Merge branch 'preview' into album-commentary-tweaks

1 files changed, 779 insertions, 55 deletions

diff --git a/src/static/client3.js b/src/static/client3.js
index 6af548d..af0c381 100644
--- a/src/static/client3.js
+++ b/src/static/client3.js
@@ -81,6 +81,31 @@ function fetchData(type, directory) {
   );
 }
 
+function dispatchInternalEvent(event, eventName, ...args) {
+  const [infoName] =
+    Object.entries(clientInfo)
+      .find(pair => pair[1].event === event);
+
+  if (!infoName) {
+    throw new Error(`Expected event to be stored on clientInfo`);
+  }
+
+  const {[eventName]: listeners} = event;
+
+  if (!listeners) {
+    throw new Error(`Event name "${eventName}" isn't stored on ${infoName}.event`);
+  }
+
+  for (const listener of listeners) {
+    try {
+      listener(...args);
+    } catch (error) {
+      console.warn(`Uncaught error in listener for ${infoName}.${eventName}`);
+      console.debug(error);
+    }
+  }
+}
+
 // JS-based links -----------------------------------------
 
 const scriptedLinkInfo = clientInfo.scriptedLinkInfo = {
@@ -329,17 +354,496 @@ if (
     });
 }
 
-// Data & info card ---------------------------------------
+// Tooltip-style hover (infrastructure) -------------------
+
+const hoverableTooltipInfo = clientInfo.hoverableTooltipInfo = {
+  settings: {
+    // Hovering has two speed settings. The normal setting is used by default,
+    // and once a tooltip is displayed as a result of hover, the entire tooltip
+    // system will enter a "fast hover mode" - hovering will activate tooltips
+    // sooner. "Fast hover mode" is disabled after a sustained duration of not
+    // hovering over any hoverables; it's meant only to accelerate switching
+    // tooltips while still deciding, or getting a quick overview across more
+    // than one tooltip.
+    normalHoverInfoDelay: 400,
+    fastHoveringInfoDelay: 150,
+    endFastHoveringDelay: 500,
+
+    // Focusing has a single speed setting, which is how long it will take to
+    // enter a functional "focus mode" (though it's not actually implemented
+    // in terms of this state). As soon as "focus mode" is entered, the tooltip
+    // for the current hoverable is displayed, and focusing another hoverable
+    // will cause the current tooltip to be swapped for that one immediately.
+    // "Focus mode" ends as soon as anything apart from a tooltip or hoverable
+    // is focused, and it will be necessary to wait on this delay again.
+    focusInfoDelay: 750,
+
+    hideTooltipDelay: 500,
+  },
 
