Start work on commands refactoring

Long term goals are:
- tab completion
- auto generate usage/info messages

16 files changed, 801 insertions, 477 deletions

diff --git a/spark-bukkit/src/main/java/me/lucko/spark/bukkit/SparkBukkitPlugin.java b/spark-bukkit/src/main/java/me/lucko/spark/bukkit/SparkBukkitPlugin.java
index a11eaf4..122ebf1 100644
--- a/spark-bukkit/src/main/java/me/lucko/spark/bukkit/SparkBukkitPlugin.java
+++ b/spark-bukkit/src/main/java/me/lucko/spark/bukkit/SparkBukkitPlugin.java
@@ -20,7 +20,7 @@
 
 package me.lucko.spark.bukkit;
 
-import me.lucko.spark.common.CommandHandler;
+import me.lucko.spark.common.SparkPlatform;
 import me.lucko.spark.sampler.ThreadDumper;
 import me.lucko.spark.sampler.TickCounter;
 
@@ -32,7 +32,7 @@ import org.bukkit.plugin.java.JavaPlugin;
 
 public class SparkBukkitPlugin extends JavaPlugin {
 
-    private final CommandHandler<CommandSender> commandHandler = new CommandHandler<CommandSender>() {
+    private final SparkPlatform<CommandSender> sparkPlatform = new SparkPlatform<CommandSender>() {
 
         private String colorize(String message) {
             return ChatColor.translateAlternateColorCodes('&', message);
@@ -48,44 +48,44 @@ public class SparkBukkitPlugin extends JavaPlugin {
         }
 
         @Override
-        protected String getVersion() {
+        public String getVersion() {
             return SparkBukkitPlugin.this.getDescription().getVersion();
         }
 
         @Override
-        protected String getLabel() {
+        public String getLabel() {
             return "spark";
         }
 
         @Override
-        protected void sendMessage(CommandSender sender, String message) {
+        public void sendMessage(CommandSender sender, String message) {
             sender.sendMessage(colorize(message));
         }
 
         @Override
-        protected void sendMessage(String message) {
+        public void sendMessage(String message) {
             String msg = colorize(message);
             broadcast(msg);
         }
 
         @Override
-        protected void sendLink(String url) {
+        public void sendLink(String url) {
             String msg = colorize("&7" + url);
             broadcast(msg);
         }
 
         @Override
-        protected void runAsync(Runnable r) {
+        public void runAsync(Runnable r) {
             getServer().getScheduler().runTaskAsynchronously(SparkBukkitPlugin.this, r);
         }
 
         @Override
-        protected ThreadDumper getDefaultThreadDumper() {
+        public ThreadDumper getDefaultThreadDumper() {
             return new ThreadDumper.Specific(new long[]{Thread.currentThread().getId()});
         }
 
         @Override
-        protected TickCounter newTickCounter() {
+        public TickCounter newTickCounter() {
             return new BukkitTickCounter(SparkBukkitPlugin.this);
         }
     };
@@ -97,7 +97,7 @@ public class SparkBukkitPlugin extends JavaPlugin {
             return true;
         }
 
-        this.commandHandler.handleCommand(sender, args);
+        this.sparkPlatform.executeCommand(sender, args);
         return true;
     }
 }
diff --git a/spark-bungeecord/src/main/java/me/lucko/spark/bungeecord/SparkBungeeCordPlugin.java b/spark-bungeecord/src/main/java/me/lucko/spark/bungeecord/SparkBungeeCordPlugin.java
index d5a4ec4..4d54b42 100644
--- a/spark-bungeecord/src/main/java/me/lucko/spark/bungeecord/SparkBungeeCordPlugin.java
+++ b/spark-bungeecord/src/main/java/me/lucko/spark/bungeecord/SparkBungeeCordPlugin.java
@@ -20,7 +20,7 @@
 
 package me.lucko.spark.bungeecord;
 
