Add system time zone designation. Closes #21.

src/pluralkit/bot/commands/__init__.py

@@ -1,4 +1,5 @@
 import asyncio
+from datetime import datetime
 
 import discord
 import re
@@ -37,14 +38,15 @@ class CommandError(Exception):
 
 
 class CommandContext:
-    def __init__(self, client: discord.Client, message: discord.Message, conn, args: str):
+    def __init__(self, client: discord.Client, message: discord.Message, conn, args: str, system: Optional[System]):
         self.client = client
         self.message = message
         self.conn = conn
         self.args = args
+        self._system = system
 
     async def get_system(self) -> Optional[System]:
-        return await db.get_system_by_account(self.conn, self.message.author.id)
+        return self._system
 
     async def ensure_system(self) -> System:
         system = await self.get_system()
@@ -57,6 +59,11 @@ class CommandContext:
     def has_next(self) -> bool:
         return bool(self.args)
 
+    def format_time(self, dt: datetime):
+        if self._system:
+            return self._system.format_time(dt)
+        return dt.isoformat(sep=" ", timespec="seconds") + " UTC"
+
     def pop_str(self, error: CommandError = None) -> Optional[str]:
         if not self.args:
             if error:
@@ -211,7 +218,8 @@ async def command_dispatch(client: discord.Client, message: discord.Message, con
             client=client,
             message=message,
             conn=conn,
-            args=remaining_string
+            args=remaining_string,
+            system=await System.get_by_account(conn, message.author.id)
         )
         await run_command(ctx, command_root)
         return True

src/pluralkit/bot/commands/switch_commands.py

@@ -124,14 +124,14 @@ async def switch_move(ctx: CommandContext):
         last_fronters = await last_switch.fetch_members(ctx.conn)
 
         members = ", ".join([member.name for member in last_fronters]) or "nobody"
-        last_absolute = last_switch.timestamp.isoformat(sep=" ", timespec="seconds")
+        last_absolute = ctx.format_time(last_switch.timestamp)
         last_relative = display_relative(last_switch.timestamp)
-        new_absolute = new_time.isoformat(sep=" ", timespec="seconds")
+        new_absolute = ctx.format_time(new_time)
         new_relative = display_relative(new_time)
 
         # Confirm with user
         switch_confirm_message = await ctx.reply(
-            "This will move the latest switch ({}) from {} UTC ({} ago) to {} UTC ({} ago). Is this OK?".format(members,
+            "This will move the latest switch ({}) from {} ({} ago) to {} ({} ago). Is this OK?".format(members,
                                                                                                         last_absolute,
                                                                                                         last_relative,
                                                                                                         new_absolute,

src/pluralkit/bot/commands/system_commands.py

@@ -2,6 +2,7 @@ from datetime import datetime, timedelta
 
 import dateparser
 import humanize
+import pytz
 
 import pluralkit.bot.embeds
 from pluralkit.bot.commands import *
@@ -29,6 +30,8 @@ async def system_root(ctx: CommandContext):
         await system_fronthistory(ctx, await ctx.ensure_system())
     elif ctx.match("frontpercent") or ctx.match("frontbreakdown") or ctx.match("frontpercentage"):
         await system_frontpercent(ctx, await ctx.ensure_system())
+    elif ctx.match("timezone") or ctx.match("tz"):
+        await system_timezone(ctx)
     elif ctx.match("set"):
         await system_set(ctx)
     elif not ctx.has_next():
@@ -95,6 +98,16 @@ async def system_description(ctx: CommandContext):
     await ctx.reply_ok("System description {}.".format("updated" if new_description else "cleared"))
 
 
+async def system_timezone(ctx: CommandContext):
+    system = await ctx.ensure_system()
+    new_tz = ctx.remaining() or None
+
+    tz = await system.set_time_zone(ctx.conn, new_tz)
+    offset = tz.utcoffset(datetime.utcnow())
+    offset_str = "UTC{:+02d}:{:02d}".format(int(offset.total_seconds() // 3600), int(offset.total_seconds() // 60 % 60))
+    await ctx.reply_ok("System time zone set to {} ({}, {}).".format(tz.tzname(datetime.utcnow()), offset_str, tz.zone))
+
+
 async def system_tag(ctx: CommandContext):
     system = await ctx.ensure_system()
     new_tag = ctx.remaining() or None
@@ -196,14 +209,14 @@ async def system_fronthistory(ctx: CommandContext, system: System):
             name = ", ".join([member.name for member in members])
 
         # Make proper date string
-        time_text = timestamp.isoformat(sep=" ", timespec="seconds")
+        time_text = ctx.format_time(timestamp)
         rel_text = display_relative(timestamp)
 
         delta_text = ""
         if i > 0:
             last_switch_time = front_history[i - 1][0]
             delta_text = ", for {}".format(display_relative(timestamp - last_switch_time))
-        lines.append("**{}** ({} UTC, {} ago{})".format(name, time_text, rel_text, delta_text))
+        lines.append("**{}** ({}, {} ago{})".format(name, time_text, rel_text, delta_text))
 
     embed = embeds.status("\n".join(lines) or "(none)")
     embed.title = "Past switches"
@@ -302,6 +315,6 @@ async def system_frontpercent(ctx: CommandContext, system: System):
         embed.add_field(name=member.name if member else "(no fronter)",
                         value="{}% ({})".format(percent, humanize.naturaldelta(front_time)))
 
