Implement download functionality

- directories are served as a zip-file

util.py

@@ -1,8 +1,10 @@
 #!/usr/bin/python3
 
 import configparser
+import hashlib
 import os
 import variables as var
+import zipfile
 
 __CONFIG = configparser.ConfigParser(interpolation=None)
 __CONFIG.read("configuration.ini", encoding='latin-1')
@@ -23,6 +25,36 @@ def get_recursive_filelist_sorted(path):
     filelist.sort()
     return filelist
 
+# - zips all files of the given zippath (must be a directory)
+# - returns the absolute path of the created zip file
+# - zip file will be in the applications tmp folder (according to configuration)
+# - format of the filename itself = prefix_hash.zip
+#       - prefix can be controlled by the caller
+#       - hash is a sha1 of the string representation of the directories' contents (which are
+#           zipped)
+def zipdir(zippath, zipname_prefix=None):
+    zipname = __CONFIG.get('bot', 'tmp_folder')
+    if zipname_prefix and '../' not in zipname_prefix:
+        zipname += zipname_prefix.strip().replace('/', '_') + '_'
+
+    files = get_recursive_filelist_sorted(zippath)
+    hash = hashlib.sha1((str(files).encode())).hexdigest()
+    zipname += hash + '.zip'
+
+    if os.path.exists(zipname):
+        return zipname
+
+    zipf = zipfile.ZipFile(zipname, 'w', zipfile.ZIP_DEFLATED)
+
+    for file in files:
+        filepath = os.path.dirname(file)
+        file_to_add = os.path.join(zippath, file)
+        add_file_as = os.path.relpath(os.path.join(zippath, file), os.path.join(zippath, '..'))
+        zipf.write(file_to_add, add_file_as)
+
+    zipf.close()
+    return zipname
+
 class Dir(object):
     def __init__(self, name):
         self.name = name