-import me.lucko.spark.common.CommandHandler;
+import me.lucko.spark.common.SparkPlatform;
 import me.lucko.spark.sampler.ThreadDumper;
 import me.lucko.spark.sampler.TickCounter;
 
@@ -35,7 +35,7 @@ import net.md_5.bungee.api.plugin.Plugin;
 
 public class SparkBungeeCordPlugin extends Plugin {
 
-    private final CommandHandler<CommandSender> commandHandler = new CommandHandler<CommandSender>() {
+    private final SparkPlatform<CommandSender> sparkPlatform = new SparkPlatform<CommandSender>() {
         private BaseComponent[] colorize(String message) {
             return TextComponent.fromLegacyText(ChatColor.translateAlternateColorCodes('&', message));
         }
@@ -50,27 +50,27 @@ public class SparkBungeeCordPlugin extends Plugin {
         }
 
         @Override
-        protected String getVersion() {
+        public String getVersion() {
             return SparkBungeeCordPlugin.this.getDescription().getVersion();
         }
 
         @Override
-        protected String getLabel() {
+        public String getLabel() {
             return "sparkbungee";
         }
 
         @Override
-        protected void sendMessage(CommandSender sender, String message) {
+        public void sendMessage(CommandSender sender, String message) {
             sender.sendMessage(colorize(message));
         }
 
         @Override
-        protected void sendMessage(String message) {
+        public void sendMessage(String message) {
             broadcast(colorize(message));
         }
 
         @Override
-        protected void sendLink(String url) {
+        public void sendLink(String url) {
             TextComponent component = new TextComponent(url);
             component.setColor(ChatColor.GRAY);
             component.setClickEvent(new ClickEvent(ClickEvent.Action.OPEN_URL, url));
@@ -78,17 +78,17 @@ public class SparkBungeeCordPlugin extends Plugin {
         }
 
         @Override
-        protected void runAsync(Runnable r) {
+        public void runAsync(Runnable r) {
             getProxy().getScheduler().runAsync(SparkBungeeCordPlugin.this, r);
         }
 
         @Override
-        protected ThreadDumper getDefaultThreadDumper() {
+        public ThreadDumper getDefaultThreadDumper() {
             return ThreadDumper.ALL;
         }
 
         @Override
-        protected TickCounter newTickCounter() {
+        public TickCounter newTickCounter() {
             throw new UnsupportedOperationException();
         }
     };
@@ -105,7 +105,7 @@ public class SparkBungeeCordPlugin extends Plugin {
                     return;
                 }
 
