Adding upstream version 9.0.3.

Signed-off-by: Daniel Baumann <daniel@debian.org>

14 files changed, 1007 insertions, 0 deletions

diff --git a/web_src/js/utils.js b/web_src/js/utils.js
new file mode 100644
index 0000000..ce0fb66
--- /dev/null
+++ b/web_src/js/utils.js
@@ -0,0 +1,144 @@
+import {encode, decode} from 'uint8-to-base64';
+
+// transform /path/to/file.ext to file.ext
+export function basename(path = '') {
+  const lastSlashIndex = path.lastIndexOf('/');
+  return lastSlashIndex < 0 ? path : path.substring(lastSlashIndex + 1);
+}
+
+// transform /path/to/file.ext to .ext
+export function extname(path = '') {
+  const lastPointIndex = path.lastIndexOf('.');
+  return lastPointIndex < 0 ? '' : path.substring(lastPointIndex);
+}
+
+// test whether a variable is an object
+export function isObject(obj) {
+  return Object.prototype.toString.call(obj) === '[object Object]';
+}
+
+// returns whether a dark theme is enabled
+export function isDarkTheme() {
+  const style = window.getComputedStyle(document.documentElement);
+  return style.getPropertyValue('--is-dark-theme').trim().toLowerCase() === 'true';
+}
+
+// strip <tags> from a string
+export function stripTags(text) {
+  return text.replace(/<[^>]*>?/g, '');
+}
+
+export function parseIssueHref(href) {
+  const path = (href || '').replace(/[#?].*$/, '');
+  const [_, owner, repo, type, index] = /([^/]+)\/([^/]+)\/(issues|pulls)\/([0-9]+)/.exec(path) || [];
+  return {owner, repo, type, index};
+}
+
+// parse a URL, either relative '/path' or absolute 'https://localhost/path'
+export function parseUrl(str) {
+  return new URL(str, str.startsWith('http') ? undefined : window.location.origin);
+}
+
+// return current locale chosen by user
+export function getCurrentLocale() {
+  return document.documentElement.lang;
+}
+
+// given a month (0-11), returns it in the documents language
+export function translateMonth(month) {
+  return new Date(Date.UTC(2022, month, 12)).toLocaleString(getCurrentLocale(), {month: 'short', timeZone: 'UTC'});
+}
+
+// given a weekday (0-6, Sunday to Saturday), returns it in the documents language
+export function translateDay(day) {
+  return new Date(Date.UTC(2022, 7, day)).toLocaleString(getCurrentLocale(), {weekday: 'short', timeZone: 'UTC'});
+}
+
+// convert a Blob to a DataURI
+export function blobToDataURI(blob) {
+  return new Promise((resolve, reject) => {
+    try {
+      const reader = new FileReader();
+      reader.addEventListener('load', (e) => {
+        resolve(e.target.result);
+      });
+      reader.addEventListener('error', () => {
+        reject(new Error('FileReader failed'));
+      });
+      reader.readAsDataURL(blob);
+    } catch (err) {
+      reject(err);
+    }
+  });
+}
+
+// convert image Blob to another mime-type format.
+export function convertImage(blob, mime) {
+  return new Promise(async (resolve, reject) => {
+    try {
+      const img = new Image();
+      const canvas = document.createElement('canvas');
+      img.addEventListener('load', () => {
+        try {
+          canvas.width = img.naturalWidth;
+          canvas.height = img.naturalHeight;
+          const context = canvas.getContext('2d');
+          context.drawImage(img, 0, 0);
+          canvas.toBlob((blob) => {
+            if (!(blob instanceof Blob)) return reject(new Error('imageBlobToPng failed'));
+            resolve(blob);
+          }, mime);
+        } catch (err) {
+          reject(err);
+        }
+      });
+      img.addEventListener('error', () => {
+        reject(new Error('imageBlobToPng failed'));
+      });
+      img.src = await blobToDataURI(blob);
+    } catch (err) {
+      reject(err);
+    }
+  });
+}
+
+export function toAbsoluteUrl(url) {
+  if (url.startsWith('http://') || url.startsWith('https://')) {
+    return url;
+  }
+  if (url.startsWith('//')) {
+    return `${window.location.protocol}${url}`; // it's also a somewhat absolute URL (with the current scheme)
+  }
+  if (url && !url.startsWith('/')) {
+    throw new Error('unsupported url, it should either start with / or http(s)://');
+  }
+  return `${window.location.origin}${url}`;
+}
+
+// Encode an ArrayBuffer into a URLEncoded base64 string.
+export function encodeURLEncodedBase64(arrayBuffer) {
+  return encode(arrayBuffer)
+    .replace(/\+/g, '-')
+    .replace(/\//g, '_')
+    .replace(/=/g, '');
+}
+
+// Decode a URLEncoded base64 to an ArrayBuffer string.
