//
// ========================================================================
// Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under
// the terms of the Eclipse Public License 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0
//
// This Source Code may also be made available under the following
// Secondary Licenses when the conditions for such availability set
// forth in the Eclipse Public License, v. 2.0 are satisfied:
// the Apache License v2.0 which is available at
// https://www.apache.org/licenses/LICENSE-2.0
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//

package org.eclipse.jetty.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

Wraps multiple exceptions.
Allows multiple exceptions to be thrown as a single exception.
The MultiException itself should not be thrown instead one of the
ifExceptionThrow* methods should be called instead.
/**
 * Wraps multiple exceptions.
 *
 * Allows multiple exceptions to be thrown as a single exception.
 *
 * The MultiException itself should not be thrown instead one of the
 * ifExceptionThrow* methods should be called instead.
 */
@SuppressWarnings("serial")
public class MultiException extends Exception
{
    private static final String DEFAULT_MESSAGE = "Multiple exceptions";

    private List<Throwable> nested;

    public MultiException()
    {
        // Avoid filling in stack trace information.
        super(DEFAULT_MESSAGE, null, false, false);
        this.nested = new ArrayList<>();
    }

    
Create a MultiException which may be thrown.
Params:
nested – The nested exceptions which will be suppressed by this
exception./**
     * Create a MultiException which may be thrown.
     *
     * @param nested The nested exceptions which will be suppressed by this
     * exception.
     */
    private MultiException(List<Throwable> nested)
    {
        super(DEFAULT_MESSAGE);
        this.nested = new ArrayList<>(nested);

        if (nested.size() > 0)
            initCause(nested.get(0));

        for (Throwable t : nested)
        {
            if (t != this && t != getCause())
                addSuppressed(t);
        }
    }

    public void add(Throwable e)
    {
        if (e instanceof MultiException)
        {
            MultiException me = (MultiException)e;
            nested.addAll(me.nested);
        }
        else
            nested.add(e);
    }

    public int size()
    {
        return (nested == null) ? 0 : nested.size();
    }

    public List<Throwable> getThrowables()
    {
        if (nested == null)
            return Collections.emptyList();
        return nested;
    }

    public Throwable getThrowable(int i)
    {
        return nested.get(i);
    }

    
Throw a multiexception.
If this multi exception is empty then no action is taken. If it
contains a single exception that is thrown, otherwise the this
multi exception is thrown.
Throws:
Exception – the Error or Exception if nested is 1, or the MultiException itself if nested is more than 1./**
     * Throw a multiexception.
     * If this multi exception is empty then no action is taken. If it
     * contains a single exception that is thrown, otherwise the this
     * multi exception is thrown.
     *
     * @throws Exception the Error or Exception if nested is 1, or the MultiException itself if nested is more than 1.
     */
    public void ifExceptionThrow()
        throws Exception
    {
        if (nested == null)
            return;

        switch (nested.size())
        {
            case 0:
                break;
            case 1:
                Throwable th = nested.get(0);
                if (th instanceof Error)
                    throw (Error)th;
                if (th instanceof Exception)
                    throw (Exception)th;
                throw new MultiException(nested);
            default:
                throw new MultiException(nested);
        }
    }

    
Throw a Runtime exception.
If this multi exception is empty then no action is taken. If it
contains a single error or runtime exception that is thrown, otherwise the this
multi exception is thrown, wrapped in a runtime exception.
Throws:
Error – If this exception contains exactly 1 Error
RuntimeException – If this exception contains 1 Throwable but it is not an error, or it contains more than 1 Throwable of any type./**
     * Throw a Runtime exception.
     * If this multi exception is empty then no action is taken. If it
     * contains a single error or runtime exception that is thrown, otherwise the this
     * multi exception is thrown, wrapped in a runtime exception.
     *
     * @throws Error If this exception contains exactly 1 {@link Error}
     * @throws RuntimeException If this exception contains 1 {@link Throwable} but it is not an error,
     * or it contains more than 1 {@link Throwable} of any type.
     */
    public void ifExceptionThrowRuntime()
        throws Error
    {
        if (nested == null)
            return;

        switch (nested.size())
        {
            case 0:
                break;
            case 1:
                Throwable th = nested.get(0);
                if (th instanceof Error)
                    throw (Error)th;
                else if (th instanceof RuntimeException)
                    throw (RuntimeException)th;
                else
                    throw new RuntimeException(th);
            default:
                throw new RuntimeException(new MultiException(nested));
        }
    }

    
Throw a multiexception.
If this multi exception is empty then no action is taken. If it
contains a any exceptions then this
multi exception is thrown.
Throws:
MultiException – the multiexception if there are nested exception/**
     * Throw a multiexception.
     * If this multi exception is empty then no action is taken. If it
     * contains a any exceptions then this
     * multi exception is thrown.
     *
     * @throws MultiException the multiexception if there are nested exception
     */
    public void ifExceptionThrowMulti()
        throws MultiException
    {
        if (nested == null)
            return;

        if (nested.size() > 0)
        {
            throw new MultiException(nested);
        }
    }

    
Throw an Exception, potentially with suppress.
If this multi exception is empty then no action is taken. If the first
exception added is an Error or Exception, then it is throw with
any additional exceptions added as suppressed. Otherwise a MultiException
is thrown, with all exceptions added as suppressed.
Throws:
Exception – the Error or Exception if at least one is added./**
     * Throw an Exception, potentially with suppress.
     * If this multi exception is empty then no action is taken. If the first
     * exception added is an Error or Exception, then it is throw with
     * any additional exceptions added as suppressed. Otherwise a MultiException
     * is thrown, with all exceptions added as suppressed.
     *
     * @throws Exception the Error or Exception if at least one is added.
     */
    public void ifExceptionThrowSuppressed()
        throws Exception
    {
        if (nested == null || nested.size() == 0)
            return;

        Throwable th = nested.get(0);
        if (!Error.class.isInstance(th) && !Exception.class.isInstance(th))
            th = new MultiException(Collections.emptyList());

        for (Throwable s : nested)
        {
            if (s != th)
                th.addSuppressed(s);
        }
        if (Error.class.isInstance(th))
            throw (Error)th;
        throw (Exception)th;
    }

    @Override
    public String toString()
    {
        StringBuilder str = new StringBuilder();
        str.append(MultiException.class.getSimpleName());
        if ((nested == null) || (nested.size() <= 0))
        {
            str.append("[]");
        }
        else
        {
            str.append(nested);
        }
        return str.toString();
    }
}