-/*
-const NORMAL_HOVER_INFO_DELAY = 750;
-const FAST_HOVER_INFO_DELAY = 250;
-const END_FAST_HOVER_DELAY = 500;
-const HIDE_HOVER_DELAY = 250;
+  state: {
+    // These maps store a record for each registered element and related state
+    // and registration info, if applicable.
+    registeredTooltips: new Map(),
+    registeredHoverables: new Map(),
+
+    // These are common across all tooltips, rather than stored individually,
+    // based on the principles that 1) only a single tooltip can be displayed
+    // at once, and 2) likewise, only a single hoverable can be hovered,
+    // focused, or otherwise active at once.
+    hoverTimeout: null,
+    focusTimeout: null,
+    touchTimeout: null,
+    hideTimeout: null,
+    currentlyShownTooltip: null,
+    currentlyActiveHoverable: null,
+    tooltipWasJustHidden: false,
+    hoverableWasRecentlyTouched: false,
+
+    // Fast hovering is a global mode which is activated as soon as any tooltip
+    // is displayed and turns off after a delay of no hoverables being hovered.
+    // Note that fast hovering may be turned off while hovering a tooltip, but
+    // it will never be turned off while idling over a hoverable.
+    fastHovering: false,
+    endFastHoveringTimeout: false,
+
+    // These track the identifiers of current touches and a record of current
+    // identifiers that are "banished" by scrolling - that is, touches which
+    // existed while the page scrolled and were probably responsible for that
+    // scrolling. This is a bit loose (we can't actually tell which touches
+    // caused the page to scroll) but it's intended to keep scrolling the page
+    // from causing the current tooltip to be hidden.
+    currentTouchIdentifiers: new Set(),
+    touchIdentifiersBanishedByScrolling: new Set(),
+  },
+
+  event: {
+    whenTooltipShouldBeShown: [],
+    whenTooltipShouldBeHidden: [],
+  },
+};
+
+// Adds DOM event listeners, so must be called during addPageListeners step.
+function registerTooltipElement(tooltip) {
+  const {state} = hoverableTooltipInfo;
+
+  if (!tooltip)
+    throw new Error(`Expected tooltip`);
+
+  if (state.registeredTooltips.has(tooltip))
+    throw new Error(`This tooltip is already registered`);
+
+  // No state or registration info here.
+  state.registeredTooltips.set(tooltip, {});
+
+  tooltip.addEventListener('mouseenter', () => {
+    handleTooltipMouseEntered(tooltip);
+  });
+
+  tooltip.addEventListener('mouseleave', () => {
+    handleTooltipMouseLeft(tooltip);
+  });
+
+  tooltip.addEventListener('focusin', event => {
+    handleTooltipReceivedFocus(tooltip, event.relatedTarget);
+  });
+
+  tooltip.addEventListener('focusout', event => {
+    // This event gets activated for tabbing *between* links inside the
+    // tooltip, which is no good and certainly doesn't represent the focus
+    // leaving the tooltip.
+    if (currentlyShownTooltipHasFocus(event.relatedTarget)) return;
+
+    handleTooltipLostFocus(tooltip, event.relatedTarget);
+  });
+}
+
+// Adds DOM event listeners, so must be called during addPageListeners step.
+function registerTooltipHoverableElement(hoverable, tooltip) {
+  const {state} = hoverableTooltipInfo;
+
+  if (!hoverable || !tooltip)
+    if (hoverable)
+      throw new Error(`Expected hoverable and tooltip, got only hoverable`);
+    else
+      throw new Error(`Expected hoverable and tooltip, got neither`);
+
+  if (!state.registeredTooltips.has(tooltip))
+    throw new Error(`Register tooltip before registering hoverable`);
+
+  if (state.registeredHoverables.has(hoverable))
+    throw new Error(`This hoverable is already registered`);
+
+  state.registeredHoverables.set(hoverable, {tooltip});
+
+  hoverable.addEventListener('mouseenter', () => {
+    handleTooltipHoverableMouseEntered(hoverable);
+  });
+
+  hoverable.addEventListener('mouseleave', () => {
+    handleTooltipHoverableMouseLeft(hoverable);
+  });
+
+  hoverable.addEventListener('focusin', event => {
+    handleTooltipHoverableReceivedFocus(hoverable, event);
+  });
+
+  hoverable.addEventListener('focusout', event => {
+    handleTooltipHoverableLostFocus(hoverable, event);
+  });
+
+  hoverable.addEventListener('touchend', event => {
+    handleTooltipHoverableTouchEnded(hoverable, event);
+  });
+
+  hoverable.addEventListener('click', event => {
+    handleTooltipHoverableClicked(hoverable, event);
+  });
+}
+
+function handleTooltipMouseEntered(tooltip) {
+  const {state} = hoverableTooltipInfo;
+
+  if (state.currentlyShownTooltip !== tooltip) return;
+
+  // Don't time out the current tooltip while hovering it.
+  if (state.hideTimeout) {
+    clearTimeout(state.hideTimeout);
+    state.hideTimeout = null;
+  }
+}
+
+function handleTooltipMouseLeft(tooltip) {
+  const {settings, state} = hoverableTooltipInfo;
+
+  if (state.currentlyShownTooltip !== tooltip) return;
+
+  // Start timing out the current tooltip when it's left. This could be
+  // canceled by mousing over a hoverable, or back over the tooltip again.
+  if (!state.hideTimeout) {
+    state.hideTimeout =
+      setTimeout(() => {
+        state.hideTimeout = null;
+        hideCurrentlyShownTooltip();
+      }, settings.hideTooltipDelay);
+  }
+}
+
+function handleTooltipReceivedFocus(tooltip) {
