Include "mimeType" in metadata for single file resources (but only when a metadata file would have otherwise been created).

src/main/java/org/qortal/arbitrary/ArbitraryDataWriter.java

@@ -1,5 +1,7 @@
 package org.qortal.arbitrary;
 
+import com.j256.simplemagic.ContentInfo;
+import com.j256.simplemagic.ContentInfoUtil;
 import org.apache.commons.io.FileUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -23,6 +25,8 @@ import javax.crypto.NoSuchPaddingException;
 import javax.crypto.SecretKey;
 import java.io.File;
 import java.io.IOException;
+import java.net.FileNameMap;
+import java.net.URLConnection;
 import java.nio.file.*;
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
@@ -48,6 +52,7 @@ public class ArbitraryDataWriter {
     private final List<String> tags;
     private final Category category;
     private List<String> files;
+    private String mimeType;
 
     private int chunkSize = ArbitraryDataFile.CHUNK_SIZE;
 
@@ -79,6 +84,7 @@ public class ArbitraryDataWriter {
         this.tags = ArbitraryDataTransactionMetadata.limitTags(tags);
         this.category = category;
         this.files = new ArrayList<>(); // Populated in buildFileList()
+        this.mimeType = null; // Populated in buildFileList()
     }
 
     public void save() throws IOException, DataException, InterruptedException, MissingDataException {
@@ -144,20 +150,41 @@ public class ArbitraryDataWriter {
     }
 
     private void buildFileList() throws IOException {
-        // Single file resources consist of a single element in the file list
+        // Check if the path already points to a single file
         boolean isSingleFile = this.filePath.toFile().isFile();
+        Path singleFilePath = null;
         if (isSingleFile) {
             this.files.add(this.filePath.getFileName().toString());
-            return;
+            singleFilePath = this.filePath;
         }
-
+        else {
-        // Multi file resources require a walk through the directory tree
+            // Multi file resources (or a single file in a directory) require a walk through the directory tree
             try (Stream<Path> stream = Files.walk(this.filePath)) {
                 this.files = stream
                         .filter(Files::isRegularFile)
                         .map(p -> this.filePath.relativize(p).toString())
                         .filter(s -> !s.isEmpty())
                         .collect(Collectors.toList());
+
+                if (this.files.size() == 1) {
+                    singleFilePath = Paths.get(this.filePath.toString(), this.files.get(0));
+                }
+            }
+        }
+
+        if (singleFilePath != null) {
+            // Single file resource, so try and determine the MIME type
+            ContentInfoUtil util = new ContentInfoUtil();
+            ContentInfo info = util.findMatch(singleFilePath.toFile());
+            if (info != null) {
+                // Attempt to extract MIME type from file contents
+                this.mimeType = info.getMimeType();
+            }
+            else {
+                // Fall back to using the filename
+                FileNameMap fileNameMap = URLConnection.getFileNameMap();
+                this.mimeType = fileNameMap.getContentTypeFor(singleFilePath.toFile().getName());
+            }
         }
     }
 
@@ -304,6 +331,7 @@ public class ArbitraryDataWriter {
             metadata.setCategory(this.category);
             metadata.setChunks(this.arbitraryDataFile.chunkHashList());
             metadata.setFiles(this.files);
+            metadata.setMimeType(this.mimeType);
             metadata.write();
 
             // Create an ArbitraryDataFile from the JSON file (we don't have a signature yet)

src/main/java/org/qortal/arbitrary/metadata/ArbitraryDataTransactionMetadata.java

@@ -20,6 +20,7 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
     private List<String> tags;
     private Category category;
     private List<String> files;
+    private String mimeType;
 
     private static int MAX_TITLE_LENGTH = 80;
     private static int MAX_DESCRIPTION_LENGTH = 500;
@@ -92,6 +93,10 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
             }
             this.files = filesList;
         }
+
+        if (metadata.has("mimeType")) {
+            this.mimeType = metadata.getString("mimeType");
+        }
     }
 
     @Override
@@ -134,6 +139,10 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
         }
         outer.put("files", files);
 
+        if (this.mimeType != null && !this.mimeType.isEmpty()) {
+            outer.put("mimeType", this.mimeType);
+        }
+
         this.jsonString = outer.toString(2);
         LOGGER.trace("Transaction metadata: {}", this.jsonString);
     }
@@ -187,6 +196,14 @@ public class ArbitraryDataTransactionMetadata extends ArbitraryDataMetadata {
         return this.files;
     }
 
