import java.io.*;
import java.nio.file.*;
import java.util.concurrent.TimeUnit;

public class PDFPrinter {
    
    // Default values
    private static final String DEFAULT_PRINTER = "null_printer";
    private static final String DEFAULT_FILE_PATH = "/usr/local/tomee/output/SystemtestScott.pdf";
    
    public static void main(String[] args) {
        String filePath = DEFAULT_FILE_PATH;
        String printerName = DEFAULT_PRINTER;
        
        System.out.println("=== PDF Printing Utility ===");
        
        // Parse command line arguments
        for (int i = 0; i < args.length; i++) {
            if (args[i].equals("-d") && i + 1 < args.length) {
                // -d option: specify printer
                printerName = args[i + 1];
                i++; // Skip next argument since we used it
            } else if (args[i].equals("-h") || args[i].equals("--help")) {
                // Help option
                printHelp();
                System.exit(0);
            } else if (args[i].equals("-l") || args[i].equals("--list")) {
                // List printers option
                try {
                    listAvailablePrinters();
                } catch (Exception e) {
                    System.err.println("ERROR: Failed to list printers: " + e.getMessage());
                }
                System.exit(0);
            } else if (!args[i].startsWith("-")) {
                // Positional argument: treat as file path
                filePath = args[i];
            } else {
                System.err.println("ERROR: Unknown option: " + args[i]);
                printHelp();
                System.exit(1);
            }
        }
        
        // Display selected options
        System.out.println("Target file: " + filePath);
        System.out.println("Printer: " + printerName);
        
        try {
            boolean success = printPDF(filePath, printerName);
            
            if (success) {
                System.out.println("SUCCESS: Print job submitted successfully!");
                System.exit(0);
            } else {
                System.out.println("FAILURE: Print job failed");
                System.exit(1);
            }
        } catch (Exception e) {
            System.err.println("ERROR: " + e.getMessage());
            System.exit(1);
        }
    }
    
    /**
     * Display help message
     */
    private static void printHelp() {
        System.out.println("Usage: java PDFPrinter [options] [file-path]");
        System.out.println();
        System.out.println("Options:");
        System.out.println("  -d <printer>     Specify printer name (default: null_printer)");
        System.out.println("  -l, --list       List available printers");
        System.out.println("  -h, --help       Display this help message");
        System.out.println();
        System.out.println("Examples:");
        System.out.println("  java PDFPrinter");
        System.out.println("    Prints default file to null_printer printer");
        System.out.println();
        System.out.println("  java PDFPrinter -d HP-LaserJet");
        System.out.println("    Prints default file to HP-LaserJet printer");
        System.out.println();
        System.out.println("  java PDFPrinter /path/to/file.pdf");
        System.out.println("    Prints specified file to null_printer printer");
        System.out.println();
        System.out.println("  java PDFPrinter /path/to/file.pdf -d Office-Printer");
        System.out.println("    Prints specified file to Office-Printer");
        System.out.println();
        System.out.println("Default values:");
        System.out.println("  File: " + DEFAULT_FILE_PATH);
        System.out.println("  Printer: " + DEFAULT_PRINTER);
    }
    
    /**
     * Prints a PDF file using the Linux 'lp' command
     * 
     * @param filePath Path to the PDF file
     * @param printerName Printer name (cannot be null, default is "null_printer")
     * @return true if print job submitted successfully
     * @throws IOException if file not found or command fails
     * @throws InterruptedException if process interrupted
     */
    public static boolean printPDF(String filePath, String printerName) 
            throws IOException, InterruptedException {
        
        // Validate printer name is not null or empty
        if (printerName == null || printerName.trim().isEmpty()) {
            printerName = DEFAULT_PRINTER;
        }
        
        // 1. Validate the file exists and is readable
        System.out.println("Validating PDF file...");
        Path pdfPath = Paths.get(filePath);
        
        if (!Files.exists(pdfPath)) {
            throw new IOException("File does not exist: " + filePath);
        }
        
        if (!Files.isReadable(pdfPath)) {
            throw new IOException("File is not readable: " + filePath);
        }
        
        if (!filePath.toLowerCase().endsWith(".pdf")) {
            System.out.println("Warning: File does not have .pdf extension");
        }
        
        long fileSize = Files.size(pdfPath);
        System.out.println("File validation passed");
        System.out.println("File size: " + fileSize + " bytes");
        
