/* Copyright 2006 aQute SARL 
    * Licensed under the Apache License, Version 2.0, see http://www.apache.org/licenses/LICENSE-2.0 */
   package com.atlassian.plugin.osgi.util;
   
   import java.io.*;
   import java.nio.*;
   import java.util.*;
   
   /**
   * Copied from the bndlib version 0.255, adding the capture of referred classes
   */
  public class Clazz {
  
  	static protected class Assoc {
  		Assoc(byte tag, int a, int b) {
  			this.tag = tag;
  			this.a = a;
  			this.b = b;
  		}
  
  		byte	tag;
  		int		a;
  		int		b;
  	}
  
  	final static byte	SkipTable[]	= { 0, // 0 non existent
  			-1, // 1 CONSTANT_utf8 UTF 8, handled in
  			// method
  			-1, // 2
  			4, // 3 CONSTANT_Integer
  			4, // 4 CONSTANT_Float
  			8, // 5 CONSTANT_Long (index +=2!)
  			8, // 6 CONSTANT_Double (index +=2!)
  			-1, // 7 CONSTANT_Class
  			2, // 8 CONSTANT_String
  			4, // 9 CONSTANT_FieldRef
  			4, // 10 CONSTANT_MethodRef
  			4, // 11 CONSTANT_InterfaceMethodRef
  			4, // 12 CONSTANT_NameAndType
  									};
  
  	String				className;
  	Object				pool[];
  	int					intPool[];
  	Map                 packageImports  = new HashMap();
      Set                 classImports    = new HashSet();
      String				path;
  
  	// static String type = "([BCDFIJSZ\\[]|L[^<>]+;)";
  	// static Pattern descriptor = Pattern.compile("\\(" + type + "*\\)(("
  	// + type + ")|V)");
  	int					minor		= 0;
  	int					major		= 0;
  
  	String				sourceFile;
  	Set					xref;
  	Set					classes;
  	Set					descriptors;
  	int					forName		= 0;
  	int					class$		= 0;
  
  	public Clazz(String path) {
  		this.path = path;
  	}
  
  	public Clazz(String path, InputStream in) throws IOException {
  		this.path = path;
  		DataInputStream din = new DataInputStream(in);
  		parseClassFile(din);
  		din.close();
  	}
  
  	Set parseClassFile(DataInputStream in) throws IOException {
  		xref = new HashSet();
  		classes = new HashSet();
  		descriptors = new HashSet();
  		
  		boolean crawl = false; // Crawl the byte code
  		int magic = in.readInt();
  		if (magic != 0xCAFEBABE)
  			throw new IOException("Not a valid class file (no CAFEBABE header)");
  
  		minor = in.readUnsignedShort(); // minor version
  		major = in.readUnsignedShort(); // major version
  		int count = in.readUnsignedShort();
  		pool = new Object[count];
  		intPool = new int[count];
  
  		process: for (int poolIndex = 1; poolIndex < count; poolIndex++) {
  			byte tag = in.readByte();
  			switch (tag) {
  			case 0:
  				break process;
  			case 1:
  				constantUtf8(in, poolIndex);
  				break;
  
  			// For some insane optimization reason are
  			// the long and the double two entries in the
 			// constant pool. See 4.4.5
 			case 5:
 				constantLong(in, poolIndex);
 				poolIndex++;
 				break;
 
 			case 6:
 				constantDouble(in, poolIndex);
 				poolIndex++;
 				break;
 
 			case 7:
 				constantClass(in, poolIndex);
 				break;
 
 			case 8:
 				constantString(in, poolIndex);
 				break;
 
 			case 10: // Method ref
 				methodRef(in, poolIndex);
 				break;
 
 			// Name and Type
 			case 12:
 				nameAndType(in, poolIndex, tag);
 				break;
 
