Add option to specify the order for printed messages

As mentioned in the previous commit, this change makes it possible to
select the first or last N matches in conjunction with the -l flag.

2 files changed, 18 insertions, 5 deletions

diff --git a/quarg/actions.py b/quarg/actions.py
index 70cde03..6aadc3d 100644
--- a/quarg/actions.py
+++ b/quarg/actions.py
@@ -45,6 +45,13 @@ class ParseDate(argparse.Action):
     def __call__(self, parser, namespace, datespec, option_string=None):
         setattr(namespace, self.dest, parse_isodate(datespec))
 
+class ParseOrder(argparse.Action):
+    def __call__(self, parser, namespace, orderspec, option_string=None):
+        if orderspec not in ['asc', 'desc']:
+            errx(f'Invalid order \'{orderspec}\'. Possible values are: asc, desc')
+
+        setattr(namespace, self.dest, orderspec)
+
 class ParseAround(argparse.Action):
     def __call__(self, parser, namespace, aroundspec, option_string=None):
         if '/' in aroundspec:
diff --git a/quarg/main.py b/quarg/main.py
index 8b9987b..69c99de 100644
--- a/quarg/main.py
+++ b/quarg/main.py
@@ -19,6 +19,7 @@ cli.add_argument('keyword', nargs='*', help='match messages containing this keyw
 cli.add_argument('-d', action='store_true', dest='debug', help='print debug and SQL query information')
 cli.add_argument('-e', action='store_true', dest='expr', help='interpret keywords as LIKE expression')
 cli.add_argument('-l', dest='limit', metavar='NUM', type=int, help='limit the number of matches')
+cli.add_argument('-o', action=actions.ParseOrder, dest='order', metavar='asc|desc', help='sort matches in this order')
 matchers = cli.add_argument_group('matching message context')
 matchers.add_argument('-b', action='append', dest='buffer', help='match this buffer')
 matchers.add_argument('-B', action=actions.ParseBufferType, dest='buftype', help='match buffers of this type')
@@ -95,7 +96,7 @@ def collect_predicates(args):
         else:
             yield fun(value)
 
-def run_query(session, predicates, limit):
+def run_query(session, predicates, args):
     start = timer()
 
     query = session.query(Backlog).join(Sender).join(Buffer).join(Network).join(QuasselUser)
@@ -103,9 +104,14 @@ def run_query(session, predicates, limit):
     for predicate in predicates:
         query = query.filter(predicate)
 
-    query = query.order_by(Backlog.time)
-    if limit:
-        query = query.limit(limit)
+    order = Backlog.time.asc()
+    if args.order == 'desc':
+        order = Backlog.time.desc()
+
+    query = query.order_by(order)
+
+    if args.limit:
+        query = query.limit(args.limit)
 
     rows = query.all()
 
@@ -130,7 +136,7 @@ def main():
     if not predicates:
         errx('Nothing to match.')
 
-    rows, time = run_query(session, predicates, args.limit)
+    rows, time = run_query(session, predicates, args)
 
     for row in rows:
         print(format_from(row))