formats: Modify layer title based on manifest

This is work towards #948

The html formatting of lists allows for an expansion UI under
the title of the layer object. The title is the layer tarball's
digest. In the Docker image layout, this can be directly taken
from the "tar_file" key. But in the OCI layout, this value is taken
from the "digest" key. This commit allows for that difference and
defaults to the layer's index if neither one of those keys exist.

Signed-off-by: Nisha K <[email protected]>

Author: Nisha K

tern/formats/html/generator.py

@@ -148,12 +148,20 @@ def manifest_handler(list_obj, indent):
 
 
 def layers_handler(list_obj, indent):
-    '''Write html code for the origins list in the report
+    '''Write html code for the layers list in the report
     with tar_file hash as title'''
     html_string = '  '*indent + '<ul class ="nested"> \n'
     for lo in list_obj:
+        # check whether the item is a dictionary that contains the "tar_file"
+        # property or not
+        if "tar_file" in lo:
+            title = str(lo["tar_file"][:10])
+        elif "digest" in lo:
+            title = str(lo["digest"][:10])
+        else:
+            title = list_obj.index(lo)
         html_string = html_string + '  '*indent + '<li><span class="caret">' \
-            + str(lo["tar_file"][:10]) + ' : ' + '</span> \n '
+            + title + ' : ' + '</span> \n '
         html_string = html_string + dict_handler(lo, indent+1)
         html_string = html_string + '  '*indent + '</li> \n'
     html_string = html_string + '  '*indent + '</ul> \n'