create logic file (TF-IDF)

src/main/java/com/distributed/search/logic/FileManager.java

 package com.distributed.search.logic;
 
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
 public class FileManager {
-}
+
+    public static List<String> getSortedDocumentNames(String directoryPath) {
+        File directory = new File(directoryPath);
+        File[] files = directory.listFiles((dir, name) -> name.endsWith(".txt"));
+
+        if (files == null) return List.of();
+
+        return Arrays.stream(files)
+                .map(File::getName)
+                .sorted()
+                .collect(Collectors.toList());
+    }
+
+    public static String readDocumentContent(String directoryPath, String fileName) throws IOException {
+        return Files.readString(Paths.get(directoryPath, fileName));
+    }
+}
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src/main/java/com/distributed/search/logic/TFIDFCalculator.java

 package com.distributed.search.logic;
 
+import java.util.Arrays;
+import java.util.List;
+
 public class TFIDFCalculator {
-}
+
+    public static List<String> getWordsFromDocument(String content) {
+        return Arrays.asList(content.toLowerCase().split("(\\.)|(\\s)|(\\k)|(\\,)|(\\?)"));
+    }
+
+    public static double calculateTermFrequency(List<String> words, String term) {
+        long count = words.stream()
+                .filter(word -> word.equalsIgnoreCase(term))
+                .count();
+        return (double) count / words.size();
+    }
+
+    public static double calculateIdf(int totalDocuments, int documentsWithTerm) {
+        if (documentsWithTerm == 0) return 0;
+        return Math.log10((double) totalDocuments / documentsWithTerm);
+    }
+}
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