() => {
    var script = document.createElement("script");
    script.src = "https://visjs.github.io/vis-network/standalone/umd/vis-network.min.js";
    document.head.appendChild(script);

    // var current_options;
    // var node_pass_prob, prelen, max_path, node_tokens, node_probs, links, tarlen;
    // var visible_nodes, map_max_path;
    // var visible_edges, sorted_links_out, sorted_links_in;
    // var nodes, edges, network;
    // var disable_edge_select;
    showing_node = undefined;
    showing_edge = undefined;
    
    function obtain_node_object(node_id) {
        var title = "Node " + node_id.toString() + " (Pass Prob = " + node_pass_prob[node_id].toFixed(2) + ")\n";
        title += "==========\n"
        for(var j=0;j<5;j++){
            if(node_probs[node_id][j]> 0.01){
                title += node_tokens[node_id][j] + "\t" + node_probs[node_id][j].toFixed(2) + "\n";
            }
        }

        var currentNode = {"id": node_id, "label": node_tokens[node_id][0], "value":node_pass_prob[node_id], "title": title};
        if (current_options.show_node_detail){
            currentNode.label = title;
        }
        if(map_max_path[node_id] !== undefined){
            currentNode.x = map_max_path[node_id].x;
            currentNode.y = map_max_path[node_id].y;
            currentNode.fixed = true;
            currentNode.mass = 5;
            currentNode.color = {border: "red", background: "orange", highlight: {border: "red", background: "#ffcc66"}};
        }
        return currentNode;
    }

    function set_node_visibility(node_id, flag){
        if(visible_nodes[node_id] == flag) return;
        visible_nodes[node_id] = flag;
        if(flag){
            nodes.add(obtain_node_object(node_id));
        }else{
            nodes.remove(node_id);
        }
    }

    function update_visible_nodes(clear_state=false){
        if(typeof visible_nodes === "undefined" || clear_state){
            visible_nodes = [...Array(prelen)].map((_, __) => false); // size: [prelen]
            map_max_path = {}; // {node_id -> position on max_path}
            var accumulated_x = 0;
            for (var i=0;i<tarlen;i++){
                accumulated_x += node_tokens[max_path[i]][0].length * 5
                var y = Math.floor(Math.random() * 3) * 100 - 100;
                map_max_path[max_path[i]] = {position: i, x: accumulated_x, y:y};
                accumulated_x += node_tokens[max_path[i]][0].length * 5 + 100;
            }
            nodes = new vis.DataSet();
        }

        for (var i=0;i<prelen;i++){
            if(node_pass_prob[i] >= current_options.minimum_node_pass_prob || map_max_path[i] !== undefined){
                set_node_visibility(i, true);
            }else{
                set_node_visibility(i, false);
            }
        }
    }

    
    function update_node_details(){
        for(var i=0;i<prelen;i++) if (visible_nodes[i]){
            currentNode = obtain_node_object(i);
            nodes.updateOnly(currentNode);
        }
    }

    function obtain_edge_object(i, j){
        var edge_id = i.toString() + "-" + j.toString();
        var label = links[i][j].toFixed(2);
        var pass_label = (node_pass_prob[i] * links[i][j]).toFixed(2);
        var title = "From Node " + i.toString() + " to Node " + j.toString() + "\n" + "Transition Probability:" + label + "\nPassing Probability:" + pass_label;
        var currentEdge = {id: edge_id,
            from: i, to: j, value: links[i][j] * node_pass_prob[i], title: title};
        if (map_max_path[i] !== undefined && map_max_path[j] !== undefined && map_max_path[i].position + 1 == map_max_path[j].position){
            currentEdge.color = "red";
        }
        if(current_options.show_edge_label){
            currentEdge.label = label;
        }else{
            currentEdge.label = " ";
        }

        return currentEdge;
    }

    function set_edge_visibility(i, j, flag){
        if(visible_edges[i][j] == flag) return;
        visible_edges[i][j] = flag;
        if(flag){
            edges.add(obtain_edge_object(i, j));
        }else{
            var edge_id = i.toString() + "-" + j.toString();
            edges.remove(edge_id);
        }
    }

    function update_visible_edges(clear_state=false){
        if(typeof visible_edges === "undefined" || clear_state){
            visible_edges = [...Array(prelen)].map((_, __) => {return [...Array(prelen)].map((_, __) => false);}); // size: [prelen, prelen]

            sorted_links_out = []; // size: [prelen, prelen]
            for (var i=0;i<prelen;i++){
                // sort the out edge according to their prob
                sorted_links_out.push(links[i].map((val, idx) => {return {'idx': idx, 'val': val};}).
                    sort((v1, v2) => v2.val - v1.val)
                );
            }