+export function decodeURLEncodedBase64(base64url) {
+  return decode(base64url
+    .replace(/_/g, '/')
+    .replace(/-/g, '+'));
+}
+
+const domParser = new DOMParser();
+const xmlSerializer = new XMLSerializer();
+
+export function parseDom(text, contentType) {
+  return domParser.parseFromString(text, contentType);
+}
+
+export function serializeXml(node) {
+  return xmlSerializer.serializeToString(node);
+}
+
+export const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
diff --git a/web_src/js/utils.test.js b/web_src/js/utils.test.js
new file mode 100644
index 0000000..c49bb2a
--- /dev/null
+++ b/web_src/js/utils.test.js
@@ -0,0 +1,189 @@
+import {
+  basename, extname, isObject, stripTags, parseIssueHref,
+  parseUrl, translateMonth, translateDay, blobToDataURI,
+  toAbsoluteUrl, encodeURLEncodedBase64, decodeURLEncodedBase64,
+  isDarkTheme, getCurrentLocale, parseDom, serializeXml, sleep,
+} from './utils.js';
+
+afterEach(() => {
+  // Reset head and body sections of the document
+  document.documentElement.innerHTML = '<head></head><body></body>';
+
+  // Remove 'lang' and 'style' attributes of html tag
+  document.documentElement.removeAttribute('lang');
+  document.documentElement.removeAttribute('style');
+});
+
+test('basename', () => {
+  expect(basename('/path/to/file.js')).toEqual('file.js');
+  expect(basename('/path/to/file')).toEqual('file');
+  expect(basename('file.js')).toEqual('file.js');
+});
+
+test('extname', () => {
+  expect(extname('/path/to/file.js')).toEqual('.js');
+  expect(extname('/path/')).toEqual('');
+  expect(extname('/path')).toEqual('');
+  expect(extname('file.js')).toEqual('.js');
+});
+
+test('isObject', () => {
+  expect(isObject({})).toBeTruthy();
+  expect(isObject([])).toBeFalsy();
+});
+
+test('should return true if dark theme is enabled', () => {
+  // When --is-dark-theme var is defined with value true
+  document.documentElement.style.setProperty('--is-dark-theme', 'true');
+  expect(isDarkTheme()).toBeTruthy();
+
+  // when --is-dark-theme var is defined with value TRUE
+  document.documentElement.style.setProperty('--is-dark-theme', 'TRUE');
+  expect(isDarkTheme()).toBeTruthy();
+});
+
+test('should return false if dark theme is disabled', () => {
+  // when --is-dark-theme var is defined with value false
+  document.documentElement.style.setProperty('--is-dark-theme', 'false');
+  expect(isDarkTheme()).toBeFalsy();
+
+  // when --is-dark-theme var is defined with value FALSE
+  document.documentElement.style.setProperty('--is-dark-theme', 'FALSE');
+  expect(isDarkTheme()).toBeFalsy();
+});
+
+test('should return false if dark theme is not defined', () => {
+  // when --is-dark-theme var is not exist
+  expect(isDarkTheme()).toBeFalsy();
+});
+
+test('stripTags', () => {
+  expect(stripTags('<a>test</a>')).toEqual('test');
+});
+
+test('parseIssueHref', () => {
+  expect(parseIssueHref('/owner/repo/issues/1')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('/owner/repo/pulls/1?query')).toEqual({owner: 'owner', repo: 'repo', type: 'pulls', index: '1'});
+  expect(parseIssueHref('/owner/repo/issues/1#hash')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('/sub/owner/repo/issues/1')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('/sub/sub2/owner/repo/pulls/1')).toEqual({owner: 'owner', repo: 'repo', type: 'pulls', index: '1'});
+  expect(parseIssueHref('/sub/sub2/owner/repo/issues/1?query')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('/sub/sub2/owner/repo/issues/1#hash')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('https://example.com/owner/repo/issues/1')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('https://example.com/owner/repo/pulls/1?query')).toEqual({owner: 'owner', repo: 'repo', type: 'pulls', index: '1'});
+  expect(parseIssueHref('https://example.com/owner/repo/issues/1#hash')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('https://example.com/sub/owner/repo/issues/1')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('https://example.com/sub/sub2/owner/repo/pulls/1')).toEqual({owner: 'owner', repo: 'repo', type: 'pulls', index: '1'});
+  expect(parseIssueHref('https://example.com/sub/sub2/owner/repo/issues/1?query')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('https://example.com/sub/sub2/owner/repo/issues/1#hash')).toEqual({owner: 'owner', repo: 'repo', type: 'issues', index: '1'});
+  expect(parseIssueHref('')).toEqual({owner: undefined, repo: undefined, type: undefined, index: undefined});
+});
+
+test('parseUrl', () => {
+  expect(parseUrl('').pathname).toEqual('/');
+  expect(parseUrl('/path').pathname).toEqual('/path');
+  expect(parseUrl('/path?search').pathname).toEqual('/path');
+  expect(parseUrl('/path?search').search).toEqual('?search');
+  expect(parseUrl('/path?search#hash').hash).toEqual('#hash');
+  expect(parseUrl('https://localhost/path').pathname).toEqual('/path');
+  expect(parseUrl('https://localhost/path?search').pathname).toEqual('/path');
+  expect(parseUrl('https://localhost/path?search').search).toEqual('?search');