 			// We get the skip count for each record type
 			// from the SkipTable. This will also automatically
 			// abort when
 			default:
 				if (tag == 2)
 					throw new IOException("Invalid tag " + tag);
 				in.skipBytes(SkipTable[tag]);
 				break;
 			}
 		}
 
 		pool(pool, intPool);
 		/*
 		 * Parse after the constant pool, code thanks to Hans Christian
 		 * Falkenberg
 		 */
 
 		int access_flags = in.readUnsignedShort(); // access
 		int this_class = in.readUnsignedShort();
 		int super_class = in.readUnsignedShort();
 		String supr =(String) pool[intPool[super_class]];
 		if ( supr != null )
 		    addReference(supr);
 		
 		className = (String) pool[intPool[this_class]];
 
 		int interfacesCount = in.readUnsignedShort();
 		in.skipBytes(interfacesCount * 2);
 
 		int fieldsCount = in.readUnsignedShort();
 		for (int i = 0; i < fieldsCount; i++) {
 			access_flags = in.readUnsignedShort(); // skip access flags
 			int name_index = in.readUnsignedShort();
 			int descriptor_index = in.readUnsignedShort();
 
 			// Java prior to 1.5 used a weird
 			// static variable to hold the com.X.class
 			// result construct. If it did not find it
 			// it would create a variable class$com$X
 			// that would be used to hold the class
 			// object gotten with Class.forName ...
 			// Stupidly, they did not actively use the
 			// class name for the field type, so bnd
 			// would not see a reference. We detect
 			// this case and add an artificial descriptor
 			String name = pool[name_index].toString(); // name_index
 			if (name.startsWith("class$")) {
 				crawl = true;
 			}
 
 			descriptors.add(new Integer(descriptor_index));
 			doAttributes(in, false);
 		}
 
 		//
 		// Check if we have to crawl the code to find
 		// the ldc(_w) <string constant> invokestatic Class.forName
 		// if so, calculate the method ref index so we
 		// can do this efficiently
 		//
 		if (crawl) {
 			forName = findMethod("java/lang/Class", "forName",
 					"(Ljava/lang/String;)Ljava/lang/Class;");
 			class$ = findMethod(className, "class$",
 					"(Ljava/lang/String;)Ljava/lang/Class;");
 		}
 
 		//
 		// Handle the methods
 		//
 		int methodCount = in.readUnsignedShort();
 		for (int i = 0; i < methodCount; i++) {
 			access_flags = in.readUnsignedShort();
 			int name_index = in.readUnsignedShort();
 			int descriptor_index = in.readUnsignedShort();
 			String s = (String) pool[name_index];
 			descriptors.add(new Integer(descriptor_index));
 			doAttributes(in, crawl);
 		}
 
 		doAttributes(in, false);
 
 		//
 		// Now iterate over all classes we found and
 		// parse those as well. We skip duplicates
 		//
 
 		for (Iterator e = classes.iterator(); e.hasNext();) {
 			int class_index = ((Integer) e.next()).shortValue();
 			doClassReference((String) pool[class_index]);
 		}
 
 		//
 		// Parse all the descriptors we found
 		//
 
 		for (Iterator e = descriptors.iterator(); e.hasNext();) {
 			Integer index = (Integer) e.next();
 			String prototype = (String) pool[index.intValue()];
 			if (prototype != null)
 				parseDescriptor(prototype);
 			else
 				System.err.println("Unrecognized descriptor: " + index);
 		}
 		Set xref = this.xref;
 		reset();
 		return xref;
 	}
 
 	protected void pool(Object[] pool, int[] intPool) {
 	}
 
 	/**
 	 * @param in
 	 * @param poolIndex
 	 * @param tag
 	 * @throws IOException
 	 */
 	protected void nameAndType(DataInputStream in, int poolIndex, byte tag)
 			throws IOException {
 		int name_index = in.readUnsignedShort();
 		int descriptor_index = in.readUnsignedShort();
 		descriptors.add(new Integer(descriptor_index));
 		pool[poolIndex] = new Assoc(tag, name_index, descriptor_index);
 	}
 
 	/**
 	 * @param in
 	 * @param poolIndex
 	 * @param tag
 	 * @throws IOException
 	 */
 	private void methodRef(DataInputStream in, int poolIndex)
 			throws IOException {
 		int class_index = in.readUnsignedShort();
 		int name_and_type_index = in.readUnsignedShort();
 		pool[poolIndex] = new Assoc((byte) 10, class_index, name_and_type_index);
 	}
 
 	/**
 	 * @param in
 	 * @param poolIndex
 	 * @throws IOException
 	 */
 	private void constantString(DataInputStream in, int poolIndex)
 			throws IOException {
 		int string_index = in.readUnsignedShort();
 		intPool[poolIndex] = string_index;
 	}
 
