer = domQuery('[data-list-entry-container]', entryNode)
          var existingElements = listEntryContainer.children || []

          for (var i = 0; i < values.length; i++) {
            var listValue = values[i]
            var listItemNode = existingElements[i]
            if (!listItemNode) {
              listItemNode = domify(
                entry.createListEntryTemplate(listValue, i, listEntryContainer),
              )
              listEntryContainer.appendChild(listItemNode)
            }
            domAttr(listItemNode, 'data-index', i)

            self._bindTemplate(element, entry, listValue, listItemNode, i)
          }

          var entriesToRemove = existingElements.length - values.length

          for (var j = 0; j < entriesToRemove; j++) {
            // remove orphaned element
            listEntryContainer.removeChild(listEntryContainer.lastChild)
          }
        } else {
          self._bindTemplate(element, entry, values, entryNode)
        }

        // update conditionally visible elements
        self.updateState(entry, entryNode)
        self.validate(entry, values, entryNode)

        // remember initial state for later dirty checking
        entry.oldValues = getFormControlValues(entryNode)
      })

      if (typeof group.label === 'function') {
        updateLabel(groupNode, '.group-label', group.label(element, groupNode))
      }

      groupVisible = groupVisible && isGroupVisible(group, element, groupNode)

      tabVisible = tabVisible || groupVisible

      toggleVisible(groupNode, groupVisible)
    })

    tabVisible = tabVisible && isTabVisible(tab, element)

    toggleVisible(tabNode, tabVisible)
    toggleVisible(tabLinkNode, tabVisible)

    checkActiveTabVisibility(tabNode, tabVisible)
  })

  // inject elements id into header
  updateLabel(panelNode, '[data-label-id]', getBusinessObject(element).id || '')
}

PropertiesPanel.prototype._createPanel = function(element, tabs) {
  var self = this

  var panelNode = domify('<div class="bpp-properties"></div>')
  var headerNode = domify(
    '<div class="bpp-properties-header">' +
        '<div class="label" data-label-id></div>' +
        '<div class="search">' +
        '<input type="search" placeholder="Search for property" />' +
        '<button><span>Search</span></button>' +
        '</div>' +
        '</div>',
  )
  var tabBarNode = domify('<div class="bpp-properties-tab-bar el-tabs"></div>')
  var tabLinksNode = domify('<ul class="bpp-properties-tabs-links"></ul>')
  var tabContainerNode = domify('<div class="bpp-properties-tabs-container"></div>')

  panelNode.appendChild(headerNode)

  forEach(tabs, function(tab, tabIndex) {
    if (!tab.id) {
      throw new Error('tab must have an id')
    }

    var tabNode = domify(
      '<div class="bpp-properties-tab el-tab" data-tab="' + escapeHTML(tab.id) + '"></div>',
    )
    var tabLinkNode = domify(
      '<li class="bpp-properties-tab-link">' +
          '<a href data-tab-target="' +
          escapeHTML(tab.id) +
          '">' +
          escapeHTML(tab.label) +
          '</a>' +
          '</li>',
    )

    var groups = tab.groups

    forEach(groups, function(group) {
      if (!group.id) {
        throw new Error('group must have an id')
      }

      var groupNode = domify(
        '<div class="bpp-properties-group" data-group="' +
          escapeHTML(group.id) +
          '">' +
          // '<span class="group-toggle"></span>' +
          '<span class="group-label">' +
          escapeHTML(group.label) +
          '</span>' +
          '</div>',
      )

      // TODO(nre): use event delegation to handle that...
      // groupNode.querySelector('.group-toggle').addEventListener('click', function(evt) {
      //   domClasses(groupNode).toggle('group-closed');
      //   evt.preventDefault();
      //   evt.stopPropagation();
      // });
      groupNode.addEventListener('click', function(evt) {
        if (!evt.defaultPrevented && domClasses(groupNode).has('group-closed')) {
          domClasses(groupNode).remove('group-closed')
        }
      })

      forEach(group.entries, function(entry) {
        if (!entry.id) {
          throw new Error('entry must have an id')
        }

        var html = entry.html

        if (typeof html === 'string') {
          html = domify(html)
        }

        // unwrap jquery
        if (html.get && html.constructor.prototype.jquery) {
          html = html.get(0)
        }

        var entryNode = domify(
          '<div class="bpp-properties-entry" data-entry="' + escapeHTML(entry.id) + '"></div>',
        )

        forEach(entry.cssClasses || [], function(cssClass) {
          domClasses(entryNode).add(cssClass)
        })

        entryNode.appendChild(html)

        groupNode.appendChild(entryNode)

        // update conditionally visible elements
        self.updateState(entry, entryNode)
      })

      tabNode.appendChild(groupNode)
    })

    tabLinksNode.appendChild(tabLinkNode)
    tabContainerNode.appendChild(tabNode)
  })

  tabBarNode.appendChild(tabLinksNode)

  panelNode.appendChild(tabBarNode)
  panelNode.appendChild(tabContainerNode)

  return panelNode
}

function setInputValue(node, value) {
  var contentEditable = isContentEditable(node)

  var oldValue = contentEditable ? node.innerText : node.value

  var selection

  // prevents input fields from having the value 'undefined'
  if (value === undefined) {
    value = ''
  }

  if (oldValue === value) {
    return
  }

  // update selection on undo/redo
  if (document.activeElement === node) {
    selection = updateSelection(getSelection(node), oldValue, value)
  }

  if (contentEditable) {
    node.innerText = value
  } else {
    node.value = value
  }

  if (selection) {
    setSelection(node, selection)
  }
}

function setSelectValue(node, value) {
  if (value !== undefined) {
    node.value = value
  }
}

function setToggleValue(node, value) {
  var nodeValue = node.value

  node.checked = value === nodeValue || (!domAttr(node, 'value') && value)
}

function setTextValue(node, value) {
  node.textContent = value
}

function getSelection(node) {
  return isContentEditable(node)
    ? getContentEditableSelection(node)
    : {
      start: node.selectionStart,
      end: node.selectionEnd
    }
}

function getContentEditableSelection(node) {
  var selection = window.getSelection()

  var focusNode = selection.focusNode
  var focusOffset = selection.focusOffset
  var anchorOffset = selection.anchorOffset

  if (!focusNode) {
    throw new Error('not selected')
  }

  // verify we have selection on the current element
  if (!node.contains(focusNode)) {
    throw new Error('not selected')
  }

  return {
    start: Math.min(focusOffset, anchorOffset),
    end: Math.max(focusOffset, anchorOffset)
  }
}

function setSelection(node, selection) {
  if (isContentEditable(node)) {
    setContentEditableSelection(node, selection)
  } else {
    node.selectionStart = selection.start
    node.selectionEnd = selection.end
  }
}

function setContentEditableSelection(node, selection) {
  var focusNode, domRange, domSelection
  focusNode = node.firstChild || node
  domRange = document.createRange()
  // (focusNode = node.firstChild || node), (domRange = document.createRange());
  domRange.setStart(focusNode, selection.start)
  domRange.setEnd(focusNode, selection.end)

  domSelection = window.getSelection()
  domSelection.removeAllRanges()
  domSelection.addRange(domRange)
}

function isImplicitRoot(element) {
  return element.id === '__implicitroot'
}