+  expect(parseUrl('https://localhost/path?search#hash').hash).toEqual('#hash');
+});
+
+test('getCurrentLocale', () => {
+  // HTML document without explicit lang
+  expect(getCurrentLocale()).toEqual('');
+
+  // HTML document with explicit lang
+  document.documentElement.setAttribute('lang', 'en-US');
+  expect(getCurrentLocale()).toEqual('en-US');
+});
+
+test('translateMonth', () => {
+  const originalLang = document.documentElement.lang;
+  document.documentElement.lang = 'en-US';
+  expect(translateMonth(0)).toEqual('Jan');
+  expect(translateMonth(4)).toEqual('May');
+  document.documentElement.lang = 'es-ES';
+  expect(translateMonth(5)).toEqual('jun');
+  expect(translateMonth(6)).toEqual('jul');
+  document.documentElement.lang = originalLang;
+});
+
+test('translateDay', () => {
+  const originalLang = document.documentElement.lang;
+  document.documentElement.lang = 'fr-FR';
+  expect(translateDay(1)).toEqual('lun.');
+  expect(translateDay(5)).toEqual('ven.');
+  document.documentElement.lang = 'pl-PL';
+  expect(translateDay(1)).toEqual('pon.');
+  expect(translateDay(5)).toEqual('pt.');
+  document.documentElement.lang = originalLang;
+});
+
+test('blobToDataURI', async () => {
+  const blob = new Blob([JSON.stringify({test: true})], {type: 'application/json'});
+  expect(await blobToDataURI(blob)).toEqual('data:application/json;base64,eyJ0ZXN0Ijp0cnVlfQ==');
+});
+
+test('toAbsoluteUrl', () => {
+  expect(toAbsoluteUrl('//host/dir')).toEqual('http://host/dir');
+  expect(toAbsoluteUrl('https://host/dir')).toEqual('https://host/dir');
+  expect(toAbsoluteUrl('http://host/dir')).toEqual('http://host/dir');
+  expect(toAbsoluteUrl('')).toEqual('http://localhost:3000');
+  expect(toAbsoluteUrl('/user/repo')).toEqual('http://localhost:3000/user/repo');
+  expect(() => toAbsoluteUrl('path')).toThrowError('unsupported');
+});
+
+test('encodeURLEncodedBase64, decodeURLEncodedBase64', () => {
+  // TextEncoder is Node.js API while Uint8Array is jsdom API and their outputs are not
+  // structurally comparable, so we convert to array to compare. The conversion can be
+  // removed once https://github.com/jsdom/jsdom/issues/2524 is resolved.
+  const encoder = new TextEncoder();
+  const uint8array = encoder.encode.bind(encoder);
+
+  expect(encodeURLEncodedBase64(uint8array('AA?'))).toEqual('QUE_'); // standard base64: "QUE/"
+  expect(encodeURLEncodedBase64(uint8array('AA~'))).toEqual('QUF-'); // standard base64: "QUF+"
+
+  expect(Array.from(decodeURLEncodedBase64('QUE/'))).toEqual(Array.from(uint8array('AA?')));
+  expect(Array.from(decodeURLEncodedBase64('QUF+'))).toEqual(Array.from(uint8array('AA~')));
+  expect(Array.from(decodeURLEncodedBase64('QUE_'))).toEqual(Array.from(uint8array('AA?')));
+  expect(Array.from(decodeURLEncodedBase64('QUF-'))).toEqual(Array.from(uint8array('AA~')));
+
+  expect(encodeURLEncodedBase64(uint8array('a'))).toEqual('YQ'); // standard base64: "YQ=="
+  expect(Array.from(decodeURLEncodedBase64('YQ'))).toEqual(Array.from(uint8array('a')));
+  expect(Array.from(decodeURLEncodedBase64('YQ=='))).toEqual(Array.from(uint8array('a')));
+});
+
+test('parseDom', () => {
+  const paragraphStr = 'This is sample paragraph';
+  const paragraphTagStr = `<p>${paragraphStr}</p>`;
+  const content = parseDom(paragraphTagStr, 'text/html');
+  expect(content.body.innerHTML).toEqual(paragraphTagStr);
+
+  // Content should have only one paragraph
+  const paragraphs = content.getElementsByTagName('p');
+  expect(paragraphs.length).toEqual(1);
+  expect(paragraphs[0].textContent).toEqual(paragraphStr);
+});
+
+test('serializeXml', () => {
+  const textStr = 'This is a sample text';
+  const tagName = 'item';
+  const node = document.createElement(tagName);
+  node.textContent = textStr;
+  expect(serializeXml(node)).toEqual(`<${tagName}>${textStr}</${tagName}>`);
+});
+
+test('sleep', async () => {
+  await testSleep(2000);
+});
+
+async function testSleep(ms) {
+  const startTime = Date.now();  // Record the start time
+  await sleep(ms);
+  const endTime = Date.now();    // Record the end time
+  const actualSleepTime = endTime - startTime;
+  expect(actualSleepTime >= ms).toBeTruthy();
+}
diff --git a/web_src/js/utils/color.js b/web_src/js/utils/color.js
new file mode 100644
index 0000000..198f97c
--- /dev/null
+++ b/web_src/js/utils/color.js
@@ -0,0 +1,33 @@
+import tinycolor from 'tinycolor2';
+
+// Returns relative luminance for a SRGB color - https://en.wikipedia.org/wiki/Relative_luminance
+// Keep this in sync with modules/util/color.go
+function getRelativeLuminance(color) {
+  const {r, g, b} = tinycolor(color).toRgb();
+  return (0.2126729 * r + 0.7151522 * g + 0.072175 * b) / 255;
+}
+
+function useLightText(backgroundColor) {
+  return getRelativeLuminance(backgroundColor) < 0.453;
+}
+
+// Given a background color, returns a black or white foreground color that the highest
+// contrast ratio. In the future, the APCA contrast function, or CSS `contrast-color` will be better.
