i2psnark: Support "preview" HTML5 play for partial files

apps/i2psnark/java/src/org/klomp/snark/Storage.java

@@ -427,15 +427,18 @@ public class Storage implements Closeable
 ****/
 
   /**
-   *  For efficiency, calculate remaining bytes for all files at once
+   *  For efficiency, calculate remaining bytes for all files at once.
+   *  Remaining bytes is rv[0]. Preview bytes is rv[1].
    *
-   *  @return number of bytes remaining for each file, use indexOf() to get index for a file
+   *  @return number of bytes remaining and number of bytes available for a preview for each file, use indexOf() to get index for a file
    *  @since 0.9.23
    */
-  public long[] remaining() {
+  public long[][] remaining() {
       long[] rv = new long[_torrentFiles.size()];
+      long[] pv = new long[_torrentFiles.size()];
+      long[][] rva = new long[][] { rv, pv };
       if (complete())
-          return rv;
+          return rva;
       long bytes = 0;
       for (int i = 0; i < _torrentFiles.size(); i++) {
           TorrentFile tf = _torrentFiles.get(i);
@@ -443,10 +446,23 @@ public class Storage implements Closeable
           long end = start + tf.length;
           int pc = (int) (bytes / piece_size);
           long rvi = 0;
-          if (!bitfield.get(pc))
+          long pvi = 0;
-              rvi = Math.min(piece_size - (start % piece_size), tf.length);
+          long first = Math.min(piece_size - (start % piece_size), tf.length);
+          if (bitfield.get(pc))
+              pvi = first;
+          else
+              rvi = first;
+          boolean preview = true;
           for (int j = pc + 1; (((long)j) * piece_size) < end && j < pieces; j++) {
-              if (!bitfield.get(j)) {
+              if (bitfield.get(j)) {
+                  if (preview) {
+                      if (((long)(j+1))*piece_size < end)
+                          pvi += piece_size;
+                      else
+                          pvi += end - (((long)j) * piece_size);
+                  }
+              } else {
+                  preview = false;
                   if (((long)(j+1))*piece_size < end)
                       rvi += piece_size;
                   else
@@ -454,9 +470,10 @@ public class Storage implements Closeable
               }
           }
           rv[i] = rvi;
+          pv[i] = pvi;
           bytes += tf.length;
       }
-      return rv;
+      return rva;
   }
 
   /**

apps/i2psnark/java/src/org/klomp/snark/web/BasicServlet.java

@@ -179,7 +179,7 @@ class BasicServlet extends HttpServlet
      * @param pathInContext The path to find a resource for.
      * @return The resource to serve or null. Returns null for directories
      */
-    public HttpContent getContent(String pathInContext)
+    public HttpContent getContent(String pathInContext, long limit)
     {
         HttpContent r = null;
         if (_warBase != null && pathInContext.startsWith(_warBase)) {
@@ -187,8 +187,12 @@ class BasicServlet extends HttpServlet
         } else {
             File f = getResource(pathInContext);
             // exists && !directory
-            if (f != null && f.isFile())
+            if (f != null && f.isFile()) {
-                r = new FileContent(f);
+                if (limit > 0)
+                    r = new LimitFileContent(f, limit);
+                else
+                    r = new FileContent(f);
+            }
         }
         return r;
     }
@@ -202,10 +206,17 @@ class BasicServlet extends HttpServlet
         String pathInfo=request.getPathInfo();
         // ??? right??
         String pathInContext = addPaths(servletpath, pathInfo);        
+        long limit = 0;
+        String slimit = request.getParameter("limit");
+        if (slimit != null) {
+            try {
+                limit = Long.parseLong(slimit);
+            } catch (NumberFormatException nfe) {}
+        }
 
         // Find the resource and content
         try {
-            HttpContent content = getContent(pathInContext);
+            HttpContent content = getContent(pathInContext, limit);
             
             // Handle resource
             if (content == null) {
@@ -468,6 +479,29 @@ class BasicServlet extends HttpServlet
         public String toString() { return "File \"" + _file + '"'; }
     }
 
+    /**
+     *  @since 0.9.45
+     */
+    private class LimitFileContent extends FileContent
+    {
+        private final long _limit;
+
+        /**
+         *  @param limit must be less than file length
+         */
+        public LimitFileContent(File file, long limit)
+        {
+            super(file);
+            _limit = Math.min(limit, file.length());
+        }
+
+        @Override
+        public long getContentLength()
+        {
+            return _limit;
+        }
+    }
+
     private class JarContent implements HttpContent
     {
         private final String _path;

