Fix HTTP 302 redirects via delegate for identifiers with slashes

src/main/java/edu/illinois/library/cantaloupe/image/MetaIdentifier.java

@@ -259,6 +259,34 @@ private void checkFrozen() {
         }
     }
 
+    /**
+     * <p>Translates the meta-identifier into a URI path component.</p>
+     *
+     * <p>Reverses {@link #fromURIPathComponent(String, DelegateProxy)}.</p>
+     *
+     * @param delegateProxy Delegate proxy.
+     */
+    public String toURIPathComponent(DelegateProxy delegateProxy) {
+        // Encode just the identifier part.
+        final Identifier originalIdentifier = getIdentifier();
+        final String slashedIdentifier = originalIdentifier.toString();
+        final String deSlashedIdentifier = StringUtils.encodeSlashes(slashedIdentifier);
+        final String encodedIdentifier = Reference.encode(deSlashedIdentifier);
+        final MetaIdentifierTransformer xformer =
+                new MetaIdentifierTransformerFactory().newInstance(delegateProxy);
+        final String serializedMetaIdentifier;
+
+        setIdentifier(new Identifier(encodedIdentifier));
+        serializedMetaIdentifier = xformer.serialize(this);
+        // Now that we've serialized the encoded meta-identifier, put it back to how it was before
+        setIdentifier(originalIdentifier);
+
+        LOGGER.debug("[Slash-substituted identifier: {}] -> [de-slashed identifier: {}] -> " +
+                        "[percent-encoded identifier: {}] -> [raw path component: {}]",
+                slashedIdentifier, deSlashedIdentifier, encodedIdentifier, serializedMetaIdentifier);
+        return serializedMetaIdentifier;
+    }
+
     @Override
     public String toString() {
         return new StandardMetaIdentifierTransformer().serialize(this);

src/main/java/edu/illinois/library/cantaloupe/resource/AbstractResource.java

@@ -13,8 +13,6 @@
 import edu.illinois.library.cantaloupe.image.Format;
 import edu.illinois.library.cantaloupe.image.Identifier;
 import edu.illinois.library.cantaloupe.image.MetaIdentifier;
-import edu.illinois.library.cantaloupe.image.MetaIdentifierTransformer;
-import edu.illinois.library.cantaloupe.image.MetaIdentifierTransformerFactory;
 import edu.illinois.library.cantaloupe.delegate.DelegateProxy;
 import edu.illinois.library.cantaloupe.delegate.DelegateProxyService;
 import edu.illinois.library.cantaloupe.delegate.UnavailableException;
@@ -594,9 +592,8 @@ protected Reference getPublicReference(MetaIdentifier newMetaIdentifier) {
         final int identifierIndex         = pathComponents.indexOf(
                 getIdentifierPathComponent());
 
-        final MetaIdentifierTransformer xformer =
-                new MetaIdentifierTransformerFactory().newInstance(getDelegateProxy());
-        final String newMetaIdentifierString = xformer.serialize(newMetaIdentifier);
+        final String newMetaIdentifierString =
+                newMetaIdentifier.toURIPathComponent(getDelegateProxy());
         publicRef.setPathComponent(identifierIndex, newMetaIdentifierString);
         return publicRef;
     }

src/main/java/edu/illinois/library/cantaloupe/util/StringUtils.java

@@ -41,6 +41,22 @@ public static String decodeSlashes(final String uriPathComponent) {
         return uriPathComponent;
     }
 
+    /**
+     * Reverses {@link #decodeSlashes(String)}.
+     *
+     * @param slashedIdentifier Identifier with slashes to be substituted.
+     * @return                  Identifier with slashes substituted.
+     */
+    public static String encodeSlashes(final String slashedIdentifier) {
+        final String substitute = Configuration.getInstance().
+                getString(Key.SLASH_SUBSTITUTE, "");
+        if (!substitute.isEmpty()) {
+            return org.apache.commons.lang3.StringUtils.replace(
+                    slashedIdentifier, "/", substitute);
+        }
+        return slashedIdentifier;
+    }
+
     public static String escapeHTML(String html) {
         StringBuilder out = new StringBuilder(Math.max(16, html.length()));
         for (int i = 0, length = html.length(); i < length; i++) {

src/test/java/edu/illinois/library/cantaloupe/image/MetaIdentifierTest.java

@@ -264,6 +264,29 @@ void testSetScaleConstraintWithFrozenInstance() {
                 () -> instance.setScaleConstraint(scaleConstraint));
     }
 
+    /* toURIPathComponent() */
+
+    @Test
+    void testToURIPathComponent() {
+        final Configuration config = Configuration.getInstance();
+        config.setProperty(Key.SLASH_SUBSTITUTE, "BUG");
+        config.setProperty(Key.META_IDENTIFIER_TRANSFORMER,
+                StandardMetaIdentifierTransformer.class.getSimpleName());
+
+        DelegateProxy delegateProxy     = TestUtil.newDelegateProxy();
+        MetaIdentifier metaIdentifier   = MetaIdentifier.builder()
+                .withIdentifier("cats/:dogs")
+                .withPageNumber(2)
+                .withScaleConstraint(2, 3)
+                .build();
+        MetaIdentifier beforeMethodCall = new MetaIdentifier(metaIdentifier);
+        String actual                   = metaIdentifier.toURIPathComponent(delegateProxy);
+        String expected                 = "catsBUG%3Adogs;2;2:3";
+        assertEquals(expected, actual);
+        // Make sure the call to toURIPathComponent didn't change the meta-identifier.
+        assertEquals(beforeMethodCall, metaIdentifier);
+    }
+
     /* toString() */
 
     @Test

src/test/java/edu/illinois/library/cantaloupe/util/StringUtilsTest.java

@@ -25,6 +25,13 @@ void testDecodeSlashes() {
         assertEquals("ca/ts", StringUtils.decodeSlashes("ca$$ts"));
     }
 
+    @Test
+    void testEncodeSlashes() {
+        Configuration.getInstance().setProperty(Key.SLASH_SUBSTITUTE, "$$");
+        assertEquals("cats", StringUtils.encodeSlashes("cats"));
+        assertEquals("ca$$ts", StringUtils.encodeSlashes("ca/ts"));
+    }
+
     @Test
     void testEscapeHTML() {
         String html = "the quick brown <script type=\"text/javascript\">alert('hi');</script> fox";