+// https://github.com/color-js/color.js/blob/eb7b53f7a13bb716ec8b28c7a56f052cd599acd9/src/contrast/APCA.js#L42
+export function contrastColor(backgroundColor) {
+  return useLightText(backgroundColor) ? '#fff' : '#000';
+}
+
+function resolveColors(obj) {
+  const styles = window.getComputedStyle(document.documentElement);
+  const getColor = (name) => styles.getPropertyValue(name).trim();
+  return Object.fromEntries(Object.entries(obj).map(([key, value]) => [key, getColor(value)]));
+}
+
+export const chartJsColors = resolveColors({
+  text: '--color-text',
+  border: '--color-secondary-alpha-60',
+  commits: '--color-primary-alpha-60',
+  additions: '--color-green',
+  deletions: '--color-red',
+});
diff --git a/web_src/js/utils/color.test.js b/web_src/js/utils/color.test.js
new file mode 100644
index 0000000..fee9afc
--- /dev/null
+++ b/web_src/js/utils/color.test.js
@@ -0,0 +1,22 @@
+import {contrastColor} from './color.js';
+
+test('contrastColor', () => {
+  expect(contrastColor('#d73a4a')).toBe('#fff');
+  expect(contrastColor('#0075ca')).toBe('#fff');
+  expect(contrastColor('#cfd3d7')).toBe('#000');
+  expect(contrastColor('#a2eeef')).toBe('#000');
+  expect(contrastColor('#7057ff')).toBe('#fff');
+  expect(contrastColor('#008672')).toBe('#fff');
+  expect(contrastColor('#e4e669')).toBe('#000');
+  expect(contrastColor('#d876e3')).toBe('#000');
+  expect(contrastColor('#ffffff')).toBe('#000');
+  expect(contrastColor('#2b8684')).toBe('#fff');
+  expect(contrastColor('#2b8786')).toBe('#fff');
+  expect(contrastColor('#2c8786')).toBe('#000');
+  expect(contrastColor('#3bb6b3')).toBe('#000');
+  expect(contrastColor('#7c7268')).toBe('#fff');
+  expect(contrastColor('#7e716c')).toBe('#fff');
+  expect(contrastColor('#81706d')).toBe('#fff');
+  expect(contrastColor('#807070')).toBe('#fff');
+  expect(contrastColor('#84b6eb')).toBe('#000');
+});
diff --git a/web_src/js/utils/dom.js b/web_src/js/utils/dom.js
new file mode 100644
index 0000000..44adc79
--- /dev/null
+++ b/web_src/js/utils/dom.js
@@ -0,0 +1,305 @@
+import {debounce} from 'throttle-debounce';
+
+function elementsCall(el, func, ...args) {
+  if (typeof el === 'string' || el instanceof String) {
+    el = document.querySelectorAll(el);
+  }
+  if (el instanceof Node) {
+    func(el, ...args);
+  } else if (el.length !== undefined) {
+    // this works for: NodeList, HTMLCollection, Array, jQuery
+    for (const e of el) {
+      func(e, ...args);
+    }
+  } else {
+    throw new Error('invalid argument to be shown/hidden');
+  }
+}
+
+/**
+ * @param el string (selector), Node, NodeList, HTMLCollection, Array or jQuery
+ * @param force force=true to show or force=false to hide, undefined to toggle
+ */
+function toggleShown(el, force) {
+  if (force === true) {
+    el.classList.remove('tw-hidden');
+  } else if (force === false) {
+    el.classList.add('tw-hidden');
+  } else if (force === undefined) {
+    el.classList.toggle('tw-hidden');
+  } else {
+    throw new Error('invalid force argument');
+  }
+}
+
+export function showElem(el) {
+  elementsCall(el, toggleShown, true);
+}
+
+export function hideElem(el) {
+  elementsCall(el, toggleShown, false);
+}
+
+export function toggleElem(el, force) {
+  elementsCall(el, toggleShown, force);
+}
+
+export function isElemHidden(el) {
+  const res = [];
+  elementsCall(el, (e) => res.push(e.classList.contains('tw-hidden')));
+  if (res.length > 1) throw new Error(`isElemHidden doesn't work for multiple elements`);
+  return res[0];
+}
+
+function applyElemsCallback(elems, fn) {
+  if (fn) {
+    for (const el of elems) {
+      fn(el);
+    }
+  }
+  return elems;
+}
+
+export function queryElemSiblings(el, selector = '*', fn) {
+  return applyElemsCallback(Array.from(el.parentNode.children).filter((child) => child !== el && child.matches(selector)), fn);
+}
+
+// it works like jQuery.children: only the direct children are selected
+export function queryElemChildren(parent, selector = '*', fn) {
+  return applyElemsCallback(parent.querySelectorAll(`:scope > ${selector}`), fn);
+}
+
+export function queryElems(selector, fn) {
+  return applyElemsCallback(document.querySelectorAll(selector), fn);
+}
+
+export function onDomReady(cb) {
+  if (document.readyState === 'loading') {
+    document.addEventListener('DOMContentLoaded', cb);
+  } else {
+    cb();
+  }
+}
+
+// checks whether an element is owned by the current document, and whether it is a document fragment or element node
+// if it is, it means it is a "normal" element managed by us, which can be modified safely.
