Add ImageEncoding enum

pgpainless-core/src/main/kotlin/org/pgpainless/algorithm/ImageEncoding.kt

@@ -0,0 +1,25 @@
+// SPDX-FileCopyrightText: 2024 Paul Schaub <info@pgpainless.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.algorithm
+
+/**
+ * Image encoding schemes for user attribute image headers.
+ * Currently, only [JPEG] is defined.
+ */
+enum class ImageEncoding(val id: Int) {
+
+    /** JPEG File Interchange Format (JFIF). */
+    JPEG(1)
+    ;
+
+    companion object {
+        @JvmStatic
+        fun requireFromId(id: Int): ImageEncoding =
+            fromId(id) ?: throw NoSuchElementException("No ImageEncoding found for id $id")
+
+        @JvmStatic
+        fun fromId(id: Int): ImageEncoding? = values().firstOrNull { id == it.id }
+    }
+}

pgpainless-core/src/test/kotlin/org/pgpainless/algorithm/ImageEncodingTest.kt

@@ -0,0 +1,24 @@
+// SPDX-FileCopyrightText: 2024 Paul Schaub <info@pgpainless.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.algorithm
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertNull
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+
+class ImageEncodingTest {
+
+    @Test
+    fun parseJpeg() {
+        assertEquals(ImageEncoding.JPEG, ImageEncoding.requireFromId(1))
+    }
+
+    @Test
+    fun parseUnknown() {
+        assertNull(ImageEncoding.fromId(11))
+        assertThrows<NoSuchElementException> { ImageEncoding.requireFromId(11) }
+    }
+}