Add parser for FLAC metadata.

[sonitus.git] / src / main / java / net / pterodactylus / sonitus / io / flac / Stream.java

diff --git a/src/main/java/net/pterodactylus/sonitus/io/flac/Stream.java b/src/main/java/net/pterodactylus/sonitus/io/flac/Stream.java
new file mode 100644 (file)
index 0000000..3b4ee59
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/io/flac/Stream.java
@@ -0,0 +1,107 @@
+/*
+ * Sonitus - MetadataBlock.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sonitus.io.flac;
+
+import static com.google.common.io.ByteStreams.readFully;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+
+import com.google.common.base.Optional;
+import com.google.common.base.Predicate;
+import com.google.common.collect.FluentIterable;
+import com.google.common.collect.Lists;
+
+/**
+ * Parser and container for information about a FLAC stream.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class Stream {
+
+       /** The metadata blocks of the stream. */
+       private final List<MetadataBlock> metadataBlocks = Lists.newArrayList();
+
+       /**
+        * Creates a new FLAC stream containing the given metadata blocks.
+        *
+        * @param metadataBlocks
+        *              The metadata blocks in order of appearance
+        */
+       private Stream(List<MetadataBlock> metadataBlocks) {
+               this.metadataBlocks.addAll(metadataBlocks);
+       }
+
+       //
+       // ACCESSORS
+       //
+
+       /**
+        * Returns all metadata blocks of the given block type, in the order they
+        * appear in this stream.
+        *
+        * @param blockType
+        *              The block type to get all metadata blocks for
+        * @return The metadata blocks of the given block type
+        */
+       public Collection<MetadataBlock> metadataBlocks(final BlockType blockType) {
+               return FluentIterable.from(metadataBlocks).filter(new Predicate<MetadataBlock>() {
+
+                       @Override
+                       public boolean apply(MetadataBlock metadataBlock) {
+                               return metadataBlock.header().blockType() == blockType;
+                       }
+               }).toList();
+       }
+
+       //
+       // STATIC METHODS
+       //
+
+       /**
+        * Parses the given input stream and returns information about the stream if it
+        * can be successfully parsed as a FLAC stream.
+        *
+        * @param inputStream
+        *              The input stream containing the FLAC stream
+        * @return The parsed FLAC stream, or {@link Optional#absent()} if no FLAC
+        *         stream could be found at the stream’s current position
+        * @throws IOException
+        *              if an I/O error occurs
+        */
+       public static Optional<Stream> parse(InputStream inputStream) throws IOException {
+               byte[] streamTag = new byte[4];
+               readFully(inputStream, streamTag);
+               if (!Arrays.equals(streamTag, new byte[] { 'f', 'L', 'a', 'C' })) {
+                       return Optional.absent();
+               }
+               List<MetadataBlock> metadataBlocks = Lists.newArrayList();
+               while (true) {
+                       MetadataBlock metadataBlock = MetadataBlock.parse(inputStream);
+                       metadataBlocks.add(metadataBlock);
+                       if (metadataBlock.header().isLastMetadataBlock()) {
+                               break;
+                       }
+               }
+               return Optional.of(new Stream(metadataBlocks));
+       }
+
+}