/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.lang;

import jdk.internal.misc.JavaLangInvokeAccess;

import jdk.internal.misc.SharedSecrets;

import static java.lang.StackWalker.Option.*;

import java.lang.StackWalker.StackFrame;

import java.util.Optional;

import java.util.OptionalInt;

class StackFrameInfo implements StackFrame {

    private final static JavaLangInvokeAccess jlInvokeAccess =

        SharedSecrets.getJavaLangInvokeAccess();

    // -XX:+MemberNameInStackFrame will initialize MemberName and all other fields;

    // otherwise, VM will set the hidden fields (injected by the VM).

    // -XX:+MemberNameInStackFrame is temporary to enable performance measurement

    //

    // Footprint improvement: MemberName::clazz and MemberName::name

    // can replace StackFrameInfo::declaringClass and StackFrameInfo::methodName

    // Currently VM sets StackFrameInfo::methodName instead of expanding MemberName::name

    final StackWalker walker;

    final Class<?> declaringClass;

    final Object memberName;

    final int bci;

    // methodName, fileName, and lineNumber will be lazily set by the VM

    // when first requested.

    private String methodName;

    private String fileName = null;     // default for unavailable filename

    private int    lineNumber = -1;     // default for unavailable lineNumber

    /*

     * Create StackFrameInfo for StackFrameTraverser and LiveStackFrameTraverser

     * to use

     */

    StackFrameInfo(StackWalker walker) {

        this.walker = walker;

        this.declaringClass = null;

        this.bci = -1;

        this.memberName = jlInvokeAccess.newMemberName();

    }

    @Override

    public String getClassName() {

        return declaringClass.getName();

    }

    @Override

    public Class<?> getDeclaringClass() {

        walker.ensureAccessEnabled(RETAIN_CLASS_REFERENCE);

        return declaringClass;

    }

    // Call the VM to set methodName, lineNumber, and fileName

    private synchronized void ensureMethodInfoInitialized() {

        if (methodName == null) {

            setMethodInfo();

        }

    }

    @Override

    public String getMethodName() {

        ensureMethodInfoInitialized();

        return methodName;

    }

    @Override

    public Optional<String> getFileName() {

        ensureMethodInfoInitialized();

        return fileName != null ? Optional.of(fileName) : Optional.empty();

    }

    @Override

    public OptionalInt getLineNumber() {

        ensureMethodInfoInitialized();

        return lineNumber > 0 ? OptionalInt.of(lineNumber) : OptionalInt.empty();

    }

    @Override

    public boolean isNativeMethod() {

        ensureMethodInfoInitialized();

        return lineNumber == -2;

    }

    @Override

    public String toString() {

        ensureMethodInfoInitialized();

        // similar format as StackTraceElement::toString

        if (isNativeMethod()) {

            return getClassName() + "." + getMethodName() + "(Native Method)";

        } else {

            // avoid allocating Optional objects

            return getClassName() + "." + getMethodName() +

                "(" + (fileName != null ? fileName : "Unknown Source") +

                      (lineNumber > 0 ? ":" + lineNumber : " bci:" + bci) + ")";

        }

    }

    /**

     * Lazily initialize method name, file name, line number

     */

    private native void setMethodInfo();

    /**

     * Fill in source file name and line number of the given StackFrame array.

     */

    static native void fillInStackFrames(int startIndex,

                                         Object[] stackframes,

                                         int fromIndex, int toIndex);

}