-                SparkBungeeCordPlugin.this.commandHandler.handleCommand(sender, args);
+                SparkBungeeCordPlugin.this.sparkPlatform.executeCommand(sender, args);
             }
         });
     }
diff --git a/spark-common/src/main/java/me/lucko/spark/common/CommandHandler.java b/spark-common/src/main/java/me/lucko/spark/common/CommandHandler.java
deleted file mode 100644
index 701dec1..0000000
--- a/spark-common/src/main/java/me/lucko/spark/common/CommandHandler.java
+++ /dev/null
@@ -1,418 +0,0 @@
-/*
- * This file is part of spark.
- *
- *  Copyright (c) lucko (Luck) <luck@lucko.me>
- *  Copyright (c) contributors
- *
- *  This program is free software: you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation, either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  This program 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 for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-package me.lucko.spark.common;
-
-import com.google.common.collect.HashMultimap;
-import com.google.common.collect.SetMultimap;
-import com.google.common.collect.Sets;
-
-import me.lucko.spark.common.http.Bytebin;
-import me.lucko.spark.memory.HeapDump;
-import me.lucko.spark.monitor.TickMonitor;
-import me.lucko.spark.sampler.Sampler;
-import me.lucko.spark.sampler.SamplerBuilder;
-import me.lucko.spark.sampler.ThreadDumper;
-import me.lucko.spark.sampler.ThreadGrouper;
-import me.lucko.spark.sampler.TickCounter;
-
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Set;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.TimeUnit;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
-/**
- * Abstract command handling class used by all platforms.
- *
- * @param <T> the sender (e.g. CommandSender) type used by the platform
- */
-public abstract class CommandHandler<T> {
-
-    /** The URL of the viewer frontend */
-    private static final String VIEWER_URL = "https://sparkprofiler.github.io/?";
-    /** The prefix used in all messages */
-    private static final String PREFIX = "&8[&fspark&8] &7";
-
-    /** Guards {@link #activeSampler} */
-    private final Object[] activeSamplerMutex = new Object[0];
-    /** The WarmRoast instance currently running, if any */
-    private Sampler activeSampler = null;
-    /** The tick monitor instance currently running, if any */
-    private ReportingTickMonitor activeTickMonitor = null;
-
-
-    // abstract methods implemented by each platform
-
-    protected abstract String getVersion();
-    protected abstract String getLabel();
-    protected abstract void sendMessage(T sender, String message);
-    protected abstract void sendMessage(String message);
-    protected abstract void sendLink(String url);
-    protected abstract void runAsync(Runnable r);
-    protected abstract ThreadDumper getDefaultThreadDumper();
-    protected abstract TickCounter newTickCounter();
-
-    private void sendPrefixedMessage(T sender, String message) {
-        sendMessage(sender, PREFIX + message);
-    }
-
-    private void sendPrefixedMessage(String message) {
-        sendMessage(PREFIX + message);
-    }
-
-    public void handleCommand(T sender, String[] args) {
-        try {
-            if (args.length == 0) {
-                sendInfo(sender);
-                return;
-            }
-
-            List<String> arguments = new ArrayList<>(Arrays.asList(args));
-            switch (arguments.remove(0).toLowerCase()) {
-                case "start":
-                    handleStart(sender, arguments);
-                    break;
-                case "info":
-                    handleInfo(sender);
-                    break;
-                case "cancel":
-                    handleCancel(sender);
-                    break;
-                case "stop":
-                case "upload":
-                case "paste":
-                    handleStop(sender);
-                    break;
-                case "monitoring":
-                    handleMonitoring(sender, arguments);
-                    break;
-                case "heap":
-                case "memory":
-                    handleHeap(sender);
-                    break;
-                default:
-                    sendInfo(sender);
-                    break;
-            }
-        } catch (IllegalArgumentException e) {
-            sendMessage(sender, "&c" + e.getMessage());
-        }
-    }
-
-    private void sendInfo(T sender) {
-        sendPrefixedMessage(sender, "&fspark profiler &7v" + getVersion());
-        sendMessage(sender, "&b&l> &7/" + getLabel() + " start");
