(function() {
    d3.layout.grid = function() {
        var mode = "equal",
            layout = _distributeEqually,
            x = d3.scale.ordinal(),
            y = d3.scale.ordinal(),
            size = [1, 1],
            actualSize = [0, 0],
            nodeSize = false,
            bands = false,
            padding = [0, 0],
            cols, rows;

        function grid(nodes) {
            return layout(nodes);
        }

        function _distributeEqually(nodes) {
            var i = -1,
                n = nodes.length,
                _cols = cols ? cols : 0,
                _rows = rows ? rows : 0,
                col, row;

            if (_rows && !_cols) {
                _cols = Math.ceil(n / _rows)
            } else {
                _cols || (_cols = Math.ceil(Math.sqrt(n)));
                _rows || (_rows = Math.ceil(n / _cols));
            }

            if (nodeSize) {
                x.domain(d3.range(_cols)).range(d3.range(0, (size[0] + padding[0]) * _cols, size[0] + padding[0]));
                y.domain(d3.range(_rows)).range(d3.range(0, (size[1] + padding[1]) * _rows, size[1] + padding[1]));
                actualSize[0] = bands ? x(_cols - 1) + size[0] : x(_cols - 1);
                actualSize[1] = bands ? y(_rows - 1) + size[1] : y(_rows - 1);
            } else if (bands) {
                x.domain(d3.range(_cols)).rangeBands([0, size[0]], padding[0], 0);
                y.domain(d3.range(_rows)).rangeBands([0, size[1]], padding[1], 0);
                actualSize[0] = x.rangeBand();
                actualSize[1] = y.rangeBand();
            } else {
                x.domain(d3.range(_cols)).rangePoints([0, size[0]]);
                y.domain(d3.range(_rows)).rangePoints([0, size[1]]);
                actualSize[0] = x(1);
                actualSize[1] = y(1);
            }

            while (++i < n) {
                col = i % _cols;
                row = Math.floor(i / _cols);
                nodes[i].x = x(col);
                nodes[i].y = y(row);
            }

            return nodes;
        }

        grid.size = function(value) {
            if (!arguments.length) return nodeSize ? actualSize : size;
            actualSize = [0, 0];
            nodeSize = (size = value) == null;
            return grid;
        };

        grid.nodeSize = function(value) {
            if (!arguments.length) return nodeSize ? size : actualSize;
            actualSize = [0, 0];
            nodeSize = (size = value) != null;
            return grid;
        };

        grid.rows = function(value) {
            if (!arguments.length) return rows;
            rows = value;
            return grid;
        };

        grid.cols = function(value) {
            if (!arguments.length) return cols;
            cols = value;
            return grid;
        };

        grid.bands = function() {
            bands = true;
            return grid;
        };

        grid.points = function() {
            bands = false;
            return grid;
        };

        grid.padding = function(value) {
            if (!arguments.length) return padding;
            padding = value;
            return grid;
        };

        return grid;
    };
})();