Эмирзаков - 3 tasks (С)

src/main/java/com/javarush/emirzakov/input.txt

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+When Al Templeton called me on the seventh of June 2011, and told me to come down to the diner, he sounded like a man who was gargling with nails.
+He also sounded like he was about to cry.
+Since Al was the toughest man I had ever known (my old man included), this was scary.
+"What's wrong?" I asked.
+"Are you sick?"
+"Just get here, Jake.
+Please."
+He hung up.
+I went.
+He’d given me a job when I needed one, washing dishes and helping him short-order.
+I owed him.
+Besides, I was worried.
+I hadn't seen him in...
+when?
+Mid-May, I guess.
+That was when he'd put the CLOSED FOR REPAIRS sign on the door of the fat-boy diner.
+When I asked him what repairs, he’d been vague.
+The sign was still on the door, but the door was unlocked.
+I went in.
+The place was dark and hot.
+The shades were pulled.
+"Al?"
+"In the booth," he whispered.
+I walked past the counter, and my footsteps echoed in the empty room.
+He was in the back booth, the one we called the Office.
+He was sitting in the shadows.
+"Al, what's going on?
+You look..."
+I stopped.
+Because he didn't look.
+Not like Al.
+The Al Templeton I knew was a big man, six-two and at least two-thirty, most of it gut.
+He was hearty.
+He was loud.
+The man in the booth was a scarecrow.
+His cheeks were hollows.
+His eyes were huge and staring.
+His hair, which had been graying, was now almost entirely white, and it was thin, wispy.
+He was wearing one of his endless supply of flannel shirts, and it hung on him like a tent.
+He must have lost sixty pounds.
+"Jesus, Al," I said.
+"What happened to you?
+Cancer?"
+He nodded.
+"Lung.
+Stage four.
+They found it when I...
+when I came back."
+"Came back?
+From where?
+Florida?
+I thought you were just closing for repairs."
+"I lied," he said, and his voice was a dry rasp.
+"I haven't been in Florida, Jake.
+I've been in 1958."
+I stared at him.
+He stared back.
+His eyes were perfectly steady.
+He meant it.
+"You're insane," I said.
+"No.
+I'm dying.
+And I need you to listen to me.
+I need you to listen to me very, very carefully.
+Because I’m going to tell you something that will change your life.
+And maybe change the world."
+He pointed toward the pantry.
+"It started in there.
+In the back.
+There's a...
+a bubble.
+A rabbit-hole.
+And it goes to the past."

src/main/java/com/javarush/emirzakov/io/FileReaderService.java

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+package com.javarush.emirzakov.io;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class FileReaderService {
+
+    public String readFromFile(String path) {
+        try {
+            return Files.readString(Path.of(path));
+        } catch (IOException e) {
+            System.out.println("Error reading file: " + e.getMessage());
+            return "";
+        }
+    }
+}

src/main/java/com/javarush/emirzakov/io/FileWriterService.java

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+package com.javarush.emirzakov.io;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class FileWriterService {
+    public void writeFile(String path, CharSequence content) {
+        try {
+            Files.writeString(Path.of(path), content);
+            System.out.println("Files successfully written to: " + path);
+        } catch (IOException e) {
+            System.out.println("Error writing to file: " + e.getMessage());
+        }
+    }
+}