-        sendMessage(sender, "       &8[&7--timeout&8 <timeout seconds>]");
-        sendMessage(sender, "       &8[&7--thread&8 <thread name>]");
-        sendMessage(sender, "       &8[&7--not-combined]");
-        sendMessage(sender, "       &8[&7--interval&8 <interval millis>]");
-        sendMessage(sender, "       &8[&7--only-ticks-over&8 <tick length millis>]");
-        sendMessage(sender, "&b&l> &7/" + getLabel() + " info");
-        sendMessage(sender, "&b&l> &7/" + getLabel() + " stop");
-        sendMessage(sender, "&b&l> &7/" + getLabel() + " cancel");
-        sendMessage(sender, "&b&l> &7/" + getLabel() + " monitoring");
-        sendMessage(sender, "       &8[&7--threshold&8 <percentage increase>]");
-    }
-
-    private void handleStart(T sender, List<String> args) {
-        SetMultimap<String, String> arguments = parseArguments(args);
-
-        int timeoutSeconds = parseInt(arguments, "timeout", "d");
-        if (timeoutSeconds != -1 && timeoutSeconds <= 10) {
-            sendPrefixedMessage(sender, "&cThe specified timeout is not long enough for accurate results to be formed. Please choose a value greater than 10.");
-            return;
-        }
-
-        if (timeoutSeconds != -1 && timeoutSeconds < 30) {
-            sendPrefixedMessage(sender, "&7The accuracy of the output will significantly improve when sampling is able to run for longer periods. Consider setting a timeout value over 30 seconds.");
-        }
-
-        int intervalMillis = parseInt(arguments, "interval", "i");
-        if (intervalMillis <= 0) {
-            intervalMillis = 4;
-        }
-
-        Set<String> threads = Sets.union(arguments.get("thread"), arguments.get("t"));
-        ThreadDumper threadDumper;
-        if (threads.isEmpty()) {
-            // use the server thread
-            threadDumper = getDefaultThreadDumper();
-        } else if (threads.contains("*")) {
-            threadDumper = ThreadDumper.ALL;
-        } else {
-            threadDumper = new ThreadDumper.Specific(threads);
-        }
-
-        ThreadGrouper threadGrouper;
-        if (arguments.containsKey("not-combined")) {
-            threadGrouper = ThreadGrouper.BY_NAME;
-        } else {
-            threadGrouper = ThreadGrouper.BY_POOL;
-        }
-
-        int ticksOver = parseInt(arguments, "only-ticks-over", "o");
-        TickCounter tickCounter = null;
-        if (ticksOver != -1) {
-            try {
-                tickCounter = newTickCounter();
-            } catch (UnsupportedOperationException e) {
-                sendPrefixedMessage(sender, "&cTick counting is not supported!");
-                return;
-            }
-        }
-
-        Sampler sampler;
-        synchronized (this.activeSamplerMutex) {
-            if (this.activeSampler != null) {
-                sendPrefixedMessage(sender, "&7An active sampler is already running.");
-                return;
-            }
-
-            sendPrefixedMessage("&7Initializing a new profiler, please wait...");
-
-            SamplerBuilder builder = new SamplerBuilder();
-            builder.threadDumper(threadDumper);
-            builder.threadGrouper(threadGrouper);
-            if (timeoutSeconds != -1) {
-                builder.completeAfter(timeoutSeconds, TimeUnit.SECONDS);
-            }
-            builder.samplingInterval(intervalMillis);
-            if (ticksOver != -1) {
-                builder.ticksOver(ticksOver, tickCounter);
-            }
-            sampler = this.activeSampler = builder.start();
-
-            sendPrefixedMessage("&bProfiler now active!");
-            if (timeoutSeconds == -1) {
-                sendPrefixedMessage("&7Use '/" + getLabel() + " stop' to stop profiling and upload the results.");
-            } else {
-                sendPrefixedMessage("&7The results will be automatically returned after the profiler has been running for " + timeoutSeconds + " seconds.");
-            }
-        }
-
-        CompletableFuture<Sampler> future = sampler.getFuture();
-
-        // send message if profiling fails
-        future.whenCompleteAsync((s, throwable) -> {
-            if (throwable != null) {
-                sendPrefixedMessage("&cSampling operation failed unexpectedly. Error: " + throwable.toString());
-                throwable.printStackTrace();
-            }
-        });
-
-        // set activeSampler to null when complete.
-        future.whenCompleteAsync((s, throwable) -> {
-            synchronized (this.activeSamplerMutex) {
