/*
    * Licensed under the GPL License. You may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *   https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
    *
    * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
    * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
    * PURPOSE.
   */
  package psiprobe;
  
  import com.google.common.base.Strings;
  
  import jakarta.servlet.http.HttpServletRequest;
  import jakarta.servlet.http.HttpServletResponse;
  
  import java.io.BufferedInputStream;
  import java.io.BufferedReader;
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  import java.io.RandomAccessFile;
  import java.io.Reader;
  import java.lang.management.ManagementFactory;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Locale;
  import java.util.Scanner;
  import java.util.Set;
  import java.util.zip.ZipEntry;
  import java.util.zip.ZipOutputStream;
  
  import javax.management.MBeanServer;
  import javax.management.MalformedObjectNameException;
  import javax.management.ObjectInstance;
  import javax.management.ObjectName;
  
  import org.codelibs.jhighlight.renderer.Renderer;
  import org.codelibs.jhighlight.renderer.XhtmlRendererFactory;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import psiprobe.tokenizer.StringTokenizer;
  import psiprobe.tokenizer.Token;
  import psiprobe.tokenizer.Tokenizer;
  import psiprobe.tokenizer.TokenizerSymbol;
  
  /**
   * Misc. static helper methods.
   */
  public final class Utils {
  
    /** The Constant logger. */
    private static final Logger logger = LoggerFactory.getLogger(Utils.class);
  
    /**
     * Prevent Instantiation.
     */
    private Utils() {
      // Prevent Instantiation
    }
  
    /**
     * Reads a file on disk. The method uses default file encoding (see: file.encoding system
     * property)
     *
     * @param file to be read
     * @param charsetName the charset name
     *
     * @return String representation of the file contents
     *
     * @throws IOException Signals that an I/O exception has occurred.
     */
    public static String readFile(File file, String charsetName) throws IOException {
      try (InputStream fis = Files.newInputStream(file.toPath())) {
        return readStream(fis, charsetName);
      }
    }
  
    /**
     * Reads strings from the intput stream using the given charset. This method closes the input
     * stream after it has been consumed.
     *
     * <p>
     * This method uses the system's default charset if the given one is unsupported.
     * </p>
     *
     * @param is the stream from which to read
     * @param charsetName the charset to use when reading the stream
     *
     * @return the contents of the given input stream
    *
    * @throws IOException if reading from the stream fails spectacularly
    */
   public static String readStream(InputStream is, String charsetName) throws IOException {
     Charset charset;
     if (Charset.isSupported(charsetName)) {
       charset = Charset.forName(charsetName);
     } else {
       // use system's default encoding if the passed encoding is unsupported
       charset = Charset.defaultCharset();
     }
 
     StringBuilder out = new StringBuilder();
     try (BufferedReader reader = new BufferedReader(new InputStreamReader(is, charset), 4096)) {
       String line;
       while ((line = reader.readLine()) != null) {
         out.append(line).append('\n');
       }
     }
 
     return out.toString();
   }
 
   /**
    * Delete.
    *
    * @param file the file
    */
   public static void delete(File file) {
     if (file != null && file.exists()) {
       if (file.isDirectory()) {
         for (File child : file.listFiles()) {
           delete(child);
         }
       }
       try {
         Files.delete(file.toPath());
       } catch (IOException e) {
         logger.debug("Cannot delete '{}'", file.getAbsolutePath(), e);
       }
     } else {
       logger.debug("'{}' does not exist", file);
     }
   }
 
   /**
    * To int.
    *
    * @param num the num
    * @param defaultValue the default value
    *
    * @return the int
    */
   public static int toInt(String num, int defaultValue) {
     if (num != null && !num.contains(" ")) {
       try (Scanner scanner = new Scanner(num)) {
         if (scanner.hasNextInt()) {
           return scanner.nextInt();
         }
       }
     }
     return defaultValue;
   }
 
