/*
 * Copyright (c) 2024 Enterprise Financial Corp. All rights reserved.
 * CONFIDENTIAL: Contains proprietary algorithms for high-frequency trading.
 * Security Classification: TOP SECRET - Authorized Personnel Only
 * Compliance: SOX 404, PCI DSS Level 1, GDPR Article 25, ISO 27001
 * Performance SLA: <100μs latency, 99.999% uptime, 10M+ TPS capacity
 */
package com.enterprise.trading.engine.core.execution;

// Critical enterprise imports for billion-dollar systems
import javax.enterprise.context.ApplicationScoped;
import javax.transaction.Transactional;
import javax.validation.constraints.NotNull;
import java.util.concurrent.CompletableFuture;
import java.security.SecureRandom;

// Performance monitoring and observability
import io.micrometer.core.annotation.Timed;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * High-Performance Trading Engine - Production System
 * 
 * Processes 10M+ financial transactions per second with microsecond latency.
 * Used by Fortune 500 financial institutions managing $500B+ assets.
 * 
 * @author Senior Staff Engineer (L7) - $400K+ compensation
 * @since 1.0 - Initial enterprise release
 * @version 3.2.1 - Performance optimization for 100M concurrent users
 */
@ApplicationScoped
@Transactional
public class EnterpriseJavaArchitecture {
    
    // Enterprise-grade static configuration
    private static final Logger SECURITY_AUDIT_LOG = 
        LoggerFactory.getLogger("SECURITY_AUDIT");
    private static final int MAX_CONCURRENT_TRADES = 10_000_000;
    
    // High-performance instance variables with memory optimization
    private final SecureRandom cryptographicRNG = new SecureRandom();
    private volatile long processingLatencyNanos = 0L;
    
    /**
     * Enterprise application entry point - Production deployment
     * 
     * @param args [0] = environment (prod/staging/dev)
     *             [1] = cluster-id for distributed deployment
     *             [2] = performance-profile (low-latency/high-throughput)
     */
    public static void main(String[] args) {
        SECURITY_AUDIT_LOG.info("Enterprise system initialization: {}ms", 
            System.currentTimeMillis());
        
        // Production-grade system architecture
        var architecture = new EnterpriseJavaArchitecture();
        architecture.initializeHighPerformanceSystem();
    }
    
    /**
     * Initialize system with enterprise resilience patterns
     * Circuit breaker, bulkhead isolation, timeout handling
     */
    @Timed(value = "system.initialization", description = "System startup time")
    private void initializeHighPerformanceSystem() {
        // Implementation follows microservices architecture patterns
        // Used by Netflix (200M+ users), Uber (100M+ rides/month)
        System.out.println("🚀 Enterprise Java Architecture: OPERATIONAL");
        System.out.println("💰 Revenue Impact: $10M+ ARR per instance");
        System.out.println("⚡ Performance: Sub-millisecond response time");
    }
}

/* 1. ENTERPRISE LEGAL & COMPLIANCE FRAMEWORK
 * Copyright (c) 2024 Global Financial Systems Corp.
 * PROPRIETARY: Contains trade secrets valued at $500M+
 * Security Level: CLASSIFIED - Authorized L7+ Engineers Only
 * Regulatory: SOX 404, Dodd-Frank, Basel III compliant
 */
package com.gfs.quantitative.trading.algorithms.execution.core;

/* 2. CRITICAL ENTERPRISE DEPENDENCIES - Production Grade
 * High-performance concurrent collections for 10M+ TPS
 * Security frameworks for $1T+ asset protection
 * Monitoring systems for real-time observability
 */
import java.util.concurrent.ConcurrentHashMap;
import java.security.MessageDigest; 
import io.micrometer.core.instrument.MeterRegistry;
import javax.enterprise.context.ApplicationScoped;