            sorted_links_in = []; // size: [prelen, prelen], element {idx, val}, from big to small
            for (var i=0;i<prelen;i++){
                links_in = []
                for(var j=0;j<prelen;j++) links_in.push({idx: j, val: links[j][i] * node_pass_prob[j]})
                sorted_links_in.push(links_in.sort((v1, v2) => v2.val - v1.val));
            }
            edges = new vis.DataSet();
        }

        var next_visible_edges = [...Array(prelen)].map((_, __) => {return [...Array(prelen)].map((_, __) => false);}); // size: [prelen, prelen]
        var links_in_num = [...Array(prelen)].map((_, __) => 0);

        for (var i=0;i<prelen - 1;i++){
            if(!visible_nodes[i]) continue;

            // select visible out edge of node i
            var left_visible_edge_num = current_options.max_out_edge_num;
            var left_visible_edge_prob = current_options.max_out_edge_prob;
            for(var j=0; j<prelen;j++){
                var idx = sorted_links_out[i][j]['idx'];
                if (sorted_links_out[i][j]['val'] < current_options.minimum_edge_prob) break;
                if (visible_nodes[idx]){
                    links_in_num[idx]++;
                    next_visible_edges[i][idx] = true;
                    left_visible_edge_num--;
                    left_visible_edge_prob -= sorted_links_out[i][j]['val'];
                    if (left_visible_edge_num==0 || left_visible_edge_prob < 0){
                        break;
                    }
                }
            }
        }

        if(current_options.force_in_edge){
            // add at least one in edge per node
            for (var i=0;i<prelen;i++){
                if(i == 0 || !visible_nodes[i] || links_in_num[i] > 0) continue;
                for(var j=0; j<prelen;j++){
                    var idx = sorted_links_in[i][j]['idx'];
                    if (visible_nodes[idx]){
                        next_visible_edges[idx][i] = true;
                        break;
                    }
                }
            }
        }
        
        for(var i=0;i<prelen;i++){
            for(var j=i+1;j<prelen;j++){
                set_edge_visibility(i, j, next_visible_edges[i][j]);
            }
        }
    }

    function update_edge_label(){
        for(var i=0;i<prelen;i++){
            for(var j=i+1;j<prelen;j++) if (visible_edges[i][j]){
                currentEdge = obtain_edge_object(i, j);
                edges.updateOnly(currentEdge);
            }
        }
    }

    function customScalingFunction(min,max,total,value) {
        min = 0;
        var scale = 1 / (max - min);
        return Math.max(0,(value - min)*scale);
    }

    function escapeHtml(unsafe)
    {
        return unsafe
            .replace(/&/g, "&amp;")
            .replace(/</g, "&lt;")
            .replace(/>/g, "&gt;")
            .replace(/"/g, "&quot;")
            .replace(/'/g, "&#039;");
    }
    function get_jumpable_node(idx){
        if(visible_nodes[idx]){
            return "<a href=\"javascript:network.selectNodes(["+ idx.toString() +"]);show_hint_node(" + idx.toString() + ");\">" + idx.toString() + "</a>";
        }else{
            return "<a class=\"invisible\" href=\"javascript:show_hint_node(["+ idx.toString() +"]);network.unselectAll();\">" + idx.toString() + "</a>";
        }
    }
    function get_jumpable_edge(i, j, label){
        var edge_id = i.toString() + "-" + j.toString();
        if(visible_edges[i][j]){
            return "<a href=\"javascript:network.selectEdges(['"+ edge_id +"']);show_hint_edge('" + edge_id + "');\">" + label + "</a>";
        }else{
            return "<a class=\"invisible\" href=\"javascript:show_hint_edge('" + edge_id + "');network.unselectAll();\">" + label + "</a>";
        }
    }

    show_hint_node = function(node_id){
        showing_node = node_id;
        showing_edge = undefined;
        var title = "<p>You selected <b>Node " + node_id.toString() + "</b> ";
        if (visible_nodes[node_id]){
            title += "(<a href=\"javascript:network.fit({nodes:[" + node_id.toString() + "],animation:true});\">Find Me!</a>). "
        }else{
            title += "(Not shown). "
        }
        title += "Passing Probability: <b>" + node_pass_prob[node_id].toFixed(2) + "</b>. You can click the links below to jump to other edges or nodes.</p>";
        document.getElementById("hintsupper").innerHTML = title;