+  const {state} = hoverableTooltipInfo;
+
+  // Cancel the tooltip-hiding timeout if it exists. The tooltip will never
+  // be hidden while it contains the focus anyway, but this ensures the timeout
+  // will be suitably reset when the tooltip loses focus.
+  if (state.hideTimeout) {
+    clearTimeout(state.hideTimeout);
+    state.hideTimeout = null;
+  }
+}
+
+function handleTooltipLostFocus(tooltip) {
+  const {settings, state} = hoverableTooltipInfo;
+
+  // Hide the current tooltip right away when it loses focus.
+  hideCurrentlyShownTooltip();
+}
+
+function handleTooltipHoverableMouseEntered(hoverable) {
+  const {event, settings, state} = hoverableTooltipInfo;
+
+  const hoverTimeoutDelay =
+    (state.fastHovering
+      ? settings.fastHoveringInfoDelay
+      : settings.normalHoverInfoDelay);
+
+  // Start a timer to show the corresponding tooltip, with the delay depending
+  // on whether fast hovering or not. This could be canceled by mousing out of
+  // the hoverable.
+  state.hoverTimeout =
+    setTimeout(() => {
+      state.hoverTimeout = null;
+      state.fastHovering = true;
+      showTooltipFromHoverable(hoverable);
+    }, hoverTimeoutDelay);
+
+  // Don't stop fast hovering while over any hoverable.
+  if (state.endFastHoveringTimeout) {
+    clearTimeout(state.endFastHoveringTimeout);
+    state.endFastHoveringTimeout = null;
+  }
+
+  // Don't time out the current tooltip while over any hoverable.
+  if (state.hideTimeout) {
+    clearTimeout(state.hideTimeout);
+    state.hideTimeout = null;
+  }
+}
+
+function handleTooltipHoverableMouseLeft(hoverable) {
+  const {settings, state} = hoverableTooltipInfo;
+
+  // Don't show a tooltip when not over a hoverable!
+  if (state.hoverTimeout) {
+    clearTimeout(state.hoverTimeout);
+    state.hoverTimeout = null;
+  }
+
+  // Start timing out fast hovering (if active) when not over a hoverable.
+  // This will only be canceled by mousing over another hoverable.
+  if (state.fastHovering && !state.endFastHoveringTimeout) {
+    state.endFastHoveringTimeout =
+      setTimeout(() => {
+        state.endFastHoveringTimeout = null;
+        state.fastHovering = false;
+      }, settings.endFastHoveringDelay);
+  }
+
+  // Start timing out the current tooltip when mousing not over a hoverable.
+  // This could be canceled by mousing over another hoverable, or over the
+  // currently shown tooltip.
+  if (state.currentlyShownTooltip && !state.hideTimeout) {
+    state.hideTimeout =
+      setTimeout(() => {
+        state.hideTimeout = null;
+        hideCurrentlyShownTooltip();
+      }, settings.hideTooltipDelay);
+  }
+}
+
+function handleTooltipHoverableReceivedFocus(hoverable) {
+  const {settings, state} = hoverableTooltipInfo;
+
+  // By default, display the corresponding tooltip after a delay.
+
+  state.focusTimeout =
+    setTimeout(() => {
+      state.focusTimeout = null;
+      showTooltipFromHoverable(hoverable);
+    }, settings.focusInfoDelay);
+
+  // If a tooltip was just hidden - which is almost certainly a result of the
+  // focus changing - then display this tooltip immediately, canceling the
+  // above timeout.
+
+  if (state.tooltipWasJustHidden) {
+    clearTimeout(state.focusTimeout);
+    state.focusTimeout = null;
+
+    showTooltipFromHoverable(hoverable);
+  }
+}
+
+function handleTooltipHoverableLostFocus(hoverable, domEvent) {
+  const {settings, state} = hoverableTooltipInfo;
+
+  // Don't show a tooltip from focusing a hoverable if it isn't focused
+  // anymore! If another hoverable is receiving focus, that will be evaluated
+  // and set its own focus timeout after we clear the previous one here.
+  if (state.focusTimeout) {
+    clearTimeout(state.focusTimeout);
+    state.focusTimeout = null;
+  }
+
+  // Unless focus is entering the tooltip itself, hide the tooltip immediately.
+  // This will set the tooltipWasJustHidden flag, which is detected by a newly
+  // focused hoverable, if applicable.
+  if (!currentlyShownTooltipHasFocus(domEvent.relatedTarget)) {
+    hideCurrentlyShownTooltip();
+  }
+}
+
+function handleTooltipHoverableTouchEnded(hoverable, domEvent) {
+  const {settings, state} = hoverableTooltipInfo;
+  const {tooltip} = state.registeredHoverables.get(hoverable);
+
+  // Don't proceed if this hoverable's tooltip is already visible - in that
+  // case touching the hoverable again should behave just like a normal click.
+  if (state.currentlyShownTooltip === tooltip) return;
+
+  const touches = Array.from(domEvent.changedTouches);
+  const identifiers = touches.map(touch => touch.identifier);
+
+  // Don't process touch events that were "banished" because the page was
+  // scrolled while those touches were active, and most likely as a result of
+  // them.
+  filterMultipleArrays(touches, identifiers,
+    (_touch, identifier) =>
+      !state.touchIdentifiersBanishedByScrolling.has(identifier));
+
+  if (empty(touches)) return;
+
+  // Don't proceed if none of the (just-ended) touches ended over the
+  // hoverable.
+  const anyTouchEndedOverHoverable =
+    touches.some(touch =>
+      hoverable.contains(
+        document.elementFromPoint(touch.clientX, touch.clientY)));
+
+  if (!anyTouchEndedOverHoverable) {
+    return;
