var data;

function getTitleAttribute(node) {
  if(typeof node['name'] !== "undefined"){
    return 'name';
  }
  switch (node['type']) {
    case "WebSite":
      if(typeof node['url'] !== "undefined") {return 'url';}
      break;
    case "ImageObject":
      if(typeof node['caption'] !== "undefined") {return 'caption';}
      if(typeof node['contentUrl'] !== "undefined") {return 'contentUrl';}
      break;
    case "PostalAddress":
      if(typeof node['addressLocality'] !== "undefined") {return 'addressLocality';}
      break;
  }
  return 'id';
}
function getNodeTitle(node){
  return node[getTitleAttribute(node)];
}
/**
Transform a flattened jsonld into a d3 compatible graph
@param Object data flattened jsonld data
@return Object graph has keys "nodes" and "links"
*/
function jsonLdToGraph(data){
  let nodes = {};
  let links = [];

  // collect all nodes
  for(let nodeId in data){
    // data[nodeId]["type"][0] = data[nodeId]["type"][0];
    nodes[data[nodeId]["id"]] = data[nodeId];
  }

  // collect all links (separate loop as we need to check nodes)
  for(let nodeId in data) {
    let node = data[nodeId];
    let currentId = node["id"];
    for(let key in node){
      let nodeAttr = Array.isArray(node[key]) ? node[key] : [node[key]];
      // // relations should always be lists (eases assumptions)
      // if(typeof node[key] !== "Array" && typeof node[key]['id'] !== "undefined") {
      //   node[key] = [node[key]];
      // }
      // every attribute is an Array after flatten(), loop them
      for(let i in nodeAttr) {
        if(key !== "id" && typeof nodeAttr[i] === "string" && nodes[nodeAttr[i]]) {
          links[links.length] = {
            "source": currentId,
            "target": nodeAttr[i],
            "name": key
            };
        }
        else if(typeof nodeAttr[i]["id"] !== "undefined") {
          // if there is just one item, flatten/expand has turned urls in objects with just an id
          // reverse this, as we don't want these separate for this project
          if (Object.keys(nodeAttr[i]).length == 1 && typeof nodes[nodeAttr[i]["id"]] === "undefined") {
              // skip
              // nodeAttr = nodeAttr[i]["id"];
          } else {
            links[links.length] = {
              "source": currentId,
              "target": nodeAttr[i]["id"],
              "name": key
              };
          }
        }
      }
    }
  }
  return {
    "nodes": Object.values(nodes),
    "links": links
  };
}

var graph;
var nodeMap = {};
jsonld.flatten(window.location.protocol + "//" + window.location.host + "/rubenvandeven.jsonld", {"@context": "https://schema.org/"},(err, flattened)=> {
  console.log(err);
  data = flattened;
  graph = jsonLdToGraph(flattened['@graph']);
  // create a map of nodes by id.
  for(let i in graph.nodes) {
    nodeMap[graph.nodes[i]['id']] = graph.nodes[i];
  }
  // console.log(graph);
  startGraph(graph);
});


function inCircle(dx, dy, r) {
  // fastest check if in circle: https://stackoverflow.com/a/7227057
  let dxAbs = Math.abs(dx);
  let dyAbs = Math.abs(dy);

  if(dxAbs > r || dyAbs > r) {
    return false;
  } else if(dxAbs + dyAbs <= r){
    return true;
  } else if( Math.pow(dx,2) + Math.pow(dy, 2) <= Math.pow(r,2)){
    return true;
  } else {
    return false;
  }
}

var nodePositions = {};
function startGraph(graph){


  // config
var nodeSize = 40;
var selectedNodeSize = 140;

// set some vars
var currentNodeIdx = 0;
var currentNodePositionRadius = 0;
var types = {};
for (let nodeIdx in graph['nodes']) {
  let type = graph['nodes'][nodeIdx]["type"];
  if(typeof types[type] == 'undefined') {
    types[type] = [];
  }
  types[type][types[type].length] = nodeIdx;
}
var graphControlsEl = document.getElementById('graphControls');
var typeLinksEl = document.getElementById('typeLinks');
var relLinksEl = document.getElementById('relLinks');

