'use strict';

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

var cmdHelper = require('../helper/CmdHelper');

var domQuery = require('min-dom').query,
    domAttr = require('min-dom').attr,
    domClosest = require('min-dom').closest;

var filter = require('lodash/filter'),
    forEach = require('lodash/forEach'),
    keys = require('lodash/keys');

var domify = require('min-dom').domify;

var entryFieldDescription = require('./EntryFieldDescription');

var updateSelection = require('selection-update');

var TABLE_ROW_DIV_SNIPPET = '<div class="bpp-field-wrapper bpp-table-row">';
var DELETE_ROW_BUTTON_SNIPPET = '<button class="clear" data-action="deleteElement">' +
                                  '<span>X</span>' +
                                '</button>';

function createInputRowTemplate(properties, canRemove) {
  var template = TABLE_ROW_DIV_SNIPPET;
  template += createInputTemplate(properties, canRemove);
  template += canRemove ? DELETE_ROW_BUTTON_SNIPPET : '';
  template += '</div>';

  return template;
}

function createInputTemplate(properties, canRemove) {
  var columns = properties.length;
  var template = '';
  forEach(properties, function(prop) {
    template += '<input class="bpp-table-row-columns-' + columns + ' ' +
                               (canRemove ? 'bpp-table-row-removable' : '') + '" ' +
                       'id="activiti-table-row-cell-input-value" ' +
                       'type="text" ' +
                       'name="' + escapeHTML(prop) + '" />';
  });
  return template;
}

function createLabelRowTemplate(labels) {
  var template = TABLE_ROW_DIV_SNIPPET;
  template += createLabelTemplate(labels);
  template += '</div>';

  return template;
}

function createLabelTemplate(labels) {
  var columns = labels.length;
  var template = '';
  forEach(labels, function(label) {
    template += '<label class="bpp-table-row-columns-' + columns + '">' + escapeHTML(label) + '</label>';
  });
  return template;
}

function pick(elements, properties) {
  return (elements || []).map(function(elem) {
    var newElement = {};
    forEach(properties, function(prop) {
      newElement[prop] = elem[prop] || '';
    });
    return newElement;
  });
}

function diff(element, node, values, oldValues, editable) {
  return filter(values, function(value, idx) {
    return !valueEqual(element, node, value, oldValues[idx], editable, idx);
  });
}

function valueEqual(element, node, value, oldValue, editable, idx) {
  if (value && !oldValue) {
    return false;
  }
  var allKeys = keys(value).concat(keys(oldValue));

  return allKeys.every(function(key) {
    var n = value[key] || undefined;
    var o = oldValue[key] || undefined;
    return !editable(element, node, key, idx) || n === o;
  });
}

function getEntryNode(node) {
  return domClosest(node, '[data-entry]', true);
}

function getContainer(node) {
  return domQuery('div[data-list-entry-container]', node);
}

function getSelection(node) {
  return {
    start: node.selectionStart,
    end: node.selectionEnd
  };
}

function setSelection(node, selection) {
  node.selectionStart = selection.start;
  node.selectionEnd = selection.end;
}

/**
 * @param  {Object} options
 * @param  {string} options.id
 * @param  {string} options.description
 * @param  {Array<string>} options.modelProperties
 * @param  {Array<string>} options.labels
 * @param  {Function} options.getElements - this callback function must return a list of business object items
 * @param  {Function} options.removeElement
 * @param  {Function} options.addElement
 * @param  {Function} options.updateElement
 * @param  {Function} options.editable
 * @param  {Function} options.setControlValue
 * @param  {Function} options.show
 *
 * @return {Object}
 */
module.exports = function(options) {

  var id = options.id,
      modelProperties = options.modelProperties,
      labels = options.labels,
      description = options.description;

  var labelRow = createLabelRowTemplate(labels);

  var getElements = options.getElements;

  var removeElement = options.removeElement,
      canRemove = typeof removeElement === 'function';

  var addElement = options.addElement,
      canAdd = typeof addElement === 'function',
      addLabel = options.addLabel || 'Add Value';

  var updateElement = options.updateElement,
      canUpdate = typeof updateElement === 'function';

  var editable = options.editable || function() { return true; },
      setControlValue = options.setControlValue;

  var show = options.show,
      canBeShown = typeof show === 'function';

  var elements = function(element, node) {
    return pick(getElements(element, node), modelProperties);
  };

  var factory = {
    id: id,
    html: (canAdd ?
      '<div class="bpp-table-add-row" ' + (canBeShown ? 'data-show="show"' : '') + '>' +
            '<label>' + escapeHTML(addLabel) + '</label>' +
            '<button class="add" data-action="addElement"><span>+</span></button>' +
          '</div>' : '') +
          '<div class="bpp-table" data-show="showTable">' +
            '<div class="bpp-field-wrapper bpp-table-row">' +
               labelRow +
            '</div>' +
            '<div data-list-entry-container>' +
            '</div>' +
          '</div>' +