 	/**
 	 * @param in
 	 * @param poolIndex
 	 * @throws IOException
 	 */
 	protected void constantClass(DataInputStream in, int poolIndex)
 			throws IOException {
 		int class_index = in.readUnsignedShort();
 		classes.add(new Integer(class_index));
 		intPool[poolIndex] = class_index;
 	}
 
 	/**
 	 * @param in
 	 * @throws IOException
 	 */
 	protected void constantDouble(DataInputStream in, int poolIndex)
 			throws IOException {
 		in.skipBytes(8);
 	}
 
 	/**
 	 * @param in
 	 * @throws IOException
 	 */
 	protected void constantLong(DataInputStream in, int poolIndex)
 			throws IOException {
 		in.skipBytes(8);
 	}
 
 	/**
 	 * @param in
 	 * @param poolIndex
 	 * @throws IOException
 	 */
 	protected void constantUtf8(DataInputStream in, int poolIndex)
 			throws IOException {
 		// CONSTANT_Utf8
 		String name = in.readUTF();
 		xref.add(name);
 		pool[poolIndex] = name;
 	}
 
 	/**
 	 * Find a method reference in the pool that points to the given class,
 	 * methodname and descriptor.
 	 * 
 	 * @param clazz
 	 * @param methodname
 	 * @param descriptor
 	 * @return index in constant pool
 	 */
 	private int findMethod(String clazz, String methodname, String descriptor) {
 		for (int i = 1; i < pool.length; i++) {
 			if (pool[i] instanceof Assoc) {
 				Assoc methodref = (Assoc) pool[i];
 				if (methodref.tag == 10) {
 					// Method ref
 					int class_index = methodref.a;
 					int class_name_index = intPool[class_index];
 					if (clazz.equals(pool[class_name_index])) {
 						int name_and_type_index = methodref.b;
 						Assoc name_and_type = (Assoc) pool[name_and_type_index];
 						if (name_and_type.tag == 12) {
 							// Name and Type
 							int name_index = name_and_type.a;
 							int type_index = name_and_type.b;
 							if (methodname.equals(pool[name_index])) {
 								if (descriptor.equals(pool[type_index])) {
 									return i;
 								}
 							}
 						}
 					}
 				}
 			}
 		}
 		return -1;
 	}
 
 	private void doClassReference(String next) {
 		if (next != null) {
 			String normalized = normalize(next);
 			if (normalized != null) {
 				classReference(normalized);
 			}
 		} else
 			throw new IllegalArgumentException("Invalid class, parent=");
 	}
 
 	/**
 	 * Called for each attribute in the class, field, or method.
 	 * 
 	 * @param in
 	 *            The stream
 	 * @throws IOException
 	 */
 	private void doAttributes(DataInputStream in, boolean crawl)
 			throws IOException {
 		int attributesCount = in.readUnsignedShort();
 		for (int j = 0; j < attributesCount; j++) {
 			// skip name CONSTANT_Utf8 pointer
 			doAttribute(in, crawl);
 		}
 	}
 
 	/**
 	 * Process a single attribute, if not recognized, skip it.
 	 * 
 	 * @param in
 	 *            the data stream
 	 * @throws IOException
 	 */
 	private void doAttribute(DataInputStream in, boolean crawl)
 			throws IOException {
 		int attribute_name_index = in.readUnsignedShort();
 		String attributeName = (String) pool[attribute_name_index];
 		long attribute_length = in.readInt();
 		attribute_length &= 0xFFFF;
 		if ("RuntimeVisibleAnnotations".equals(attributeName))
 			doAnnotations(in);
 		else if ("RuntimeVisibleParameterAnnotations".equals(attributeName))
 			doParameterAnnotations(in);
 		else if ("SourceFile".equals(attributeName))
 			doSourceFile(in);
 		else if ("Code".equals(attributeName) && crawl)
 			doCode(in);
 		else {
 			if (attribute_length > 0x7FFFFFFF) {
 				throw new IllegalArgumentException("Attribute > 2Gb");
 			}
 			in.skipBytes((int) attribute_length);
 		}
 	}
 
