/*
 * 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 com.oracle.truffle.api.debug;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.Truffle;
import com.oracle.truffle.api.frame.FrameInstance;
import com.oracle.truffle.api.frame.FrameInstanceVisitor;
import com.oracle.truffle.api.frame.MaterializedFrame;
import com.oracle.truffle.api.instrument.StandardSyntaxTag;
import com.oracle.truffle.api.nodes.Node;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * This event is delivered to all
 * {@link com.oracle.truffle.api.vm.TruffleVM.Builder#onEvent(com.oracle.truffle.api.vm.EventConsumer)
 * registered event handlers} when an execution is suspended on a
 * {@link Debugger#setLineBreakpoint(int, com.oracle.truffle.api.source.LineLocation, boolean)
 * breakpoint} or during {@link #prepareStepInto(int) stepping}. Methods in this event can only be
 * used while the handlers process the event. Then the state of the event becomes invalid and
 * subsequent calls to the event methods yield {@link IllegalStateException}. One can call
 * {@link #getDebugger()} and keep reference to it for as long as necessary.
 */
@SuppressWarnings("javadoc")
public final class SuspendedEvent {
    private final List<String> recentWarnings;
    private final MaterializedFrame mFrame;
    private final Node astNode;
    private final List<FrameInstance> frames;
    private final Debugger debugger;

    SuspendedEvent(Debugger prepares, Node astNode, MaterializedFrame mFrame, List<String> recentWarnings, final int stackDepth) {
        this.debugger = prepares;
        this.astNode = astNode;
        this.mFrame = mFrame;
        this.recentWarnings = recentWarnings;

        this.frames = new ArrayList<>();
        // Map the Truffle stack for this execution, ignore nested executions
        // The top (current) frame is not produced by the iterator.
        frames.add(Truffle.getRuntime().getCurrentFrame());
        Truffle.getRuntime().iterateFrames(new FrameInstanceVisitor<FrameInstance>() {
            int frameCount = 1;

            @Override
            public FrameInstance visitFrame(FrameInstance frameInstance) {
                if (frameCount < stackDepth) {
                    frames.add(frameInstance);
                    frameCount++;
                    return null;
                }
                return frameInstance;
            }
        });

    }

    /**
     * Debugger associated with the just suspended execution. This debugger remains valid after the
     * event is processed, it is possible and suggested to keep a reference to it and use it any
     * time later when evaluating sources in the {@link com.oracle.truffle.api.vm.TruffleVM}.
     *
     * @return instance of debugger associated with the just suspended execution and any subsequent
     *         ones in the same {@link com.oracle.truffle.api.vm.TruffleVM}.
     */
    public Debugger getDebugger() {
        return debugger;
    }

    public Node getNode() {
        return astNode;
    }

    public MaterializedFrame getFrame() {
        return mFrame;
    }

    public List<String> getRecentWarnings() {
        return Collections.unmodifiableList(recentWarnings);
    }

    /**
     * Gets the stack frames from the currently halted {@link com.oracle.truffle.api.vm.TruffleVM}
     * execution.
     *
     * @return list of stack frames
     */
    @CompilerDirectives.TruffleBoundary
    public List<FrameInstance> getStack() {
        return Collections.unmodifiableList(frames);
    }

    /**
     * Prepare to execute in Continue mode when guest language program execution resumes. In this
     * mode:
     * <ul>
     * <li>Execution will continue until either:
     * <ol>
     * <li>execution arrives at a node to which an enabled breakpoint is attached,
     * <strong>or:</strong></li>
     * <li>execution completes.</li>
     * </ol>
     * </ul>
     */
    public void prepareContinue() {
        debugger.prepareContinue();
    }

    /**
     * Prepare to execute in StepInto mode when guest language program execution resumes. In this
     * mode:
     * <ul>
     * <li>User breakpoints are disabled.</li>
     * <li>Execution will continue until either:
     * <ol>
     * <li>execution arrives at a node with the tag {@linkplain StandardSyntaxTag#STATEMENT
     * STATMENT}, <strong>or:</strong></li>
     * <li>execution completes.</li>
     * </ol>
     * <li>StepInto mode persists only through one resumption (i.e. {@code stepIntoCount} steps),
     * and reverts by default to Continue mode.</li>
     * </ul>
     *
     * @param stepCount the number of times to perform StepInto before halting
     * @throws IllegalArgumentException if the specified number is {@code <= 0}
     */
    public void prepareStepInto(int stepCount) {
        debugger.prepareStepInto(stepCount);
    }

    /**
     * Prepare to execute in StepOut mode when guest language program execution resumes. In this
     * mode:
     * <ul>
     * <li>User breakpoints are enabled.</li>
     * <li>Execution will continue until either:
     * <ol>
     * <li>execution arrives at the nearest enclosing call site on the stack, <strong>or</strong></li>
     * <li>execution completes.</li>
     * </ol>
     * <li>StepOut mode persists only through one resumption, and reverts by default to Continue
     * mode.</li>
     * </ul>
     */
    public void prepareStepOut() {
        debugger.prepareStepOut();
    }

    /**
     * Prepare to execute in StepOver mode when guest language program execution resumes. In this
     * mode:
     * <ul>
     * <li>Execution will continue until either:
     * <ol>
     * <li>execution arrives at a node with the tag {@linkplain StandardSyntaxTag#STATEMENT
     * STATEMENT} when not nested in one or more function/method calls, <strong>or:</strong></li>
     * <li>execution arrives at a node to which a breakpoint is attached and when nested in one or
     * more function/method calls, <strong>or:</strong></li>
     * <li>execution completes.</li>
     * </ol>
     * <li>StepOver mode persists only through one resumption (i.e. {@code stepOverCount} steps),
     * and reverts by default to Continue mode.</li>
     * </ul>
     *
     * @param stepCount the number of times to perform StepInto before halting
     * @throws IllegalArgumentException if the specified number is {@code <= 0}
     */
    public void prepareStepOver(int stepCount) {
        debugger.prepareStepOver(stepCount);
    }
}