From 4210f5c776dab2439cecb1e19dc3997109cab400 Mon Sep 17 00:00:00 2001
From: mathieui <mathieui@mathieui.net>
Date: Fri, 22 May 2020 17:13:11 +0200
Subject: Convert all datetimes to UTC when doing comparisons

---
 poezio/common.py      | 17 ++++++++++++++++-
 poezio/mam.py         | 11 ++++-------
 poezio/tabs/muctab.py |  4 ++--
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/poezio/common.py b/poezio/common.py
index 7cddc306..98870dda 100644
--- a/poezio/common.py
+++ b/poezio/common.py
@@ -8,7 +8,11 @@
 Various useful functions.
 """
 
-from datetime import datetime, timedelta
+from datetime import (
+    datetime,
+    timedelta,
+    timezone,
+)
 from pathlib import Path
 from typing import Dict, List, Optional, Tuple, Union
 
@@ -488,3 +492,14 @@ def unique_prefix_of(a: str, b: str) -> str:
             return a[:i+1]
     # both are equal, return a
     return a
+
+
+def to_utc(time: datetime) -> datetime:
+    """Convert a datetime-aware time zone into raw UTC"""
+    tzone = datetime.now().astimezone().tzinfo
+    if time.tzinfo is not None:  # Convert to UTC
+        time = time.astimezone(tz=timezone.utc)
+    else:  # Assume local tz, convert to URC
+        time = time.replace(tzinfo=tzone).astimezone(tz=timezone.utc)
+    # Return an offset-naive datetime
+    return time.replace(tzinfo=None)
diff --git a/poezio/mam.py b/poezio/mam.py
index ee5b1be8..4171de5e 100644
--- a/poezio/mam.py
+++ b/poezio/mam.py
@@ -25,6 +25,7 @@ from poezio.theming import get_theme
 from poezio import tabs
 from poezio import xhtml, colors
 from poezio.config import config
+from poezio.common import to_utc
 from poezio.text_buffer import TextBuffer, HistoryGap
 from poezio.ui.types import (
     BaseMessage,
@@ -89,7 +90,6 @@ def make_line(
         user=None,
     )
 
-
 async def get_mam_iterator(
         core,
         groupchat: bool,
@@ -181,14 +181,11 @@ async def fetch_history(tab: tabs.Tab,
                 break
     if end is None:
         end = datetime.now()
-    tzone = datetime.now().astimezone().tzinfo
-    end = end.replace(tzinfo=tzone).astimezone(tz=timezone.utc)
-    end = end.replace(tzinfo=None)
+    end = to_utc(end)
     end = datetime.strftime(end, '%Y-%m-%dT%H:%M:%SZ')
 
     if start is not None:
-        start = start.replace(tzinfo=tzone).astimezone(tz=timezone.utc)
-        start = start.replace(tzinfo=None)
+        start = to_utc(start)
         start = datetime.strftime(start, '%Y-%m-%dT%H:%M:%SZ')
 
     mam_iterator = await get_mam_iterator(
@@ -224,7 +221,7 @@ async def on_new_tab_open(tab: tabs.Tab) -> None:
     amount = 2 * tab.text_win.height
     end = datetime.now()
     for message in tab._text_buffer.messages:
-        if isinstance(message, Message) and message.time < end:
+        if isinstance(message, Message) and to_utc(message.time) < to_utc(end):
             end = message.time
             break
     end = end - timedelta(microseconds=1)
diff --git a/poezio/tabs/muctab.py b/poezio/tabs/muctab.py
index 0cb3d859..5939db31 100644
--- a/poezio/tabs/muctab.py
+++ b/poezio/tabs/muctab.py
@@ -31,7 +31,7 @@ from poezio import multiuserchat as muc
 from poezio import timed_events
 from poezio import windows
 from poezio import xhtml
-from poezio.common import safeJID
+from poezio.common import safeJID, to_utc
 from poezio.config import config
 from poezio.core.structs import Command
 from poezio.decorators import refresh_wrapper, command_args_parser
@@ -158,7 +158,7 @@ class MucTab(ChatTab):
         """
         status = self.core.get_status()
         if self.last_connection:
-            delta = datetime.now() - self.last_connection
+            delta = to_utc(datetime.now()) - to_utc(self.last_connection)
             seconds = delta.seconds + delta.days * 24 * 3600
         else:
             seconds = self._text_buffer.find_last_message()
-- 
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