FEATURE: allow customizing default timezone for email. (#32964)

1. Changes default email format to llll (eg: Tue, May 8, 2018 2:00 AM)
from 2018-05-08T00:00:00Z UTC which is not nice on the eyes
2. Adds `discourse_local_dates_email_timezone` which allows configuring
default timezone in emails
3. Improved help text on site settings (format / timezone)

---------

Co-authored-by: Gary Pendergast <gary@pento.net>

plugins/discourse-local-dates/assets/javascripts/lib/discourse-markdown/discourse-local-dates.js

@@ -30,8 +30,10 @@ function addLocalDate(attributes, state, buffer, applyDataAttributes) {
 
   const emailFormat =
     state.md.options.discourse.datesEmailFormat || moment.defaultFormat;
+  const emailTimezone =
+    state.md.options.discourse.datesEmailTimezone || "Etc/UTC";
 
-  attributes.emailPreview = `${dateTime.utc().format(emailFormat)} UTC`;
+  attributes.emailPreview = `${dateTime.utc().tz(emailTimezone).format(emailFormat)}`;
 
   let token = new state.Token("span_open", "span", 1);
   token.attrs = [["class", "discourse-local-date"]];
@@ -112,6 +114,7 @@ export function setup(helper) {
 
   helper.registerOptions((opts, siteSettings) => {
     opts.datesEmailFormat = siteSettings.discourse_local_dates_email_format;
+    opts.datesEmailTimezone = siteSettings.discourse_local_dates_email_timezone;
 
     opts.features["discourse-local-dates"] =
       !!siteSettings.discourse_local_dates_enabled;

plugins/discourse-local-dates/config/locales/server.en.yml

@@ -3,4 +3,5 @@ en:
     discourse_local_dates_enabled: "Enable the discourse-local-dates feature. This will add support to local timezone aware dates in posts using the [date] element"
     discourse_local_dates_default_formats: "Frequently used date time formats, see: <a target='_blank' rel='noopener' href='https://momentjs.com/docs/#/parsing/string-format/'>momentjs string format</a>"
     discourse_local_dates_default_timezones: "Default list of timezones, must be a valid <a target='_blank' rel='noopener' href='https://en.wikipedia.org/wiki/List_of_tz_database_time_zones'>TZ</a>"
-    discourse_local_dates_email_format: "Format used to display a date in emails"
+    discourse_local_dates_email_format: "Format used to display a date in emails, examples: 'LLLL', 'llll' or 'YYYY-MM-DDTHH:mm:ss[Z]'. see: <a target='_blank' rel='noopener' href='https://momentjs.com/docs/#/parsing/string-format/'>momentjs string format</a>"
+    discourse_local_dates_email_timezone: "Timezone used to display dates in emails, must be a valid <a target='_blank' rel='noopener' href='https://en.wikipedia.org/wiki/List_of_tz_database_time_zones'>TZ</a>"

plugins/discourse-local-dates/config/settings.yml

@@ -1,6 +1,10 @@
 plugins:
+  discourse_local_dates_email_timezone:
+    default: "Etc/UTC"
+    client: true
+    area: "localization"
   discourse_local_dates_email_format:
-    default: "YYYY-MM-DDTHH:mm:ss[Z]"
+    default: "llll z"
     client: true
   discourse_local_dates_enabled:
     default: true

plugins/discourse-local-dates/db/migrate/20250529021721_add_utc_to_setting.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+class AddUtcToSetting < ActiveRecord::Migration[7.2]
+  def up
+    # we changed the setting so UTC is no longer appended, we append it now in the format
+    execute <<~SQL
+      UPDATE site_settings
+      SET value = value || ' z'
+      WHERE name = 'discourse_local_dates_email_format'
+    SQL
+  end
+
+  def down
+    execute <<~SQL
+      UPDATE site_settings
+      SET value = REPLACE(value, ' z', '')
+      WHERE name = 'discourse_local_dates_email_format'
+    SQL
+  end
+end

plugins/discourse-local-dates/spec/integration/local_dates_spec.rb

@@ -1,7 +1,10 @@
 # frozen_string_literal: true
 
 RSpec.describe "Local Dates" do
-  before { freeze_time DateTime.parse("2018-11-10 12:00") }
+  before do
+    SiteSetting.discourse_local_dates_email_format = "YYYY-MM-DDTHH:mm:ss[Z] z"
+    freeze_time DateTime.parse("2018-11-10 12:00")
+  end
 
   it "should work without timezone" do
     post = Fabricate(:post, raw: <<~MD)

plugins/discourse-local-dates/spec/lib/pretty_text_spec.rb

@@ -19,6 +19,7 @@ RSpec.describe PrettyText do
 
   describe "emails simplified rendering" do
     it "works with default markup" do
+      SiteSetting.discourse_local_dates_email_format = "YYYY-MM-DDTHH:mm:ss[Z] z"
       cooked = PrettyText.cook("[date=2018-05-08]")
       cooked_mail =
         generate_html(
@@ -31,6 +32,7 @@ RSpec.describe PrettyText do
     end
 
     it "works with time" do
+      SiteSetting.discourse_local_dates_email_format = "YYYY-MM-DDTHH:mm:ss[Z] UTC"
       cooked = PrettyText.cook("[date=2018-05-08  time=20:00:00]")
       cooked_mail =
         generate_html(
@@ -44,6 +46,7 @@ RSpec.describe PrettyText do
     end
 
     it "works with multiple timezones" do
+      SiteSetting.discourse_local_dates_email_format = "YYYY-MM-DDTHH:mm:ss[Z] UTC"
       cooked =
         PrettyText.cook(
           '[date=2023-05-08 timezone="Europe/Paris" timezones="America/Los_Angeles|Pacific/Auckland"]',
@@ -60,8 +63,28 @@ RSpec.describe PrettyText do
       expect(PrettyText.format_for_email(cooked)).to match_html(cooked_mail)
     end
 
+    describe "discourse_local_dates_email_timezone" do
+      before do
+        SiteSetting.discourse_local_dates_email_timezone = "Europe/Paris"
+        SiteSetting.discourse_local_dates_email_format = "llll"
+      end
+
+      it "uses the site setting" do
+        cooked = PrettyText.cook("[date=2018-05-08]")
+
+        cooked_mail =
+          generate_html(
+            "Tue, May 8, 2018 2:00 AM",
+            date: "2018-05-08",
+            email_preview: "Tue, May 8, 2018 2:00 AM",
+          )
+
+        expect(PrettyText.format_for_email(cooked)).to match_html(cooked_mail)
+      end
+    end
+
     describe "discourse_local_dates_email_format" do
-      before { SiteSetting.discourse_local_dates_email_format = "DD/MM" }
+      before { SiteSetting.discourse_local_dates_email_format = "DD/MM UTC" }
 
       it "uses the site setting" do
         cooked = PrettyText.cook("[date=2018-05-08]")