import java.io.; import java.util.;

public class NotesApp {

// Directory to store all note files
private static final String NOTES_DIRECTORY = "notes/";
private static final String FILE_EXTENSION = ".txt";
private static Scanner scanner = new Scanner(System.in);

public static void main(String[] args) {
    // Create notes directory if it doesn't exist
    createNotesDirectory();
    
    System.out.println("=== Welcome to Java Notes Manager ===");
    System.out.println("A simple file I/O demonstration app\n");
    
    boolean running = true;
    while (running) {
        displayMenu();
        int choice = getChoice();
        
        switch (choice) {
            case 1:
                createNote();
                break;
            case 2:
                readNote();
                break;
            case 3:
                listAllNotes();
                break;
            case 4:
                deleteNote();
                break;
            case 5:
                searchNotes();
                break;
            case 6:
                running = false;
                System.out.println("Thank you for using Notes Manager!");
                break;
            default:
                System.out.println("Invalid choice. Please try again.");
        }
        System.out.println(); // Add spacing between operations
    }
    scanner.close();
}

/**
 * Creates the notes directory if it doesn't exist
 * Demonstrates basic File operations
 */
private static void createNotesDirectory() {
    File directory = new File(NOTES_DIRECTORY);
    if (!directory.exists()) {
        boolean created = directory.mkdir();
        if (created) {
            System.out.println("Created notes directory: " + NOTES_DIRECTORY);
        }
    }
}

/**
 * Displays the main menu options
 */
private static void displayMenu() {
    System.out.println("=== Notes Manager Menu ===");
    System.out.println("1. Create New Note");
    System.out.println("2. Read Note");
    System.out.println("3. List All Notes");
    System.out.println("4. Delete Note");
    System.out.println("5. Search Notes");
    System.out.println("6. Exit");
    System.out.print("Enter your choice (1-6): ");
}

/**
 * Gets user's menu choice with basic input validation
 */
private static int getChoice() {
    try {
        return Integer.parseInt(scanner.nextLine());
    } catch (NumberFormatException e) {
        return -1; // Invalid choice
    }
}

/**
 * Creates a new note and saves it to a file using FileWriter
 * Demonstrates writing to files with proper exception handling
 */
private static void createNote() {
    System.out.println("\n=== Create New Note ===");
    System.out.print("Enter note title: ");
    String title = scanner.nextLine().trim();
    
    if (title.isEmpty()) {
        System.out.println("Title cannot be empty!");
        return;
    }
    
    // Clean title for filename (remove special characters)
    String filename = title.replaceAll("[^a-zA-Z0-9\\s]", "").replaceAll("\\s+", "_");
    String filepath = NOTES_DIRECTORY + filename + FILE_EXTENSION;
    
    System.out.println("Enter your note content (type 'END' on a new line to finish):");
    StringBuilder content = new StringBuilder();
    String line;
    
    // Collect multi-line input
    while (!(line = scanner.nextLine()).equals("END")) {
        content.append(line).append("\n");
    }
    
    // Write note to file using FileWriter
    try (FileWriter writer = new FileWriter(filepath)) {
        // Write title and creation timestamp
        writer.write("Title: " + title + "\n");
        writer.write("Created: " + new Date() + "\n");
        writer.write("=" + "=".repeat(50) + "\n");
        writer.write(content.toString());
        
        System.out.println("✓ Note saved successfully as: " + filename + FILE_EXTENSION);
        
    } catch (IOException e) {
        System.out.println("✗ Error saving note: " + e.getMessage());
    }
}

/**
 * Reads and displays a note from file using FileReader and BufferedReader
 * Demonstrates reading from files with proper resource management
 */
private static void readNote() {
    System.out.println("\n=== Read Note ===");
    
    // Show available notes first
    listAvailableNotes();
    
    System.out.print("Enter note filename (without .txt): ");
    String filename = scanner.nextLine().trim();
    
    if (filename.isEmpty()) {
        System.out.println("Filename cannot be empty!");
        return;
    }
    
    String filepath = NOTES_DIRECTORY + filename + FILE_EXTENSION;
    File file = new File(filepath);
    
    if (!file.exists()) {
        System.out.println("✗ Note not found: " + filename + FILE_EXTENSION);
        return;
    }
    