+export function isDocumentFragmentOrElementNode(el) {
+  try {
+    return el.ownerDocument === document && el.nodeType === Node.ELEMENT_NODE || el.nodeType === Node.DOCUMENT_FRAGMENT_NODE;
+  } catch {
+    // in case the el is not in the same origin, then the access to nodeType would fail
+    return false;
+  }
+}
+
+// autosize a textarea to fit content. Based on
+// https://github.com/github/textarea-autosize
+// ---------------------------------------------------------------------
+// Copyright (c) 2018 GitHub, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to
+// permit persons to whom the Software is furnished to do so, subject to
+// the following conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+// ---------------------------------------------------------------------
+export function autosize(textarea, {viewportMarginBottom = 0} = {}) {
+  let isUserResized = false;
+  // lastStyleHeight and initialStyleHeight are CSS values like '100px'
+  let lastMouseX, lastMouseY, lastStyleHeight, initialStyleHeight;
+
+  function onUserResize(event) {
+    if (isUserResized) return;
+    if (lastMouseX !== event.clientX || lastMouseY !== event.clientY) {
+      const newStyleHeight = textarea.style.height;
+      if (lastStyleHeight && lastStyleHeight !== newStyleHeight) {
+        isUserResized = true;
+      }
+      lastStyleHeight = newStyleHeight;
+    }
+
+    lastMouseX = event.clientX;
+    lastMouseY = event.clientY;
+  }
+
+  function overflowOffset() {
+    let offsetTop = 0;
+    let el = textarea;
+
+    while (el !== document.body && el !== null) {
+      offsetTop += el.offsetTop || 0;
+      el = el.offsetParent;
+    }
+
+    const top = offsetTop - document.defaultView.scrollY;
+    const bottom = document.documentElement.clientHeight - (top + textarea.offsetHeight);
+    return {top, bottom};
+  }
+
+  function resizeToFit() {
+    if (isUserResized) return;
+    if (textarea.offsetWidth <= 0 && textarea.offsetHeight <= 0) return;
+
+    try {
+      const {top, bottom} = overflowOffset();
+      const isOutOfViewport = top < 0 || bottom < 0;
+
+      const computedStyle = getComputedStyle(textarea);
+      const topBorderWidth = parseFloat(computedStyle.borderTopWidth);
+      const bottomBorderWidth = parseFloat(computedStyle.borderBottomWidth);
+      const isBorderBox = computedStyle.boxSizing === 'border-box';
+      const borderAddOn = isBorderBox ? topBorderWidth + bottomBorderWidth : 0;
+
+      const adjustedViewportMarginBottom = bottom < viewportMarginBottom ? bottom : viewportMarginBottom;
+      const curHeight = parseFloat(computedStyle.height);
+      const maxHeight = curHeight + bottom - adjustedViewportMarginBottom;
+
+      textarea.style.height = 'auto';
+      let newHeight = textarea.scrollHeight + borderAddOn;
+
+      if (isOutOfViewport) {
+        // it is already out of the viewport:
+        // * if the textarea is expanding: do not resize it
+        if (newHeight > curHeight) {
+          newHeight = curHeight;
+        }
+        // * if the textarea is shrinking, shrink line by line (just use the
+        //   scrollHeight). do not apply max-height limit, otherwise the page
+        //   flickers and the textarea jumps
+      } else {
+        // * if it is in the viewport, apply the max-height limit
+        newHeight = Math.min(maxHeight, newHeight);
+      }
+
+      textarea.style.height = `${newHeight}px`;
+      lastStyleHeight = textarea.style.height;
+    } finally {
+      // ensure that the textarea is fully scrolled to the end, when the cursor
+      // is at the end during an input event
+      if (textarea.selectionStart === textarea.selectionEnd &&
+          textarea.selectionStart === textarea.value.length) {
+        textarea.scrollTop = textarea.scrollHeight;
+      }
+    }
+  }
+
+  function onFormReset() {
+    isUserResized = false;
+    if (initialStyleHeight !== undefined) {
+      textarea.style.height = initialStyleHeight;
+    } else {
+      textarea.style.removeProperty('height');
+    }
+  }
+
+  textarea.addEventListener('mousemove', onUserResize);
+  textarea.addEventListener('input', resizeToFit);
+  textarea.form?.addEventListener('reset', onFormReset);
+  initialStyleHeight = textarea.style.height ?? undefined;
+  if (textarea.value) resizeToFit();
+
+  return {
+    resizeToFit,
+    destroy() {
+      textarea.removeEventListener('mousemove', onUserResize);
+      textarea.removeEventListener('input', resizeToFit);
+      textarea.form?.removeEventListener('reset', onFormReset);
+    },
+  };
+}
+
+export function onInputDebounce(fn) {
+  return debounce(300, fn);
+}
+
+// Set the `src` attribute on an element and returns a promise that resolves once the element
+// has loaded or errored. Suitable for all elements mention in:
+// https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/load_event
+export function loadElem(el, src) {
+  return new Promise((resolve) => {
+    el.addEventListener('load', () => resolve(true), {once: true});
+    el.addEventListener('error', () => resolve(false), {once: true});
+    el.src = src;
+  });
+}
+
+// some browsers like PaleMoon don't have "SubmitEvent" support, so polyfill it by a tricky method: use the last clicked button as submitter
+// it can't use other transparent polyfill patches because PaleMoon also doesn't support "addEventListener(capture)"
+const needSubmitEventPolyfill = typeof SubmitEvent === 'undefined';
+
+export function submitEventSubmitter(e) {
+  return needSubmitEventPolyfill ? (e.target._submitter || null) : e.submitter;
+}
+
+function submitEventPolyfillListener(e) {
+  const form = e.target.closest('form');
+  if (!form) return;
+  form._submitter = e.target.closest('button:not([type]), button[type="submit"], input[type="submit"]');
+}
+
+export function initSubmitEventPolyfill() {
+  if (!needSubmitEventPolyfill) return;
+  console.warn(`This browser doesn't have "SubmitEvent" support, use a tricky method to polyfill`);
+  document.body.addEventListener('click', submitEventPolyfillListener);
+  document.body.addEventListener('focus', submitEventPolyfillListener);
+}
+
+/**
+ * Check if an element is visible, equivalent to jQuery's `:visible` pseudo.
