import * as d3 from "https://cdn.jsdelivr.net/npm/d3@7/+esm";

function getOrCreateNode(id, name, nodes, dict) {
    let node = dict[id];
    if (!node) {
        node = {}
        node.id = id;
        node.name = name;
        nodes.push(node);
        dict[id] = node;
    }
    return node;
}

function toGraphData(data) {
    let graph = {};
    let nodes = graph.nodes = [];
    let links = graph.links = [];
    let idToNode = [];
    let columns = data.head.vars;
    data.results.bindings.forEach(item => {
        const srcID = item[columns[0]].value;
        const trgtID = item[columns[1]].value;
        const src = getOrCreateNode(srcID, srcID, nodes, idToNode);
        const trgt = getOrCreateNode(trgtID, trgtID, nodes, idToNode);
        let link = {};
        link.source = src.id;
        link.target = trgt.id;
        links.push(link);
    });
    return graph;
}


function drawGraph(data, containerID, width = 500, height = 300) {
    let graph = toGraphData(data)
    let container = d3.select(containerID);
    let svg = container.append('svg').attr("width", width).attr("height", height);
    // arrow def
    svg.append('defs').append('marker')
        .attr('id', 'arrowhead')
        .attr('viewBox', '-0 -5 10 10')
        .attr('refX', 13)
        .attr('refY', 0)
        .attr('orient', 'auto')
        .attr('markerWidth', 13)
        .attr('markerHeight', 13)
        .attr('xoverflow', 'visible')
        .append('svg:path')
        .attr('d', 'M 0,-5 L 10 ,0 L 0,5')
        .attr('fill', '#808080')
        .style('stroke', 'none');

    let nodes = graph.nodes;
    let links = graph.links;
    let simulation = d3.forceSimulation()
        .force("link", d3.forceLink().id(function (d) {
            return d.id;
        }).distance(80))
        .force("charge", d3.forceManyBody().strength(-100))
        .force("center", d3.forceCenter(width / 2, height / 2));

    let link = svg.selectAll(".link")
        .data(links)
        .enter()
        .append("line")
        .attr("class", "link")
        .attr('marker-end', 'url(#arrowhead)')
        .style('stroke', '#808080');

    let node = svg.selectAll(".node")
        .data(nodes)
        .enter()
        .append("g")
        .attr("class", "node")
        .call(d3.drag()
            .on("start", dragstarted)
            .on("drag", dragged)
            .on("end", dragended));

    node.append("circle")
        .attr("r", 5)
        .attr("fill", "#006496")

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

    node.append("text")
        .attr("dy", -3)
        .text(function (d) {
            return d.id
        });

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

    simulation.force("link").links(links);

    function ticked() {
        link
            .attr("x1", function (d) {
                return getX(d.source.x);
            })
            .attr("y1", function (d) {
                return getY(d.source.y);
            })
            .attr("x2", function (d) {
                return getX(d.target.x);
            })
            .attr("y2", function (d) {
                return getY(d.target.y);
            });

        node.attr("transform",
            function (d) {
                const dx = getX(d.x);
                const dy = getY(d.y);
                return "translate(" + dx + ", " + dy + ")";
            }
        );

        function getX(x) {
            let dx = x;
            if (dx < 20) dx = 20;
            if (dx > width - 20) dx = width - 20;
            return dx;
        }

        function getY(y) {
            let dy = y;
            if (dy < 20) dy = 20;
            if (dy > height - 20) dy = height - 20;
            return dy;
        }

    }


    function dragstarted(event) {
        if (!event.active) simulation.alphaTarget(0.3).restart()
        event.subject.fx = event.subject.x;
        event.subject.fy = event.subject.y;
    }

    function dragged(event) {
        event.subject.fx = event.x;
        event.subject.fy = event.y;
    }

    function dragended(event) {
        if (!event.active) simulation.alphaTarget(0);
        event.subject.fx = null;
        event.subject.fy = null;
    }
}

export {drawGraph, toGraphData};
export default drawGraph;