+  }
+
+  if (state.touchTimeout) {
+    clearTimeout(state.touchTimeout);
+    state.touchTimeout = null;
+  }
+
+  // Show the tooltip right away.
+  showTooltipFromHoverable(hoverable);
+
+  // Set a state, for a brief but not instantaneous period, indicating that a
+  // hoverable was recently touched. The touchend event may precede the click
+  // event by some time, and we don't want to navigate away from the page as
+  // a result of the click event which this touch precipitated.
+  state.hoverableWasRecentlyTouched = true;
+  state.touchTimeout =
+    setTimeout(() => {
+      state.hoverableWasRecentlyTouched = false;
+    }, 250);
+}
+
+function handleTooltipHoverableClicked(hoverable, domEvent) {
+  const {state} = hoverableTooltipInfo;
+  const {tooltip} = state.registeredHoverables.get(hoverable);
+
+  // Don't navigate away from the page if the this hoverable was recently
+  // touched (and had its tooltip activated). That flag won't be set if its
+  // tooltip was already open before the touch.
+  if (
+    state.currentlyActiveHoverable === hoverable &&
+    state.hoverableWasRecentlyTouched
+  ) {
+    event.preventDefault();
+  }
+}
+
+function currentlyShownTooltipHasFocus(focusElement = document.activeElement) {
+  const {state} = hoverableTooltipInfo;
+
+  const {
+    currentlyShownTooltip: tooltip,
+    currentlyActiveHoverable: hoverable,
+  } = state;
+
+  // If there's no tooltip, it can't possibly have focus.
+  if (!tooltip) return false;
+
+  // If the tooltip literally contains (or is) the focused element, then that's
+  // the principle condition we're looking for.
+  if (tooltip.contains(focusElement)) return true;
+
+  // If the hoverable *which opened the tooltip* is focused, then that also
+  // represents the tooltip being focused (in its currently shown state).
+  if (hoverable.contains(focusElement)) return true;
+
+  return false;
+}
+
+function hideCurrentlyShownTooltip() {
+  const {event, state} = hoverableTooltipInfo;
+  const {currentlyShownTooltip: tooltip} = state;
+
+  // If there was no tooltip to begin with, we're functionally in the desired
+  // state already, so return true.
+  if (!tooltip) return true;
+
+  // Never hide the tooltip if it's focused.
+  if (currentlyShownTooltipHasFocus()) return false;
+
+  state.currentlyShownTooltip = null;
+  state.currentlyActiveHoverable = null;
+
+  // Set this for one tick of the event cycle.
+  state.tooltipWasJustHidden = true;
+  setTimeout(() => {
+    state.tooltipWasJustHidden = false;
+  });
+
+  dispatchInternalEvent(event, 'whenTooltipShouldBeHidden', {tooltip});
+
+  return true;
+}
+
+function showTooltipFromHoverable(hoverable) {
+  const {event, state} = hoverableTooltipInfo;
+  const {tooltip} = state.registeredHoverables.get(hoverable);
+
+  if (!hideCurrentlyShownTooltip()) return false;
+
+  state.currentlyShownTooltip = tooltip;
+  state.currentlyActiveHoverable = hoverable;
+
+  state.tooltipWasJustHidden = false;
+
+  dispatchInternalEvent(event, 'whenTooltipShouldBeShown', {hoverable, tooltip});
+
+  return true;
+}
+
+function addHoverableTooltipPageListeners() {
+  const {state} = hoverableTooltipInfo;
+
+  const getTouchIdentifiers = domEvent =>
+    Array.from(domEvent.changedTouches)
+      .map(touch => touch.identifier)
+      .filter(identifier => typeof identifier !== 'undefined');
+
+  document.body.addEventListener('touchstart', domEvent => {
+    for (const identifier of getTouchIdentifiers(domEvent)) {
+      state.currentTouchIdentifiers.add(identifier);
+    }
+  });
+
+  window.addEventListener('scroll', () => {
+    for (const identifier of state.currentTouchIdentifiers) {
+      state.touchIdentifiersBanishedByScrolling.add(identifier);
+    }
+  });
+
+  document.body.addEventListener('touchend', domEvent => {
+    setTimeout(() => {
+      for (const identifier of getTouchIdentifiers(domEvent)) {
+        state.currentTouchIdentifiers.delete(identifier);
+        state.touchIdentifiersBanishedByScrolling.delete(identifier);
+      }
+    });
+  });
+
+  document.body.addEventListener('touchend', domEvent => {
+    const hoverables = Array.from(state.registeredHoverables.keys());
+    const tooltips = Array.from(state.registeredTooltips.keys());
+
+    const touches = Array.from(domEvent.changedTouches);
+    const identifiers = touches.map(touch => touch.identifier);
+
+    // Don't process touch events that were "banished" because the page was
+    // scrolled while those touches were active, and most likely as a result of
+    // them.
+    filterMultipleArrays(touches, identifiers,
+      (_touch, identifier) =>
+        !state.touchIdentifiersBanishedByScrolling.has(identifier));
+
+    if (empty(touches)) return;
+
+    const anyTouchOverAnyHoverableOrTooltip =
+      touches.some(({clientX, clientY}) => {
+        const element = document.elementFromPoint(clientX, clientY);
+        if (hoverables.some(el => el.contains(element))) return true;
+        if (tooltips.some(el => el.contains(element))) return true;
+        return false;
+      });
+
+    if (!anyTouchOverAnyHoverableOrTooltip) {
+      hideCurrentlyShownTooltip();
+    }
+  });
+}
+
+clientSteps.addPageListeners.push(addHoverableTooltipPageListeners);
 