// make controls
for (let typeName in types) {
  let typeLinkEl = document.createElement("li");
  let typeLinkAEl = document.createElement("a");
  typeLinkAEl.innerHTML = typeName;
  typeLinkAEl.addEventListener('click', function(){
    centerByType(typeName);
    // positionNodesInCenter(types[typeName]);
  });
  typeLinkEl.append(typeLinkAEl);
  typeLinksEl.appendChild(typeLinkEl);
}


// make svg
var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d["id"]; }).strength(.005))
    .force("charge", d3.forceManyBody()) // doesn't seem necessary?
    .force("collision", d3.forceCollide(nodeSize * 1.1)) // avoid overlapping nodes
    // .force("center", d3.forceCenter(width / 2, height / 2)) // position around center

    // .force("x", d3.forceX())
    // .force("y", d3.forceY())
    // .force("y", d3.forceY())
  ;


var link = svg.append("g")
    .attr("class", "links")
  .selectAll(".relationship")
  .data(graph['links'])
  .enter().append("g")
    .attr("class", function(d){return "relationship "+d.name;})
    ;
var linkLine = link
    // .append("line");
    .append("line").attr("marker-end", "url(#arrowHead)")
    ;
var linkText = link
    .append("text")
      .text(function(d){
        return d.name;
        // snake_case: return d.name.replace(/(?:^|\.?)([A-Z])/g, function (x,y){return "_" + y.toLowerCase()}).replace(/^_/, "");
      })

    ;

 var node = svg.append("g")
    .attr("class", "nodes")
    .selectAll(".node")
      .data(graph.nodes)
    .enter().append("g")
      .attr("class", function(d) { return 'node ' + d['type']; })
      ;
var getViewbox = function() {
  return svg.attr("viewBox").split(" ").map(parseFloat);
}
var positionNodesInCenter = function(idxs) {
  let viewBox = getViewbox();
  let cx = viewBox[0] + viewBox[2]/2;
  let cy = viewBox[1] + viewBox[3]/2;

  if(typeof idxs == "object" && idxs !== null && idxs.length == 1) {
    idxs = idxs[0];
  }

  nodePositions = {}; // reset
  if(idxs === null) {
    return;
  }
  else if(typeof idxs == "object") {
    // array or object -> each
    // calculate grid:
    // let itemsX = 4;
    // let itemsY = Math.ceil(idxs.length/itemsX);
    // console.log(itemsX,itemsY);
    // let rowDiffX = viewBox[3] * (1/(itemsX+1));
    // let rowDiffY = viewBox[2] * (1/(itemsY+1));
    // console.log(rowDiffX, rowDiffY);
    // for (var i = 0; i < idxs.length; i++) {
    //   nodePositions[idxs[i]] = [
    //     cx - itemsX/2*rowDiffX + rowDiffX * ((i % itemsX)),
    //     cy - itemsY/2*rowDiffY  + rowDiffY * (Math.floor(i / itemsX))
    //   ];
    // }
    positionNodesInCircle(idxs);
    console.log(nodePositions);
  }
  else{
    nodePositions[idxs] = [
      cx,
      cy
    ];
  }

  node.each(function(d,nIdx,nodeEls){
    if(typeof nodePositions[nIdx] != 'undefined') {
      nodeEls[nIdx].classList.add('centeredNode');
      nodeEls[nIdx].classList.add('visibleNode');
    } else {
      nodeEls[nIdx].classList.remove('centeredNode');
    }
  });