        // 2. Build the lp command - ALWAYS use -d option with printerName
        ProcessBuilder pb;
        System.out.println("Using printer: " + printerName);
        pb = new ProcessBuilder("lp", "-d", printerName, filePath);
        
        // 3. Configure ProcessBuilder
        pb.redirectErrorStream(true); // Combine stdout and stderr
        
        // 4. Execute the command
        System.out.println("Executing: " + String.join(" ", pb.command()));
        
        Process process;
        try {
            process = pb.start();
        } catch (IOException e) {
            throw new IOException("Failed to start lp command. Is CUPS/lp installed? " + 
                                 "Install with: sudo apt-get install cups-client", e);
        }
        
        // 5. Capture and display output
        StringBuilder output = new StringBuilder();
        try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(process.getInputStream()))) {
            
            String line;
            while ((line = reader.readLine()) != null) {
                output.append(line).append("\n");
                System.out.println("lp output: " + line);
            }
        }
        
        // 6. Wait for completion with timeout (60 seconds)
        System.out.println("Waiting for print job submission...");
        boolean completed = process.waitFor(60, TimeUnit.SECONDS);
        
        if (!completed) {
            process.destroyForcibly();
            throw new IOException("Print command timed out after 60 seconds");
        }
        
        // 7. Check exit code
        int exitCode = process.exitValue();
        
        if (exitCode == 0) {
            // Success - extract job ID if available
            String response = output.toString();
            if (response.contains("request id is")) {
                String jobId = extractJobId(response);
                System.out.println("Print job ID: " + jobId);
            }
            return true;
        } else {
            // Failure - provide helpful error messages
            String errorMsg = output.toString().trim();
            if (errorMsg.contains("No such file or directory")) {
                throw new IOException("lp command not found. Install CUPS: sudo apt-get install cups-client");
            } else if (errorMsg.contains("Unable to open")) {
                throw new IOException("Printer error: " + errorMsg);
            } else if (errorMsg.contains("invalid destination")) {
                throw new IOException("Invalid printer name: " + printerName + 
                    ". Use -l option to list available printers.");
            } else if (errorMsg.contains("Unsupported format")) {
                throw new IOException("PDF format not supported by printer");
            } else if (!errorMsg.isEmpty()) {
                throw new IOException("Print failed: " + errorMsg);
            } else {
                throw new IOException("Print failed with exit code: " + exitCode);
            }
        }
    }
    
    /**
     * Extracts print job ID from lp output
     */
    private static String extractJobId(String response) {
        // Example: "request id is HP-LaserJet-123 (1 file(s))"
        if (response.contains("request id is")) {
            String[] parts = response.split("request id is");
            if (parts.length > 1) {
                String jobPart = parts[1].trim();
                int endIndex = jobPart.indexOf(" (");
                if (endIndex > 0) {
                    return jobPart.substring(0, endIndex);
                }
                return jobPart;
            }
        }
        return "Unknown";
    }
    
    /**
     * Utility method to check available printers
     */
    public static void listAvailablePrinters() throws IOException, InterruptedException {
        System.out.println("\n=== Available Printers ===");
        System.out.println("Looking for printers...");
        
        ProcessBuilder pb = new ProcessBuilder("lpstat", "-p");
        pb.redirectErrorStream(true);
        
        Process process = pb.start();
        
        try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(process.getInputStream()))) {
            
            boolean hasPrinters = false;
            String line;
            while ((line = reader.readLine()) != null) {
                if (line.startsWith("printer ")) {
                    hasPrinters = true;
                    String printerName = line.split("\\s+")[1];
                    String status = line.contains("enabled") ? "[ENABLED]" : "[DISABLED]";
                    System.out.println(status + " " + printerName);
                }
            }
            
            if (!hasPrinters) {
                System.out.println("No printers found via lpstat.");
                System.out.println("\nTroubleshooting steps:");
                System.out.println("1. Check if CUPS is running: sudo systemctl status cups");
                System.out.println("2. Check all print services: lpstat -v");
                System.out.println("3. Install CUPS if needed: sudo apt-get install cups cups-client");
            } else {
                System.out.println("\nNote: Default printer is 'null_printer'");
            }
        }
        
        process.waitFor();
    }
}