✨ Implement predicate permissions (#210)

Co-authored-by: Josh Taylor <me@broccol.ai>

cloud-core/src/main/java/cloud/commandframework/Command.java

@@ -34,6 +34,7 @@ import cloud.commandframework.meta.CommandMeta;
 import cloud.commandframework.meta.SimpleCommandMeta;
 import cloud.commandframework.permission.CommandPermission;
 import cloud.commandframework.permission.Permission;
+import cloud.commandframework.permission.PredicatePermission;
 import cloud.commandframework.types.tuples.Pair;
 import cloud.commandframework.types.tuples.Triplet;
 import io.leangen.geantyref.TypeToken;
@@ -1032,6 +1033,24 @@ public class Command<C> {
             );
         }
 
+        /**
+         * Specify a command permission
+         *
+         * @param permission Command permission
+         * @return New builder instance using the command permission
+         */
+        public @NonNull Builder<C> permission(final @NonNull PredicatePermission<C> permission) {
+            return new Builder<>(
+                    this.commandManager,
+                    this.commandMeta,
+                    this.senderType,
+                    this.commandComponents,
+                    this.commandExecutionHandler,
+                    permission,
+                    this.flags
+            );
+        }
+
         /**
          * Specify a command permission
          *

cloud-core/src/main/java/cloud/commandframework/CommandManager.java

@@ -55,6 +55,7 @@ import cloud.commandframework.meta.CommandMeta;
 import cloud.commandframework.permission.CommandPermission;
 import cloud.commandframework.permission.OrPermission;
 import cloud.commandframework.permission.Permission;
+import cloud.commandframework.permission.PredicatePermission;
 import cloud.commandframework.services.ServicePipeline;
 import cloud.commandframework.services.State;
 import io.leangen.geantyref.TypeToken;
@@ -277,6 +278,7 @@ public abstract class CommandManager<C> {
      * @param permission Permission node
      * @return {@code true} if the sender has the permission, else {@code false}
      */
+    @SuppressWarnings("unchecked")
     public boolean hasPermission(
             final @NonNull C sender,
             final @NonNull CommandPermission permission
@@ -287,6 +289,9 @@ public abstract class CommandManager<C> {
         if (permission instanceof Permission) {
             return hasPermission(sender, permission.toString());
         }
+        if (permission instanceof PredicatePermission) {
+            return ((PredicatePermission<C>) permission).hasPermission(sender);
+        }
         for (final CommandPermission innerPermission : permission.getPermissions()) {
             final boolean hasPermission = this.hasPermission(sender, innerPermission);
             if (permission instanceof OrPermission) {

cloud-core/src/main/java/cloud/commandframework/permission/PredicatePermission.java

@@ -0,0 +1,75 @@
+//
+// MIT License
+//
+// Copyright (c) 2020 Alexander Söderberg & Contributors
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+package cloud.commandframework.permission;
+
+import cloud.commandframework.keys.CloudKey;
+import cloud.commandframework.keys.CloudKeyHolder;
+import cloud.commandframework.keys.SimpleCloudKey;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.function.Predicate;
+
+/**
+ * A functional {@link CommandPermission} implementation
+ *
+ * @param <C> Command sender type
+ * @since 1.4.0
+ */
+@FunctionalInterface
+public interface PredicatePermission<C> extends CommandPermission, CloudKeyHolder<Void> {
+
+    /**
+     * Create a new predicate permission
+     *
+     * @param key Key that identifies the permission node
+     * @param predicate Predicate that determines whether or not the sender has the permission
+     * @param <C> Command sender type
+     * @return Created permission node
+     */
+    static <C> PredicatePermission<C> of(final @NonNull CloudKey<Void> key, final @NonNull Predicate<C> predicate) {
+        return new WrappingPredicatePermission<>(key, predicate);
+    }
+
+    @Override
+    @SuppressWarnings("FunctionalInterfaceMethodChanged")
+    default @NonNull CloudKey<Void> getKey() {
+        return SimpleCloudKey.of(this.getClass().getSimpleName());
+    }
+
+    /**
+     * Check whether or not the given sender has this permission
+     *
+     * @param sender Sender to check for
+     * @return {@code true} if the sender has the given permission, else {@code false}
+     */
+    boolean hasPermission(C sender);
+
+    @Override
+    default @NonNull Collection<@NonNull CommandPermission> getPermissions() {
+        return Collections.singleton(this);
+    }
+
+}

cloud-core/src/main/java/cloud/commandframework/permission/WrappingPredicatePermission.java

@@ -0,0 +1,59 @@
+//
+// MIT License
+//
+// Copyright (c) 2020 Alexander Söderberg & Contributors
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+package cloud.commandframework.permission;
+
+import cloud.commandframework.keys.CloudKey;
+import org.checkerframework.checker.nullness.qual.NonNull;
+
+import java.util.function.Predicate;
+
+final class WrappingPredicatePermission<C> implements PredicatePermission<C> {
+
+    private final CloudKey<Void> key;
+    private final Predicate<C> predicate;
+
+    WrappingPredicatePermission(
+            final @NonNull CloudKey<Void> key,
+            final @NonNull Predicate<C> predicate
+    ) {
+        this.key = key;
+        this.predicate = predicate;
+    }
+
+    @Override
+    public boolean hasPermission(final C sender) {
+        return this.predicate.test(sender);
+    }
+
+    @Override
+    public @NonNull CloudKey<Void> getKey() {
+        return this.key;
+    }
+
+    @Override
+    public String toString() {
+        return this.key.getName();
+    }
+
+}

cloud-core/src/test/java/cloud/commandframework/CommandPermissionTest.java

@@ -25,13 +25,16 @@ package cloud.commandframework;
 
 import cloud.commandframework.arguments.standard.IntegerArgument;
 import cloud.commandframework.execution.CommandExecutionCoordinator;
+import cloud.commandframework.keys.SimpleCloudKey;
 import cloud.commandframework.meta.CommandMeta;
 import cloud.commandframework.meta.SimpleCommandMeta;
+import cloud.commandframework.permission.PredicatePermission;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
 
 import java.util.concurrent.CompletionException;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 class CommandPermissionTest {
 
@@ -64,6 +67,22 @@ class CommandPermissionTest {
         );
     }
 
+    @Test
+    void testPredicatePermissions() {
+        final AtomicBoolean condition = new AtomicBoolean(true);
+        manager.command(manager.commandBuilder("predicate").permission(PredicatePermission.of(
+                SimpleCloudKey.of("boolean"), $ -> condition.get()
+        )));
+        // First time should succeed
+        manager.executeCommand(new TestCommandSender(), "predicate").join();
+        // Now we force it to fail
+        condition.set(false);
+        Assertions.assertThrows(
+                CompletionException.class,
+                () -> manager.executeCommand(new TestCommandSender(), "predicate").join()
+        );
+    }
+
 
     private static final class PermissionOutputtingCommandManager extends CommandManager<TestCommandSender> {