          // add description below table entry field
          (description ? entryFieldDescription(description) : ''),

    get: function(element, node) {
      var boElements = elements(element, node, this.__invalidValues);

      var invalidValues = this.__invalidValues;

      delete this.__invalidValues;

      forEach(invalidValues, function(value, idx) {
        var element = boElements[idx];

        forEach(modelProperties, function(prop) {
          element[prop] = value[prop];
        });
      });

      return boElements;
    },

    set: function(element, values, node) {
      var action = this.__action || {};
      delete this.__action;

      if (action.id === 'delete-element') {
        return removeElement(element, node, action.idx);
      }
      else if (action.id === 'add-element') {
        return addElement(element, node);
      }
      else if (canUpdate) {
        var commands = [],
            valuesToValidate = values;

        if (typeof options.validate !== 'function') {
          valuesToValidate = diff(element, node, values, elements(element, node), editable);
        }

        var self = this;

        forEach(valuesToValidate, function(value) {
          var validationError,
              idx = values.indexOf(value);

          if (typeof options.validate === 'function') {
            validationError = options.validate(element, value, node, idx);
          }

          if (!validationError) {
            var cmd = updateElement(element, value, node, idx);

            if (cmd) {
              commands.push(cmd);
            }
          } else {
            // cache invalid value in an object by index as key
            self.__invalidValues = self.__invalidValues || {};
            self.__invalidValues[idx] = value;

            // execute a command, which does not do anything
            commands.push(cmdHelper.updateProperties(element, {}));
          }
        });

        return commands;
      }
    },
    createListEntryTemplate: function(value, index, selectBox) {
      return createInputRowTemplate(modelProperties, canRemove);
    },

    addElement: function(element, node, event, scopeNode) {
      var template = domify(createInputRowTemplate(modelProperties, canRemove));

      var container = getContainer(node);
      container.appendChild(template);

      this.__action = {
        id: 'add-element'
      };

      return true;
    },

    deleteElement: function(element, node, event, scopeNode) {
      var container = getContainer(node);
      var rowToDelete = event.delegateTarget.parentNode;
      var idx = parseInt(domAttr(rowToDelete, 'data-index'), 10);

      container.removeChild(rowToDelete);

      this.__action = {
        id: 'delete-element',
        idx: idx
      };

      return true;
    },

    editable: function(element, rowNode, input, prop, value, idx) {
      var entryNode = domClosest(rowNode, '[data-entry]');
      return editable(element, entryNode, prop, idx);
    },

    show: function(element, entryNode, node, scopeNode) {
      entryNode = getEntryNode(entryNode);
      return show(element, entryNode, node, scopeNode);
    },

    showTable: function(element, entryNode, node, scopeNode) {
      entryNode = getEntryNode(entryNode);
      var elems = elements(element, entryNode);
      return elems && elems.length && (!canBeShown || show(element, entryNode, node, scopeNode));
    },

    validateListItem: function(element, value, node, idx) {
      if (typeof options.validate === 'function') {
        return options.validate(element, value, node, idx);
      }
    }

  };

  // Update/set the selection on the correct position.
  // It's the same code like for an input value in the PropertiesPanel.js.
  if (setControlValue) {
    factory.setControlValue = function(element, rowNode, input, prop, value, idx) {
      var entryNode = getEntryNode(rowNode);

      var isReadOnly = domAttr(input, 'readonly');
      var oldValue = input.value;

      var selection;

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

      // when the attribute 'readonly' exists, ignore the comparison
      // with 'oldValue' and 'value'
      if (!!isReadOnly && oldValue === value) {
        return;
      }

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

      setControlValue(element, entryNode, input, prop, value, idx);

      if (selection) {
        setSelection(input, selection);
      }

    };
  }

  return factory;

};