    // Read file using FileReader and BufferedReader
    try (FileReader fileReader = new FileReader(filepath);
         BufferedReader bufferedReader = new BufferedReader(fileReader)) {
        
        System.out.println("\n" + "=".repeat(60));
        String line;
        while ((line = bufferedReader.readLine()) != null) {
            System.out.println(line);
        }
        System.out.println("=".repeat(60));
        
    } catch (IOException e) {
        System.out.println("✗ Error reading note: " + e.getMessage());
    }
}

/**
 * Lists all available note files
 * Demonstrates directory listing and file filtering
 */
private static void listAllNotes() {
    System.out.println("\n=== All Notes ===");
    listAvailableNotes();
}

/**
 * Helper method to list available notes with file information
 */
private static void listAvailableNotes() {
    File directory = new File(NOTES_DIRECTORY);
    File[] files = directory.listFiles((dir, name) -> name.endsWith(FILE_EXTENSION));
    
    if (files == null || files.length == 0) {
        System.out.println("No notes found. Create your first note!");
        return;
    }
    
    System.out.println("Available notes:");
    for (int i = 0; i < files.length; i++) {
        File file = files[i];
        String name = file.getName().replace(FILE_EXTENSION, "");
        long size = file.length();
        Date modified = new Date(file.lastModified());
        
        System.out.printf("%d. %s (%d bytes, modified: %tc)%n", 
                        i + 1, name, size, modified);
    }
}

/**
 * Deletes a note file
 * Demonstrates file deletion operations
 */
private static void deleteNote() {
    System.out.println("\n=== Delete Note ===");
    
    listAvailableNotes();
    
    System.out.print("Enter note filename to delete (without .txt): ");
    String filename = scanner.nextLine().trim();
    
    if (filename.isEmpty()) {
        System.out.println("Filename cannot be empty!");
        return;
    }
    
    String filepath = NOTES_DIRECTORY + filename + FILE_EXTENSION;
    File file = new File(filepath);
    
    if (!file.exists()) {
        System.out.println("✗ Note not found: " + filename + FILE_EXTENSION);
        return;
    }
    
    System.out.print("Are you sure you want to delete '" + filename + "'? (y/N): ");
    String confirmation = scanner.nextLine().trim().toLowerCase();
    
    if (confirmation.equals("y") || confirmation.equals("yes")) {
        if (file.delete()) {
            System.out.println("✓ Note deleted successfully: " + filename + FILE_EXTENSION);
        } else {
            System.out.println("✗ Failed to delete note: " + filename + FILE_EXTENSION);
        }
    } else {
        System.out.println("Delete operation cancelled.");
    }
}

/**
 * Searches for content across all notes
 * Demonstrates reading multiple files and text searching
 */
private static void searchNotes() {
    System.out.println("\n=== Search Notes ===");
    System.out.print("Enter search term: ");
    String searchTerm = scanner.nextLine().trim();
    
    if (searchTerm.isEmpty()) {
        System.out.println("Search term cannot be empty!");
        return;
    }
    
    File directory = new File(NOTES_DIRECTORY);
    File[] files = directory.listFiles((dir, name) -> name.endsWith(FILE_EXTENSION));
    
    if (files == null || files.length == 0) {
        System.out.println("No notes to search.");
        return;
    }
    
    System.out.println("Searching for: \"" + searchTerm + "\"");
    System.out.println("-".repeat(40));
    
    boolean found = false;
    String searchLower = searchTerm.toLowerCase();
    
    for (File file : files) {
        try (FileReader fileReader = new FileReader(file);
             BufferedReader bufferedReader = new BufferedReader(fileReader)) {
            
            String line;
            int lineNumber = 1;
            boolean fileHasMatch = false;
            
            while ((line = bufferedReader.readLine()) != null) {
                if (line.toLowerCase().contains(searchLower)) {
                    if (!fileHasMatch) {
                        System.out.println("\n📝 " + file.getName().replace(FILE_EXTENSION, ""));
                        fileHasMatch = true;
                        found = true;
                    }
                    System.out.printf("   Line %d: %s%n", lineNumber, line.trim());
                }
                lineNumber++;
            }
            
        } catch (IOException e) {
            System.out.println("Error searching file " + file.getName() + ": " + e.getMessage());
        }
    }
    
    if (!found) {
        System.out.println("No matches found for: \"" + searchTerm + "\"");
    }
}

}