Add Option to Minimise hosts File

This option (--minimise, -m) differs from compress (--compress, -c) in
that it keeps each host on a different line, while still removing
unnecessary newlines and comments.

This is necessary because many implementations of URL blockers that rely
on hosts files do not conform to the standard which allows multiple
hosts on a single line.

updateHostsFile.py

@@ -63,6 +63,7 @@ def get_defaults():
         "extensionspath": path_join_robust(BASEDIR_PATH, "extensions"),
         "extensions": [],
         "compress": False,
+        "minimise": False,
         "outputsubfolder": "",
         "hostfilename": "hosts",
         "targetip": "0.0.0.0",
@@ -126,6 +127,11 @@ def main():
                              "putting multiple domains in "
                              "each line. Improve the "
                              "performances under Windows.")
+    parser.add_argument("--minimise", "-m", dest="minimise",
+                        default=False, action="store_true",
+                        help="Minimise the hosts file "
+                             "ignoring non-necessary lines "
+                             "(empty lines and comments).")
 
     global settings
 
@@ -186,6 +192,12 @@ def main():
         compressed_file = tempfile.NamedTemporaryFile()
         remove_dups_and_excl(merge_file, exclusion_regexes, compressed_file)
         compress_file(compressed_file, settings["targetip"], final_file)
+    elif settings["minimise"]:
+        final_file = open(path_join_robust(settings["outputpath"], "hosts"),
+                          "w+b" if PY3 else "w+")
+        minimised_file = tempfile.NamedTemporaryFile()
+        remove_dups_and_excl(merge_file, exclusion_regexes, minimised_file)
+        minimise_file(minimised_file, settings["targetip"], final_file)
     else:
         final_file = remove_dups_and_excl(merge_file, exclusion_regexes)
 
@@ -686,6 +698,37 @@ def compress_file(input_file, target_ip, output_file):
     input_file.close()
 
 
+def minimise_file(input_file, target_ip, output_file):
+    """
+    Reduce the file dimension removing non-necessary lines (empty lines and
+    comments).
+
+    Parameters
+    ----------
+    input_file : file
+        The file object that contains the hostnames that we are reducing.
+    target_ip : str
+        The target IP address.
+    output_file : file
+        The file object that will contain the reduced hostnames.
+    """
+
+    input_file.seek(0)  # reset file pointer
+    write_data(output_file, '\n')
+
+    lines = []
+    for line in input_file.readlines():
+        line = line.decode("UTF-8")
+
+        if line.startswith(target_ip):
+            lines.append(line[:line.find('#')].strip() + '\n')
+
+    for line in lines:
+        write_data(output_file, line)
+
+    input_file.close()
+
+
 def remove_dups_and_excl(merge_file, exclusion_regexes, output_file=None):
     """
     Remove duplicates and remove hosts that we are excluding.