(function(BpmnJS, $) {

  var container = $('#js-drop-zone');

  var canvas = $('#js-canvas');
  
  var renderer = new BpmnJS({ container: canvas, width: '100%', height: '100%' });

  var newDiagramXML =
'<?xml version="1.0" encoding="UTF-8"?>' +
'<bpmn2:definitions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:bpmn2="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xsi:schemaLocation="http://www.omg.org/spec/BPMN/20100524/MODEL BPMN20.xsd" id="sample-diagram" targetNamespace="http://bpmn.io/schema/bpmn">' +
'  <bpmn2:process id="Process_1" isExecutable="false">' +
'    <bpmn2:startEvent id="StartEvent_1"/>' +
'  </bpmn2:process>' +
'  <bpmndi:BPMNDiagram id="BPMNDiagram_1">' +
'    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_1">' +
'      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">' +
'        <dc:Bounds height="36.0" width="36.0" x="412.0" y="240.0"/>' +
'      </bpmndi:BPMNShape>' +
'    </bpmndi:BPMNPlane>' +
'  </bpmndi:BPMNDiagram>' +
'</bpmn2:definitions>';

  function createNewDiagram() {
    openDiagram(newDiagramXML);
  }

  function openDiagram(xml) {

    renderer.importXML(xml, function(err) {
      
      if (err) {
        container
          .removeClass('with-diagram')
          .addClass('with-error');

        container.find('.error pre').text(err.message);

        console.error(err);
      } else {
        container
          .removeClass('with-error')
          .addClass('with-diagram');
      }


    });
  }

  function saveSVG(done) {
    renderer.saveSVG(done);
  }

  function saveDiagram(done) {

    renderer.saveXML({ format: true }, function(err, xml) {
      done(err, xml);
    });
  }

  ////// file drag / drop ///////////////////////

  // check file api availability
  if (!window.FileList || !window.FileReader) {
    window.alert(
      'Looks like you use an older browser that does not support drag and drop. ' +
      'Try using Chrome, Firefox or the Internet Explorer > 10.');
    
    return;
  }

  (function onFileDrop(container, callback) {

    function handleFileSelect(e) {
      e.stopPropagation();
      e.preventDefault();

      var files = e.dataTransfer.files;

      var file = files[0];
        
      var reader = new FileReader();

      reader.onload = function(e) {

        var xml = e.target.result;

        callback(xml);
      };

      reader.readAsText(file);
    }

    function handleDragOver(e) {
      e.stopPropagation();
      e.preventDefault();

      e.dataTransfer.dropEffect = 'copy'; // Explicitly show this is a copy.
    }

    container.get(0).addEventListener('dragover', handleDragOver, false);
    container.get(0).addEventListener('drop', handleFileSelect, false);

  })(container, openDiagram);


  $(document).on('ready', function() {

    $('#js-create-diagram').click(function(e) {
      e.stopPropagation();
      e.preventDefault();

      createNewDiagram();
    });

    var downloadLink = $('#js-download-diagram');
    var downloadSvgLink = $('#js-download-svg');

    $('.buttons a').click(function(e) {
      if (!$(this).is('.active')) {
        e.preventDefault();
        e.stopPropagation();
      }
    });
    
    function setEncoded(link, name, data) {
      var encodedData = encodeURIComponent(data);

      if (data) {
        link.addClass('active').attr({
          'href': 'data:application/bpmn20-xml;charset=UTF-8,' + encodedData,
          'download': name
        });
      } else {
        link.removeClass('active');
      }
    }
    
    var _ = require('lodash');

    var exportArtifacts = _.debounce(function() {

      saveSVG(function(err, svg) {
        setEncoded(downloadSvgLink, 'diagram.svg', err ? null : svg);
      });

      saveDiagram(function(err, xml) {
        setEncoded(downloadLink, 'diagram.bpmn', err ? null : xml);
      });
    }, 500);

    renderer.on('commandStack.changed', exportArtifacts);
  });

})(window.BpmnJS, require('jquery'));