GeoKnow/Jassa-Core

/**
 * Returns an object:
 * {
 *    limit:
 *    offset:
 *    subLimit:
 *    subOffset:
 * }
 *
 */
var PageExpandUtils = {
    computeRange: function(limit, offset, pageSize) {
        // Example: If pageSize=100 and offset = 130, then we will adjust the offset to 100, and use a subOffset of 30
        var o = offset || 0;
        var subOffset = o % pageSize;
        o -= subOffset;
        // Adjust the limit to a page boundary; the original limit becomes the subLimit
        // And we will extend the new limit to the page boundary again.
        // Example: If pageSize=100 and limit = 130, then we adjust the new limit to 200
        var l = limit;
        var subLimit = null;
        if(l) {
            subLimit = l;

            var mod = l % pageSize;

            //console.log('l = ' + l + ' pageSize = ' + pageSize + ' tmp = ' + tmp);
            // If the mod is 0 (i.e. no remainder), we do not increase the limit.
            var extra = mod ? pageSize - mod : 0;
            l += extra;
        }

        var result = {
            limit: l,
            offset: o,
            subLimit: subLimit,
            subOffset:subOffset
        };

        //console.log(JSON.stringify(result));
        return result;
    }
};

module.exports = PageExpandUtils;