-                if (sampler == this.activeSampler) {
-                    this.activeSampler = null;
-                }
-            }
-        });
-
-        // await the result
-        if (timeoutSeconds != -1) {
-            future.thenAcceptAsync(s -> {
-                sendPrefixedMessage("&7The active sampling operation has completed! Uploading results...");
-                handleUpload(s);
-            });
-        }
-    }
-
-    private void handleInfo(T sender) {
-        synchronized (this.activeSamplerMutex) {
-            if (this.activeSampler == null) {
-                sendPrefixedMessage(sender, "&7There isn't an active sampling task running.");
-            } else {
-                long timeout = this.activeSampler.getEndTime();
-                if (timeout == -1) {
-                    sendPrefixedMessage(sender, "&7There is an active sampler currently running, with no defined timeout.");
-                } else {
-                    long timeoutDiff = (timeout - System.currentTimeMillis()) / 1000L;
-                    sendPrefixedMessage(sender, "&7There is an active sampler currently running, due to timeout in " + timeoutDiff + " seconds.");
-                }
-
-                long runningTime = (System.currentTimeMillis() - this.activeSampler.getStartTime()) / 1000L;
-                sendPrefixedMessage(sender, "&7It has been sampling for " + runningTime + " seconds so far.");
-            }
-        }
-    }
-
-    private void handleStop(T sender) {
-        synchronized (this.activeSamplerMutex) {
-            if (this.activeSampler == null) {
-                sendPrefixedMessage(sender, "&7There isn't an active sampling task running.");
-            } else {
-                this.activeSampler.cancel();
-                sendPrefixedMessage("&7The active sampling operation has been stopped! Uploading results...");
-                handleUpload(this.activeSampler);
-                this.activeSampler = null;
-            }
-        }
-    }
-
-    private void handleCancel(T sender) {
-        synchronized (this.activeSamplerMutex) {
-            if (this.activeSampler == null) {
-                sendPrefixedMessage(sender, "&7There isn't an active sampling task running.");
-            } else {
-                this.activeSampler.cancel();
-                this.activeSampler = null;
-                sendPrefixedMessage("&bThe active sampling task has been cancelled.");
-            }
-        }
-    }
-
-    private void handleUpload(Sampler sampler) {
-        runAsync(() -> {
-            byte[] output = sampler.formCompressedDataPayload();
-            try {
-                String pasteId = Bytebin.postCompressedContent(output);
-                sendPrefixedMessage("&bSampling results:");
-                sendLink(VIEWER_URL + pasteId);
-            } catch (IOException e) {
-                sendPrefixedMessage("&cAn error occurred whilst uploading the results.");
-                e.printStackTrace();
-            }
-        });
-    }
-
-    private void handleMonitoring(T sender, List<String> args) {
-        SetMultimap<String, String> arguments = parseArguments(args);
-
-        if (this.activeTickMonitor == null) {
-
-            int threshold = parseInt(arguments, "threshold", "t");
-            if (threshold == -1) {
-                threshold = 100;
-            }
-
-            try {
-                TickCounter tickCounter = newTickCounter();
-                this.activeTickMonitor = new ReportingTickMonitor(tickCounter, threshold);
-            } catch (UnsupportedOperationException e) {
-                sendPrefixedMessage(sender, "&cNot supported!");
-            }
-        } else {
-            this.activeTickMonitor.close();
-            this.activeTickMonitor = null;
-            sendPrefixedMessage("&7Tick monitor disabled.");
-        }
-    }
-
-    private void handleHeap(T sender) {
-        runAsync(() -> {
-            sendPrefixedMessage("&7Creating a new heap dump, please wait...");
-
-            HeapDump heapDump;
-            try {
-                heapDump = HeapDump.createNew();
-            } catch (Exception e) {
-                sendPrefixedMessage("&cAn error occurred whilst inspecting the heap.");
-                e.printStackTrace();
-                return;
-            }
-
-            byte[] output = heapDump.formCompressedDataPayload();
-            try {
-                String pasteId = Bytebin.postCompressedContent(output);
-                sendPrefixedMessage("&bHeap dump output:");
