Add more features to clock

internal/assets/static/main.js

@@ -103,7 +103,7 @@ function updateRelativeTimeForElements(elements)
         if (timestamp === undefined)
             continue
 
-        element.innerText = relativeTimeSince(timestamp);
+        element.textContent = relativeTimeSince(timestamp);
     }
 }
 
@@ -341,18 +341,110 @@ function afterContentReady(callback) {
     contentReadyCallbacks.push(callback);
 }
 
-function updateClocks(elements, formatter) {
-    const currentDate = new Date();
-    for (const elem of elements) {
-        elem.textContent = formatter.format(currentDate);
+const weekDayNames = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
+const monthNames = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
+
+function makeSettableTimeElement(element, hourFormat) {
+    const fragment = document.createDocumentFragment();
+    const hour = document.createElement('span');
+    const minute = document.createElement('span');
+    const amPm = document.createElement('span');
+    fragment.append(hour, document.createTextNode(':'), minute);
+
+    if (hourFormat == '12h') {
+        fragment.append(document.createTextNode(' '), amPm);
     }
+
+    element.append(fragment);
+
+    return (date) => {
+        const hours = date.getHours();
+
+        if (hourFormat == '12h') {
+            amPm.textContent = hours < 12 ? 'AM' : 'PM';
+            hour.textContent = hours % 12 || 12;
+        } else {
+            hour.textContent = hours < 10 ? '0' + hours : hours;
+        }
+
+        const minutes = date.getMinutes();
+        minute.textContent = minutes < 10 ? '0' + minutes : minutes;
+    };
+};
+
+function timeInZone(now, zone) {
+    let timeInZone;
+
+    try {
+        timeInZone = new Date(now.toLocaleString('en-US', { timeZone: zone }));
+    } catch (e) {
+        // TODO: indicate to the user that this is an invalid timezone
+        console.error(e);
+        timeInZone = now
+    }
+
+    const diffInHours = Math.round((timeInZone.getTime() - now.getTime()) / 1000 / 60 / 60);
+
+    return { time: timeInZone, diffInHours: diffInHours };
 }
 
 function setupClocks() {
-    const clockFormatter = new Intl.DateTimeFormat(undefined, {minute: "numeric", hour: "numeric"});
-    const elements = document.getElementsByClassName("glance-clock");
-    updateClocks(elements, clockFormatter)
-    setInterval(() => {updateClocks(elements, clockFormatter)}, 1000);
+    const clocks = document.getElementsByClassName('clock');
+
+    if (clocks.length == 0) {
+        return;
+    }
+
+    const updateCallbacks = [];
+
+    for (var i = 0; i < clocks.length; i++) {
+        const clock = clocks[i];
+        const hourFormat = clock.dataset.hourFormat;
+        const localTimeContainer = clock.querySelector('[data-local-time]');
+        const localDateElement = localTimeContainer.querySelector('[data-date]');
+        const localWeekdayElement = localTimeContainer.querySelector('[data-weekday]');
+        const localYearElement = localTimeContainer.querySelector('[data-year]');
+        const timeZoneContainers = clock.querySelectorAll('[data-time-in-zone]');
+
+        const setLocalTime = makeSettableTimeElement(
+            localTimeContainer.querySelector('[data-time]'),
+            hourFormat
+        );
+
+        updateCallbacks.push((now) => {
+            setLocalTime(now);
+            localDateElement.textContent = now.getDate() + ' ' + monthNames[now.getMonth()];
+            localWeekdayElement.textContent = weekDayNames[now.getDay()];
+            localYearElement.textContent = now.getFullYear();
+        });
+
+        for (var z = 0; z < timeZoneContainers.length; z++) {
+            const timeZoneContainer = timeZoneContainers[z];
+            const diffElement = timeZoneContainer.querySelector('[data-time-diff]');
+
+            const setZoneTime = makeSettableTimeElement(
+                timeZoneContainer.querySelector('[data-time]'),
+                hourFormat
+            );
+
+            updateCallbacks.push((now) => {
+                const { time, diffInHours } = timeInZone(now, timeZoneContainer.dataset.timeInZone);
+                setZoneTime(time);
+                diffElement.textContent = (diffInHours <= 0 ? diffInHours : '+' + diffInHours) + 'h';
+            });
+        }
+    }
+
+    const updateClocks = () => {
+        const now = new Date();
+
+        for (var i = 0; i < updateCallbacks.length; i++)
+            updateCallbacks[i](now);
+
+        setTimeout(updateClocks, (60 - now.getSeconds()) * 1000);
+    };
+
+    updateClocks();
 }
 
 async function setupPage() {