+ * Note: This function doesn't account for all possible visibility scenarios.
+ * @param {HTMLElement} element The element to check.
+ * @returns {boolean} True if the element is visible.
+ */
+export function isElemVisible(element) {
+  if (!element) return false;
+
+  return Boolean(element.offsetWidth || element.offsetHeight || element.getClientRects().length);
+}
+
+// extract text and images from "paste" event
+export function getPastedContent(e) {
+  const images = [];
+  for (const item of e.clipboardData?.items ?? []) {
+    if (item.type?.startsWith('image/')) {
+      images.push(item.getAsFile());
+    }
+  }
+  const text = e.clipboardData?.getData?.('text') ?? '';
+  return {text, images};
+}
+
+// replace selected text in a textarea while preserving editor history, e.g. CTRL-Z works after this
+export function replaceTextareaSelection(textarea, text) {
+  const before = textarea.value.slice(0, textarea.selectionStart ?? undefined);
+  const after = textarea.value.slice(textarea.selectionEnd ?? undefined);
+  let success = true;
+
+  textarea.contentEditable = 'true';
+  try {
+    success = document.execCommand('insertText', false, text);
+  } catch {
+    success = false;
+  }
+  textarea.contentEditable = 'false';
+
+  if (success && !textarea.value.slice(0, textarea.selectionStart ?? undefined).endsWith(text)) {
+    success = false;
+  }
+
+  if (!success) {
+    textarea.value = `${before}${text}${after}`;
+    textarea.dispatchEvent(new CustomEvent('change', {bubbles: true, cancelable: true}));
+  }
+}
+
+// Warning: Do not enter any unsanitized variables here
+export function createElementFromHTML(htmlString) {
+  const div = document.createElement('div');
+  div.innerHTML = htmlString.trim();
+  return div.firstChild;
+}
diff --git a/web_src/js/utils/dom.test.js b/web_src/js/utils/dom.test.js
new file mode 100644
index 0000000..fd7d97c
--- /dev/null
+++ b/web_src/js/utils/dom.test.js
@@ -0,0 +1,5 @@
+import {createElementFromHTML} from './dom.js';
+
+test('createElementFromHTML', () => {
+  expect(createElementFromHTML('<a>foo<span>bar</span></a>').outerHTML).toEqual('<a>foo<span>bar</span></a>');
+});
diff --git a/web_src/js/utils/image.js b/web_src/js/utils/image.js
new file mode 100644
index 0000000..ed5d98e
--- /dev/null
+++ b/web_src/js/utils/image.js
@@ -0,0 +1,47 @@
+export async function pngChunks(blob) {
+  const uint8arr = new Uint8Array(await blob.arrayBuffer());
+  const chunks = [];
+  if (uint8arr.length < 12) return chunks;
+  const view = new DataView(uint8arr.buffer);
+  if (view.getBigUint64(0) !== 9894494448401390090n) return chunks;
+
+  const decoder = new TextDecoder();
+  let index = 8;
+  while (index < uint8arr.length) {
+    const len = view.getUint32(index);
+    chunks.push({
+      name: decoder.decode(uint8arr.slice(index + 4, index + 8)),
+      data: uint8arr.slice(index + 8, index + 8 + len),
+    });
+    index += len + 12;
+  }
+
+  return chunks;
+}
+
+// decode a image and try to obtain width and dppx. If will never throw but instead
+// return default values.
+export async function imageInfo(blob) {
+  let width = 0; // 0 means no width could be determined
+  let dppx = 1; // 1 dot per pixel for non-HiDPI screens
+
+  if (blob.type === 'image/png') { // only png is supported currently
+    try {
+      for (const {name, data} of await pngChunks(blob)) {
+        const view = new DataView(data.buffer);
+        if (name === 'IHDR' && data?.length) {
+          // extract width from mandatory IHDR chunk
+          width = view.getUint32(0);
+        } else if (name === 'pHYs' && data?.length) {
+          // extract dppx from optional pHYs chunk, assuming pixels are square
+          const unit = view.getUint8(8);
+          if (unit === 1) {
+            dppx = Math.round(view.getUint32(0) / 39.3701) / 72; // meter to inch to dppx
+          }
+        }
+      }
+    } catch {}
+  }
+
+  return {width, dppx};
+}
diff --git a/web_src/js/utils/image.test.js b/web_src/js/utils/image.test.js
new file mode 100644
index 0000000..ba47582
--- /dev/null
+++ b/web_src/js/utils/image.test.js
@@ -0,0 +1,29 @@
+import {pngChunks, imageInfo} from './image.js';
+
+const pngNoPhys = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAAAAAA6fptVAAAADUlEQVQIHQECAP3/AAAAAgABzePRKwAAAABJRU5ErkJggg==';
+const pngPhys = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAIAAAD91JpzAAAACXBIWXMAABYlAAAWJQFJUiTwAAAAEElEQVQI12OQNZcAIgYIBQAL8gGxdzzM0A==';
+const pngEmpty = 'data:image/png;base64,';
+