-    embed.set_footer(text="Since {} UTC ({} ago)".format(span_start.isoformat(sep=" ", timespec="seconds"),
+    embed.set_footer(text="Since {} ({} ago)".format(ctx.format_time(span_start),
                                                      display_relative(span_start)))
     await ctx.reply(embed=embed)

src/pluralkit/bot/embeds.py

@@ -172,7 +172,7 @@ async def member_card(conn, member: Member) -> discord.Embed:
     return card
 
 
-async def front_status(switch: Switch, conn) -> discord.Embed:
+async def front_status(ctx: "CommandContext", switch: Switch, conn) -> discord.Embed:
     if switch:
         embed = status("")
         fronter_names = [member.name for member in await switch.fetch_members(conn)]
@@ -186,7 +186,7 @@ async def front_status(switch: Switch, conn) -> discord.Embed:
 
         if switch.timestamp:
             embed.add_field(name="Since",
-                            value="{} UTC ({})".format(switch.timestamp.isoformat(sep=" ", timespec="seconds"),
+                            value="{} ({})".format(ctx.format_time(switch.timestamp),
                                                    display_relative(switch.timestamp)))
     else:
         embed = error("No switches logged.")

src/pluralkit/db.py

@@ -334,7 +334,8 @@ async def create_tables(conn):
         tag         text,
         avatar_url  text,
         token       text,
-        created     timestamp not null default (current_timestamp at time zone 'utc')
+        created     timestamp not null default (current_timestamp at time zone 'utc'),
+        ui_tz       text not null default 'UTC'
     )""")
     await conn.execute("""create table if not exists members (
         id          serial primary key,

src/pluralkit/errors.py

@@ -93,3 +93,8 @@ class MembersAlreadyFrontingError(PluralKitError):
 class DuplicateSwitchMembersError(PluralKitError):
     def __init__(self):
         super().__init__("Duplicate members in member list.")
+
+
+class InvalidTimeZoneError(PluralKitError):
+    def __init__(self, tz_name: str):
+        super().__init__("Invalid time zone designation \"{}\".\n\nFor a list of valid time zone designations, see the `TZ database name` column here: <https://en.wikipedia.org/wiki/List_of_tz_database_time_zones#List>.".format(tz_name))

src/pluralkit/system.py

@@ -5,13 +5,29 @@ from collections.__init__ import namedtuple
 from datetime import datetime
 from typing import Optional, List, Tuple
 
+import pytz
+
 from pluralkit import db, errors
 from pluralkit.member import Member
 from pluralkit.switch import Switch
 from pluralkit.utils import generate_hid, contains_custom_emoji, validate_avatar_url_or_raise
 
 
-class System(namedtuple("System", ["id", "hid", "name", "description", "tag", "avatar_url", "token", "created"])):
+def canonicalize_tz_name(name: str) -> Optional[str]:
+    # First, try a direct search
+    try:
+        pytz.timezone(name)
+        return name
+    except pytz.UnknownTimeZoneError:
+        pass
+
+    # Then check last fragment of common time zone identifiers
+    name_map = {tz.split("/")[-1].replace("_", " "): tz for tz in pytz.common_timezones}
+    if name in name_map:
+        return name_map[name]
+
+
+class System(namedtuple("System", ["id", "hid", "name", "description", "tag", "avatar_url", "token", "created", "ui_tz"])):
     id: int
     hid: str
     name: str
@@ -20,6 +36,8 @@ class System(namedtuple("System", ["id", "hid", "name", "description", "tag", "a
     avatar_url: str
     token: str
     created: datetime
+    # pytz-compatible time zone name, usually Olson-style (eg. Europe/Amsterdam)
+    ui_tz: str
 
     @staticmethod
     async def get_by_id(conn, system_id: int) -> Optional["System"]:
@@ -206,6 +224,36 @@ class System(namedtuple("System", ["id", "hid", "name", "description", "tag", "a
                 inner_message = leading_mentions + inner_message
                 return member, inner_message
 
+    def format_time(self, dt: datetime) -> str:
+        """
+        Localizes the given `datetime` to a string based on the system's preferred time zone.
+
+        Assumes `dt` is a naïve `datetime` instance set to UTC, which is consistent with the rest of PluralKit.
+        """
+        tz = pytz.timezone(self.ui_tz)
+
+        # Set to aware (UTC), convert to tz, set to naive (tz), then format and append name
+        return tz.normalize(pytz.utc.localize(dt)).replace(tzinfo=None).isoformat(sep=" ", timespec="seconds") + " " + tz.tzname(dt)
+
+    async def set_time_zone(self, conn, tz_name: str) -> pytz.tzinfo:
+        """
+        Sets the system time zone to the time zone represented by the given string.
+
+        If `tz_name` is None or an empty string, will default to UTC.
+        If `tz_name` does not represent a valid time zone string, will raise InvalidTimeZoneError.
+
+        :raises: InvalidTimeZoneError
+        :returns: The `pytz.tzinfo` instance of the newly set time zone.
+        """
+
+        canonical_name = canonicalize_tz_name(tz_name)
+        if not canonical_name:
+            raise errors.InvalidTimeZoneError(tz_name)
+        tz = pytz.timezone(canonical_name)
+
+        await db.update_system_field(conn, self.id, "ui_tz", tz.zone)
+        return tz
+
     def to_json(self):
         return {
             "id": self.hid,

src/requirements.txt

@@ -6,3 +6,4 @@ https://github.com/Rapptz/discord.py/archive/860d6a9ace8248dfeec18b8b159e7b757d9
 humanize
 uvloop; sys.platform != 'win32' and sys.platform != 'cygwin' and sys.platform != 'cli'
 ciso8601
+pytz