Implement Fabric Permission API

fabric-permission-api-v1/build.gradle

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+version = getSubprojectVersion(project)
+
+loom {
+	accessWidenerPath = file('src/main/resources/fabric-permission-api-v1.classtweaker')
+}
+
+moduleDependencies(project, [
+	":fabric-api-base"
+])
+
+testDependencies(project, [
+	":fabric-command-api-v2",
+	":fabric-lifecycle-events-v1"
+])

fabric-permission-api-v1/src/main/java/net/fabricmc/fabric/api/permission/v1/MutablePermissionContext.java

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+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.permission.v1;
+
+import org.jspecify.annotations.Nullable;
+
+/**
+ * Mutable version of {@link PermissionContext}, intended for creation of custom context conditions.
+ */
+public interface MutablePermissionContext extends PermissionContext {
+	<T> MutablePermissionContext set(PermissionContext.Key<T> key, @Nullable T value);
+}

fabric-permission-api-v1/src/main/java/net/fabricmc/fabric/api/permission/v1/PermissionCheckCallback.java

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+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.permission.v1;
+
+import java.util.Objects;
+import java.util.concurrent.CompletableFuture;
+
+import org.jetbrains.annotations.ApiStatus;
+import org.jspecify.annotations.Nullable;
+
+import net.minecraft.resources.Identifier;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.impl.permission.PermissionCheckCallbackImpl;
+
+/**
+ * The event used for getting the permission result for given context.
+ * Implemented callbacks for this event should be thread safe, as permission methods can be called from another thread.
+ * Additionally, the execution should be reasonably fast for non-player and online player cases.
+ * Offline player checks are allowed to be slower and can happen asynchronously.
+ *
+ * <p>When implementing this callback, only {@link PermissionCheckCallback#onPermissionCheck} needs to be implemented,
+ * but for better performance in case of support for async lookup, the {@link PermissionCheckCallback#onAsyncPermissionCheck}
+ * method should also be implemented. In case it wasn't it will default to running {@link PermissionCheckCallback#onPermissionCheck}
+ * on current thread.
+ *
+ * <p>To check for permissions, you should use dedicated methods from {@link PermissionContextOwner} interface
+ * and it's implementations over invoking this event.
+ */
+public interface PermissionCheckCallback {
+	/**
+	 * Registers the permission callback.
+	 *
+	 * @param callback permission check callback to register
+	 */
+	static void register(PermissionCheckCallback callback) {
+		register(Event.DEFAULT_PHASE, callback);
+	}
+
+	/**
+	 * Registers the permission callback.
+	 *
+	 * @param phase ordering phase to place the callback
+	 * @param callback permission check callback to register
+	 */
+	static void register(Identifier phase, PermissionCheckCallback callback) {
+		Objects.requireNonNull(phase, "phase can't be null!");
+		Objects.requireNonNull(callback, "callback can't be null!");
+
+		PermissionCheckCallbackImpl.MAIN_EVENT.register(phase, callback::onPermissionCheck);
+		PermissionCheckCallbackImpl.ASYNC_EVENT.register(phase, callback::onAsyncPermissionCheck);
+	}
+
+	/**
+	 * Orders the phases in provided order.
+	 *
+	 * @param firstPhase the id of the phase that should happen first
+	 * @param lastPhase the id of the phase that should happen last
+	 */
+	static void addPhaseOrdering(Identifier firstPhase, Identifier lastPhase) {
+		Objects.requireNonNull(firstPhase, "firstPhase can't be null!");
+		Objects.requireNonNull(lastPhase, "lastPhase can't be null!");
+
+		PermissionCheckCallbackImpl.MAIN_EVENT.addPhaseOrdering(firstPhase, lastPhase);
+		PermissionCheckCallbackImpl.ASYNC_EVENT.addPhaseOrdering(firstPhase, lastPhase);
+	}
+
+	/**
+	 * Main check method, executes on current thread.
+	 *
+	 * @param context        context to check for
+	 * @param permission     a permission node representing a permission
+	 * @param <T>            type of permission
+	 * @return value of type T if present, null to pass through.
+	 */
+	@ApiStatus.OverrideOnly
+	@Nullable
+	<T> T onPermissionCheck(PermissionContext context, PermissionNode<T> permission);
+
+	/**
+	 * Async permission check method.
+	 *
+	 * @param context        context to check for
+	 * @param permission     a permission node representing a permission
+	 * @param <T>            type of permission
+	 * @return a completable future value of type T if present, null or null containing completable future to quickly pass through to next callback.
+	 */
+	@ApiStatus.OverrideOnly
+	default <T> CompletableFuture<@Nullable T> onAsyncPermissionCheck(PermissionContext context, PermissionNode<T> permission) {
+		return CompletableFuture.completedFuture(this.onPermissionCheck(context, permission));
+	}
+}