feat(model): Add HierarchyFilter class

This class allows defining filters for elements in the hierarchy based on
element IDs. This is going to be used to select only the elements a user
has access to.

Signed-off-by: Oliver Heger <[email protected]>

Author: oheger-bosch

model/src/commonMain/kotlin/util/HierarchyFilter.kt

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2025 The ORT Server Authors (See <https://github.com/eclipse-apoapsis/ort-server/blob/main/NOTICE>)
+ *
+ * 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
+ *
+ *     https://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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * License-Filename: LICENSE
+ */
+
+package org.eclipse.apoapsis.ortserver.model.util
+
+import org.eclipse.apoapsis.ortserver.model.CompoundHierarchyId
+
+/**
+ * A data class that holds information about elements in the hierarchy the current user has access to. A filter
+ * instance is created based on the user's permissions and can be used to generate `WHERE` conditions for database
+ * queries to only select accessible entities.
+ *
+ * In ORT Server's role model, permissions granted on higher levels of the hierarchy inherit down to lower levels.
+ * Therefore, if a user can access a specific element, the elements below in the hierarchy are accessible as well. It
+ * is, however, possible that permissions on specific elements are restricted on lower levels by explicit role
+ * assignments. Such elements must then be excluded.
+ *
+ * There is also the case that an element on a higher level is implicitly accessible because the user has permissions
+ * on lower levels. Such elements must be added to results, but not their child elements.
+ *
+ * All these conditions are reflected by the different properties of this class.
+ */
+data class HierarchyFilter(
+    /**
+     * A [Map] with the IDs of elements that should be included together with their child element, grouped by their
+     * hierarchy level.
+     */
+    val transitiveIncludes: Map<Int, List<CompoundHierarchyId>>,
+
+    /**
+     * A [Map] with the IDs of elements that should be included, but without their child elements, grouped by their
+     * hierarchy level.
+     */
+    val nonTransitiveIncludes: Map<Int, List<CompoundHierarchyId>>,
+
+    /**
+     * A [Map] with the IDs of elements that should be excluded because of restricted permissions on lower levels of
+     * the hierarchy, grouped by their hierarchy level.
+     */
+    val excludes: Map<Int, List<CompoundHierarchyId>>,
+
+    /**
+     * A flag whether this filter is a wildcard filter, which means that it matches all elements in the hierarchy.
+     * If this is *true*, all other properties can be ignored, and no filter condition needs to be generated. Filters
+     * of this type are created if the user has superuser rights.
+     */
+    val isWildcard: Boolean = false
+) {
+    companion object {
+        /**
+         * A special instance of [HierarchyFilter] that declares itself as a wildcard filter and therefore matches
+         * all entities. This filter should not alter any query results.
+         */
+        val WILDCARD = HierarchyFilter(
+            transitiveIncludes = emptyMap(),
+            nonTransitiveIncludes = emptyMap(),
+            excludes = emptyMap(),
+            isWildcard = true
+        )
+    }
+}