src/main/java/com/javarush/emirzakov/main/java/Runner.java

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+package com.javarush.emirzakov.main.java;
+
+
+import com.javarush.emirzakov.io.FileReaderService;
+import com.javarush.emirzakov.io.FileWriterService;
+import com.javarush.emirzakov.service.BruteForceAction;
+import com.javarush.emirzakov.service.DecryptAction;
+import com.javarush.emirzakov.service.EncryptAction;
+import com.javarush.emirzakov.service.TextUtils;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Scanner;
+
+public class Runner {
+    public static void main(String[] args) {
+
+        FileReaderService fileReader = new FileReaderService();
+
+        try (Scanner scanner = new Scanner(System.in)) {
+            System.out.println("Enter text directly, or specify a file path: ");
+            String input = scanner.nextLine();
+
+            String text;
+            Path path = Path.of(input);
+            if (Files.exists(path) && Files.isRegularFile(path)) {
+                System.out.println("File has been found and read!");
+                text = fileReader.readFromFile(input);
+            } else {
+                text = input;
+                System.out.println("Using input text directly");
+            }
+            String normalized = TextUtils.normalize(text);
+
+            System.out.println("Normalized text: ");
+            System.out.println(normalized.substring(0, Math.min(300, normalized.length())) + "...");
+
+
+            System.out.println("\nChoose action: ");
+            System.out.println("1 - Encrypt");
+            System.out.println("2 - Decrypt");
+            System.out.println("3 - Brute Force (try to find key automatically)");
+
+            int choice = readInt(scanner, "Enter choice (1-3): ");
+            String message = "Enter key (integer): ";
+            String result = null;
+
+            switch (choice) {
+                case 1 -> {
+                    int key = readInt(scanner, message);
+                    EncryptAction encryptAction = new EncryptAction();
+                    result = encryptAction.execute(text, key);
+                }
+                case 2 -> {
+                    int key = readInt(scanner, message);
+                    DecryptAction decryptAction = new DecryptAction();
+                    result = decryptAction.execute(text, key);
+                }
+                case 3 -> {
+                    BruteForceAction bf = new BruteForceAction();
+                    BruteForceAction.Result best = bf.findBestByStopWords(text);
+
+                    if (best != null) {
+                        System.out.println("\n Brute-force result:");
+                        System.out.println("Key: " + best.key + " Score: " + best.score);
+                        System.out.println("Candidate text:\n" + best.text);
+                        result = best.text;
+                    } else {
+                        System.out.println("No likely candidate found by brute force.");
+                    }
+                }
+                default -> System.out.println("Unknown action. Exiting.");
+            }
+            if (result != null) {
+                System.out.println("\n=== Result ===");
+                System.out.println(result);
+
+                System.out.println("\nDo you want to save the result to a file? (y/n)");
+                String answer = scanner.nextLine().trim().toLowerCase();
+                if (answer.equals("y")) {
+                    System.out.println("Enter path to file: ");
+                    String filePath = scanner.nextLine().trim();
+
+                    FileWriterService fileWriter = new FileWriterService();
+                    fileWriter.writeFile(filePath, result);
+                }
+            }
+        }
+    }
+
+    private static int readInt(Scanner scanner, String prompt) {
+        while (true) {
+            System.out.println(prompt);
+            String line = scanner.nextLine().trim();
+            if (line.isEmpty()) {
+                System.out.println("Please enter 1, 2, or 3, then press Enter.");
+                continue;
+            }
+            if (!line.matches("\\d+")) {
+                System.out.println("Please enter a valid integer.");
+                continue;
+            }
+            try {
+                return Integer.parseInt(line);
+            } catch (NumberFormatException e) {
+                System.out.println("Number too large. Try again.");
+            }
+        }
+    }
+}

src/main/java/com/javarush/emirzakov/model/Alphabet.java

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+package com.javarush.emirzakov.model;
+
+public class Alphabet {
+    private final char[] ALPHABET;
+
+    private static final char[] ENGLISH = "abcdefghijklmnopqrstuvwxyz".toCharArray();
+
+    private static final char[] RUSSIAN = "абвгдеёжзийклмнопрстуфхцчшщъыьэюя".toCharArray();
+
+
+    public Alphabet(String text) {
+        if (text.matches(".*[а-яА-ЯёЁ].*")) {
+            ALPHABET = RUSSIAN;
+        } else {
+            ALPHABET = ENGLISH;
+        }
+    }
+
+    public int getCharIndex(char c) {
+        for (int i = 0; i < ALPHABET.length; i++) {
+            if (Character.toLowerCase(ALPHABET[i]) == Character.toLowerCase(c)) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    public char getCharByIndex(int index) {
+        int i = index % ALPHABET.length;
+        if (i < 0) i += ALPHABET.length;
+        return ALPHABET[i];
+    }
+
+    public int length() {
+        return ALPHABET.length;
+    }
+
+}