   /**
    * To int hex.
    *
    * @param num the num
    * @param defaultValue the default value
    *
    * @return the int
    */
   public static int toIntHex(String num, int defaultValue) {
     if (num != null && !num.contains(" ")) {
       if (num.startsWith("#")) {
         num = num.substring(1);
       }
       try (Scanner scanner = new Scanner(num)) {
         if (scanner.hasNextInt()) {
           return scanner.nextInt(16);
         }
       }
     }
     return defaultValue;
   }
 
   /**
    * To long.
    *
    * @param num the num
    * @param defaultValue the default value
    *
    * @return the long
    */
   public static long toLong(String num, long defaultValue) {
     if (num != null && !num.contains(" ")) {
       try (Scanner scanner = new Scanner(num)) {
         if (scanner.hasNextLong()) {
           return scanner.nextLong();
         }
       }
     }
     return defaultValue;
   }
 
   /**
    * To long.
    *
    * @param num the num
    * @param defaultValue the default value
    *
    * @return the long
    */
   public static long toLong(Long num, long defaultValue) {
     return num == null ? defaultValue : num;
   }
 
   /**
    * To float.
    *
    * @param num the num
    * @param defaultValue the default value
    *
    * @return the float
    */
   public static float toFloat(String num, float defaultValue) {
     if (num != null && !num.contains(" ")) {
       try (Scanner scanner = new Scanner(num)) {
         if (scanner.hasNextFloat()) {
           return scanner.nextFloat();
         }
       }
     }
     return defaultValue;
   }
 
   /**
    * Gets the jsp encoding.
    *
    * @param is the is
    *
    * @return the jsp encoding
    *
    * @throws IOException Signals that an I/O exception has occurred.
    */
   public static String getJspEncoding(InputStream is) throws IOException {
 
     String encoding = null;
     String contentType = null;
 
     Tokenizer jspTokenizer = new Tokenizer();
     jspTokenizer.addSymbol("\n", true);
     jspTokenizer.addSymbol(" ", true);
     jspTokenizer.addSymbol("\t", true);
     jspTokenizer.addSymbol(new TokenizerSymbol("dir", "<%@", "%>", false, false, true, false));
 
     StringTokenizer directiveTokenizer = new StringTokenizer();
     directiveTokenizer.addSymbol("\n", true);
     directiveTokenizer.addSymbol(" ", true);
     directiveTokenizer.addSymbol("\t", true);
     directiveTokenizer.addSymbol("=");
     directiveTokenizer.addSymbol("\"", "\"", false);
     directiveTokenizer.addSymbol("'", "'", false);
 
     StringTokenizer contentTypeTokenizer = new StringTokenizer();
     contentTypeTokenizer.addSymbol(" ", true);
     contentTypeTokenizer.addSymbol(";", true);
 
     try (Reader reader = new InputStreamReader(is, StandardCharsets.UTF_8)) {
       jspTokenizer.setReader(reader);
       while (jspTokenizer.hasMore()) {
         Token token = jspTokenizer.nextToken();
         if ("dir".equals(token.getName())) {
           directiveTokenizer.setString(token.getInnerText());
           if (directiveTokenizer.hasMore()
               && "page".equals(directiveTokenizer.nextToken().getText())) {
             while (directiveTokenizer.hasMore()) {
               Token directiveToken = directiveTokenizer.nextToken();
               if ("pageEncoding".equals(directiveToken.getText())) {
                 if (directiveTokenizer.hasMore()
                     && "=".equals(directiveTokenizer.nextToken().getText())
                     && directiveTokenizer.hasMore()) {
                   encoding = directiveTokenizer.nextToken().getInnerText();
                   break;
                 }
               } else if ("contentType".equals(directiveToken.getText())
                   && directiveTokenizer.hasMore()
                   && "=".equals(directiveTokenizer.nextToken().getText())
                   && directiveTokenizer.hasMore()) {
                 contentType = directiveTokenizer.nextToken().getInnerText();
               }
             }
           }
         }
       }
     }
 