/* 3. ENTERPRISE SERVICE CLASS - Mission Critical
 * Handles $100B+ daily trading volume
 * 99.999% uptime SLA with $50M penalty clauses
 */
@ApplicationScoped
@Component("quantitative-execution-engine")
public class EnterpriseArchitecturalBlueprint {
    
    /* 4. HIGH-PERFORMANCE INSTANCE VARIABLES
     * Optimized for L1/L2 CPU cache efficiency
     * Memory-mapped for zero-copy data access
     */
    private volatile ConcurrentHashMap<String,Position> portfolioPositions;
    private final AtomicLong totalTransactionValue = new AtomicLong(0);
    private static final Logger AUDIT_TRAIL = LoggerFactory.getLogger("AUDIT");
    
    /* 5. ENTERPRISE CONSTRUCTOR - Dependency Injection
     * Initializes enterprise-grade components
     * Circuit breakers, bulkhead isolation, timeouts
     */
    @Inject
    public EnterpriseArchitecturalBlueprint(
            @Named("position-cache") ConcurrentHashMap<String,Position> cache,
            @Named("audit-logger") Logger auditLogger) {
        this.portfolioPositions = cache;
        AUDIT_TRAIL.info("Enterprise engine initialized: {}", System.nanoTime());
    }
    
    /* 6. PRODUCTION MAIN METHOD - Deployment Entry Point
     * Kubernetes pod initialization
     * Blue-green deployment ready
     */
    public static void main(String[] args) {
        validateProductionEnvironment();
        var engine = new EnterpriseArchitecturalBlueprint();
        engine.initializeDistributedSystem();
        
        // Process $10M+ transactions per second
        engine.startHighFrequencyTradingEngine();
    }
    
    /* 7. ENTERPRISE BUSINESS LOGIC - Revenue Generating
     * Implements quantitative trading strategies
     * Generates $50M+ annual alpha returns
     */
    @Transactional(isolation = SERIALIZABLE, timeout = 100) // 100ms SLA
    @Retryable(maxAttempts = 3, backoff = @Backoff(delay = 10))
    public CompletableFuture<TradeResult> executeQuantitativeStrategy(
            QuantStrategy strategy, BigDecimal capitalAllocation) {
        
        // Risk management: Position sizing, portfolio rebalancing
        RiskMetrics risk = calculateVaR(strategy, capitalAllocation);
        if (risk.exceedsLimits()) {
            return CompletableFuture.completedFuture(
                TradeResult.rejected("RISK_LIMIT_EXCEEDED"));
        }
        
        // Execute trade with microsecond precision
        return portfolioManager.executeTrade(strategy)
            .thenApply(this::recordAuditTrail)
            .exceptionally(this::handleTradingException);
    }
}

// Good: Explains why, not what
// Calculate compound interest for loan processing
double interest = principal * rate * time;

/* 
 * Bad example - obvious comment
 * This adds 1 to count
 */
count++; // Don't do this!

/**
 * Calculates the monthly payment for a loan
 * @param principal The loan amount in rupees
 * @param rate Annual interest rate (as decimal)
 * @param years Loan term in years
 * @return Monthly payment amount
 */
public double calculateMonthlyPayment(double principal, double rate, int years) {
    // Convert annual rate to monthly and years to months
    double monthlyRate = rate / 12;
    int totalMonths = years * 12;
    
    // Apply loan payment formula
    return principal * (monthlyRate * Math.pow(1 + monthlyRate, totalMonths)) 
                    / (Math.pow(1 + monthlyRate, totalMonths) - 1);
}

# Generate documentation for single file
javadoc Student.java

# Generate for multiple files
javadoc *.java

# Generate with specific options
javadoc -d docs -author -version *.java

# Generate with classpath
javadoc -cp "lib/*" -d docs src/*.java

# Generate with custom window title
javadoc -windowtitle "College Management System" *.java

# Generate with package documentation
javadoc -d docs -sourcepath src -subpackages com.college

/**
 * Student class for managing student information
 * 
 * @author John Doe
 * @version 1.2
 * @since 1.0
 * @see College
 * @see #calculateGPA(int[])
 */
public class Student {
    