  // restart animation (they call that 'alpha' in d3 force)
  simulation.alpha(1);
  simulation.restart();
}
var positionNodesInCircle = function(idxs, r) {
  let viewBox = getViewbox();
  if(typeof r == 'undefined') {
    if(idxs.length == 1) {
      r = viewBox[2] / 6;
    } else {
      r = viewBox[2] / (4 + Math.max(0, 2.5 - idxs.length));
    }
  }
  currentNodePositionRadius = r;
  let cx = viewBox[0] + viewBox[2]/2;
  let cy = viewBox[1] + viewBox[3]/2;

  let stepSize = 2*Math.PI / idxs.length;
  for (var i = 0; i < idxs.length; i++) {
    nodePositions[idxs[i]] = [
      cx + Math.sin(stepSize * i) * r,
      cy + Math.cos(stepSize * i) * r
    ];
  }

    // restart animation (they call that 'alpha' in d3 force)
    console.log("reset alpha");
    simulation.alpha(1);
    simulation.restart();
}
var centerByType = function(types) {
  if(!Array.isArray(types)) {
    types = [types];
  }
  let idxs = [];
  for(let idx in graph.nodes) {
    if(types.indexOf(graph.nodes[idx]['type']) > -1) {
      idxs[idxs.length] = idx;
    }
  }
  deselectNode();
  positionNodesInCenter(idxs.length ? idxs : null);
}

var selectedNodeTransition = d3.transition()
  .duration(750)
  .ease(d3.easeLinear);

var nodeDetailEl = document.getElementById("nodeDetails");

var createRelationshipEl = function(relNode, i) {
  let el = document.createElement("dd");
  el.classList.add('relLink');
  let titleEl = document.createElement('a');
  titleEl.innerHTML = getNodeTitle(relNode);
  titleEl.classList.add('nodeTitle');
  titleEl.classList.add('nodeTitleNr'+i);
  titleEl.addEventListener('click',function(e){
    let idx = graph.nodes.indexOf(relNode);
    selectNode(idx);
  });
  let typeEl = document.createElement('a');
  typeEl.classList.add('nodeType')
  typeEl.innerHTML = relNode['type']
  typeEl.addEventListener('click',function(e){
    centerByType(relNode['type']);
  });
  el.appendChild(titleEl);
  el.appendChild(typeEl);
  // el.innerHTML = `${getNodeTitle(relNode)} (${relNode['type']})`;
  return el;
}

var setDetails = function(nodeDatum, nodeIdx) {
  document.body.classList.add("detailsOpen");
  while (nodeDetailEl.hasChildNodes()) {
      nodeDetailEl.removeChild(nodeDetailEl.lastChild);
  }


  let relUp = [];
  let relDown = [];
  let titleAttr = getTitleAttribute(nodeDatum);
  let titleEl = document.createElement('h2');
  titleEl.innerHTML = getNodeTitle(nodeDatum);

  let typeEl = document.createElement('span');
  typeEl.classList.add('nodeType')
  typeEl.innerHTML = nodeDatum['type']
  typeEl.addEventListener('click',function(e){
    centerByType(nodeDatum['type']);
  });
  titleEl.appendChild(typeEl);
  nodeDetailEl.appendChild(titleEl);

  let listEl  = document.createElement("dl");
  // listEl.innerHTML += `<dt>type</dt><dd>${nodeDatum['type']}</dd>`;
  for (let attr in nodeDatum) {
    if([
      'id','x','y','index','type','vy','vx','fx','fy','leftX','rightX', titleAttr
    ].indexOf(attr) != -1) {
      continue;
    }