-let fastHover = false;
-let endFastHoverTimeout = null;
+// Data & info card ---------------------------------------
 
+/*
 function colorLink(a, color) {
   console.warn('Info card link colors temporarily disabled: chroma.js required, no dependency linking for client.js yet');
   return;
@@ -505,53 +1009,6 @@ const infoCard = (() => {
   };
 })();
 
-function makeInfoCardLinkHandlers(type) {
-  let hoverTimeout = null;
-
-  return {
-    mouseenter(evt) {
-      hoverTimeout = setTimeout(
-        () => {
-          fastHover = true;
-          infoCard.show(type, evt.target);
-        },
-        fastHover ? FAST_HOVER_INFO_DELAY : NORMAL_HOVER_INFO_DELAY);
-
-      clearTimeout(endFastHoverTimeout);
-      endFastHoverTimeout = null;
-
-      infoCard.cancelHide();
-    },
-
-    mouseleave() {
-      clearTimeout(hoverTimeout);
-
-      if (fastHover && !endFastHoverTimeout) {
-        endFastHoverTimeout = setTimeout(() => {
-          endFastHoverTimeout = null;
-          fastHover = false;
-        }, END_FAST_HOVER_DELAY);
-      }
-
-      infoCard.readyHide();
-    },
-  };
-}
-
-const infoCardLinkHandlers = {
-  track: makeInfoCardLinkHandlers('track'),
-};
-
-function addInfoCardLinkHandlers(type) {
-  for (const a of document.querySelectorAll(`a[data-${type}]`)) {
-    for (const [eventName, handler] of Object.entries(
-      infoCardLinkHandlers[type]
-    )) {
-      a.addEventListener(eventName, handler);
-    }
-  }
-}
-
 // Info cards are disa8led for now since they aren't quite ready for release,
 // 8ut you can try 'em out 8y setting this localStorage flag!
 //
@@ -576,6 +1033,7 @@ const hashLinkInfo = clientInfo.hashLinkInfo = {
   },
 
