AI-Powered Playlist Generator: Crafting Custom Vibes With Deeplearning4j and MongoDB

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<dependencies>
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    <!-- Spring Boot Starter for Web API -->
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    <dependency>
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        <groupId>org.springframework.boot</groupId>
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        <artifactId>spring-boot-starter-web</artifactId>
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    </dependency>
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    <!-- ND4J: Core Numerical Processing -->
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    <dependency>
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        <groupId>org.nd4j</groupId>
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        <artifactId>${nd4j.backend}</artifactId>
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        <version>${1.0.0-M2.1}</version>
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    </dependency>
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    <!-- DataVec for working with data -->
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    <dependency>
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        <groupId>org.datavec</groupId>
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        <artifactId>datavec-api</artifactId>
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        <version>${1.0.0-M2.1}</version>
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    </dependency>
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    <!-- DeepLearning4j Core -->
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    <dependency>
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        <groupId>org.deeplearning4j</groupId>
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        <artifactId>deeplearning4j-core</artifactId>
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        <version>${1.0.0-M2.1}</version>
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    </dependency>
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    <!-- DeepLearning4j NLP for Text Processing -->
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    <dependency>
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        <groupId>org.deeplearning4j</groupId>
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        <artifactId>deeplearning4j-nlp</artifactId>
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        <version>${1.0.0-M2.1}</version>
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    </dependency>
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    <!-- Apache Commons CSV -->
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    <dependency>
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        <groupId>org.apache.commons</groupId>
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        <artifactId>commons-csv</artifactId>
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        <version>1.9.0</version>
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    </dependency>
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    <!-- MongoDB Driver -->
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    <dependency>
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        <groupId>org.mongodb</groupId>
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        <artifactId>mongodb-driver-sync</artifactId>
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        <version>5.2.0</version>
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    </dependency>
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    <dependency>
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        <groupId>org.mongodb</groupId>
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        <artifactId>mongodb-driver-core</artifactId>
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        <version>5.2.0</version>
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    </dependency>
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    <dependency>
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        <groupId>org.mongodb</groupId>
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        <artifactId>bson</artifactId>
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        <version>5.2.0</version>
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    </dependency>
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    <!-- JUnit for testing -->
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    <dependency>
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        <groupId>org.junit.jupiter</groupId>
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        <artifactId>junit-jupiter-api</artifactId>
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        <version>5.7.0</version>
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        <scope>test</scope>
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    </dependency>
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</dependencies>

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import java.util.List;  
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public class Song {  
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    private String title;  
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    private String artist;  
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    private String lyrics;  
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    private List<Double> embedding;  
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    public Song(String title, String artist, String lyrics, List<Double> embedding) {  
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        this.title = title;  
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        this.artist = artist;  
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        this.lyrics = lyrics;  
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        this.embedding = embedding;  
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    }  
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    public String getTitle() {  
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        return title;  
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    }  
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    public void setTitle(String title) {  
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        this.title = title;  
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    }  
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    public String getArtist() {  
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        return artist;  
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    }  
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    public void setArtist(String artist) {  
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        this.artist = artist;  
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    }  
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    public String getLyrics() {  
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        return lyrics;  
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    }  
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    public void setLyrics(String lyrics) {  
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        this.lyrics = lyrics;  
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    }  
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    public List<Double> getEmbedding() {  
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        return embedding;  
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    }  
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    public void setEmbedding(List<Double> embedding) {  
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        this.embedding = embedding;  
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    }  
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}

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import java.util.List;  
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public class Playlist {  
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    private String playlistName;  
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    private List<Song> songs;  
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    public Playlist() {  
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    }  
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    public Playlist(String playlistName, List<Song> songs) {  
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        this.playlistName = playlistName;  
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        this.songs = songs;  
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    }  
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    public String getPlaylistName() {  
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        return playlistName;  
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    }  
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    public void setPlaylistName(String playlistName) {  
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        this.playlistName = playlistName;  
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    }  
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    public List<Song> getSongs() {  
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        return songs;  
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    }  
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    public void setSongs(List<Song> songs) {  
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        this.songs = songs;  
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    }  
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}

