var modularity = require('../../');//require('ngraph.louvain');
var coarsen = require('ngraph.coarsen');

module.exports = function (graph, maxDepth) {
    var clusters = modularity(graph);

    var clustersByLevel = [];

    maxDepth = maxDepth || 5;

    var getNodesByCluster = function (graph, clusters) {
        var byCluster = {};

        var nodeCnt = 0;
        graph.forEachNode(function (node) {
            var cls = clusters.getClass(node.id);
            if (!byCluster[cls]) byCluster[cls] = [];
            byCluster[cls].push(node.id);
            nodeCnt++;
        });

        clustersByLevel.push(byCluster);
    };

    var clusterAgain = function (clusters) {
        graph = coarsen(graph, clusters);
        clusters = modularity(graph);

        getNodesByCluster(graph, clusters);
        return clusters;
    };

    var depth = 0;
    getNodesByCluster(graph, clusters);
    while (clusters.canCoarse() && depth++ < (maxDepth - 1)) {
        clusters = clusterAgain(clusters);
    }

    var clusterIdsByNode = {};

    var explode = function (level, cid, parentIds) {
        var arr = clustersByLevel[level][cid];
        if (level === 0) {
            arr.forEach(function (nodeId, i) {
                clusterIdsByNode[nodeId] = parentIds;
            });
        } else {
            arr.forEach(function (nextId, i) {
                var pids = parentIds.slice(0);//clone
                pids.push(nextId);
                explode(level - 1, nextId, pids);
            });
        }
    };

    Object.keys(clustersByLevel[clustersByLevel.length - 1]).forEach(function (cid) {
        explode(clustersByLevel.length - 1, cid, [cid]);
    });

    return {
        getClass: function (nodeId) {
            if (!clusterIdsByNode[nodeId]) return null;
            return clusterIdsByNode[nodeId][0];
        }
    };
};