feat: add calendar configuration for first day of the week

Author: Ahmedhossamdev

.env.example

@@ -20,6 +20,9 @@ PUBLIC_OBA_SERVER_URL="https://api.pugetsound.onebusaway.org/"
 
 PUBLIC_OTP_SERVER_URL=""
 
+# 1 TUE, 2 WED, 3 THU, 4 FRI, 5 SAT, 6 SUN, 0 MON 
+PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK=6
+
 # Analytics
 PUBLIC_ANALYTICS_DOMAIN=""
 PUBLIC_ANALYTICS_ENABLED=true

README.md

@@ -28,6 +28,10 @@ See `.env.example` for an example of the required keys and values.
 - `PUBLIC_ANALYTICS_ENABLED` - boolean: (optional).
 - `PUBLIC_ANALYTICS_API_HOST` - string: (optional).
 
+## Calendar Configuration
+
+- `PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK` - number: (optional) Sets the first day of the week for calendar components. Use 0 for Monday, 1 for Tuesday, 2 for Wednesday, 3 for Thursday, 4 for Friday, 5 for Saturday, 6 for Sunday. Defaults to 0 (Monday).
+
 ### OBA Server
 
 - `PUBLIC_OBA_SERVER_URL` - string: (required) Your OBA API server's URL.

src/config/calendarConfig.js

@@ -0,0 +1,30 @@
+import { env } from '$env/dynamic/public';
+
+/**
+ * Get the first day of the week for calendar components
+ * @returns {number} 0 for Monday, 1 for Tuesday, 2 for Wednesday, 3 for Thursday, 4 for Friday, 5 for Saturday, 6 for Sunday
+ */
+export function getFirstDayOfWeek() {
+	const configValue = env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK;
+
+	// Default to Monday (0) if not configured
+	if (!configValue) {
+		return 0;
+	}
+
+	const dayValue = parseInt(configValue, 10);
+
+	if (
+		isNaN(dayValue) ||
+		dayValue < 0 ||
+		dayValue > 6 ||
+		dayValue.toString() !== configValue.trim()
+	) {
+		console.warn(
+			'Invalid PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK value. Must be 0-6 (0=Monday, 6=Sunday). Using Monday (0) as default.'
+		);
+		return 0;
+	}
+
+	return dayValue;
+}

src/routes/stops/[stopID]/schedule/+page.svelte

@@ -9,6 +9,7 @@
 	import { Datepicker } from 'flowbite-svelte';
 	import { onMount } from 'svelte';
 	import { t } from 'svelte-i18n';
+	import { getFirstDayOfWeek } from '$config/calendarConfig.js';
 
 	let selectedDate = $state(new Date());
 	let prevSelectedDate = $state(null);
@@ -144,7 +145,11 @@
 
 			<div class="mb-4 flex gap-4">
 				<div class="z-20 min-w-32 md:w-[30%]">
-					<Datepicker bind:value={selectedDate} inputClass="w-96" />
+					<Datepicker
+						bind:value={selectedDate}
+						inputClass="w-96"
+						firstDayOfWeek={getFirstDayOfWeek()}
+					/>
 				</div>
 
 				<div class="flex-1 text-right">

src/tests/config/calendarConfig.test.js

@@ -0,0 +1,105 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+// Mock the environment module
+vi.mock('$env/dynamic/public', () => ({
+	env: {}
+}));
+
+import { getFirstDayOfWeek } from '$config/calendarConfig.js';
+
+import { env } from '$env/dynamic/public';
+
+describe('getFirstDayOfWeek', () => {
+	beforeEach(() => {
+		vi.clearAllMocks();
+
+		Object.keys(env).forEach((key) => delete env[key]);
+	});
+
+	it('returns 0 (Monday) by default when no configuration is set', () => {
+		expect(getFirstDayOfWeek()).toBe(0);
+	});
+
+	it('returns 0 (Monday) when environment variable is undefined', () => {
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = undefined;
+		expect(getFirstDayOfWeek()).toBe(0);
+	});
+
+	it('returns 0 (Monday) when environment variable is empty string', () => {
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = '';
+		expect(getFirstDayOfWeek()).toBe(0);
+	});
+
+	it('returns the configured value for all valid day values (0-6)', () => {
+		// Test all valid values: 0=Monday, 1=Tuesday, 2=Wednesday, 3=Thursday, 4=Friday, 5=Saturday, 6=Sunday
+		for (let i = 0; i <= 6; i++) {
+			env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = i.toString();
+			expect(getFirstDayOfWeek()).toBe(i);
+		}
+	});
+
+	it('returns 0 (Monday) and shows warning for values above 6', () => {
+		const consoleSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = '7';
+		expect(getFirstDayOfWeek()).toBe(0);
+		expect(consoleSpy).toHaveBeenCalledWith(
+			'Invalid PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK value. Must be 0-6 (0=Monday, 6=Sunday). Using Monday (0) as default.'
+		);
+
+		consoleSpy.mockRestore();
+	});
+
+	it('returns 0 (Monday) and shows warning for negative values', () => {
+		const consoleSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = '-1';
+		expect(getFirstDayOfWeek()).toBe(0);
+		expect(consoleSpy).toHaveBeenCalledWith(
+			'Invalid PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK value. Must be 0-6 (0=Monday, 6=Sunday). Using Monday (0) as default.'
+		);
+
+		consoleSpy.mockRestore();
+	});
+
+	it('returns 0 (Monday) and shows warning for non-numeric values', () => {
+		const consoleSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+
+		// Test various non-numeric strings
+		const invalidValues = ['invalid', 'monday', 'sunday', 'abc', '1.5', '2.0'];
+
+		invalidValues.forEach((value) => {
+			env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = value;
+			expect(getFirstDayOfWeek()).toBe(0);
+		});
+
+		expect(consoleSpy).toHaveBeenCalledWith(
+			'Invalid PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK value. Must be 0-6 (0=Monday, 6=Sunday). Using Monday (0) as default.'
+		);
+
+		consoleSpy.mockRestore();
+	});
+
+	it('handles numeric strings correctly', () => {
+		// Test that string numbers are parsed correctly
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = '6';
+		expect(getFirstDayOfWeek()).toBe(6);
+
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = '0';
+		expect(getFirstDayOfWeek()).toBe(0);
+	});
+
+	it('handles edge case of "0" string vs undefined/empty', () => {
+		// "0" should be valid and return 0
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = '0';
+		expect(getFirstDayOfWeek()).toBe(0);
+
+		// undefined should return default 0
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = undefined;
+		expect(getFirstDayOfWeek()).toBe(0);
+
+		// empty string should return default 0
+		env.PUBLIC_CALENDAR_FIRST_DAY_OF_WEEK = '';
+		expect(getFirstDayOfWeek()).toBe(0);
+	});
+});