dcms/helpers/sorting.js

CMS library for Node.js

module.exports = function(options, callback) {
	if(options.query) {
		options.offset = parseInt(options.query.offset) || 0;
		options.source = parseInt(options.query.source) || 0;
		options.target = parseInt(options.query.target) || 0;
	}
	
	var model = options.model,
	find = options.find || {},
	
	offset = Math.max(options.offset, 0),
	source = offset + Math.max(options.source, 0),
	target = offset + Math.max(options.target, 0),
	
	sort = options.sort || {},
	order = options.order || 1,
	priority = options.field || 'priority';
	
	sort[priority] = order;
	
	model.find(find)
	.sort(sort)
	.skip(source)
	.limit(1)
	.exec(function(err, entity) {
		if(err) return next(err);
		
		if(!entity.length)
			return callback(new Error('Source not found'));
		
		entity = entity[0];
		
		model.find(find)
		.sort(sort)
		.skip(target ? target-1 : target)
		.limit(2)
		.exec(function(err, between) {
			if(err) return next(err);

			if(!between.length)
				return callback(new Error('Target not found'));
			
			if(between.length > 1 && target > 0) {
				entity[priority] = (between[0][priority] + between[1][priority]) * 0.5;
				
				var floor = Math.floor(entity[priority]);
				if(between[0][priority] !== floor && between[1][priority] !== floor)
					entity[priority] = floor;
			} else {
				entity[priority] = between[0][priority];
				if(target)
					entity[priority] += (1000 * order);
				else
					entity[priority] -= (1000 * order);
			}
			
			entity.save(function(err) {
				callback(err, entity, between);
			});
		});
	});
};