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@Service
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public class EmbeddingService {
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private final Map<String, INDArray> gloveEmbeddings = new HashMap<>();  
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private final DefaultTokenizerFactory tokenizerFactory = new DefaultTokenizerFactory();  
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private final Set<String> stopWords;  // Set of stop words for filtering  
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@Value("${embedding.model.path}")  
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private String preTrainedGlovePath;  
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public EmbeddingService() {  
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    tokenizerFactory.setTokenPreProcessor(new CommonPreprocessor());  
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    stopWords = loadStopWords();  
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}  
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@PostConstruct  
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private void init() throws IOException {  
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    loadGloveModel(preTrainedGlovePath);  
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}  
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private void loadGloveModel(String preTrainedGlovePath) throws IOException {  
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    InputStream gloveStream = getClass().getResourceAsStream("/glove.840B.300d.txt");  
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    if (gloveStream == null) {  
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        throw new IOException("GloVe model not found in resources: " + preTrainedGlovePath);  
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    }  
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    try (BufferedReader reader = new BufferedReader(new InputStreamReader(gloveStream))) {  
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        String line;  
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        while ((line = reader.readLine()) != null) {  
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            String[] split = line.split(" ");  
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            String word = split[0];  
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            float[] vector = new float[300];  // 300-dimensional GloVe vector  
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            for (int i = 1; i < split.length; i++) {  
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                vector[i - 1] = Float.parseFloat(split[i]);  
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            }  
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            INDArray wordVector = Nd4j.create(vector);  
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            gloveEmbeddings.put(word, wordVector);  
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        }  
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    }  
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}
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private Set<String> loadStopWords() {  
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    return new HashSet<>(Arrays.asList(  
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            "the", "a", "an", "and", "is", "in", "at", "of", "to", "for", "with", "on", "by", "this", "that", "it", "i", "you", "they", "we", "but", "or", "as", "if", "when"  
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    ));  
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}

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 private String removeBracketedText(String text) {  
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    return text.replaceAll("\\[.*?]", "").trim();  
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}  
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public List<String> tokenizeText(String text) {  
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    text = removeBracketedText(text);  
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    Tokenizer tokenizer = tokenizerFactory.create(text);  
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    List<String> tokens = new ArrayList<>();  
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    while (tokenizer.hasMoreTokens()) {  
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        String token = tokenizer.nextToken();  
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        if (!stopWords.contains(token)) {  
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            tokens.add(token);  
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        }  
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    }  
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    return tokens;  
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}

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public INDArray getEmbeddingForWord(String word) {  
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    return gloveEmbeddings.getOrDefault(word, null);  
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}  
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public List<Double> getEmbeddingForText(List<String> tokens) {  
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    INDArray embedding = null;  
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    int validTokenCount = 0;  
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    for (String token : tokens) {  
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        INDArray wordVector = getEmbeddingForWord(token);  
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        if (wordVector != null) {  
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            if (embedding == null) {  
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                embedding = wordVector.dup();  // Duplicate the word vector  
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            } else {  
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                embedding.addi(wordVector);  // Sum the word embeddings  
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            }  
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            validTokenCount++;  
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        }  
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    }  
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    if (embedding != null && validTokenCount > 0) {  
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        embedding.divi(validTokenCount);  
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        return convertINDArrayToDoubleList(embedding);  
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    }  
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    return Collections.emptyList();  // Return an empty list if no valid embeddings  
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}  
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private List<Double> convertINDArrayToDoubleList(INDArray indArray) {  
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    double[] array = indArray.toDoubleVector();   
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    List<Double> doubleList = new ArrayList<>();  
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    for (double value : array) {  
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        doubleList.add(value);  
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    }  
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    return doubleList;  
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}  
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public List<Double> embedText(String text) {  
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    List<String> tokens = tokenizeText(text);  
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    return getEmbeddingForText(tokens);  
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}

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import com.mongodb.client.MongoClient;  
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import com.mongodb.client.MongoClients;  
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import org.springframework.context.annotation.Bean;  
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import org.springframework.context.annotation.Configuration;  
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import org.springframework.beans.factory.annotation.Value;  
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@Configuration  
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public class MongoDBConfig {  
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    @Value("${mongodb.uri}")  
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    private String mongoUri;  
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    @Bean  
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    public MongoClient mongoClient() {  
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        return MongoClients.create(mongoUri);
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    }  
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}