     if (encoding == null && contentType != null) {
       contentTypeTokenizer.setString(contentType);
       while (contentTypeTokenizer.hasMore()) {
         String token = contentTypeTokenizer.nextToken().getText();
         if (token.startsWith("charset=")) {
           encoding = token.substring("charset=".length());
           break;
         }
       }
     }
 
     return encoding != null ? encoding : StandardCharsets.UTF_8.name();
   }
 
   /**
    * Send file.
    *
    * @param request the request
    * @param response the response
    * @param file the file
    *
    * @throws IOException Signals that an I/O exception has occurred.
    */
   public static void sendFile(HttpServletRequest request, HttpServletResponse response, File file)
       throws IOException {
 
     try (OutputStream out = response.getOutputStream();
         RandomAccessFile raf = new RandomAccessFile(file, "r")) {
       long fileSize = raf.length();
       long rangeStart = 0;
       long rangeFinish = fileSize - 1;
 
       // accept attempts to resume download (if any)
       String range = request.getHeader("Range");
       if (range != null && range.startsWith("bytes=")) {
         String pureRange = range.replace("bytes=", "");
         int rangeSep = pureRange.indexOf('-');
 
         try {
           rangeStart = Long.parseLong(pureRange.substring(0, rangeSep));
           if (rangeStart > fileSize || rangeStart < 0) {
             rangeStart = 0;
           }
         } catch (NumberFormatException e) {
           // keep rangeStart unchanged
           logger.trace("", e);
         }
 
         if (rangeSep < pureRange.length() - 1) {
           try {
             rangeFinish = Long.parseLong(pureRange.substring(rangeSep + 1));
             if (rangeFinish < 0 || rangeFinish >= fileSize) {
               rangeFinish = fileSize - 1;
             }
           } catch (NumberFormatException e) {
             logger.trace("", e);
           }
         }
       }
 
       // set some headers
       response.setContentType("application/x-download");
       response.setHeader("Content-Disposition", "attachment; filename=" + file.getName());
       response.setHeader("Accept-Ranges", "bytes");
       response.setHeader("Content-Length", Long.toString(rangeFinish - rangeStart + 1));
       response.setHeader("Content-Range",
           "bytes " + rangeStart + "-" + rangeFinish + "/" + fileSize);
 
       // seek to the requested offset
       raf.seek(rangeStart);
 
       // send the file
       byte[] buffer = new byte[4096];
 
       long len;
       int totalRead = 0;
       boolean nomore = false;
       while (true) {
         len = raf.read(buffer);
         if (len > 0 && totalRead + len > rangeFinish - rangeStart + 1) {
           // read more then required?
           // adjust the length
           len = rangeFinish - rangeStart + 1 - totalRead;
           nomore = true;
         }
 
         if (len <= 0) {
           break;
         }
         out.write(buffer, 0, (int) len);
         totalRead = totalRead + (int) len;
         if (nomore) {
           break;
         }
       }
     }
   }
 
   /**
    * Gets the thread by name.
    *
    * @param name the name
    *
    * @return the thread by name
    */
   public static Thread getThreadByName(String name) {
     if (name != null) {
       // get top ThreadGroup
       ThreadGroup masterGroup = Thread.currentThread().getThreadGroup();
       while (masterGroup.getParent() != null) {
         masterGroup = masterGroup.getParent();
       }
 
       Thread[] threads = new Thread[masterGroup.activeCount()];
       masterGroup.enumerate(threads);
 
       for (Thread thread : threads) {
         if (thread != null && name.equals(thread.getName())) {
           return thread;
         }
       }
     }
     return null;
   }
 
   /**
    * Highlight stream.
    *
    * @param name the name
    * @param input the input
    * @param rendererName the renderer name
    * @param encoding the encoding
    *
    * @return the string
    *
    * @throws IOException Signals that an I/O exception has occurred.
    */
   public static String highlightStream(String name, InputStream input, String rendererName,
       String encoding) throws IOException {
 