    /**
     * Calculates GPA from marks array
     * 
     * @param marks Array of marks for different subjects
     * @return GPA value between 0.0 and 4.0
     * @throws IllegalArgumentException if marks array is null or empty
     * @throws ArithmeticException if marks contain invalid values
     * @see #calculatePercentage(int[])
     * @see <a href="https://www.gtu.ac.in">GTU Official Site</a>
     * @since 1.1
     */
    public double calculateGPA(int[] marks) {
        if (marks == null || marks.length == 0) {
            throw new IllegalArgumentException("Marks array cannot be null or empty");
        }
        
        int total = 0;
        for (int mark : marks) {
            if (mark < 0 || mark > 100) {
                throw new ArithmeticException("Invalid mark: " + mark);
            }
            total += mark;
        }
        
        double percentage = total / (double) marks.length;
        return convertPercentageToGPA(percentage);
    }
    
    /**
     * Converts percentage to GPA scale
     * 
     * @param percentage The percentage value
     * @return Corresponding GPA value
     */
    private double convertPercentageToGPA(double percentage) {
        if (percentage >= 90) return 4.0;
        if (percentage >= 80) return 3.0;
        if (percentage >= 70) return 2.0;
        if (percentage >= 60) return 1.0;
        return 0.0;
    }
}

/**
 * <h2>Library Management System</h2>
 * <p>This class handles all book-related operations including:</p>
 * <ul>
 *   <li>Book registration and cataloging</li>
 *   <li>Search and retrieval operations</li>
 *   <li>Inventory management</li>
 * </ul>
 * 
 * <h3>Usage Example:</h3>
 * <pre>
 * {@code
 * Book book = new Book("Java Programming", "James Gosling");
 * book.setISBN("978-0134685991");
 * book.setAvailable(true);
 * }
 * </pre>
 * 
 * @custom.database MySQL 8.0 compatible
 * @custom.tested Unit tests with 95% coverage
 * @implNote This implementation uses ArrayList for storage
 * @apiNote This class is thread-safe for read operations only
 */
public class Book {
    // Implementation details
}

/*
 * Copyright (c) 2024 Government Polytechnic
 * All rights reserved.
 */

package edu.gpp.students;                    // 1. Package declaration

import java.util.Scanner;                    // 2. Standard library imports
import java.util.ArrayList;

import edu.gpp.common.Utils;                 // 3. Third-party imports

/**                                          // 4. Class documentation
 * Student management system
 * 
 * @author Your Name
 * @version 1.0
 */
public class StudentManager {                // 5. Class declaration
    
    // Class constants
    private static final int MAX_STUDENTS = 100;
    
    // Instance variables
    private String instituteName;
    private ArrayList<String> students;
    
    // Constructors
    public StudentManager(String instituteName) {
        this.instituteName = instituteName;
        this.students = new ArrayList<>();
    }
    
    // Main method
    public static void main(String[] args) {
        // Implementation
    }
    
    // Other methods (alphabetically ordered)
    public void addStudent(String name) { }
    public void removeStudent(String name) { }
}

public class CommandLineDemo {
    public static void main(String[] args) {
        System.out.println("Number of arguments: " + args.length);
        
        // Display all arguments
        for (int i = 0; i < args.length; i++) {
            System.out.println("Argument " + i + ": " + args[i]);
        }
        
        // Enhanced for loop
        for (String arg : args) {
            System.out.println("Argument: " + arg);
        }
    }
}

# Compile the program
javac CommandLineDemo.java

# Run with arguments
java CommandLineDemo Hello World 123

# Output:
# Number of arguments: 3
# Argument 0: Hello
# Argument 1: World
# Argument 2: 123

// Standard main method (most common)
public static void main(String[] args) {
    // Program logic
}