apps/i2psnark/java/src/org/klomp/snark/web/I2PSnarkServlet.java

@@ -3375,9 +3375,11 @@ public class I2PSnarkServlet extends BasicServlet {
 
         List<Sorters.FileAndIndex> fileList = new ArrayList<Sorters.FileAndIndex>(ls.length);
         // precompute remaining for all files for efficiency
-        long[] remainingArray = (storage != null) ? storage.remaining() : null;
+        long[][] arrays = (storage != null) ? storage.remaining() : null;
+        long[] remainingArray = (arrays != null) ? arrays[0] : null;
+        long[] previewArray = (arrays != null) ? arrays[1] : null;
         for (int i = 0; i < ls.length; i++) {
-            fileList.add(new Sorters.FileAndIndex(ls[i], storage, remainingArray));
+            fileList.add(new Sorters.FileAndIndex(ls[i], storage, remainingArray, previewArray));
         }
 
         boolean showSort = fileList.size() > 1;
@@ -3546,25 +3548,30 @@ public class I2PSnarkServlet extends BasicServlet {
             if (mime == null)
                 mime = "";
 
-            boolean isAudio = false;
+            boolean isAudio = isAudio(mime);
-            boolean isVideo = false;
+            boolean isVideo = !isAudio && isVideo(mime);
             buf.append("<td class=\"snarkFileIcon\">");
-            if (complete) {
+            String preview = null;
-                isAudio = isAudio(mime);
+            if (complete || (isAudio && fai.preview > 1024*100) || (isVideo && fai.preview > 1024*1024)) {
-                isVideo = !isAudio && isVideo(mime);
+                String ppath = complete ? path : path + "?limit=" + fai.preview;
+                if (!complete) {
+                    double pct = fai.preview / (double) fai.length;
+                    preview = "<br>" + _t("Preview") + ": " +
+                              (new DecimalFormat("0.00%")).format(pct);
+                }
                 if (isAudio || isVideo) {
                     // HTML5
                     if (isAudio)
                         buf.append("<audio");
                     else
                         buf.append("<video");
-                    buf.append(" controls><source src=\"").append(path).append("\" type=\"").append(mime).append("\">");
+                    buf.append(" controls><source src=\"").append(ppath).append("\" type=\"").append(mime).append("\">");
                 }
-                buf.append("<a href=\"").append(path).append("\">");
+                buf.append("<a href=\"").append(ppath).append("\">");
                 if (mime.startsWith("image/")) {
                     // thumbnail
                     buf.append("<img alt=\"\" border=\"0\" class=\"thumb\" src=\"")
-                       .append(path).append("\"></a>");
+                       .append(ppath).append("\"></a>");
                 } else {
                     buf.append(toImg(icon, _t("Open"))).append("</a>");
                 }
@@ -3588,6 +3595,8 @@ public class I2PSnarkServlet extends BasicServlet {
             buf.append(DataHelper.escapeHTML(item.getName()));
             if (complete)
                 buf.append("</a>");
+            if (preview != null)
+                buf.append(preview);
             buf.append("</td><td align=right class=\"snarkFileSize\">");
             if (!item.isDirectory())
                 buf.append(formatSize(length));
@@ -3755,7 +3764,7 @@ public class I2PSnarkServlet extends BasicServlet {
             return null;
         List<Sorters.FileAndIndex> fileList = new ArrayList<Sorters.FileAndIndex>(ls.length);
         // precompute remaining for all files for efficiency
-        long[] remainingArray = (storage != null) ? storage.remaining() : null;
+        long[] remainingArray = (storage != null) ? storage.remaining()[0] : null;
         for (int i = 0; i < ls.length; i++) {
             fileList.add(new Sorters.FileAndIndex(ls[i], storage, remainingArray));
         }

apps/i2psnark/java/src/org/klomp/snark/web/Sorters.java

@@ -374,6 +374,7 @@ class Sorters {
         public final boolean isDirectory;
         public final long length;
         public final long remaining;
+        public final long preview;
         public final int priority;
         public final int index;
 
@@ -382,15 +383,25 @@ class Sorters {
          *  @param remainingArray precomputed, non-null iff storage is non-null
          */
         public FileAndIndex(File file, Storage storage, long[] remainingArray) {
+            this(file, storage, remainingArray, null);
+        }
+
+        /**
+         *  @param storage may be null
+         *  @param remainingArray precomputed, non-null iff storage is non-null
+         */
+        public FileAndIndex(File file, Storage storage, long[] remainingArray, long[] previewArray) {
             this.file = file;
             index = storage != null ? storage.indexOf(file) : -1;
             if (index >= 0) {
                 isDirectory = false;
                 remaining = remainingArray[index];
+                preview = previewArray != null ? previewArray[index] : 0;
                 priority = storage.getPriority(index);
             } else {
                 isDirectory = file.isDirectory();
                 remaining = -1;
+                preview = 0;
                 priority = -999;
             }
             length = isDirectory ? 0 : file.length();