+    public void setMimeType(String mimeType) {
+        this.mimeType = mimeType;
+    }
+
+    public String getMimeType() {
+        return this.mimeType;
+    }
+
     public boolean containsChunk(byte[] chunk) {
         for (byte[] c : this.chunks) {
             if (Arrays.equals(c, chunk)) {

src/main/java/org/qortal/data/arbitrary/ArbitraryResourceMetadata.java

@@ -16,16 +16,18 @@ public class ArbitraryResourceMetadata {
     private Category category;
     private String categoryName;
     private List<String> files;
+    private String mimeType;
 
     public ArbitraryResourceMetadata() {
     }
 
-    public ArbitraryResourceMetadata(String title, String description, List<String> tags, Category category, List<String> files) {
+    public ArbitraryResourceMetadata(String title, String description, List<String> tags, Category category, List<String> files, String mimeType) {
         this.title = title;
         this.description = description;
         this.tags = tags;
         this.category = category;
         this.files = files;
+        this.mimeType = mimeType;
 
         if (category != null) {
             this.categoryName = category.getName();
@@ -40,6 +42,7 @@ public class ArbitraryResourceMetadata {
         String description = transactionMetadata.getDescription();
         List<String> tags = transactionMetadata.getTags();
         Category category = transactionMetadata.getCategory();
+        String mimeType = transactionMetadata.getMimeType();
 
         // We don't always want to include the file list as it can be too verbose
         List<String> files = null;
@@ -47,11 +50,11 @@ public class ArbitraryResourceMetadata {
             files = transactionMetadata.getFiles();
         }
 
-        if (title == null && description == null && tags == null && category == null && files == null) {
+        if (title == null && description == null && tags == null && category == null && files == null && mimeType == null) {
             return null;
         }
 
-        return new ArbitraryResourceMetadata(title, description, tags, category, files);
+        return new ArbitraryResourceMetadata(title, description, tags, category, files, mimeType);
     }
 
     public List<String> getFiles() {

src/test/java/org/qortal/test/arbitrary/ArbitraryTransactionMetadataTests.java

@@ -118,6 +118,7 @@ public class ArbitraryTransactionMetadataTests extends Common {
             assertEquals(description, arbitraryDataFile.getMetadata().getDescription());
             assertEquals(tags, arbitraryDataFile.getMetadata().getTags());
             assertEquals(category, arbitraryDataFile.getMetadata().getCategory());
+            assertEquals("text/plain", arbitraryDataFile.getMetadata().getMimeType());
 
             // Now build the latest data state for this name
             ArbitraryDataReader arbitraryDataReader = new ArbitraryDataReader(name, ResourceIdType.NAME, service, identifier);
@@ -168,6 +169,7 @@ public class ArbitraryTransactionMetadataTests extends Common {
             assertEquals(description, arbitraryDataFile.getMetadata().getDescription());
             assertEquals(tags, arbitraryDataFile.getMetadata().getTags());
             assertEquals(category, arbitraryDataFile.getMetadata().getCategory());
+            assertEquals("text/plain", arbitraryDataFile.getMetadata().getMimeType());
 
             // Delete the file, to simulate that it hasn't been fetched from the network yet
             arbitraryDataFile.delete();
@@ -230,6 +232,7 @@ public class ArbitraryTransactionMetadataTests extends Common {
             assertEquals(description, arbitraryDataFile.getMetadata().getDescription());
             assertEquals(tags, arbitraryDataFile.getMetadata().getTags());
             assertEquals(category, arbitraryDataFile.getMetadata().getCategory());
+            assertEquals("text/plain", arbitraryDataFile.getMetadata().getMimeType());
 
             // Now build the latest data state for this name
             ArbitraryDataReader arbitraryDataReader = new ArbitraryDataReader(name, ResourceIdType.NAME, service, identifier);
@@ -318,9 +321,11 @@ public class ArbitraryTransactionMetadataTests extends Common {
             assertTrue(resourceMetadata.getFiles().contains("file.txt"));
 
             // Ensure it's not returned when specified to be excluded
-            // The entire object will be null because there is no metadata
             ArbitraryResourceMetadata resourceMetadataSimple = ArbitraryResourceMetadata.fromTransactionMetadata(arbitraryDataFile.getMetadata(), false);
-            assertNull(resourceMetadataSimple);
+            assertNull(resourceMetadataSimple.getFiles());
+
+            // Single-file resources should have a MIME type
+            assertEquals("text/plain", arbitraryDataFile.getMetadata().getMimeType());
         }
     }
 
@@ -369,6 +374,9 @@ public class ArbitraryTransactionMetadataTests extends Common {
             // The entire object will be null because there is no metadata
             ArbitraryResourceMetadata resourceMetadataSimple = ArbitraryResourceMetadata.fromTransactionMetadata(arbitraryDataFile.getMetadata(), false);
             assertNull(resourceMetadataSimple);
+
+            // Multi-file resources won't have a MIME type
+            assertEquals(null, arbitraryDataFile.getMetadata().getMimeType());
         }
     }