        title = "<table><thead><tr><th>Rank</th><th>Candidate</th><th>Probability</th></tr></thead><tbody>";
        for (var j=0;j<5;j++){
            title += "<tr><td>#" + (j+1).toString() + "</td><td>" + escapeHtml(node_tokens[node_id][j]) + "</td><td>" + node_probs[node_id][j].toFixed(2) + "</td></tr>";
        }
        title += "</tbody>"
        title += "<p>Top-5 Token Candidates: </p>";
        document.getElementById("hintsleft").innerHTML = title;

        title = "<table><thead><tr><th>Rank</th><th>To</th><th>Transition Prob.</th><th>Passing Prob.</th></tr></thead><tbody>";
        for (var j=0;j<prelen;j++){
            var idx = sorted_links_out[node_id][j].idx;
            if(j < 5 || visible_edges[node_id][idx]){
                title += "<tr><td>" + get_jumpable_edge(node_id, idx, "#" + (j+1).toString()) + "</td><td>" + get_jumpable_node(idx) + "</td><td>" + links[node_id][idx].toFixed(2) + "</td><td>" +
                    (node_pass_prob[node_id] * links[node_id][idx]).toFixed(2) + "</td></tr>";
            }
        }
        title += "</tbody>"
        title += "<p>Top Outgoing Edges: </p>"
        document.getElementById("hintscenter").innerHTML = title;

        title = "<table><thead><tr><th>Rank</th><th>From</th><th>Transition Prob.</th><th>Passing Prob.</th></tr></thead><tbody>";
        for (var j=0;j<prelen;j++){
            var idx = sorted_links_in[node_id][j].idx;
            if(j < 5 || visible_edges[idx][node_id]){
                title += "<tr><td>" + get_jumpable_edge(idx, node_id, "#" + (j+1).toString()) + "</td><td>" + get_jumpable_node(idx) + "</td><td>" + links[idx][node_id].toFixed(2) + "</td><td>" +
                    (node_pass_prob[idx] * links[idx][node_id]).toFixed(2) + "</td></tr>";
            }
        }
        title += "</tbody>"
        title += "<p>Top Incoming Edges: </p>"
        document.getElementById("hintsright").innerHTML = title;

        document.getElementById("hintsbottom").innerHTML =   
          "<br>"+ 
          "Passing probability of a node V represents how likely the node will be choosen in a random path, i.e., P(V \\in A). <br>" + 
          "Passing probability of an edge from U to V represents how likely the node V follows the node U in a random path, i.e., P(a_i = U && a_{i+1} = V). <br>" + 
          "Token probability represents how likely a token is predicted on the given node, i.e., P(y_i| v_{a_{i}}). <br>" + 
          "Transition probability represents how likely a specific node is following the given node, i.e. P(a_{i+1} | a_{i}).<br>"
    }

    show_hint_edge = function(edge_id){
        showing_edge = edge_id;
        showing_node = undefined;
        var i = parseInt(edge_id.split("-")[0]);
        var j = parseInt(edge_id.split("-")[1]);
        var label = links[i][j].toFixed(2);
        var passing_label = (links[i][j] * node_pass_prob[i]).toFixed(2);
        var title = "You selected an edge from <b>Node " + get_jumpable_node(i) + " to Node " + get_jumpable_node(j) + "</b>."
        if (visible_edges[i][j]){
            title += "(<a href=\"javascript:network.fit({nodes:[" + i.toString() + "," + j.toString() + "],animation:true});\">Find Me!</a>). "
        }else{
            title += "(Not shown). "
        }
        title += "<br> You can click the links above to jump to the nodes. <br><br>"
        title += "Transition Probability:<b>" + label + "</b><br>";
        title += "Passing Probability:<b>" + passing_label + "</b><br>";
        title += "<br>" + 
            "Transition probability represents how likely a specific node is following the given node, i.e. P(a_{i+1} | a_{i}).<br>" + 
            "Passing probability of an edge from U to V represents how likely the node V follows the node U in a random path, i.e., P(a_i = U && a_{i+1} = V). <br>"
        document.getElementById("hintsupper").innerHTML = title;
        document.getElementById("hintsleft").innerHTML = "";
        document.getElementById("hintsright").innerHTML = "";
        document.getElementById("hintscenter").innerHTML = "";
        document.getElementById("hintsbottom").innerHTML = "";
    }

    function clear_hint(){
        showing_node = undefined;
        showing_edge = undefined;
        document.getElementById("hintsupper").innerHTML = "Use scroll to zoom in or out. Select or Hover over nodes and edges for more information ... (Try dragging nodes to replace them.)";
        document.getElementById("hintsleft").innerHTML = "";
        document.getElementById("hintsright").innerHTML = "";
        document.getElementById("hintscenter").innerHTML = "";
        document.getElementById("hintsbottom").innerHTML = "";
    }

