From f59e02cf251d981b5d786ecdd9a9258a79b3abe7 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <me@as-cii.com>
Date: Thu, 2 Sep 2021 19:15:05 +0200
Subject: [PATCH] Use macOS API to retrieve the local timezone

The `time` crate currently doesn't have a reliable way to get that.
In the future, `NSSystemTimeZoneDidChangeNotification` could be
used to keep the cached timezone up-to-date.

Co-Authored-By: Max Brunsfeld <max@zed.dev>
---
 Cargo.lock                        |  1 +
 gpui/Cargo.toml                   |  1 +
 gpui/src/platform.rs              |  3 +++
 gpui/src/platform/mac/platform.rs |  9 +++++++++
 gpui/src/platform/test.rs         |  5 +++++
 zed/Cargo.toml                    |  2 +-
 zed/src/chat_panel.rs             | 15 ++++++++++-----
 7 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index fdb5a30352589b0fe0664c648b721c38d631a2df..89169c0efd64af3fea51c014a8e096f5c4c492c5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2187,6 +2187,7 @@ dependencies = [
  "simplelog",
  "smallvec",
  "smol",
+ "time 0.3.2",
  "tiny-skia",
  "tree-sitter",
  "usvg",
diff --git a/gpui/Cargo.toml b/gpui/Cargo.toml
index b6b29c39e2541cad4837f68f217ba58910786d95..11a855cd40c087c4aed6fc278adfbdb7ded92952 100644
--- a/gpui/Cargo.toml
+++ b/gpui/Cargo.toml
@@ -27,6 +27,7 @@ serde = { version = "1.0.125", features = ["derive"] }
 serde_json = "1.0.64"
 smallvec = { version = "1.6", features = ["union"] }
 smol = "1.2"
+time = { version = "0.3" }
 tiny-skia = "0.5"
 tree-sitter = "0.19"
 usvg = "0.14"
diff --git a/gpui/src/platform.rs b/gpui/src/platform.rs
index 21679ae877bb2dab58006bfccf15fe7f54bcfefd..b58ad381a29f9804ea999f70278bd6db1521dde5 100644
--- a/gpui/src/platform.rs
+++ b/gpui/src/platform.rs
@@ -26,6 +26,7 @@ use std::{
     rc::Rc,
     sync::Arc,
 };
+use time::UtcOffset;
 
 pub trait Platform: Send + Sync {
     fn dispatcher(&self) -> Arc<dyn Dispatcher>;
@@ -49,6 +50,8 @@ pub trait Platform: Send + Sync {
     fn read_credentials(&self, url: &str) -> Option<(String, Vec<u8>)>;
 
     fn set_cursor_style(&self, style: CursorStyle);
+
+    fn local_timezone(&self) -> UtcOffset;
 }
 
 pub(crate) trait ForegroundPlatform {
diff --git a/gpui/src/platform/mac/platform.rs b/gpui/src/platform/mac/platform.rs
index 861984a24761ccc1dbe2fe92601383d3c44d8e88..4d81fe964a0b80584527a7cce9936a7b133a4fab 100644
--- a/gpui/src/platform/mac/platform.rs
+++ b/gpui/src/platform/mac/platform.rs
@@ -42,6 +42,7 @@ use std::{
     slice, str,
     sync::Arc,
 };
+use time::UtcOffset;
 
 const MAC_PLATFORM_IVAR: &'static str = "platform";
 static mut APP_CLASS: *const Class = ptr::null();
@@ -558,6 +559,14 @@ impl platform::Platform for MacPlatform {
             let _: () = msg_send![cursor, set];
         }
     }
+
+    fn local_timezone(&self) -> UtcOffset {
+        unsafe {
+            let local_timezone: id = msg_send![class!(NSTimeZone), localTimeZone];
+            let seconds_from_gmt: NSInteger = msg_send![local_timezone, secondsFromGMT];
+            UtcOffset::from_whole_seconds(seconds_from_gmt.try_into().unwrap()).unwrap()
+        }
+    }
 }
 
 unsafe fn get_foreground_platform(object: &mut Object) -> &MacForegroundPlatform {
diff --git a/gpui/src/platform/test.rs b/gpui/src/platform/test.rs
index 3295fb63822eba6fc36324826e58e27929439cc6..004b1f94a9ba86b4ce4aad710828b42bcae73023 100644
--- a/gpui/src/platform/test.rs
+++ b/gpui/src/platform/test.rs
@@ -9,6 +9,7 @@ use std::{
     rc::Rc,
     sync::Arc,
 };
+use time::UtcOffset;
 
 pub struct Platform {
     dispatcher: Arc<dyn super::Dispatcher>,
@@ -136,6 +137,10 @@ impl super::Platform for Platform {
     fn set_cursor_style(&self, style: CursorStyle) {
         *self.cursor.lock() = style;
     }
+
+    fn local_timezone(&self) -> UtcOffset {
+        UtcOffset::UTC
+    }
 }
 
 impl Window {
diff --git a/zed/Cargo.toml b/zed/Cargo.toml
index b77ed8caff0bd7c27310870b88aad5112206fefd..17314ebd6542473e0ed7d36c098df251ea7af07d 100644
--- a/zed/Cargo.toml
+++ b/zed/Cargo.toml
@@ -49,7 +49,7 @@ smallvec = { version = "1.6", features = ["union"] }
 smol = "1.2.5"
 surf = "2.2"
 tempdir = { version = "0.3.7", optional = true }
-time = { version = "0.3", features = ["local-offset"] }
+time = { version = "0.3" }
 tiny_http = "0.8"
 toml = "0.5"
 tree-sitter = "0.19.5"
diff --git a/zed/src/chat_panel.rs b/zed/src/chat_panel.rs
index 6edac94b2ec61b6cb6ec1ef35eb8dadd3998270b..6b52f7edfd970d781e798959d2af91925fe090f0 100644
--- a/zed/src/chat_panel.rs
+++ b/zed/src/chat_panel.rs
@@ -25,6 +25,7 @@ pub struct ChatPanel {
     input_editor: ViewHandle<Editor>,
     channel_select: ViewHandle<Select>,
     settings: watch::Receiver<Settings>,
+    local_timezone: UtcOffset,
 }
 
 pub enum Event {}
@@ -94,6 +95,7 @@ impl ChatPanel {
             input_editor,
             channel_select,
             settings,
+            local_timezone: cx.platform().local_timezone(),
         };
 
         this.init_active_channel(cx);
@@ -204,7 +206,7 @@ impl ChatPanel {
                         .with_child(
                             Container::new(
                                 Label::new(
-                                    format_timestamp(message.timestamp, now),
+                                    format_timestamp(message.timestamp, now, self.local_timezone),
                                     theme.timestamp.text.clone(),
                                 )
                                 .boxed(),
@@ -314,10 +316,13 @@ impl View for ChatPanel {
     }
 }
 
-fn format_timestamp(mut timestamp: OffsetDateTime, mut now: OffsetDateTime) -> String {
-    let local_offset = UtcOffset::current_local_offset().unwrap_or(UtcOffset::UTC);
-    timestamp = timestamp.to_offset(local_offset);
-    now = now.to_offset(local_offset);
+fn format_timestamp(
+    mut timestamp: OffsetDateTime,
+    mut now: OffsetDateTime,
+    local_timezone: UtcOffset,
+) -> String {
+    timestamp = timestamp.to_offset(local_timezone);
+    now = now.to_offset(local_timezone);
 
     let today = now.date();
     let date = timestamp.date();