use dedicated hash object instead of byte[] for caps

this way we can store the algo alongside the object

src/main/java/im/conversations/android/xmpp/EntityCapabilities.java

@@ -5,6 +5,7 @@ import com.google.common.collect.Collections2;
 import com.google.common.collect.ComparisonChain;
 import com.google.common.collect.Ordering;
 import com.google.common.hash.Hashing;
+import com.google.common.io.BaseEncoding;
 import im.conversations.android.xmpp.model.data.Data;
 import im.conversations.android.xmpp.model.data.Field;
 import im.conversations.android.xmpp.model.disco.info.Feature;
@@ -15,7 +16,7 @@ import java.util.Comparator;
 import java.util.List;
 
 public final class EntityCapabilities {
-    public static byte[] hash(final InfoQuery info) {
+    public static EntityCapsHash hash(final InfoQuery info) {
         final StringBuilder s = new StringBuilder();
         final List<Identity> orderedIdentities =
                 Ordering.from(
@@ -76,7 +77,8 @@ public final class EntityCapabilities {
                 }
             }
         }
-        return Hashing.sha1().hashString(s.toString(), StandardCharsets.UTF_8).asBytes();
+        return new EntityCapsHash(
+                Hashing.sha1().hashString(s.toString(), StandardCharsets.UTF_8).asBytes());
     }
 
     private static String clean(String s) {
@@ -86,4 +88,23 @@ public final class EntityCapabilities {
     private static String blankNull(String s) {
         return s == null ? "" : clean(s);
     }
+
+    public abstract static class Hash {
+        public final byte[] hash;
+
+        protected Hash(byte[] hash) {
+            this.hash = hash;
+        }
+
+        public String encoded() {
+            return BaseEncoding.base64().encode(hash);
+        }
+    }
+
+    public static class EntityCapsHash extends Hash {
+
+        protected EntityCapsHash(byte[] hash) {
+            super(hash);
+        }
+    }
 }

src/main/java/im/conversations/android/xmpp/EntityCapabilities2.java

@@ -1,5 +1,8 @@
 package im.conversations.android.xmpp;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import com.google.common.base.CaseFormat;
 import com.google.common.base.Joiner;
 import com.google.common.base.Strings;
 import com.google.common.collect.Collections2;
@@ -25,13 +28,28 @@ public class EntityCapabilities2 {
 
     private static final char FILE_SEPARATOR = 0x1c;
 
-    public static byte[] hash(final InfoQuery info) {
+    public static EntityCaps2Hash hash(final InfoQuery info) {
-        return hash(Hashing.sha256(), info);
+        return hash(Algorithm.SHA_256, info);
     }
 
-    public static byte[] hash(HashFunction hashFunction, final InfoQuery info) {
+    public static EntityCaps2Hash hash(final Algorithm algorithm, final InfoQuery info) {
-        final String algo = algorithm(info);
+        final String result = algorithm(info);
-        return hashFunction.hashString(algo, StandardCharsets.UTF_8).asBytes();
+        final var hashFunction = toHashFunction(algorithm);
+        return new EntityCaps2Hash(
+                algorithm, hashFunction.hashString(result, StandardCharsets.UTF_8).asBytes());
+    }
+
+    private static HashFunction toHashFunction(final Algorithm algorithm) {
+        switch (algorithm) {
+            case SHA_1:
+                return Hashing.sha1();
+            case SHA_256:
+                return Hashing.sha256();
+            case SHA_512:
+                return Hashing.sha512();
+            default:
+                throw new IllegalArgumentException("Unknown hash algorithm");
+        }
     }
 
