From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Mark Vainomaa <mikroskeem@mikroskeem.eu>
Date: Sun, 17 Mar 2019 21:46:27 +0200
Subject: [PATCH] Add GS4 Query event


diff --git a/src/main/java/com/destroystokyo/paper/event/server/GS4QueryEvent.java b/src/main/java/com/destroystokyo/paper/event/server/GS4QueryEvent.java
new file mode 100644
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000
--- /dev/null
+++ b/src/main/java/com/destroystokyo/paper/event/server/GS4QueryEvent.java
@@ -0,0 +0,0 @@
+package com.destroystokyo.paper.event.server;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import org.bukkit.Server;
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.jetbrains.annotations.ApiStatus;
+import org.jspecify.annotations.NullMarked;
+
+/**
+ * This event is fired if server is getting queried over GS4 Query protocol.
+ * <br>
+ * Adapted from Velocity's ProxyQueryEvent
+ *
+ * @author Mark Vainomaa
+ */
+@NullMarked
+public final class GS4QueryEvent extends Event {
+
+    private static final HandlerList HANDLER_LIST = new HandlerList();
+
+    private final QueryType queryType;
+    private final InetAddress querierAddress;
+    private QueryResponse response;
+
+    @ApiStatus.Internal
+    public GS4QueryEvent(final QueryType queryType, final InetAddress querierAddress, final QueryResponse response) {
+        super(true); // should always be called async
+        this.queryType = queryType;
+        this.querierAddress = querierAddress;
+        this.response = response;
+    }
+
+    /**
+     * Get query type
+     *
+     * @return query type
+     */
+    public QueryType getQueryType() {
+        return this.queryType;
+    }
+
+    /**
+     * Get querier address
+     *
+     * @return querier address
+     */
+    public InetAddress getQuerierAddress() {
+        return this.querierAddress;
+    }
+
+    /**
+     * Get query response
+     *
+     * @return query response
+     */
+    public QueryResponse getResponse() {
+        return this.response;
+    }
+
+    /**
+     * Set query response
+     *
+     * @param response query response
+     */
+    public void setResponse(final QueryResponse response) {
+        this.response = Preconditions.checkNotNull(response, "response");
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return HANDLER_LIST;
+    }
+
+    public static HandlerList getHandlerList() {
+        return HANDLER_LIST;
+    }
+
+    /**
+     * The type of query
+     */
+    public enum QueryType {
+        /**
+         * Basic query asks only a subset of information, such as motd, game type (hardcoded to <pre>MINECRAFT</pre>), map,
+         * current players, max players, server port and server motd
+         */
+        BASIC,
+
+        /**
+         * Full query asks pretty much everything present on this event (only hardcoded values cannot be modified here).
+         */
+        FULL
+    }
+
+    public static final class QueryResponse {
+
+        private final String motd;
+        private final String gameVersion;
+        private final String map;
+        private final int currentPlayers;
+        private final int maxPlayers;
+        private final String hostname;
+        private final int port;
+        private final Collection<String> players;
+        private final String serverVersion;
+        private final Collection<PluginInformation> plugins;
+
+        private QueryResponse(final String motd, final String gameVersion, final String map, final int currentPlayers, final int maxPlayers, final String hostname, final int port, final Collection<String> players, final String serverVersion, final Collection<PluginInformation> plugins) {
+            this.motd = motd;
+            this.gameVersion = gameVersion;
+            this.map = map;
+            this.currentPlayers = currentPlayers;
+            this.maxPlayers = maxPlayers;
+            this.hostname = hostname;
+            this.port = port;
+            this.players = players;
+            this.serverVersion = serverVersion;
+            this.plugins = plugins;
+        }
+
+        /**
+         * Get motd which will be used to reply to the query. By default, it is {@link Server#getMotd()}.
+         *
+         * @return motd
+         */
+        public String getMotd() {
+            return this.motd;
+        }
+
+        /**
+         * Get game version which will be used to reply to the query. By default, supported Minecraft versions range is sent.
+         *
+         * @return game version
+         */
+        public String getGameVersion() {
+            return this.gameVersion;
+        }
+
+        /**
+         * Get map name which will be used to reply to the query. By default {@code world} is sent.
+         *
+         * @return map name
+         */
+        public String getMap() {
+            return this.map;
+        }
+
+        /**
+         * Get current online player count which will be used to reply to the query.
+         *
+         * @return online player count
+         */
+        public int getCurrentPlayers() {
+            return this.currentPlayers;
+        }
+
+        /**
+         * Get max player count which will be used to reply to the query.
+         *
+         * @return max player count
+         */
+        public int getMaxPlayers() {
+            return this.maxPlayers;
+        }
+
+        /**
+         * Get server (public facing) hostname.
+         *
+         * @return server hostname
+         */
+        public String getHostname() {
+            return this.hostname;
+        }
+
+        /**
+         * Get server (public facing) port.
+         *
+         * @return server port
+         */
+        public int getPort() {
+            return this.port;
+        }
+
+        /**
+         * Get collection of players which will be used to reply to the query.
+         *
+         * @return collection of players
+         */
+        public Collection<String> getPlayers() {
+            return this.players;
+        }
+
+        /**
+         * Get server software (name and version) which will be used to reply to the query.
+         *
+         * @return server software
+         */
+        public String getServerVersion() {
+            return this.serverVersion;
+        }
+
+        /**
+         * Get list of plugins which will be used to reply to the query.