    // approach all as array
    let nodeAttr = Array.isArray(nodeDatum[attr]) ? nodeDatum[attr] : [nodeDatum[attr]];
    for (let i in nodeAttr) {
      // check if relationship:
      if(typeof nodeAttr[i] === "string" && nodeMap[nodeAttr[i]]) {
        continue;
      } else if(typeof nodeAttr[i]['id'] !== 'undefined') {
        continue;
      }
      if(attr == 'url') {
        listEl.innerHTML += `<dt class='dt-${attr}'>${attr}</dt><dd class='dd-${attr}'><a href='${nodeAttr[i]}'>${nodeAttr[i]}</a></dd>`;
      } else if(attr == 'contentUrl') {
        listEl.innerHTML += `<dt class='dt-${attr}'>${attr}</dt><dd class='dd-${attr}'><a href='${nodeAttr[i]}'>${nodeAttr[i]}</a></dd>`;
        listEl.innerHTML += `<dd class='dd-contentobject'><object data='${nodeAttr[i]}'></object></dd>`;
      } else {
        listEl.innerHTML += `<dt class='dt-${attr}'>${attr}</dt><dd class='dd-${attr}'>${nodeAttr[i]}</dd>`;
      }
    }
  }
  nodeDetailEl.appendChild(listEl);

  let relTitleEl = document.createElement("h4");
  relTitleEl.classList.add('linkTitle');
  relTitleEl.innerHTML = "links";
  nodeDetailEl.appendChild(relTitleEl);

  let relsEl = document.createElement("dl");
  // collect relationships
  for (var i = 0; i < graph.links.length; i++) {
    let link = graph.links[i];
    if(link['source']['id'] == nodeDatum['id']) {
      if(typeof relDown[link['name']] == "undefined") {
        relDown[link['name']] = [];
      }
      relDown[link['name']][relDown[link['name']].length] = link['target'];
    }
    if(link['target']['id'] == nodeDatum['id']) {
      if(typeof relUp[link['name']] == "undefined") {
        relUp[link['name']] = [];
      }
      relUp[link['name']][relUp[link['name']].length] = link['source'];
    }
  }

  // relationships / links in <dl>
  for(let attr in relDown) {
    let attrEl = document.createElement("dt");
    attrEl.innerHTML = attr;
    relsEl.appendChild(attrEl);
    for(let i in relDown[attr]) {
      let rel = relDown[attr][i];
      relsEl.appendChild(createRelationshipEl(rel));
      if(typeof rel['contentUrl'] != 'undefined') {
        let ddEl = document.createElement('dd')
        ddEl.classList.add('dd-contentobject');
        ddEl.innerHTML = `<object data='${rel['contentUrl']}'></object>`
        relsEl.appendChild(ddEl);
      }
    }
  }

  for(let attr in relUp) {
    let attrEl = document.createElement("dt");
    attrEl.innerHTML = attr;
    relsEl.appendChild(attrEl);
    for(let i in relUp[attr]) {
      let rel = relUp[attr][i];
      relsEl.appendChild(createRelationshipEl(rel, i));
      if(typeof rel['contentUrl'] != 'undefined') {
        let ddEl = document.createElement('dd')
        ddEl.classList.add('dd-contentobject');
        ddEl.innerHTML = `<object data='${rel['contentUrl']}'></object>`
        relsEl.appendChild(ddEl);
      }
    }
  }

  nodeDetailEl.appendChild(relsEl);

  node.each(function(d,nIdx,nodeEls){
    if(nIdx == nodeIdx) {
      nodeEls[nIdx].classList.add('selectedNode');
    } else {
      nodeEls[nIdx].classList.remove('selectedNode');
    }
  });
};
var closeDetails = function() {
  document.body.classList.remove("detailsOpen");
}

/**
 * Select a node, and center it + show details
 * @param  int idx    The index of the node in the graph.nodes array
 * @param  Element|null nodeEl Optional, provide node element, so loop doesn't have to be used to change the Element
 * @return void
 */
var selectNode = function(idx){
  let nodeEl = null;
  let nodeDatum = null;
  node.each(function(d,nIdx,nodeEls){
    if(nIdx == idx) {
      nodeEl = nodeEls[idx];
      nodeDatum = d;
    }
  });
  if(!nodeEl) {
    return;
  }

  // set global var
  positionNodesInCenter(idx);

