/*

 * Copyright (c) 2016, 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 jdk.internal.jshell.jdi;

import java.util.HashMap;

import java.util.Objects;

import com.sun.jdi.ReferenceType;

import java.util.List;

/**

 * Tracks the state of a class.

 */

class ClassTracker {

    private final JDIEnv jdiEnv;

    private final HashMap<String, ClassInfo> map;

    ClassTracker(JDIEnv jdiEnv) {

        this.jdiEnv = jdiEnv;

        this.map = new HashMap<>();

    }

    /**

     * Associates a class name, class bytes, and ReferenceType.

     */

    class ClassInfo {

        // The name of the class -- always set

        private final String className;

        // The corresponding compiled class bytes when a load or redefine

        // is started.  May not be the loaded bytes.  May be null.

        private byte[] bytes;

        // The class bytes successfully loaded/redefined into the remote VM.

        private byte[] loadedBytes;

        // The corresponding JDI ReferenceType.  Used by redefineClasses and

        // acts as indicator of successful load (null if not loaded).

        private ReferenceType rt;

        private ClassInfo(String className) {

            this.className = className;

        }

        String getClassName() {

            return className;

        }

        byte[] getLoadedBytes() {

            return loadedBytes;

        }

        byte[] getBytes() {

            return bytes;

        }

        private void setBytes(byte[] potentialBytes) {

            this.bytes = potentialBytes;

        }

        // The class has been successful loaded redefined.  The class bytes

        // sent are now actually loaded.

        void markLoaded() {

            loadedBytes = bytes;

        }

        // Ask JDI for the ReferenceType, null if not loaded.

        ReferenceType getReferenceTypeOrNull() {

            if (rt == null) {

                rt = nameToRef(className);

            }

            return rt;

        }

        private ReferenceType nameToRef(String name) {

            List<ReferenceType> rtl = jdiEnv.vm().classesByName(name);

            if (rtl.size() != 1) {

                return null;

            }

            return rtl.get(0);

        }

        @Override

        public boolean equals(Object o) {

            return o instanceof ClassInfo

                    && ((ClassInfo) o).className.equals(className);

        }

        @Override

        public int hashCode() {

            return Objects.hashCode(this.className);

        }

    }

    // Map a class name to the current compiled class bytes.

    ClassInfo classInfo(String className, byte[] bytes) {

        ClassInfo ci = get(className);

        ci.setBytes(bytes);

        return ci;

    }

    // Lookup the ClassInfo by class name, create if it does not exist.

    ClassInfo get(String className) {

        return map.computeIfAbsent(className, k -> new ClassInfo(k));

    }

}