-                sendLink(VIEWER_URL + pasteId);
-            } catch (IOException e) {
-                sendPrefixedMessage("&cAn error occurred whilst uploading the data.");
-                e.printStackTrace();
-            }
-        });
-    }
-
-    private class ReportingTickMonitor extends TickMonitor {
-        ReportingTickMonitor(TickCounter tickCounter, int percentageChangeThreshold) {
-            super(tickCounter, percentageChangeThreshold);
-        }
-
-        @Override
-        protected void sendMessage(String message) {
-            sendPrefixedMessage(message);
-        }
-    }
-
-    private int parseInt(SetMultimap<String, String> arguments, String longArg, String shortArg) {
-        Iterator<String> it = Sets.union(arguments.get(longArg), arguments.get(shortArg)).iterator();
-        if (it.hasNext()) {
-            try {
-                return Math.abs(Integer.parseInt(it.next()));
-            } catch (NumberFormatException e) {
-                throw new IllegalArgumentException("Invalid input for '" + longArg + "' argument. Please specify a number!");
-            }
-        }
-        return -1; // undefined
-    }
-
-    private static final Pattern FLAG_REGEX = Pattern.compile("--(.+)$|-([a-zA-z])$");
-
-    private static SetMultimap<String, String> parseArguments(List<String> args) {
-        SetMultimap<String, String> arguments = HashMultimap.create();
-
-        String flag = null;
-        List<String> value = null;
-
-        for (int i = 0; i < args.size(); i++) {
-            String arg = args.get(i);
-
-            Matcher matcher = FLAG_REGEX.matcher(arg);
-            boolean matches = matcher.matches();
-
-            if (flag == null || matches) {
-                if (!matches) {
-                    throw new IllegalArgumentException("Expected flag at position " + i + " but got '" + arg + "' instead!");
-                }
-
-                String match = matcher.group(1);
-                if (match == null) {
-                    match = matcher.group(2);
-                }
-
-                // store existing value, if present
-                if (flag != null) {
-                    arguments.put(flag, String.join(" ", value));
-                }
-
-                flag = match.toLowerCase();
-                value = new ArrayList<>();
-            } else {
-                // part of a value
-                value.add(arg);
-            }
-        }
-
-        // store remaining value, if present
-        if (flag != null) {
-            arguments.put(flag, String.join(" ", value));
-        }
-
-        return arguments;
-    }
-    
-}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java b/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
new file mode 100644
index 0000000..57c205f
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/SparkPlatform.java
@@ -0,0 +1,115 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common;
+
+import com.google.common.collect.ImmutableList;
+
+import me.lucko.spark.common.command.Arguments;
+import me.lucko.spark.common.command.Command;
+import me.lucko.spark.common.command.modules.HeapModule;
+import me.lucko.spark.common.command.modules.MonitoringModule;
+import me.lucko.spark.common.command.modules.SamplerModule;
+import me.lucko.spark.sampler.ThreadDumper;
+import me.lucko.spark.sampler.TickCounter;
+
+import java.util.List;
+
+/**
+ * Abstract command handling class used by all platforms.
+ *
+ * @param <S> the sender (e.g. CommandSender) type used by the platform
+ */
+public abstract class SparkPlatform<S> {
+
+    /** The URL of the viewer frontend */
+    public static final String VIEWER_URL = "https://sparkprofiler.github.io/?";
+    /** The prefix used in all messages */
+    private static final String PREFIX = "&8[&fspark&8] &7";
+    
+    private static <T> List<Command<T>> prepareCommands() {
+        ImmutableList.Builder<Command<T>> builder = ImmutableList.builder();
+        new SamplerModule<T>().registerCommands(builder::add);
+        new MonitoringModule<T>().registerCommands(builder::add);
+        new HeapModule<T>().registerCommands(builder::add);
+        return builder.build();
+    }
+
+    private final List<Command<S>> commands = prepareCommands();
+    
+    // abstract methods implemented by each platform
+
+    public abstract String getVersion();
+    public abstract String getLabel();
+    public abstract void sendMessage(S sender, String message);
+    public abstract void sendMessage(String message);