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mongodb.uri=mongodb+srv://<username>:<password>@cluster.mongodb.net/?retryWrites=true&w=majority

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mongodb.database=music  
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mongodb.collection=songs

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import com.mongodb.client.MongoClient;
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import com.mongodb.client.MongoCollection;
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import com.mongodb.client.MongoDatabase;
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import org.bson.Document;
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import org.example.model.Song;
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import org.springframework.beans.factory.annotation.Value;
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import org.springframework.stereotype.Repository;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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@Repository
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public class MongoDBRepository {
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    private final MongoCollection<Document> songCollection;
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    public MongoDBRepository(MongoClient mongoClient,
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                             @Value("${mongodb.database}") String databaseName,
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                             @Value("${mongodb.collection}") String collectionName) {
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        MongoDatabase database = mongoClient.getDatabase(databaseName);
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        this.songCollection = database.getCollection(collectionName);
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    }
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    /**
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     * Store the song embedding along with song details
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     *
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     * @param lyrics The song lyrics
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     * @param title The song title
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     * @param artist The artist name
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     * @param embedding The vector embedding for the song
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     */
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    public void storeEmbedding(String lyrics, String title, String artist, List<Double> embedding) {
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        Document songDocument = new Document()
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                .append("title", title)
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                .append("artist", artist)
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                .append("lyrics", lyrics)
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                .append("embedding", embedding);
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        songCollection.insertOne(songDocument);
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    }
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    /**
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     * Fetch similar songs using MongoDB's $vectorSearch aggregation based on the playlist embedding.
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     *
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     * @param playlistEmbedding The playlist title embedding used as the query vector
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     * @return List of Song objects representing similar songs
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     */
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    public List<Song> getSimilarSongs(List<Double> playlistEmbedding) {
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        List<Document> similarSongsDocs = new ArrayList<>();
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        // Perform the vector search using the generated embedding
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        String indexName = "vector_index";
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        int numCandidates = 150;
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        int limit = 10;
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        List<Document> pipeline = Arrays.asList(
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                new Document("$vectorSearch",
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                        new Document("index", indexName)
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                                .append("path", "embedding")
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                                .append("queryVector", playlistEmbedding)
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                                .append("numCandidates", numCandidates)
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                                .append("limit", limit)
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                ),
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                new Document("$limit", limit)
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        );
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        try {
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            songCollection.aggregate(pipeline).into(similarSongsDocs);
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        } catch (Exception e) {
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            throw new RuntimeException("Failed to retrieve similar songs", e);
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        }
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        List<Song> similarSongs = new ArrayList<>();
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        for (Document doc : similarSongsDocs) {
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            Song song = new Song(
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                    doc.getString("title"),
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                    doc.getString("artist"),
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                    doc.getString("lyrics"),
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                    doc.getList("embedding", Double.class)
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            );
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            similarSongs.add(song);
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        }
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        return similarSongs;
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    }
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}

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{   
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	"fields": [     
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		{       
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		"type": "vector",       
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		"path": "embedding",       
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		"numDimensions": 300,  // The number of dimensions of the vectors
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		"similarity": "dotProduct"  // Similarity metric (cosine, euclidean, or dotProduct)
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		}   
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	] 
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}

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@Service
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public class PlaylistService {
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    private final EmbeddingService embeddingService;
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    private final MongoDBRepository songRepository;
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    public PlaylistService(EmbeddingService embeddingService, MongoDBRepository songRepository) {
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        this.embeddingService = embeddingService;
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        this.songRepository = songRepository;
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    }
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}

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 public Playlist generatePlaylist(String playlistName) {  
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    // Generate the embedding for the playlist title  
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    List<Double> playlistEmbedding = embeddingService.embedText(playlistName);  
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    if (playlistEmbedding == null || playlistEmbedding.isEmpty()) {  
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        throw new RuntimeException("Failed to generate embedding for playlist: " + playlistName);  
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    }  
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    // Query the database to find similar songs  
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    List<Song> similarSongs = songRepository.getSimilarSongs(playlistEmbedding);  
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    // Construct and return the Playlist  
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    return new Playlist(playlistName, similarSongs);  
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}