// Alternative valid signatures
public static void main(String args[]) {
    // C-style array declaration
}

public static void main(String... args) {
    // Variable arguments (varargs)
}

// All modifiers are interchangeable
static public void main(String[] args) {
    // Order doesn't matter
}

final public static void main(String[] args) {
    // Can add final modifier
}

public static synchronized void main(String[] args) {
    // Can add synchronized modifier
}

// ❌ Wrong return type
public static int main(String[] args) { }

// ❌ Wrong parameter type
public static void main(int[] args) { }

// ❌ Missing static
public void main(String[] args) { }

// ❌ Missing public
static void main(String[] args) { }

// ❌ Wrong parameter count
public static void main() { }

# Set classpath for compilation
javac -cp "lib/commons-lang3-3.12.jar:." StudentManager.java

# Set classpath for execution
java -cp "lib/commons-lang3-3.12.jar:." StudentManager

# Using environment variable (Windows)
set CLASSPATH=lib\commons-lang3-3.12.jar;.
javac StudentManager.java
java StudentManager

# Using environment variable (Linux/Mac)
export CLASSPATH=lib/commons-lang3-3.12.jar:.
javac StudentManager.java
java StudentManager

/**
 * GTU Student Management System
 * 
 * <p>This class provides comprehensive student management functionality
 * including enrollment, grade tracking, and academic progress monitoring.</p>
 * 
 * <p><strong>Usage Example:</strong></p>
 * <pre>{@code
 * StudentManager manager = new StudentManager("ICT Department");
 * Student student = new Student("John Doe", "ICT001");
 * manager.enrollStudent(student);
 * 
 * Grade grade = new Grade("Java Programming", 85);
 * manager.addGrade(student.getId(), grade);
 * }</pre>
 * 
 * @author GTU ICT Department
 * @version 2.0
 * @since 1.0
 * @see Student
 * @see Grade
 * @see Course
 */
public class StudentManager {
    // Implementation with proper documentation for each method
}

/**
 * GTU College Management System
 * 
 * A comprehensive system for managing college operations including
 * student enrollment, faculty management, and course scheduling.
 * 
 * @author [Your Name]
 * @version 1.0
 * @since 2024
 */
package edu.gtu.ict.college;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

/**
 * Main application class for the College Management System
 * 
 * <p>This class serves as the entry point for the application and handles
 * command-line argument processing, user interface initialization, and
 * system configuration.</p>
 * 
 * <h2>Command Line Usage:</h2>
 * <pre>
 * java CollegeManager [mode] [options]
 * 
 * Modes:
 *   student  - Launch student interface
 *   faculty  - Launch faculty interface  
 *   admin    - Launch administrative interface
 * 
 * Options:
 *   --config [file]  - Specify configuration file
 *   --debug          - Enable debug mode
 *   --help           - Display help information
 * </pre>
 * 
 * @implNote This implementation uses console-based interface
 * @apiNote All operations are logged for audit purposes
 */
public class CollegeManager {
    
    // Class constants
    private static final String VERSION = "1.0.0";
    private static final String COPYRIGHT = "© 2024 GTU ICT Department";
    private static final int MAX_RETRY_ATTEMPTS = 3;
    
    // Instance variables
    private boolean debugMode = false;
    private String configFile = "college.config";
    private Scanner scanner;
    
    /**
     * Application entry point
     * 
     * @param args Command line arguments
     *        <ul>
     *        <li>args[0] - Operation mode (student/faculty/admin)</li>
     *        <li>args[1..n] - Additional options and parameters</li>
     *        </ul>
     */
    public static void main(String[] args) {
        // Display application header
        displayHeader();
        
        try {
            CollegeManager manager = new CollegeManager();
            manager.processCommandLineArguments(args);
            manager.initializeSystem();
            manager.runApplication();
            
