/*
 * Copyright  2000-2004 The Apache Software Foundation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); 
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License. 
 *
 */
package org.apache.bcel.classfile;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.bcel.Constants;

/**
 * This class is derived from <em>Attribute</em> and represents a reference to a
 * GJ attribute.
 * 
 * @version $Id: Signature.java 386056 2006-03-15 11:31:56Z tcurdt $
 * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
 * @see Attribute
 */
public final class Signature extends Attribute {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private int signature_index;

	/**
	 * Initialize from another object. Note that both objects use the same
	 * references (shallow copy). Use clone() for a physical copy.
	 */
	public Signature(Signature c) {
		this(c.getNameIndex(), c.getLength(), c.getSignatureIndex(), c
				.getConstantPool());
	}

	/**
	 * Construct object from file stream.
	 * 
	 * @param name_index
	 *            Index in constant pool to CONSTANT_Utf8
	 * @param length
	 *            Content length in bytes
	 * @param file
	 *            Input stream
	 * @param constant_pool
	 *            Array of constants
	 * @throws IOException
	 */
	Signature(int name_index, int length, DataInputStream file,
			ConstantPool constant_pool) throws IOException {
		this(name_index, length, file.readUnsignedShort(), constant_pool);
	}

	/**
	 * @param name_index
	 *            Index in constant pool to CONSTANT_Utf8
	 * @param length
	 *            Content length in bytes
	 * @param signature_index
	 *            Index in constant pool to CONSTANT_Utf8
	 * @param constant_pool
	 *            Array of constants
	 */
	public Signature(int name_index, int length, int signature_index,
			ConstantPool constant_pool) {
		super(Constants.ATTR_SIGNATURE, name_index, length, constant_pool);
		this.signature_index = signature_index;
	}

	/**
	 * Called by objects that are traversing the nodes of the tree implicitely
	 * defined by the contents of a Java class. I.e., the hierarchy of methods,
	 * fields, attributes, etc. spawns a tree of objects.
	 * 
	 * @param v
	 *            Visitor object
	 */
	@Override
	public void accept(Visitor v) {
		// System.err.println("Visiting non-standard Signature object");
		v.visitSignature(this);
	}

	/**
	 * Dump source file attribute to file stream in binary format.
	 * 
	 * @param file
	 *            Output file stream
	 * @throws IOException
	 */
	@Override
	public final void dump(DataOutputStream file) throws IOException {
		super.dump(file);
		file.writeShort(signature_index);
	}

	/**
	 * @return Index in constant pool of source file name.
	 */
	public final int getSignatureIndex() {
		return signature_index;
	}

	/**
	 * @param signature_index
	 *            the index info the constant pool of this signature
	 */
	public final void setSignatureIndex(int signature_index) {
		this.signature_index = signature_index;
	}

	/**
	 * @return GJ signature.
	 */
	public final String getSignature() {
		ConstantUtf8 c = (ConstantUtf8) constant_pool.getConstant(
				signature_index, Constants.CONSTANT_Utf8);
		return c.getBytes();
	}

	/**
	 * Extends ByteArrayInputStream to make 'unreading' chars possible.
	 */
	private static final class MyByteArrayInputStream extends
			ByteArrayInputStream {

		MyByteArrayInputStream(String data) {
			super(data.getBytes());
		}

		final String getData() {
			return new String(buf);
		}

		final void unread() {
			if (pos > 0) {
				pos--;
			}
		}
	}

	private static boolean identStart(int ch) {
		return ch == 'T' || ch == 'L';
	}

	private static final void matchIdent(MyByteArrayInputStream in,
			StringBuffer buf) {
		int ch;
		if ((ch = in.read()) == -1) {
			throw new RuntimeException("Illegal signature: " + in.getData()
					+ " no ident, reaching EOF");
		}
		// System.out.println("return from ident:" + (char)ch);
		if (!identStart(ch)) {
			StringBuffer buf2 = new StringBuffer();
			int count = 1;
			while (Character.isJavaIdentifierPart((char) ch)) {
				buf2.append((char) ch);
				count++;
				ch = in.read();
			}
			if (ch == ':') { // Ok, formal parameter
				in.skip("Ljava/lang/Object".length());
				buf.append(buf2);
				ch = in.read();
				in.unread();
				// System.out.println("so far:" + buf2 + ":next:" +(char)ch);
			} else {
				for (int i = 0; i < count; i++) {
					in.unread();
				}
			}
			return;
		}
		StringBuffer buf2 = new StringBuffer();
		ch = in.read();
		do {
			buf2.append((char) ch);
			ch = in.read();
			// System.out.println("within ident:"+ (char)ch);
		} while ((ch != -1)
				&& (Character.isJavaIdentifierPart((char) ch) || (ch == '/')));
		buf.append(buf2.toString().replace('/', '.'));
		// System.out.println("regular return ident:"+ (char)ch + ":" + buf2);
		if (ch != -1) {
			in.unread();
		}
	}

	private static final void matchGJIdent(MyByteArrayInputStream in,
			StringBuffer buf) {
		int ch;
		matchIdent(in, buf);
		ch = in.read();
		if ((ch == '<') || ch == '(') { // Parameterized or method
			// System.out.println("Enter <");
			buf.append((char) ch);
			matchGJIdent(in, buf);
			while (((ch = in.read()) != '>') && (ch != ')')) { // List of
																// parameters
				if (ch == -1) {
					throw new RuntimeException("Illegal signature: "
							+ in.getData() + " reaching EOF");
				}
				// System.out.println("Still no >");
				buf.append(", ");
				in.unread();
				matchGJIdent(in, buf); // Recursive call
			}
			// System.out.println("Exit >");
			buf.append((char) ch);
		} else {
			in.unread();
		}
		ch = in.read();
		if (identStart(ch)) {
			in.unread();
			matchGJIdent(in, buf);
		} else if (ch == ')') {
			in.unread();
			return;
		} else if (ch != ';') {
			throw new RuntimeException("Illegal signature: " + in.getData()
					+ " read " + (char) ch);
		}
	}

	public static String translate(String s) {
		// System.out.println("Sig:" + s);
		StringBuffer buf = new StringBuffer();
		matchGJIdent(new MyByteArrayInputStream(s), buf);
		return buf.toString();
	}

	public static final boolean isFormalParameterList(String s) {
		return s.startsWith("<") && (s.indexOf(':') > 0);
	}

	public static final boolean isActualParameterList(String s) {
		return s.startsWith("L") && s.endsWith(">;");
	}

	/**
	 * @return String representation
	 */
	@Override
	public final String toString() {
		String s = getSignature();
		return "Signature(" + s + ")";
	}

	/**
	 * @return deep copy of this attribute
	 */
	@Override
	public Attribute copy(ConstantPool _constant_pool) {
		return (Signature) clone();
	}
}