  /* DISABLED: Make selected nodes bigger
  // update collision: the selected node should get plenty of space.
  simulation.force("collision").radius(function(d, idx){
    if(typeof nodePositions[idx] != 'undefined'){
      return selectedNodeSize * 1.2;
    }
    return nodeSize * 1.1;
  });
  node.each(function(d, idx, nodeEls){
    let nodeEl = nodeEls[idx];
    let nodeD3 = d3.select(nodeEl);
    let circleD3 = nodeD3.select('circle');

    if(typeof nodePositions[idx] !== 'undefined') {
      circleD3.transition(selectedNodeTransition).attr('r', selectedNodeSize);
      // nodeEl.getElementsByTagName("circle")[0].attributes.r.value = selectedNodeSize;
    } else {
      circleD3.transition(selectedNodeTransition).attr('r', nodeSize);
      // nodeEl.getElementsByTagName("circle")[0].attributes.r.value = nodeSize;
    }
  });
  */
  let linkedIdxs = [];
  link.each(function(d,idx,linkEls,q){
    if(d.source == nodeDatum || d.target == nodeDatum) {
      linkEls[idx].classList.add('activeLink','visibleLink');
      linkEls[idx].getElementsByTagName("line")[0].setAttribute("marker-end", "url(#arrowHeadSelected)");
      node.filter(function(a, fnodeIdx){
        let r = a.id == d.source.id || a.id == d.target.id; //connected node: true/false
        if(r && linkedIdxs.indexOf(fnodeIdx) === -1){
          linkedIdxs[linkedIdxs.length] = fnodeIdx;
        }
        return r;
     }).classed('visibleNode', true);

    } else {
      linkEls[idx].classList.remove('activeLink');
      linkEls[idx].getElementsByTagName("line")[0].setAttribute("marker-end", "url(#arrowHead)");
    }
  });

  let i = linkedIdxs.indexOf(idx);

  if(i !== -1) {
    linkedIdxs.splice(i, 1);
  }

  positionNodesInCircle(linkedIdxs);

  setDetails(nodeDatum ,idx);
}
var deselectNode = function() {
  positionNodesInCenter(null);
  link.each(function(d,idx,linkEls,q){
    linkEls[idx].classList.remove('activeLink');
    linkEls[idx].getElementsByTagName("line")[0].setAttribute("marker-end", "url(#arrowHead)")
  });
  closeDetails();
}

simulation.force('centerActive', function force(alpha) {
  // let currentNode = node.selectAll('.detail');
  // console.log(currentNode);
  node.each(function(d, idx, nodes){
    let n = d;
    let k = alpha * 0.1;
    if(typeof nodePositions[idx] != 'undefined') {
        n.vx -= (n.x - nodePositions[idx][0]) * k * 5;
        n.vy -= (n.y - nodePositions[idx][1]) * k * 5;
    } else {
      // if it's not positioned, move it out of the circle
      if(currentNodePositionRadius < 1) {
        return;
      }

      let viewBox = getViewbox();
      let cx = viewBox[0] + viewBox[2]/2;
      let cy = viewBox[1] + viewBox[3]/2;

      let dx = n.x - cx;
      let dy = n.y - cy;
      if(!inCircle(dx, dy, currentNodePositionRadius)) {
        return;
      }

      n.vx += dx * k /5;
      n.vy += dy * k /5;
    }
  });
});

//path to curve the tile
var nodePath = node.append("path")
          .attr("id", function(d,idx){return "nodePath"+idx;})
          .attr("d", function(){
            var r = nodeSize * 0.9;
            var startX = nodeSize;
            // M cx cy
            // m -r, 0
            // a r,r 0 1,0 (r * 2),0
            // a r,r 0 1,0 -(r * 2),0
            // return 'M' + nodeSize/2 + ' ' + nodeSize/2 + ' ' +
            return 'M' + 0 + ' ' + 0 + ' ' +
                  'm -' + r + ', 0'+' ' +
                  'a ' + r +','+r+' 0 1,0 '+ (r*2) +',0 '+
                  'a ' + r +','+r+' 0 1,0 -'+ (r*2) +',0'
                  ;
            // return 'm' + startX + ',' + nodeSize + ' ' +
              // 'a' + r + ',' + r + ' 0 0 0 ' + (2*r) + ',0';
          })
          ;

