'use strict';

import util from 'util';

const GRAPH_NODE = '    "%s" [label="%s"]';
const GRAPH_NODE_URL = '    "%s" [label="%s", URL="%s", fontcolor=blue]';
const GRAPH_LINK = '    "%s" -> "%s"';

/**
 * Convert a graph to the DOT format.
 *
 * @param graph Graph to convert.
 * @param [title=identity] Function giving the name of each node.
 * @param [url=none] Function given the URL of each node, or an empty string
 * if a node has no URL.
 * @return DOT representation of the graph.
 */
export const graphToDOT = (graph, title = id => id, url = () => '') =>
{
    const ser = graph.serialize();

    // Convert nodes
    const nodes = ser.nodes.map(({id}) =>
    {
        const nodeTitle = title(id);
        const nodeUrl = url(id);

        if (url === '')
        {
            return util.format(GRAPH_NODE, id, nodeTitle);
        }
        else
        {
            return util.format(GRAPH_NODE_URL, id, nodeTitle, nodeUrl);
        }
    }
    ).join('\n');

    // Convert edges
    const links = ser.links.map(({source, target}) =>
        util.format(GRAPH_LINK, source, target)
    ).join('\n');

    return (
        'digraph epenser {\n'
        + nodes
        + '\n'
        + links
        + '\n}'
    );
};