   event: {
+    beforeHashLinkScrolls: [],
     whenHashLinkClicked: [],
   },
 };
@@ -638,6 +1096,21 @@ function addHashLinkListeners() {
         return;
       }
 
+      // Don't do anything if the target element isn't actually visible!
+      if (target.offsetParent === null) {
+        return;
+      }
+
+      // Allow event handlers to prevent scrolling.
+      for (const handler of event.beforeHashLinkScrolls) {
+        if (handler({
+          link: hashLink,
+          target,
+        }) === false) {
+          return;
+        }
+      }
+
       // Hide skipper box right away, so the layout is updated on time for the
       // math operations coming up next.
       const skipper = document.getElementById('skippers');
@@ -672,9 +1145,12 @@ function addHashLinkListeners() {
 
       processScrollingAfterHashLinkClicked();
 
+      dispatchInternalEvent(event, 'whenHashLinkClicked', {link: hashLink});
+
       for (const handler of event.whenHashLinkClicked) {
         handler({
           link: hashLink,
+          target,
         });
       }
     });
@@ -959,6 +1435,8 @@ clientSteps.addPageListeners.push(addScrollListenerForStickyHeadings);
 
 // Image overlay ------------------------------------------
 
+// TODO: Update to clientSteps style.
+
 function addImageOverlayClickHandlers() {
   const container = document.getElementById('image-overlay-container');
 
@@ -1244,8 +1722,100 @@ function loadImage(imageUrl, onprogress) {
   });
 }
 
+// "Additional names" box ---------------------------------
+
+const additionalNamesBoxInfo = clientInfo.additionalNamesBox = {
+  box: null,
+  links: null,
+  mainContentContainer: null,
+
+  state: {
+    visible: false,
+  },
+};
+
+function getAdditionalNamesBoxReferences() {
+  const info = additionalNamesBoxInfo;
+
+  info.box =
+    document.getElementById('additional-names-box');
+
+  info.links =
+    document.querySelectorAll('a[href="#additional-names-box"]');
+
+  info.mainContentContainer =
+    document.querySelector('#content .main-content-container');
+}
+
+function addAdditionalNamesBoxInternalListeners() {
+  const info = additionalNamesBoxInfo;
+
+  hashLinkInfo.event.beforeHashLinkScrolls.push(({target}) => {
+    if (target === info.box) {
+      return false;
+    }
+  });
+}
+
+function addAdditionalNamesBoxListeners() {
+  const info = additionalNamesBoxInfo;
+
+  for (const link of info.links) {
+    link.addEventListener('click', domEvent => {
+      handleAdditionalNamesBoxLinkClicked(domEvent);
+    });
+  }
+}
+
+function handleAdditionalNamesBoxLinkClicked(domEvent) {
+  const info = additionalNamesBoxInfo;
+  const {state} = info;
+
+  domEvent.preventDefault();
+
+  if (!info.box || !info.mainContentContainer) return;
+
+  const margin =
+    +(cssProp(info.box, 'scroll-margin-top').replace('px', ''));
+
+  const {top} =
+    (state.visible
+      ? info.box.getBoundingClientRect()
+      : info.mainContentContainer.getBoundingClientRect());
+
+  if (top + 20 < margin || top > 0.4 * window.innerHeight) {
+    if (!state.visible) {
+      toggleAdditionalNamesBox();
+    }
+
+    window.scrollTo({
+      top: window.scrollY + top - margin,
+      behavior: 'smooth',
+    });
+  } else {
+    toggleAdditionalNamesBox();
+  }
+}
+
+function toggleAdditionalNamesBox() {
+  const info = additionalNamesBoxInfo;
+  const {state} = info;
+
+  state.visible = !state.visible;
+  info.box.style.display =
+    (state.visible
+      ? 'block'
+      : 'none');
+}
+
+clientSteps.getPageReferences.push(getAdditionalNamesBoxReferences);
+clientSteps.addInternalListeners.push(addAdditionalNamesBoxInternalListeners);
+clientSteps.addPageListeners.push(addAdditionalNamesBoxListeners);
+
 // Group contributions table ------------------------------
 