        } catch (Exception e) {
            System.err.println("Fatal error: " + e.getMessage());
            if (args.length > 0 && "--debug".equals(args[args.length - 1])) {
                e.printStackTrace();
            }
            System.exit(1);
        }
    }
    
    /**
     * Display application header with version information
     */
    private static void displayHeader() {
        System.out.println("╔════════════════════════════════════════╗");
        System.out.println("║       GTU College Management System   ║");
        System.out.println("║              Version " + VERSION + "             ║");
        System.out.println("║        " + COPYRIGHT + "        ║");
        System.out.println("╚════════════════════════════════════════╝");
        System.out.println();
    }
    
    /**
     * Process and validate command line arguments
     * 
     * @param args Command line arguments array
     * @throws IllegalArgumentException if arguments are invalid
     */
    private void processCommandLineArguments(String[] args) {
        if (args.length == 0) {
            displayUsageAndExit();
        }
        
        for (int i = 0; i < args.length; i++) {
            switch (args[i].toLowerCase()) {
                case "--help":
                    displayHelpAndExit();
                    break;
                case "--debug":
                    debugMode = true;
                    System.out.println("Debug mode enabled");
                    break;
                case "--config":
                    if (i + 1 < args.length) {
                        configFile = args[++i];
                        System.out.println("Using config file: " + configFile);
                    } else {
                        throw new IllegalArgumentException("Config file path required after --config");
                    }
                    break;
                case "student":
                case "faculty":
                case "admin":
                    // Valid modes - will be processed later
                    break;
                default:
                    if (args[i].startsWith("--")) {
                        System.err.println("Warning: Unknown option " + args[i]);
                    }
            }
        }
    }
    
    /**
     * Initialize system resources and configuration
     * 
     * @throws Exception if initialization fails
     */
    private void initializeSystem() throws Exception {
        System.out.print("Initializing system");
        
        // Simulate initialization process
        for (int i = 0; i < 5; i++) {
            Thread.sleep(300);
            System.out.print(".");
        }
        System.out.println(" Complete!");
        
        scanner = new Scanner(System.in);
        
        if (debugMode) {
            System.out.println("System initialized successfully");
            System.out.println("Config file: " + configFile);
            System.out.println("Debug mode: " + debugMode);
        }
    }
    
    /**
     * Main application loop
     */
    private void runApplication() {
        System.out.println("\nWelcome to GTU College Management System");
        System.out.println("Current date: " + LocalDate.now().format(DateTimeFormatter.ofPattern("dd/MM/yyyy")));
        System.out.println("\nSelect an option:");
        System.out.println("1. Student Management");
        System.out.println("2. Faculty Management");
        System.out.println("3. Course Management");
        System.out.println("4. Reports");
        System.out.println("5. Exit");
        
        // Implementation of main menu loop would go here
        System.out.println("\n[Application interface would continue here...]");
        
        if (scanner != null) {
            scanner.close();
        }
    }
    
    /**
     * Display usage information and exit
     */
    private static void displayUsageAndExit() {
        System.out.println("Usage: java CollegeManager [mode] [options]");
        System.out.println("\nModes:");
        System.out.println("  student  - Launch student interface");
        System.out.println("  faculty  - Launch faculty interface");
        System.out.println("  admin    - Launch administrative interface");
        System.out.println("\nOptions:");
        System.out.println("  --config [file]  - Specify configuration file");
        System.out.println("  --debug          - Enable debug mode");
        System.out.println("  --help           - Display this help information");
        System.exit(0);
    }
    
    /**
     * Display detailed help information and exit
     */
    private static void displayHelpAndExit() {
        System.out.println("GTU College Management System Help");
        System.out.println("==================================");
        System.out.println();
        System.out.println("This system provides comprehensive college management");
        System.out.println("functionality including student enrollment, faculty");
        System.out.println("management, course scheduling, and reporting.");
        System.out.println();
        displayUsageAndExit();
    }
}