node.call(d3.drag()
        .on("start", dragstarted)
        .on("drag", dragged)
        .on("end", dragended))
  .on("click", function(d, idx, nodes){
    let node = nodes[idx];
    // if(typeof nodePositions[idx] == 'undefined') {
    selectNode(idx, node, d);
    // } else {
    //   node.parentNode.classList.toggle('detail');
    // }
    });

svg.call(d3.drag()
        .on("start", function(){
          svg.node().classList.add("dragging");
        })
        .on("drag", function(){
          moveViewboxPx(d3.event.dx, d3.event.dy);
        })
        .on("end", function(){
          svg.node().classList.remove("dragging");
        }));

node.append('circle')
    .attr("r", nodeSize)
    .attr("class", "nodeBg")
    ;
node.append('circle')
    .attr("r", nodeSize * 1.08) // nodeSize + margin
    .attr("class", "highlightCircle")
    ;

node.append('text')
    .append("textPath")
    .attr( "xlink:href",function(d, idx){return '#nodePath'+idx;})
    .text(getNodeTitle);

node.each(function(d) {
    if(!d.contentUrl) {
      return;
    }
    d3.select(this).append('svg:image')
    .attr("xlink:href", d.contentUrl)
    .attr("width", nodeSize*2)
    .attr("height", nodeSize*2)
    .attr("transform","translate(-"+nodeSize+" -"+nodeSize+")")
    .attr("clip-path","url(#clipNodeImage)")
    .attr("preserveAspectRatio","xMidYMid slice")
    ;
  });

// node.append("title")
//     .text(function(d) { return d.id; });

simulation
    .nodes(graph.nodes)
    .on("tick", ticked);

simulation.force("link")
    .links(graph.links)
  .distance(function(l){
    switch (l.name) {
      case 'publishedAt':
        return 400;
      case 'image':
        return 100;
      default:
        return 200;
    }
  }) // distance between the nodes / link length
  // .charge(-100)
;

// run on each draw
function ticked() {
  graph.nodes.forEach(function (d, idx) {
              d.leftX = d.rightX = d.x;

  // fix first node on center
  //             if(idx === 0) {
  //               d.fx = width/2;
  //               d.fy = height/2;
  //               return;
              // }
          });

  linkLine.each(function (d) {
            var sourceX, targetX, midX, dx, dy, angle;

            // This mess makes the arrows exactly perfect.
            // thanks to http://bl.ocks.org/curran/9b73eb564c1c8a3d8f3ab207de364bf4
            if( d.source.rightX < d.target.leftX ){
              sourceX = d.source.rightX;
              targetX = d.target.leftX;
            } else if( d.target.rightX < d.source.leftX ){
              targetX = d.target.rightX;
              sourceX = d.source.leftX;
            } else if (d.target.isCircle) {
              targetX = sourceX = d.target.x;
            } else if (d.source.isCircle) {
              targetX = sourceX = d.source.x;
            } else {
              midX = (d.source.x + d.target.x) / 2;
              if(midX > d.target.rightX){
                midX = d.target.rightX;
              } else if(midX > d.source.rightX){
                midX = d.source.rightX;
              } else if(midX < d.target.leftX){
                midX = d.target.leftX;
              } else if(midX < d.source.leftX){
                midX = d.source.leftX;
              }
              targetX = sourceX = midX;
            }

            dx = targetX - sourceX;
            dy = d.target.y - d.source.y;
            angle = Math.atan2(dx, dy);

