/*

 * Copyright (c) 2016, 2019, 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

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package sun.tools.common;

import java.net.URISyntaxException;

import java.util.ArrayList;

import java.util.Collection;

import java.util.List;

import java.util.stream.Collectors;

import com.sun.tools.attach.VirtualMachine;

import com.sun.tools.attach.VirtualMachineDescriptor;

import sun.jvmstat.monitor.MonitorException;

import sun.jvmstat.monitor.MonitoredHost;

import sun.jvmstat.monitor.MonitoredVm;

import sun.jvmstat.monitor.MonitoredVmUtil;

import sun.jvmstat.monitor.VmIdentifier;

/**

 * Class for finding process matching a process argument,

 * excluding tool it self and returning a list containing

 * the process identifiers.

 */

public class ProcessArgumentMatcher {

    private String matchClass;

    private String singlePid;

    public ProcessArgumentMatcher(String pidArg) {

        if (pidArg == null || pidArg.isEmpty()) {

            throw new IllegalArgumentException("Pid string is invalid");

        }

        if (pidArg.charAt(0) == '-') {

            throw new IllegalArgumentException("Unrecognized " + pidArg);

        }

        try {

            long pid = Long.parseLong(pidArg);

            if (pid != 0) {

                singlePid = String.valueOf(pid);

            }

        } catch (NumberFormatException nfe) {

            matchClass = pidArg;

        }

    }

    private static String getExcludeStringFrom(Class<?> excludeClass) {

        if (excludeClass == null) {

            return "";

        }

        Module m = excludeClass.getModule();

        if (m.isNamed()) {

            return m.getName() + "/" + excludeClass.getName();

        }

        return excludeClass.getName();

    }

    private static boolean check(VirtualMachineDescriptor vmd, String excludeClass, String partialMatch) {

        // Try to get the main class name using (platform specific) ProcessHelper

        String mainClass = ProcessHelper.getMainClass(vmd.id());

        // If the main class name could not be retrieved by ProcessHelper, get it with the attach mechanism

        if (mainClass == null) {

            try {

                VmIdentifier vmId = new VmIdentifier(vmd.id());

                MonitoredHost monitoredHost = MonitoredHost.getMonitoredHost(vmId);

                MonitoredVm monitoredVm = monitoredHost.getMonitoredVm(vmId, -1);

                mainClass = MonitoredVmUtil.mainClass(monitoredVm, true);

                monitoredHost.detach(monitoredVm);

            } catch (NullPointerException npe) {

                // There is a potential race, where a running java app is being

                // queried, unfortunately the java app has shutdown after this

                // method is started but before getMonitoredVM is called.

                // If this is the case, then the /tmp/hsperfdata_xxx/pid file

                // will have disappeared and we will get a NullPointerException.

                // Handle this gracefully....

                return false;

            } catch (MonitorException | URISyntaxException e) {

                return false;

            }

        }

        if (excludeClass != null && mainClass.equals(excludeClass)) {

            return false;

        }

        if (partialMatch != null && mainClass.indexOf(partialMatch) == -1) {

            return false;

        }

        return true;

    }

    private static Collection<VirtualMachineDescriptor> getSingleVMD(String pid) {

        Collection<VirtualMachineDescriptor> vids = new ArrayList<>();

        List<VirtualMachineDescriptor> vmds = VirtualMachine.list();

        for (VirtualMachineDescriptor vmd : vmds) {

            if (check(vmd, null, null)) {

                if (pid.equals(vmd.id())) {

                    vids.add(vmd);

                }

            }

        }

        return vids;

    }

    private static Collection<VirtualMachineDescriptor> getVMDs(Class<?> excludeClass, String partialMatch) {

        String excludeCls = getExcludeStringFrom(excludeClass);

        Collection<VirtualMachineDescriptor> vids = new ArrayList<>();

        List<VirtualMachineDescriptor> vmds = VirtualMachine.list();

        for (VirtualMachineDescriptor vmd : vmds) {

            if (check(vmd, excludeCls, partialMatch)) {

                vids.add(vmd);

            }

        }

        return vids;

    }

    public Collection<VirtualMachineDescriptor> getVirtualMachineDescriptors() {

        if (singlePid != null) {

            return getSingleVMD(singlePid);

        } else {

            return getVMDs(null, matchClass);

        }

    }

    public Collection<String> getVirtualMachinePids(Class<?> excludeClass) {

        if (singlePid != null) {

            // There is a bug in AttachProvider, when VM is debuggee-suspended it's not listed by the AttachProvider.

            // If we are talking about a specific pid, just return it.

            return List.of(singlePid);

        } else {

            return getVMDs(excludeClass, matchClass).stream().map(x -> {return x.id();}).collect(Collectors.toList());

        }

    }

}