+async function dataUriToBlob(datauri) {
+  return await (await globalThis.fetch(datauri)).blob();
+}
+
+test('pngChunks', async () => {
+  expect(await pngChunks(await dataUriToBlob(pngNoPhys))).toEqual([
+    {name: 'IHDR', data: new Uint8Array([0, 0, 0, 1, 0, 0, 0, 1, 8, 0, 0, 0, 0])},
+    {name: 'IDAT', data: new Uint8Array([8, 29, 1, 2, 0, 253, 255, 0, 0, 0, 2, 0, 1])},
+    {name: 'IEND', data: new Uint8Array([])},
+  ]);
+  expect(await pngChunks(await dataUriToBlob(pngPhys))).toEqual([
+    {name: 'IHDR', data: new Uint8Array([0, 0, 0, 2, 0, 0, 0, 2, 8, 2, 0, 0, 0])},
+    {name: 'pHYs', data: new Uint8Array([0, 0, 22, 37, 0, 0, 22, 37, 1])},
+    {name: 'IDAT', data: new Uint8Array([8, 215, 99, 144, 53, 151, 0, 34, 6, 8, 5, 0, 11, 242, 1, 177])},
+  ]);
+  expect(await pngChunks(await dataUriToBlob(pngEmpty))).toEqual([]);
+});
+
+test('imageInfo', async () => {
+  expect(await imageInfo(await dataUriToBlob(pngNoPhys))).toEqual({width: 1, dppx: 1});
+  expect(await imageInfo(await dataUriToBlob(pngPhys))).toEqual({width: 2, dppx: 2});
+  expect(await imageInfo(await dataUriToBlob(pngEmpty))).toEqual({width: 0, dppx: 1});
+});
diff --git a/web_src/js/utils/match.js b/web_src/js/utils/match.js
new file mode 100644
index 0000000..17fdfed
--- /dev/null
+++ b/web_src/js/utils/match.js
@@ -0,0 +1,43 @@
+import emojis from '../../../assets/emoji.json';
+
+const maxMatches = 6;
+
+function sortAndReduce(map) {
+  const sortedMap = new Map(Array.from(map.entries()).sort((a, b) => a[1] - b[1]));
+  return Array.from(sortedMap.keys()).slice(0, maxMatches);
+}
+
+export function matchEmoji(queryText) {
+  const query = queryText.toLowerCase().replaceAll('_', ' ');
+  if (!query) return emojis.slice(0, maxMatches).map((e) => e.aliases[0]);
+
+  // results is a map of weights, lower is better
+  const results = new Map();
+  for (const {aliases} of emojis) {
+    const mainAlias = aliases[0];
+    for (const [aliasIndex, alias] of aliases.entries()) {
+      const index = alias.replaceAll('_', ' ').indexOf(query);
+      if (index === -1) continue;
+      const existing = results.get(mainAlias);
+      const rankedIndex = index + aliasIndex;
+      results.set(mainAlias, existing ? existing - rankedIndex : rankedIndex);
+    }
+  }
+
+  return sortAndReduce(results);
+}
+
+export function matchMention(queryText) {
+  const query = queryText.toLowerCase();
+
+  // results is a map of weights, lower is better
+  const results = new Map();
+  for (const obj of window.config.mentionValues ?? []) {
+    const index = obj.key.toLowerCase().indexOf(query);
+    if (index === -1) continue;
+    const existing = results.get(obj);
+    results.set(obj, existing ? existing - index : index);
+  }
+
+  return sortAndReduce(results);
+}
diff --git a/web_src/js/utils/match.test.js b/web_src/js/utils/match.test.js
new file mode 100644
index 0000000..1e30b45
--- /dev/null
+++ b/web_src/js/utils/match.test.js
@@ -0,0 +1,50 @@
+import {matchEmoji, matchMention} from './match.js';
+
+test('matchEmoji', () => {
+  expect(matchEmoji('')).toEqual([
+    '+1',
+    '-1',
+    '100',
+    '1234',
+    '1st_place_medal',
+    '2nd_place_medal',
+  ]);
+
+  expect(matchEmoji('hea')).toEqual([
+    'headphones',
+    'headstone',
+    'health_worker',
+    'hear_no_evil',
+    'heard_mcdonald_islands',
+    'heart',
+  ]);
+
+  expect(matchEmoji('hear')).toEqual([
+    'hear_no_evil',
+    'heard_mcdonald_islands',
+    'heart',
+    'heart_decoration',
+    'heart_eyes',
+    'heart_eyes_cat',
+  ]);
+
+  expect(matchEmoji('poo')).toEqual([
+    'poodle',
+    'hankey',
+    'spoon',
+    'bowl_with_spoon',
+  ]);
+
+  expect(matchEmoji('1st_')).toEqual([
+    '1st_place_medal',
+  ]);
+
+  expect(matchEmoji('jellyfis')).toEqual([
+    'jellyfish',
+  ]);
+});
+
+test('matchMention', () => {
+  expect(matchMention('')).toEqual(window.config.mentionValues.slice(0, 6));
+  expect(matchMention('user4')).toEqual([window.config.mentionValues[3]]);
+});
diff --git a/web_src/js/utils/time.js b/web_src/js/utils/time.js
new file mode 100644
index 0000000..7c7eabd
--- /dev/null
+++ b/web_src/js/utils/time.js
@@ -0,0 +1,72 @@
+import dayjs from 'dayjs';
+import utc from 'dayjs/plugin/utc.js';
+import {getCurrentLocale} from '../utils.js';
+
+dayjs.extend(utc);
+
+/**
+ * Returns an array of millisecond-timestamps of start-of-week days (Sundays)
+ *
+ * @param startConfig The start date. Can take any type that `Date` accepts.
+ * @param endConfig The end date. Can take any type that `Date` accepts.