            /* DISABLED
            srcSize = (typeof nodePositions[d.source.index] != 'undefined') ? selectedNodeSize : nodeSize;
            tgtSize = (typeof nodePositions[d.target.index] != 'undefined') ? selectedNodeSize : nodeSize;
            */
            let srcSize = nodeSize;
            let tgtSize = nodeSize;

            // Compute the line endpoint such that the arrow
            // is touching the edge of the node rectangle perfectly.
            d.sourceX = sourceX + Math.sin(angle) * srcSize;
            d.targetX = targetX - Math.sin(angle) * tgtSize;
            d.sourceY = d.source.y + Math.cos(angle) * srcSize;
            d.targetY = d.target.y - Math.cos(angle) * tgtSize;
          })
          .attr("x1", function(d) { return d.sourceX; })
          .attr("y1", function(d) { return d.sourceY; })
          .attr("x2", function(d) { return d.targetX; })
          .attr("y2", function(d) { return d.targetY; });
  linkText.attr("transform", function(d){
    let dx = (d.target.x - d.source.x) /2;
    let dy = (d.target.y - d.source.y) /2;
    let x = d.source.x + dx;
    let y = d.source.y + dy;
    let deg = Math.atan(dy / dx) * 180 / Math.PI;
    return "translate("+x+" "+y+") rotate("+deg+") translate(0, -10)";
  });
  // linkPath.attr("d", function(d) {
  //       var x1 = d.source.x,
  //           y1 = d.source.y,
  //           x2 = d.target.x,
  //           y2 = d.target.y,
  //           dx = x2 - x1,
  //           dy = y2 - y1,
  //           dr = Math.sqrt(dx * dx + dy * dy),

  //           // Defaults for normal edge.
  //           drx = dr,
  //           dry = dr,
  //           xRotation = 0, // degrees
  //           largeArc = 0, // 1 or 0
  //           sweep = 1; // 1 or 0

  //           // Self edge.
  //           if ( x1 === x2 && y1 === y2 ) {
  //             // Fiddle with this angle to get loop oriented.
  //             xRotation = -45;

  //             // Needs to be 1.
  //             largeArc = 1;

  //             // Change sweep to change orientation of loop.
  //             //sweep = 0;

  //             // Make drx and dry different to get an ellipse
  //             // instead of a circle.
  //             drx = 30;
  //             dry = 20;

  //             // For whatever reason the arc collapses to a point if the beginning
  //             // and ending points of the arc are the same, so kludge it.
  //             x2 = x2 + 1;
  //             y2 = y2 + 1;
  //           }

  //      return "M" + x1 + "," + y1 + "A" + drx + "," + dry + " " + xRotation + "," + largeArc + "," + sweep + " " + x2 + "," + y2;
  //     });

      node.attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; });
}

function dragstarted(d,idx,nodes) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  let nodeEl = nodes[idx];
  d.fx = d.x;
  d.fy = d.y;
  // nodeEl.style.fill = '#00f';
  nodeEl.classList.add('drag');
}

// use to validate drag
// function validate(x, a, b) {
//     if (x =< a) return a;
//     return b;
// }

function dragged(d, idx) {
  d.fx = d3.event.x;
  d.fy = d3.event.y;
}

function dragended(d, idx, nodes) {
  if (!d3.event.active) simulation.alphaTarget(0);
  let nodeEl = nodes[idx];
  d.fx = null;
  d.fy = null;
  nodeEl.classList.remove('drag');
}

function moveViewboxPx(dx, dy){
  let viewBox = svg.attr("viewBox").split(" ").map(parseFloat);
  viewBox[0] -= dx * 1;
  viewBox[1] -= dy * 1;
  svg.attr("viewBox", viewBox.join(" "));
}

// start by selecting the first node :-)
// selectNode(currentNodeIdx+1);
// positionNodesInCenter(currentNodeIdx);
selectNode(currentNodeIdx); //deselectNode();
closeDetails();
// positionNodesInCenter(currentNodeIdx+1);
}