src/main/java/com/javarush/emirzakov/model/StopWords.java

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+package com.javarush.emirzakov.model;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+public final class StopWords {
+    public static final Set<String> RUSSIAN = new HashSet<>(Arrays.asList(
+            "и", "в", "на", "не", "что", "как", "я", "он", "она", "но", "с",
+            "за", "по", "то", "этот", "это", "для", "вы", "мы", "они"
+    ));
+    public static final Set<String> ENGLISH = new HashSet<>(Arrays.asList(
+            "and", "the", "in", "of", "to", "a", "is", "it", "by", "for",
+            "on", "that", "this", "with", "as", "you", "I", "we", "he", "she"
+    ));
+
+    private StopWords() {
+
+    }
+}

src/main/java/com/javarush/emirzakov/service/BruteForceAction.java

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+package com.javarush.emirzakov.service;
+
+import com.javarush.emirzakov.model.Alphabet;
+import com.javarush.emirzakov.model.StopWords;
+
+import java.util.List;
+import java.util.Set;
+
+public class BruteForceAction {
+
+    public static class Result {
+        public final int key;
+        public final String text;
+        public final int score;
+
+        public Result(int key, String text, int score) {
+            this.key = key;
+            this.text = text;
+            this.score = score;
+        }
+    }
+
+    public Result findBestByStopWords(String cipherText) {
+        if (cipherText == null || cipherText.isBlank()) return null;
+
+        DecryptAction decryptAction = new DecryptAction();
+        int N = new Alphabet(cipherText).length();
+
+        int bestScore = -1;
+        Result best = null;
+
+        for (int k = 0; k < N; k++) {
+            String candidate = decryptAction.execute(cipherText, k);
+            String sample = shortenForAnalysis(candidate);
+            String norm = TextUtils.normalize(sample);
+            List<String> tokens = TextUtils.tokenize(norm);
+
+            int rusMatches = countStopWords(tokens, StopWords.RUSSIAN);
+            int engMatches = countStopWords(tokens, StopWords.ENGLISH);
+            int matches = Math.max(rusMatches, engMatches);
+
+            if (matches > bestScore) {
+                bestScore = matches;
+                best = new Result(k, candidate, matches);
+            }
+        }
+        return best;
+    }
+
+    private String shortenForAnalysis(String text) {
+        int maxLen = 1000;
+        if (text == null) return "";
+        if (text.length() <= maxLen) return text;
+
+        int cutIndex = text.lastIndexOf(' ', maxLen);
+        if (cutIndex == -1) {
+            cutIndex = maxLen;
+        }
+        return text.substring(0, cutIndex).trim();
+    }
+
+    private int countStopWords(List<String> tokens, Set<String> stopSet) {
+        if (tokens == null || tokens.isEmpty() || stopSet == null || stopSet.isEmpty()) return 0;
+        int count = 0;
+        for (String t : tokens) {
+            if (stopSet.contains(t)) count++;
+        }
+        return count;
+    }
+
+}

src/main/java/com/javarush/emirzakov/service/CryptoAction.java

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+package com.javarush.emirzakov.service;
+
+import com.javarush.emirzakov.model.Alphabet;
+
+public abstract class CryptoAction {
+
+    protected char shiftChar(char c, int key, Alphabet alphabet) {
+        if (!Character.isLetter(c)) return c;
+
+        boolean isUpper = Character.isUpperCase(c);
+        char lower = Character.toLowerCase(c);
+        int index = alphabet.getCharIndex(lower);
+
+        if (index == -1) {
+            return c;
+        }
+        char shifted = alphabet.getCharByIndex(index + key);
+        return isUpper ? Character.toUpperCase(shifted) : shifted;
+    }
+
+    public abstract String execute(String text, int key);
+}

src/main/java/com/javarush/emirzakov/service/DecryptAction.java

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+package com.javarush.emirzakov.service;
+
+import com.javarush.emirzakov.model.Alphabet;
+
+public class DecryptAction extends CryptoAction {
+
+    @Override
+    public String execute(String text, int key) {
+        Alphabet alphabet = new Alphabet(text);
+        StringBuilder result = new StringBuilder();
+        for (int i = 0; i < text.length(); i++) {
+            char ch = text.charAt(i);
+            result.append(shiftChar(ch, -key, alphabet));
+        }
+        return result.toString();
+    }
+}