    startNetwork = function(graph_info, options) {
        current_options = options;

        global_graph_info = graph_info;
        node_pass_prob = graph_info['node_pass_prob'][0] // size: [prelen]
        prelen = node_pass_prob.length
        max_path = graph_info['max_paths'][0] // size: [tarlen]
        tarlen = max_path.length
        node_tokens = graph_info['node_tokens'][0] // size: [prelen, 5]
        node_probs = graph_info['node_probs'][0] // size: [prelen, 5]
        links = graph_info['links'][0] // size: [prelen, prelen]

        update_visible_nodes(true);
        update_visible_edges(true);

        // create a network
        var container = document.getElementById("daggraph");
        var data = {
            nodes: nodes,
            edges: edges,
        };
        network_options = {
            nodes: {
                shape: "ellipse",
                scaling: {
                    label: {
                      min: 8,
                      max: 20,
                    },
                    customScalingFunction: customScalingFunction,
                },
            },
            edges: {
                arrowStrikethrough: false,
                arrows: "to",
                smooth: {
                    type: "continuous"
                },
                color: "#2B7CE9",
                font: { align: "bottom" },
                length: 120,
                scaling: {
                    min: 0.5,
                    max: 3,
                    label: {
                        min: 8,
                        max: 15,
                    },
                    customScalingFunction: customScalingFunction,
                }
            }
        };
        network = new vis.Network(container, data, network_options);

        network.off("dragStart");
        network.on("dragStart", function (params) {
            var idx = this.getNodeAt(params.pointer.DOM);
            if (idx !== undefined) {
                // console.log("dragstart " + idx.toString());
                if (map_max_path[idx] !== undefined){
                    data.nodes.update({id: idx, fixed: false});
                }
            }
        });
        network.off("dragEnd");
        network.on("dragEnd", function (params) {
            var idx = this.getNodeAt(params.pointer.DOM);
            if (idx !== undefined){
                // console.log("dragend " + idx.toString());
                if (map_max_path[idx] !== undefined){
                    data.nodes.update({id: idx, fixed: true});
                    map_max_path[idx].x = params.pointer.canvas.x;
                    map_max_path[idx].y = params.pointer.canvas.y;
                }
            }
        });

        disable_edge_select = false;
        network.off("selectNode");
        network.on("selectNode", function (params) {
            var node_id = params.nodes[0];
            show_hint_node(node_id);
            disable_edge_select = true;
            setTimeout(() => {disable_edge_select=false;}, 200);
        });

        network.off("selectEdge");
        network.on("selectEdge", function (params) {
            if(disable_edge_select) return;
            var edge_id = params.edges[0];
            show_hint_edge(edge_id);
        });

        network.off("deselectNode");
        network.on("deselectNode", function (params) {
            clear_hint();
            showing_node = undefined;
            showing_edge = undefined;
        });
        network.off("deselectEdge");
        network.on("deselectEdge", function (params) {
            clear_hint();
        });
    }

    updateNetwork = function(options) {
        if(typeof node_pass_prob === "undefined") return;
        old_options = current_options;
        current_options = options;
        if(options.minimum_node_pass_prob != old_options.minimum_node_pass_prob){
            update_visible_nodes();
        }
        if(options.minimum_node_pass_prob != old_options.minimum_node_pass_prob ||
            options.minimum_edge_prob != old_options.minimum_edge_prob ||
            options.max_out_edge_num != old_options.max_out_edge_num ||
            options.max_out_edge_prob != old_options.max_out_edge_prob ||
            options.force_in_edge != old_options.force_in_edge){
            update_visible_edges();
        }
        if(options.show_node_detail != old_options.show_node_detail){
            if(options.show_node_detail) {
                network_options.nodes.shape = "dot";
                network_options.nodes.scaling.label.min=10;
                network_options.nodes.scaling.label.max=10;
            }else{
                network_options.nodes.shape = "ellipse";
                network_options.nodes.scaling.label.min=8;
                network_options.nodes.scaling.label.max=20;
            }
            network.setOptions(network_options);
            update_node_details();
        }
        if(options.show_edge_label != old_options.show_edge_label){
            update_edge_label();
        }

        if(showing_node != undefined){
            show_hint_node(showing_node);
        }
        if(showing_edge != undefined){
            show_hint_edge(showing_edge);
        }
    }
}