 	/**
 	 * <pre>
 	 * Code_attribute {
 	 * 		u2 attribute_name_index;
 	 * 		u4 attribute_length;
 	 * 		u2 max_stack;
 	 * 		u2 max_locals;
 	 * 		u4 code_length;
 	 * 		u1 code[code_length];
 	 * 		u2 exception_table_length;
 	 * 		{    	u2 start_pc;
 	 * 		      	u2 end_pc;
 	 * 		      	u2  handler_pc;
 	 * 		      	u2  catch_type;
 	 * 		}	exception_table[exception_table_length];
 	 * 		u2 attributes_count;
 	 * 		attribute_info attributes[attributes_count];
 	 * 	}
 	 * </pre>
 	 * 
 	 * @param in
 	 * @param pool
 	 * @throws IOException
 	 */
 	private void doCode(DataInputStream in) throws IOException {
 		/* int max_stack = */in.readUnsignedShort();
 		/* int max_locals = */in.readUnsignedShort();
 		int code_length = in.readInt();
 		byte code[] = new byte[code_length];
 		in.readFully(code);
 		crawl(code);
 		int exception_table_length = in.readUnsignedShort();
 		in.skipBytes(exception_table_length * 8);
 		doAttributes(in, false);
 	}
 
 	/**
 	 * We must find Class.forName references ...
 	 * 
 	 * @param code
 	 */
 	protected void crawl(byte[] code) {
 		ByteBuffer bb = ByteBuffer.wrap(code);
 		bb.order(ByteOrder.BIG_ENDIAN);
 		int lastReference = -1;
 
 		while (bb.remaining() > 0) {
 			int instruction = 0xFF & bb.get();
 			switch (instruction) {
 			case OpCodes.ldc:
 				lastReference = 0xFF & bb.get();
 				break;
 
 			case OpCodes.ldc_w:
 				lastReference = 0xFFFF & bb.getShort();
 				break;
 
 			case OpCodes.invokestatic:
 				int methodref = 0xFFFF & bb.getShort();
 				if ((methodref == forName || methodref == class$) &&
 						lastReference != -1 &&
 						pool[intPool[lastReference]] instanceof String) {
 					String clazz = (String) pool[intPool[lastReference]];
 					doClassReference(clazz.replace('.', '/'));
 				}
 				break;
 
 			case OpCodes.tableswitch:
 				// Skip to place divisible by 4
 				while ((bb.position() & 0x3) != 0)
 					bb.get();
 				int deflt = bb.getInt();
 				int low = bb.getInt();
 				int high = bb.getInt();
 				bb.position(bb.position() + (high - low + 1) * 4);
 				lastReference = -1;
 				break;
 
 			case OpCodes.lookupswitch:
 				// Skip to place divisible by 4
 				while ((bb.position() & 0x3) != 0)
 					bb.get();
 				deflt = bb.getInt();
 				int npairs = bb.getInt();
 				bb.position(bb.position() + npairs * 8);
 				lastReference = -1;
 				break;
 
 			default:
 				lastReference = -1;
 				bb.position(bb.position() + OpCodes.OFFSETS[instruction]);
 			}
 		}
 	}
 
 	private void doSourceFile(DataInputStream in) throws IOException {
 		int sourcefile_index = in.readUnsignedShort();
 		this.sourceFile = pool[sourcefile_index].toString();
 	}
 
 	private void doParameterAnnotations(DataInputStream in) throws IOException {
 		int num_parameters = in.readUnsignedByte();
 		for (int p = 0; p < num_parameters; p++) {
 			int num_annotations = in.readUnsignedShort(); // # of annotations
 			for (int a = 0; a < num_annotations; a++) {
 				doAnnotation(in);
 			}
 		}
 	}
 
 	private void doAnnotations(DataInputStream in) throws IOException {
 		int num_annotations = in.readUnsignedShort(); // # of annotations
 		for (int a = 0; a < num_annotations; a++) {
 			doAnnotation(in);
 		}
 	}
 
 	private void doAnnotation(DataInputStream in) throws IOException {
 		int type_index = in.readUnsignedShort();
 		descriptors.add(new Integer(type_index));
 		int num_element_value_pairs = in.readUnsignedShort();
 		for (int v = 0; v < num_element_value_pairs; v++) {
 			/* int element_name_index = */in.readUnsignedShort();
 			doElementValue(in);
 		}
 	}
 