+         *
+         * @return collection of plugins
+         */
+        public Collection<PluginInformation> getPlugins() {
+            return this.plugins;
+        }
+
+        /**
+         * Creates a new {@link Builder} instance from data represented by this response.
+         *
+         * @return {@link QueryResponse} builder
+         */
+        public Builder toBuilder() {
+            return QueryResponse.builder()
+                .motd(this.getMotd())
+                .gameVersion(this.getGameVersion())
+                .map(this.getMap())
+                .currentPlayers(this.getCurrentPlayers())
+                .maxPlayers(this.getMaxPlayers())
+                .hostname(this.getHostname())
+                .port(this.getPort())
+                .players(this.getPlayers())
+                .serverVersion(this.getServerVersion())
+                .plugins(this.getPlugins());
+        }
+
+        /**
+         * Creates a new {@link Builder} instance.
+         *
+         * @return {@link QueryResponse} builder
+         */
+        public static Builder builder() {
+            return new Builder();
+        }
+
+        /**
+         * A builder for {@link QueryResponse} objects.
+         */
+        public static final class Builder {
+
+            private @MonotonicNonNull String motd;
+            private @MonotonicNonNull String gameVersion;
+            private @MonotonicNonNull String map;
+            private @MonotonicNonNull String hostname;
+            private @MonotonicNonNull String serverVersion;
+
+            private int currentPlayers;
+            private int maxPlayers;
+            private int port;
+
+            private final List<String> players = new ArrayList<>();
+            private final List<PluginInformation> plugins = new ArrayList<>();
+
+            private Builder() {
+            }
+
+            public Builder motd(final String motd) {
+                this.motd = Preconditions.checkNotNull(motd, "motd");
+                return this;
+            }
+
+            public Builder gameVersion(final String gameVersion) {
+                this.gameVersion = Preconditions.checkNotNull(gameVersion, "gameVersion");
+                return this;
+            }
+
+            public Builder map(final String map) {
+                this.map = Preconditions.checkNotNull(map, "map");
+                return this;
+            }
+
+            public Builder currentPlayers(final int currentPlayers) {
+                Preconditions.checkArgument(currentPlayers >= 0, "currentPlayers cannot be negative");
+                this.currentPlayers = currentPlayers;
+                return this;
+            }
+
+            public Builder maxPlayers(final int maxPlayers) {
+                Preconditions.checkArgument(maxPlayers >= 0, "maxPlayers cannot be negative");
+                this.maxPlayers = maxPlayers;
+                return this;
+            }
+
+            public Builder hostname(final String hostname) {
+                this.hostname = Preconditions.checkNotNull(hostname, "hostname");
+                return this;
+            }
+
+            public Builder port(final int port) {
+                Preconditions.checkArgument(port >= 1 && port <= 65535, "port must be between 1-65535");
+                this.port = port;
+                return this;
+            }
+
+            public Builder players(final Collection<String> players) {
+                this.players.addAll(Preconditions.checkNotNull(players, "players"));
+                return this;
+            }
+
+            public Builder players(final String... players) {
+                this.players.addAll(Arrays.asList(Preconditions.checkNotNull(players, "players")));
+                return this;
+            }
+
+            public Builder clearPlayers() {
+                this.players.clear();
+                return this;
+            }
+
+            public Builder serverVersion(final String serverVersion) {
+                this.serverVersion = Preconditions.checkNotNull(serverVersion, "serverVersion");
+                return this;
+            }
+
+            public Builder plugins(final Collection<PluginInformation> plugins) {
+                this.plugins.addAll(Preconditions.checkNotNull(plugins, "plugins"));
+                return this;
+            }
+
+            public Builder plugins(final PluginInformation... plugins) {
+                this.plugins.addAll(Arrays.asList(Preconditions.checkNotNull(plugins, "plugins")));
+                return this;
+            }
+
+            public Builder clearPlugins() {
+                this.plugins.clear();
+                return this;
+            }
+
+            /**
+             * Builds new {@link QueryResponse} with supplied data.
+             *
+             * @return response
+             */
+            public QueryResponse build() {
+                return new QueryResponse(
+                    Preconditions.checkNotNull(this.motd, "motd"),
+                    Preconditions.checkNotNull(this.gameVersion, "gameVersion"),
+                    Preconditions.checkNotNull(this.map, "map"),
+                    this.currentPlayers,
+                    this.maxPlayers,
+                    Preconditions.checkNotNull(this.hostname, "hostname"),
+                    this.port,
+                    ImmutableList.copyOf(this.players),
+                    Preconditions.checkNotNull(this.serverVersion, "serverVersion"),
+                    ImmutableList.copyOf(this.plugins)
+                );
+            }
+        }
+
+        /**
+         * Plugin information
+         */
+        public static class PluginInformation {
+
+            private String name;
+            private String version;
+
+            public PluginInformation(final String name, final String version) {
+                this.name = Preconditions.checkNotNull(name, "name");
+                this.version = Preconditions.checkNotNull(version, "version");
+            }
+
+            public String getName() {
+                return this.name;
+            }
+
+            public void setName(final String name) {
+                this.name = name;
+            }
+
+            public void setVersion(final String version) {
+                this.version = version;
+            }
+
+            public String getVersion() {
+                return this.version;
+            }
+
+            public static PluginInformation of(final String name, final String version) {
+                return new PluginInformation(name, version);
+            }
+        }
+    }
+}