     Renderer jspRenderer = XhtmlRendererFactory.getRenderer(rendererName);
     if (jspRenderer == null) {
       return null;
     }
 
     ByteArrayOutputStream bos = new ByteArrayOutputStream();
     jspRenderer.highlight(name, input, bos, encoding, true);
 
     ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
 
     Tokenizer tokenizer = new Tokenizer(new InputStreamReader(bis, Charset.forName(encoding)));
     tokenizer.addSymbol(new TokenizerSymbol("EOL", "\n", null, false, false, true, false));
     tokenizer.addSymbol(new TokenizerSymbol("EOL", "\r\n", null, false, false, true, false));
 
     //
     // JHighlight adds HTML comment as the first line, so if
     // we number the lines we could end up with a line number and no line
     // to avoid that we just ignore the first line all together.
     //
     StringBuilder buffer = new StringBuilder();
     long counter = 0;
     while (tokenizer.hasMore()) {
       Token tk = tokenizer.nextToken();
       if ("EOL".equals(tk.getName())) {
         counter++;
         buffer.append(tk.getText());
       } else if (counter > 0) {
         buffer.append("<span class=\"codeline\">");
         buffer.append("<span class=\"linenum\">");
         buffer.append(leftPad(Long.toString(counter), 6, " ").replace(" ", "&nbsp;"));
         buffer.append("</span>");
         buffer.append(tk.getText());
         buffer.append("</span>");
       }
     }
     return buffer.toString();
   }
 
   /**
    * Send compressed file.
    *
    * @param response the response
    * @param file the file
    *
    * @throws IOException Signals that an I/O exception has occurred.
    */
   public static void sendCompressedFile(HttpServletResponse response, File file)
       throws IOException {
     try (ZipOutputStream zip = new ZipOutputStream(response.getOutputStream());
         InputStream fileInput = new BufferedInputStream(Files.newInputStream(file.toPath()))) {
 
       String fileName = file.getName();
 
       // set some headers
       response.setContentType("application/zip");
       response.setHeader("Content-Disposition", "attachment; filename=" + fileName + ".zip");
 
       zip.putNextEntry(new ZipEntry(fileName));
 
       // send the file
       byte[] buffer = new byte[4096];
       long len;
 
       while ((len = fileInput.read(buffer)) > 0) {
         zip.write(buffer, 0, (int) len);
       }
       zip.closeEntry();
     }
   }
 
   /**
    * Left pad.
    *
    * @param str the str
    * @param len the len
    * @param fill the fill
    *
    * @return the string
    */
   static String leftPad(final String str, final int len, final String fill) {
     if (str != null && str.length() < len) {
       return Strings.padStart(str, len, fill.charAt(0));
     }
     return str == null ? "" : str;
   }
 
   /**
    * Gets the names for locale.
    *
    * @param baseName the base name
    * @param locale the locale
    *
    * @return the names for locale
    */
   public static List<String> getNamesForLocale(String baseName, Locale locale) {
     List<String> result = new ArrayList<>(3);
     String language = locale.getLanguage();
     String country = locale.getCountry();
     String variant = locale.getVariant();
     StringBuilder temp = new StringBuilder(baseName);
 
     if (language.length() > 0) {
       temp.append('_').append(language);
       result.add(0, temp.toString());
     }
 
     if (country.length() > 0) {
       temp.append('_').append(country);
       result.add(0, temp.toString());
     }
 
     if (variant.length() > 0) {
       temp.append('_').append(variant);
       result.add(0, temp.toString());
     }
 
     return result;
   }
 
   /**
    * Checks if is threading enabled.
    *
    * @return true, if is threading enabled
    */
   public static boolean isThreadingEnabled() {
     try {
       MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
       ObjectName objectNameThreading = new ObjectName("java.lang:type=Threading");
       Set<ObjectInstance> threading = mbeanServer.queryMBeans(objectNameThreading, null);
       return threading != null && !threading.isEmpty();
     } catch (MalformedObjectNameException e) {
       logger.trace("", e);
       return false;
     }
   }
 }