 	private void doElementValue(DataInputStream in) throws IOException {
 		int tag = in.readUnsignedByte();
 		switch (tag) {
 		case 'B':
 		case 'C':
 		case 'D':
 		case 'F':
 		case 'I':
 		case 'J':
 		case 'S':
 		case 'Z':
 		case 's':
 			/* int const_value_index = */
 			in.readUnsignedShort();
 			break;
 
 		case 'e':
 			int type_name_index = in.readUnsignedShort();
 			descriptors.add(new Integer(type_name_index));
 			/* int const_name_index = */
 			in.readUnsignedShort();
 			break;
 
 		case 'c':
 			int class_info_index = in.readUnsignedShort();
 			descriptors.add(new Integer(class_info_index));
 			break;
 
 		case '@':
 			doAnnotation(in);
 			break;
 
 		case '[':
 			int num_values = in.readUnsignedShort();
 			for (int i = 0; i < num_values; i++) {
 				doElementValue(in);
 			}
 			break;
 
 		default:
 			throw new IllegalArgumentException(
 					"Invalid value for Annotation ElementValue tag " + tag);
 		}
 	}
 
     void classReference(String clazz) {
         String pack = getPackage(clazz);
         packageReference(pack);
         classImports.add(clazz);
     }
 
     void packageReference(String pack) {
 		if (pack.indexOf('<') >= 0)
 			System.out.println("Oops: " + pack);
 		if (!packageImports.containsKey(pack))
 			packageImports.put(pack, new HashMap());
 	}
 
 	void parseDescriptor(String prototype) {
 		addReference(prototype);
 		StringTokenizer st = new StringTokenizer(prototype, "(;)", true);
 		while (st.hasMoreTokens()) {
 			if (st.nextToken().equals("(")) {
 				String token = st.nextToken();
 				while (!token.equals(")")) {
 					addReference(token);
 					token = st.nextToken();
 				}
 				token = st.nextToken();
 				addReference(token);
 			}
 		}
 	}
 
 	private void addReference(String token) {
 		while (token.startsWith("["))
 			token = token.substring(1);
 
 		if (token.startsWith("L")) {
 			String clazz = normalize(token.substring(1));
 			if (clazz.startsWith("java/"))
 				return;
             classReference(clazz);
         }
 	}
 
 	static String normalize(String s) {
 		if (s.startsWith("[L"))
 			return normalize(s.substring(2));
 		if (s.startsWith("["))
 			if (s.length() == 2)
 				return null;
 			else
 				return normalize(s.substring(1));
 		if (s.endsWith(";"))
 			return normalize(s.substring(0, s.length() - 1));
 		return s + ".class";
 	}
 
 	public static String getPackage(String clazz) {
 		int n = clazz.lastIndexOf('/');
 		if (n < 0)
 			return ".";
 		return clazz.substring(0, n).replace('/', '.');
 	}
 
 	public Map getReferred() {
 		return packageImports;
 	}
 
     public Set getReferredClasses() {
         return classImports;
     }
 
     String getClassName() {
 		return className;
 	}
 
 	public String getPath() {
 		return path;
 	}
 
 	public Set xref(InputStream in) throws IOException {
 		DataInputStream din = new DataInputStream(in);
 		Set set = parseClassFile(din);
 		din.close();
 		return set;
 	}
 
 	public String getSourceFile() {
 		return sourceFile;
 	}
 
 	/**
 	 * .class construct for different compilers
 	 * 
 	 * sun 1.1 Detect static variable class$com$acme$MyClass 1.2 " 1.3 " 1.4 "
 	 * 1.5 ldc_w (class) 1.6 "
 	 * 
 	 * eclipse 1.1 class$0, ldc (string), invokestatic Class.forName 1.2 " 1.3 "
 	 * 1.5 ldc (class) 1.6 "
 	 * 
 	 * 1.5 and later is not an issue, sun pre 1.5 is easy to detect the static
 	 * variable that decodes the class name. For eclipse, the class$0 gives away
 	 * we have a reference encoded in a string.
 	 * compilerversions/compilerversions.jar contains test versions of all
 	 * versions/compilers.
 	 */
 
 	public void reset() {
 		pool = null;
 		intPool = null;
 		xref = null;
 		classes = null;
 		descriptors = null;
 	}
 
 }