lego.js

'use strict';

exports.isStar = false;

function compareFunctions(a, b) {
    var obj = {
        select: 3,
        format: 2,
        filterIn: 4,
        sortBy: 5,
        limit: 1
    };

    return (obj[a.name] < obj[b.name]) ? 1 : -1;
}

function filterCollection(property, values, record, result) {
    for (var j = 0; j < values.length; j++) {
        if (record[property] === values[j]) {
            result.push(record);
        }
    }
}

exports.query = function () {
    var queryArgs = [].slice.call(arguments);
    if (queryArgs.length === 1) {
        return queryArgs[0];
    }
    var changedCollection = queryArgs[0];

    queryArgs.splice(0, 1);
    queryArgs.sort(compareFunctions);
    for (var i = 0; i < queryArgs.length; i++) {
        changedCollection = queryArgs[i](changedCollection);
    }

    return changedCollection;
};

exports.select = function () {
    var args = [].slice.call(arguments);

    return function select(collection) {
        var result = [];
        for (var i = 0; i < collection.length; i++) {
            result.push({});
            for (var j = 0; j < args.length; j++) {
                result[i][args[j]] = collection[i][args[j]];
            }
        }

        return result;
    };
};

exports.filterIn = function (property, values) {

    return function filterIn(collection) {
        var result = [];
        for (var i = 0; i < collection.length; i++) {
            filterCollection(property, values, collection[i], result);
        }

        return result;
    };
};

exports.sortBy = function (property, order) {
    return function sortBy(collection) {
        collection.sort(function (a, b) {
            var coefficient;
            if (order === 'asc') {
                coefficient = -1;
            }
            if (order === 'desc') {
                coefficient = 1;
            }
            if (a[property] < b[property]) {
                return Number(coefficient) * 1;
            }
            if (a[property] > b[property]) {
                return -1 * Number(coefficient);
            }

            return 0;
        });

        return collection;
    };
};

exports.format = function (property, formatter) {

    return function format(collection) {
        var result = [];
        for (var i = 0; i < collection.length; i++) {
            var a = formatter(collection[i][property]);
            collection[i][property] = a;
            result.push(collection[i]);
        }

        return result;
    };
};

exports.limit = function (count) {
    return function limit(collection) {
        var result = collection.splice(0, count);

        return result;
    };
};

if (exports.isStar) {

    exports.or = function () {
        return;
    };

    exports.and = function () {
        return;
    };
}