     private static String asHex(final String message) {
@@ -128,4 +146,36 @@ public class EntityCapabilities2 {
                                                         EntityCapabilities2::extension)))
                 + FILE_SEPARATOR;
     }
+
+    public static class EntityCaps2Hash extends EntityCapabilities.Hash {
+
+        public final Algorithm algorithm;
+
+        protected EntityCaps2Hash(final Algorithm algorithm, byte[] hash) {
+            super(hash);
+            this.algorithm = algorithm;
+        }
+    }
+
+    public enum Algorithm {
+        SHA_1,
+        SHA_256,
+        SHA_512;
+
+        public static Algorithm tryParse(@Nullable final String name) {
+            try {
+                return valueOf(
+                        CaseFormat.LOWER_HYPHEN.to(
+                                CaseFormat.UPPER_UNDERSCORE, Strings.nullToEmpty(name)));
+            } catch (final IllegalArgumentException e) {
+                return null;
+            }
+        }
+
+        @NonNull
+        @Override
+        public String toString() {
+            return CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_HYPHEN, super.toString());
+        }
+    }
 }

src/main/java/im/conversations/android/xmpp/manager/DiscoManager.java

@@ -46,8 +46,8 @@ public class DiscoManager extends AbstractManager {
                         throw new IllegalStateException(
                                 "Node in response did not match node in request");
                     }
-                    final byte[] caps = EntityCapabilities.hash(infoQuery);
+                    final byte[] caps = EntityCapabilities.hash(infoQuery).hash;
-                    final byte[] caps2 = EntityCapabilities2.hash(infoQuery);
+                    final byte[] caps2 = EntityCapabilities2.hash(infoQuery).hash;
                     getDatabase()
                             .discoDao()
                             .set(getAccount(), entity, node, caps, caps2, infoQuery);

src/test/java/im/conversations/android/xmpp/EntityCapabilitiesTest.java

@@ -3,7 +3,6 @@ package im.conversations.android.xmpp;
 import static org.hamcrest.CoreMatchers.instanceOf;
 import static org.hamcrest.MatcherAssert.assertThat;
 
-import com.google.common.io.BaseEncoding;
 import eu.siacs.conversations.xml.Element;
 import eu.siacs.conversations.xml.XmlElementReader;
 import im.conversations.android.xmpp.model.disco.info.InfoQuery;
@@ -34,7 +33,7 @@ public class EntityCapabilitiesTest {
         final Element element = XmlElementReader.read(xml.getBytes(StandardCharsets.UTF_8));
         assertThat(element, instanceOf(InfoQuery.class));
         final InfoQuery info = (InfoQuery) element;
-        final String var = BaseEncoding.base64().encode(EntityCapabilities.hash(info));
+        final String var = EntityCapabilities.hash(info).encoded();
         Assert.assertEquals("QgayPKawpkPSDYmwT/WM94uAlu0=", var);
     }
 
@@ -74,7 +73,7 @@ public class EntityCapabilitiesTest {
         final Element element = XmlElementReader.read(xml.getBytes(StandardCharsets.UTF_8));
         assertThat(element, instanceOf(InfoQuery.class));
         final InfoQuery info = (InfoQuery) element;
-        final String var = BaseEncoding.base64().encode(EntityCapabilities.hash(info));
+        final String var = EntityCapabilities.hash(info).encoded();
         Assert.assertEquals("q07IKJEyjvHSyhy//CH0CxmKi8w=", var);
     }
 
@@ -104,7 +103,7 @@ public class EntityCapabilitiesTest {
         final Element element = XmlElementReader.read(xml.getBytes(StandardCharsets.UTF_8));
         assertThat(element, instanceOf(InfoQuery.class));
         final InfoQuery info = (InfoQuery) element;
-        final String var = BaseEncoding.base64().encode(EntityCapabilities2.hash(info));
+        final String var = EntityCapabilities2.hash(info).encoded();
         Assert.assertEquals("kzBZbkqJ3ADrj7v08reD1qcWUwNGHaidNUgD7nHpiw8=", var);
     }
 
@@ -180,7 +179,7 @@ public class EntityCapabilitiesTest {
         final Element element = XmlElementReader.read(xml.getBytes(StandardCharsets.UTF_8));
         assertThat(element, instanceOf(InfoQuery.class));
         final InfoQuery info = (InfoQuery) element;
-        final String var = BaseEncoding.base64().encode(EntityCapabilities2.hash(info));
+        final String var = EntityCapabilities2.hash(info).encoded();
         Assert.assertEquals("u79ZroNJbdSWhdSp311mddz44oHHPsEBntQ5b1jqBSY=", var);
     }
 }