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import org.apache.commons.csv.CSVFormat;  
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import org.apache.commons.csv.CSVParser;  
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import org.apache.commons.csv.CSVRecord;  
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import org.example.repository.MongoDBRepository;  
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import org.example.service.EmbeddingService;  
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import org.springframework.stereotype.Component;  
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import java.io.InputStreamReader;  
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import java.io.Reader;  
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import java.util.List;  
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import java.util.Objects;  
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@Component  
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public class SongLyricsProcessor {  
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    private final EmbeddingService embeddingService;  
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    private final MongoDBRepository mongoDBRepository;  
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    public SongLyricsProcessor(EmbeddingService embeddingService, MongoDBRepository mongoDBRepository) {  
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        this.embeddingService = embeddingService;  
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        this.mongoDBRepository = mongoDBRepository;  
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    }  
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    public void processAndStoreLyrics(String csvFilePath) throws Exception {  
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        Reader reader = new InputStreamReader(  
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                Objects.requireNonNull(getClass().getClassLoader().getResourceAsStream(csvFilePath))  
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        );  
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        CSVFormat csvFormat = CSVFormat.DEFAULT.builder()  
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                .setHeader()  
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                .setSkipHeaderRecord(true)  
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                .build();  
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        CSVParser csvParser = new CSVParser(reader, csvFormat);  
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        for (CSVRecord record : csvParser) {  
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            String title = record.get("title");  
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            String artist = record.get("artist");  
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            String lyrics = record.get("lyrics");  
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            String languageCld3 = record.get("language_cld3");  
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            String languageFt = record.get("language_ft");  
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            // Check if both language_cld3 and language_ft are 'en' (English)  
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            if (!"en".equalsIgnoreCase(languageCld3) || !"en".equalsIgnoreCase(languageFt)) {  
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                continue;  
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            }  
47
  
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            // Tokenize the lyrics and generate the embedding  
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            List<Double> lyricsEmbedding = embeddingService.embedText(lyrics);  
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            // Store the title, artist, lyrics, and embedding in MongoDB  
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            mongoDBRepository.storeEmbedding(lyrics, title, artist, lyricsEmbedding);  
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        }  
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        csvParser.close();  
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    }  
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}

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@RestController
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public class PlaylistController {
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    private final PlaylistService playlistService;
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    private final SongLyricsProcessor songLyricsProcessor;
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    public PlaylistController(PlaylistService playlistService, SongLyricsProcessor songLyricsProcessor) {
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        this.playlistService = playlistService;
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        this.songLyricsProcessor = songLyricsProcessor;
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    }
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    @GetMapping("/loadSampleData")
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    public void loadSampleData(@RequestParam String fileName) throws Exception {
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        songLyricsProcessor.processAndStoreLyrics(fileName);
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    }
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}

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@GetMapping("/newPlaylist")
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public Playlist newPlaylist(@RequestParam String playlistName) {
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	return playlistService.generatePlaylist(playlistName);
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}

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curl -X GET "http://localhost:8080/loadSampleData?fileName=song_lyrics.csv"

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curl -X GET "http://localhost:8080/newPlaylist?playlistName=sad%20girl%20wistful%20Friday%20evening"

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{
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	"playlistName": "sad girl wistful Friday evening",
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	"songs": [
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	    {
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			"title": "When A Woman Loves",
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			"artist": "R. Kelly",
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			"lyrics": "...",
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			"embedding": "...",
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	    },
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	    {
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			"title": "Lonely",
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			"artist": "Akon",
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			"lyrics": "...",
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			"embedding": "...",
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	    },
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	    {
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			"title": "Monster",
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			"artist": "Lady Gaga",
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			"lyrics": "...",
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			"embedding": "...",
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	    },
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	    {
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			"title": "All the Boys",
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			"artist": "Keri Hilson",
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			"lyrics": "...",
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			"embedding": "...",
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	    }
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	]
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}