+ */
+export function startDaysBetween(startDate, endDate) {
+  const start = dayjs.utc(startDate);
+  const end = dayjs.utc(endDate);
+
+  let current = start;
+
+  // Ensure the start date is a Sunday
+  while (current.day() !== 0) {
+    current = current.add(1, 'day');
+  }
+
+  const startDays = [];
+  while (current.isBefore(end)) {
+    startDays.push(current.valueOf());
+    current = current.add(1, 'week');
+  }
+
+  return startDays;
+}
+
+export function firstStartDateAfterDate(inputDate) {
+  if (!(inputDate instanceof Date)) {
+    throw new Error('Invalid date');
+  }
+  const dayOfWeek = inputDate.getUTCDay();
+  const daysUntilSunday = 7 - dayOfWeek;
+  const resultDate = new Date(inputDate.getTime());
+  resultDate.setUTCDate(resultDate.getUTCDate() + daysUntilSunday);
+  return resultDate.valueOf();
+}
+
+export function fillEmptyStartDaysWithZeroes(startDays, data) {
+  const result = {};
+
+  for (const startDay of startDays) {
+    result[startDay] = data[startDay] || {'week': startDay, 'additions': 0, 'deletions': 0, 'commits': 0};
+  }
+
+  return Object.values(result);
+}
+
+let dateFormat;
+
+// format a Date object to document's locale, but with 24h format from user's current locale because this
+// option is a personal preference of the user, not something that the document's locale should dictate.
+export function formatDatetime(date) {
+  if (!dateFormat) {
+    // TODO: replace `hour12` with `Intl.Locale.prototype.getHourCycles` once there is broad browser support
+    dateFormat = new Intl.DateTimeFormat(getCurrentLocale(), {
+      day: 'numeric',
+      month: 'short',
+      year: 'numeric',
+      hour: 'numeric',
+      hour12: !Number.isInteger(Number(new Intl.DateTimeFormat([], {hour: 'numeric'}).format())),
+      minute: '2-digit',
+      timeZoneName: 'short',
+    });
+  }
+  return dateFormat.format(date);
+}
diff --git a/web_src/js/utils/time.test.js b/web_src/js/utils/time.test.js
new file mode 100644
index 0000000..dbe5d7d
--- /dev/null
+++ b/web_src/js/utils/time.test.js
@@ -0,0 +1,40 @@
+import {firstStartDateAfterDate, startDaysBetween, fillEmptyStartDaysWithZeroes} from './time.js';
+
+test('startDaysBetween', () => {
+  expect(startDaysBetween(new Date('2024-02-15'), new Date('2024-04-18'))).toEqual([
+    1708214400000,
+    1708819200000,
+    1709424000000,
+    1710028800000,
+    1710633600000,
+    1711238400000,
+    1711843200000,
+    1712448000000,
+    1713052800000,
+  ]);
+});
+
+test('firstStartDateAfterDate', () => {
+  const expectedDate = new Date('2024-02-18').getTime();
+  expect(firstStartDateAfterDate(new Date('2024-02-15'))).toEqual(expectedDate);
+
+  expect(() => firstStartDateAfterDate('2024-02-15')).toThrowError('Invalid date');
+});
+test('fillEmptyStartDaysWithZeroes with data', () => {
+  expect(fillEmptyStartDaysWithZeroes([1708214400000, 1708819200000, 1708819300000], {
+    1708214400000: {'week': 1708214400000, 'additions': 1, 'deletions': 2, 'commits': 3},
+    1708819200000: {'week': 1708819200000, 'additions': 4, 'deletions': 5, 'commits': 6},
+  })).toEqual([
+    {'week': 1708214400000, 'additions': 1, 'deletions': 2, 'commits': 3},
+    {'week': 1708819200000, 'additions': 4, 'deletions': 5, 'commits': 6},
+    {
+      'additions': 0,
+      'commits': 0,
+      'deletions': 0,
+      'week': 1708819300000,
+    }]);
+});
+
+test('fillEmptyStartDaysWithZeroes with empty array', () => {
+  expect(fillEmptyStartDaysWithZeroes([], {})).toEqual([]);
+});
diff --git a/web_src/js/utils/url.js b/web_src/js/utils/url.js
new file mode 100644
index 0000000..470ece3
--- /dev/null
+++ b/web_src/js/utils/url.js
@@ -0,0 +1,15 @@
+export function pathEscapeSegments(s) {
+  return s.split('/').map(encodeURIComponent).join('/');
+}
+
+function stripSlash(url) {
+  return url.endsWith('/') ? url.slice(0, -1) : url;
+}
+
+export function isUrl(url) {
+  try {
+    return stripSlash((new URL(url).href)).trim() === stripSlash(url).trim();
+  } catch {
+    return false;
+  }
+}
diff --git a/web_src/js/utils/url.test.js b/web_src/js/utils/url.test.js
new file mode 100644
index 0000000..08c6373
--- /dev/null
+++ b/web_src/js/utils/url.test.js
@@ -0,0 +1,13 @@
+import {pathEscapeSegments, isUrl} from './url.js';
+
+test('pathEscapeSegments', () => {
+  expect(pathEscapeSegments('a/b/c')).toEqual('a/b/c');
+  expect(pathEscapeSegments('a/b/ c')).toEqual('a/b/%20c');
+});
+
+test('isUrl', () => {
+  expect(isUrl('https://example.com')).toEqual(true);
+  expect(isUrl('https://example.com/')).toEqual(true);
+  expect(isUrl('https://example.com/index.html')).toEqual(true);
+  expect(isUrl('/index.html')).toEqual(false);
+});