function dateRangePath() {
    var orientation = 'horizontal';
    var cellSize = 10;
    var offset = null;
    var closed = true;

    function path(t0, t1) {
        if (offset) t1 = offset(t0);
        var d0 = t0.getDay(); 
        var d1 = t1.getDay();
        var w0 = weekOfYear(t0);
        var w1 = weekOfYear(t1);
        
        var context = d3.path();
        if (orientation === 'horizontal') {
            if (closed) {
                context.moveTo((w0 + 1) * cellSize, d0 * cellSize);
                context.lineTo(w0 * cellSize, d0 * cellSize);
                context.lineTo(w0 * cellSize, 7 * cellSize);
                context.lineTo(w1 * cellSize, 7 * cellSize);
                context.lineTo(w1 * cellSize, (d1 + 1) * cellSize);
                context.lineTo((w1 + 1) * cellSize, (d1 + 1) * cellSize);
                context.lineTo((w1 + 1) * cellSize, 0);
                context.lineTo((w0 + 1) * cellSize, 0);
                context.closePath();
            } else {
                context.moveTo((w0 + 1) * cellSize, d0 * cellSize);
                if (d0 === 0) context.moveTo(w0 * cellSize,d0 * cellSize);
                else context.lineTo(w0 * cellSize,d0 * cellSize);
                context.lineTo(w0 * cellSize, 7 * cellSize);
                context.moveTo(w1 * cellSize, 7 * cellSize);
                context.lineTo(w1 * cellSize, (d1 + 1) * cellSize);
                if (d1 === 6) context.moveTo((w1 + 1) * cellSize, (d1 + 1) * cellSize);
                else context.lineTo((w1 + 1) * cellSize, (d1 + 1) * cellSize);
                context.lineTo((w1 + 1) * cellSize, 0);
                context.moveTo((w0 + 1) * cellSize, 0);
                context.lineTo((w0 + 1) * cellSize, d0 * cellSize);
            }
        } else if (orientation === 'vertical') {
            if (closed) {
                context.moveTo(d0 * cellSize, (w0 + 1) * cellSize);
                context.lineTo(d0 * cellSize, w0 * cellSize);
                context.lineTo(7 * cellSize, w0 * cellSize);
                context.lineTo(7 * cellSize, w1 * cellSize);
                context.lineTo((d1 + 1) * cellSize, w1 * cellSize);
                context.lineTo((d1 + 1) * cellSize, (w1 + 1) * cellSize);
                context.lineTo(0, (w1 + 1) * cellSize);
                context.lineTo(0, (w0 + 1) * cellSize);
                context.closePath();
            } else {
                context.moveTo(d0 * cellSize, (w0 + 1) * cellSize);
                if (d0 === 0) context.moveTo(d0 * cellSize, w0 * cellSize);
                else context.lineTo(d0 * cellSize, w0 * cellSize);
                context.lineTo(7 * cellSize, w0 * cellSize);
                context.moveTo(7 * cellSize, w1 * cellSize);
                context.lineTo((d1 + 1) * cellSize, w1 * cellSize);
                if (d1 === 6) context.moveTo((d1 + 1) * cellSize, (w1 + 1) * cellSize);
                else context.lineTo((d1 + 1) * cellSize, (w1 + 1) * cellSize);
                context.lineTo(0, (w1 + 1) * cellSize);
                context.moveTo(0, (w0 + 1) * cellSize);
                context.lineTo(d0 * cellSize, (w0 + 1) * cellSize);
            }
        }
        return context.toString();
    }

    path.orientation = function(_) {
        if (!arguments.length) return orientation;
        if (['horizontal', 'vertical'].indexOf(_) === -1) {
            throw new Error('orientation must be either "horizonal" or "vertical"');
        }
        orientation = _;
        return path;
    };

    path.closed = function(_) {
        if (!arguments.length) return closed;
        closed = _;
        return path;
    };

    path.cellSize = function(_) {
        if (!arguments.length) return cellSize;
        cellSize = _;
        return path;
    };

    path.offset = function(_) {
        if (!arguments.length) return offset;
        if (typeof(_) === 'number') {
            offset = function(t0) { 
                return new Date(t0.getFullYear(), t0.getMonth(), t0.getDay() + _); 
            };
        } else if (typeof(_) === 'function') {
            offset = _;
        } else {
            throw new Error('offset must be either a number (of days) or a function taking the starting date');
        }
        return path;
    };

    function weekOfYear(date) {
        return d3.timeWeek
            .count(d3.timeYear(date), date);
    }

    return path;
}