var MongoClient = require('mongodb').MongoClient;
    MongoClient.connect(process.env.DATABASE_URI, function(err, db) {
        if (err) {
            response.error(err);
            return;
        }

        var CountriesCollection = db.collection("Pais");
        CountriesCollection.find({}, {
            "code_tatoeba": 1,
            "idioma": 1,
            "bandera_file": 1
        }).toArray(function(error, countries) {

            var PortugueseCountries = [],
                ItalianCountries = [],
                SpanishCountries = [],
                FrenchCountries = [],
                EnglishCountries = [],
                RussianCountries = [],
                GermanCountries = [];

            for (var i = 0; i < countries.length; i++) {
                switch (countries[i].idioma) {
                    case "Português":
                        PortugueseCountries.push("Pais$" + countries[i]._id);
                        break;
                    case "Italiano":
                        ItalianCountries.push("Pais$" + countries[i]._id);
                        break;
                    case "Español":
                        SpanishCountries.push("Pais$" + countries[i]._id);
                        break;
                    case "Français":
                        FrenchCountries.push("Pais$" + countries[i]._id);
                        break;
                    case "Pусский":
                        RussianCountries.push("Pais$" + countries[i]._id);
                        break;
                    case "Deutsch":
                        GermanCountries.push("Pais$" + countries[i]._id);
                        break;
                    case "English":
                        EnglishCountries.push("Pais$" + countries[i]._id);
                        break;

                }
            }

            var AudiosCollection = db.collection("Audios");
            AudiosCollection.count({
                "_p_pais": {
                    $in: PortugueseCountries
                }
            }, function(error, countPortugueseAudios) {
                var limitPortuguese = 2;
                var skipPortuguese = getSkipCountryCount(countPortugueseAudios, limitPortuguese);
                var queries = generateQueryForAudiosRecommendation(PortugueseCountries, limitPortuguese, skipPortuguese);
                AudiosCollection.find(queries[0], queries[1]).toArray(function(error, PortugueseAudios) {

                    AudiosCollection.count({
                        "_p_pais": {
                            $in: ItalianCountries
                        }
                    }, function(error, countItalianAudios) {
                        var limitItalian = 1;
                        var skipItalian = getSkipCountryCount(countItalianAudios, limitItalian);
                        queries = generateQueryForAudiosRecommendation(ItalianCountries, limitItalian, skipItalian);
                        AudiosCollection.find(queries[0], queries[1]).toArray(function(error, ItalianAudios) {

                            AudiosCollection.count({
                                "_p_pais": {
                                    $in: SpanishCountries
                                }
                            }, function(error, countSpanishAudios) {
                                var limitSpanish = 3;
                                var skipSpanish = getSkipCountryCount(countSpanishAudios, limitSpanish);
                                queries = generateQueryForAudiosRecommendation(SpanishCountries, limitSpanish, skipSpanish);
                                AudiosCollection.find(queries[0], queries[1]).toArray(function(error, SpanishAudios) {

                                    AudiosCollection.count({
                                        "_p_pais": {
                                            $in: FrenchCountries
                                        }
                                    }, function(error, countFrenchAudios) {
                                        var limitFrench = 3;
                                        var skipFrench = getSkipCountryCount(countFrenchAudios, limitFrench);
                                        queries = generateQueryForAudiosRecommendation(FrenchCountries, limitFrench, skipFrench);
                                        AudiosCollection.find(queries[0], queries[1]).toArray(function(error, FrenchAudios) {

                                            AudiosCollection.count({
                                                "_p_pais": {
                                                    $in: RussianCountries
                                                }
                                            }, function(error, countRussianAudios) {
                                                var limitRussian = 1;
                                                var skipRussian = getSkipCountryCount(countRussianAudios, limitRussian);
                                                queries = generateQueryForAudiosRecommendation(RussianCountries, limitRussian, skipRussian);
                                                AudiosCollection.find(queries[0], queries[1]).toArray(function(error, RussianAudios) {

                                                    AudiosCollection.count({
                                                        "_p_pais": {
                                                            $in: GermanCountries
                                                        }
                                                    }, function(error, countGermanAudios) {
                                                        var limitGerman = 2;
                                                        var skipGerman = getSkipCountryCount(countGermanAudios, limitGerman);
                                                        queries = generateQueryForAudiosRecommendation(GermanCountries, limitGerman, skipGerman);
                                                        AudiosCollection.find(queries[0], queries[1]).toArray(function(error, GermanAudios) {

                                                            AudiosCollection.count({
                                                                "_p_pais": {
                                                                    $in: EnglishCountries
                                                                }
                                                            }, function(error, countEnglishAudios) {
                                                                var limitEnglish = 3;
                                                                var skipEnglish = getSkipCountryCount(countEnglishAudios, limitEnglish);
                                                                queries = generateQueryForAudiosRecommendation(EnglishCountries, limitEnglish, skipEnglish);
                                                                AudiosCollection.find(queries[0], queries[1]).toArray(function(error, EnglishAudios) {

                                                                    var audios = [];
                                                                    PortugueseAudios.forEach(function(audio) {
                                                                        audios.push(audio);
                                                                    });
                                                                    ItalianAudios.forEach(function(audio) {
                                                                        audios.push(audio);
                                                                    });
                                                                    SpanishAudios.forEach(function(audio) {
                                                                        audios.push(audio);
                                                                    });
                                                                    FrenchAudios.forEach(function(audio) {
                                                                        audios.push(audio);
                                                                    });
                                                                    RussianAudios.forEach(function(audio) {
                                                                        audios.push(audio);
                                                                    });
                                                                    GermanAudios.forEach(function(audio) {
                                                                        audios.push(audio);
                                                                    });
                                                                    EnglishAudios.forEach(function(audio) {
                                                                        audios.push(audio);
                                                                    });

                                                                    for (var i = 0; i < audios.length; i++) {
                                                                        for (var j = 0; j < countries.length; j++) {
                                                                            if ("Pais$" + countries[j]._id == audios[i]._p_pais) {
                                                                                audios[i].image = process.env.filesPath + countries[j].bandera_file;
                                                                                audios[i].word = audios[i].palabra;
                                                                                delete audios[i]._p_pais;
                                                                                delete audios[i].palabra;

                                                                                j = countries.length;
                                                                            }
                                                                        }
                                                                    }

                                                                    response.success(shuffle(audios));
                                                                });
                                                            });
                                                        });
                                                    });
                                                });
                                            });
                                        });
                                    });
                                });
                            });
                        });
                    });
                });
            });
        });
    });