+    public abstract void sendLink(String url);
+    public abstract void runAsync(Runnable r);
+    public abstract ThreadDumper getDefaultThreadDumper();
+    public abstract TickCounter newTickCounter();
+
+    public void sendPrefixedMessage(S sender, String message) {
+        sendMessage(sender, PREFIX + message);
+    }
+
+    public void sendPrefixedMessage(String message) {
+        sendMessage(PREFIX + message);
+    }
+
+    public void executeCommand(S sender, String[] args) {
+        if (args.length == 0) {
+            sendInfo(sender);
+            return;
+        }
+
+        Arguments arguments = new Arguments(args);
+        String alias = arguments.raw().remove(0).toLowerCase();
+
+        for (Command<S> command : this.commands) {
+            if (command.aliases().contains(alias)) {
+                try {
+                    command.executor().execute(this, sender, arguments);
+                } catch (IllegalArgumentException e) {
+                    sendMessage(sender, "&c" + e.getMessage());
+                }
+                return;
+            }
+        }
+
+        sendInfo(sender);
+    }
+
+    private void sendInfo(S sender) {
+        // todo automagically generate this
+        sendPrefixedMessage(sender, "&fspark &7v" + getVersion());
+        sendMessage(sender, "&b&l> &7/spark start");
+        sendMessage(sender, "       &8[&7--timeout&8 <timeout seconds>]");
+        sendMessage(sender, "       &8[&7--thread&8 <thread name>]");
+        sendMessage(sender, "       &8[&7--not-combined]");
+        sendMessage(sender, "       &8[&7--interval&8 <interval millis>]");
+        sendMessage(sender, "       &8[&7--only-ticks-over&8 <tick length millis>]");
+        sendMessage(sender, "&b&l> &7/spark info");
+        sendMessage(sender, "&b&l> &7/spark stop");
+        sendMessage(sender, "&b&l> &7/spark cancel");
+        sendMessage(sender, "&b&l> &7/spark monitoring");
+        sendMessage(sender, "       &8[&7--threshold&8 <percentage increase>]");
+    }
+
+}
diff --git a/spark-common/src/main/java/me/lucko/spark/common/command/Arguments.java b/spark-common/src/main/java/me/lucko/spark/common/command/Arguments.java
new file mode 100644
index 0000000..4189174
--- /dev/null
+++ b/spark-common/src/main/java/me/lucko/spark/common/command/Arguments.java
@@ -0,0 +1,100 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.common.command;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.SetMultimap;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class Arguments {
+    private static final Pattern FLAG_REGEX = Pattern.compile("^--(.+)$");
+
+    private final List<String> rawArgs;
+    private final SetMultimap<String, String> parsedArgs;
+
+    public Arguments(String[] args) {
+        this.rawArgs = new ArrayList<>(Arrays.asList(args));
+        this.parsedArgs = HashMultimap.create();
+
+        String flag = null;
+        List<String> value = null;
+
+        for (int i = 0; i < this.rawArgs.size(); i++) {
+            String arg = this.rawArgs.get(i);
+
+            Matcher matcher = FLAG_REGEX.matcher(arg);
+            boolean matches = matcher.matches();
+
+            if (flag == null || matches) {
+                if (!matches) {
+                    throw new IllegalArgumentException("Expected flag at position " + i + " but got '" + arg + "' instead!");
+                }
+
+                // store existing value, if present
+                if (flag != null) {
+                    this.parsedArgs.put(flag, String.join(" ", value));
+                }
+
+                flag = matcher.group(1).toLowerCase();
+                value = new ArrayList<>();
+            } else {
+                // part of a value
+                value.add(arg);
+            }
+        }
+
+        // store remaining value, if present
+        if (flag != null) {
+            this.parsedArgs.put(flag, String.join(" ", value));
+        }
+    }
+
+    public List<String> raw() {
+        return this.rawArgs;
+    }
+
+    public int intFlag(String key) {
+        Iterator<String> it = this.parsedArgs.get(key).iterator();
+        if (it.hasNext()) {
+            try {
+                return Math.abs(Integer.parseInt(it.next()));
+            } catch (NumberFormatException e) {
+                throw new IllegalArgumentException("Invalid input for '" + key + "' argument. Please specify a number!");
+            }
+        }
+        return -1; // undefined
+    }
+
+    public Set<String> stringFlag(String key)