+// TODO: Update to clientSteps style.
+
 const groupContributionsTableInfo =
   Array.from(document.querySelectorAll('#content dl'))
     .filter(dl => dl.querySelector('a.group-contributions-sort-button'))
@@ -1278,6 +1848,160 @@ for (const info of groupContributionsTableInfo) {
   });
 }
 
+// Artist link icon tooltips ------------------------------
+
+const externalIconTooltipInfo = clientInfo.externalIconTooltipInfo = {
+  hoverableLinks: null,
+  iconContainers: null,
+};
+
+function getExternalIconTooltipReferences() {
+  const info = externalIconTooltipInfo;
+
+  const spans =
+    Array.from(document.querySelectorAll('span.contribution.has-tooltip'));
+
+  info.hoverableLinks =
+    spans
+      .map(span => span.querySelector('a'));
+
+  info.iconContainers =
+    spans
+      .map(span => span.querySelector('span.icons-tooltip'));
+}
+
+function addExternalIconTooltipInternalListeners() {
+  const info = externalIconTooltipInfo;
+
+  hoverableTooltipInfo.event.whenTooltipShouldBeShown.push(({tooltip}) => {
+    if (!info.iconContainers.includes(tooltip)) return;
+    showExternalIconTooltip(tooltip);
+  });
+
+  hoverableTooltipInfo.event.whenTooltipShouldBeHidden.push(({tooltip}) => {
+    if (!info.iconContainers.includes(tooltip)) return;
+    hideExternalIconTooltip(tooltip);
+  });
+}
+
+function showExternalIconTooltip(iconContainer) {
+  iconContainer.classList.add('visible');
+  iconContainer.inert = false;
+}
+
+function hideExternalIconTooltip(iconContainer) {
+  iconContainer.classList.remove('visible');
+  iconContainer.inert = true;
+}
+
+function addExternalIconTooltipPageListeners() {
+  const info = externalIconTooltipInfo;
+
+  for (const {hoverable, tooltip} of stitchArrays({
+    hoverable: info.hoverableLinks,
+    tooltip: info.iconContainers,
+  })) {
+    registerTooltipElement(tooltip);
+    registerTooltipHoverableElement(hoverable, tooltip);
+  }
+}
+
+clientSteps.getPageReferences.push(getExternalIconTooltipReferences);
+clientSteps.addInternalListeners.push(addExternalIconTooltipInternalListeners);
+clientSteps.addPageListeners.push(addExternalIconTooltipPageListeners);
+
+/*
+const linkIconTooltipInfo =
+  Array.from(document.querySelectorAll('span.contribution.has-tooltip'))
+    .map(span => ({
+      mainLink: span.querySelector('a'),
+      iconsContainer: span.querySelector('span.icons-tooltip'),
+      iconLinks: span.querySelectorAll('span.icons-tooltip a'),
+    }));
+
+for (const info of linkIconTooltipInfo) {
+  const focusElements =
+    [info.mainLink, ...info.iconLinks];
+
+  const hoverElements =
+    [info.mainLink, info.iconsContainer];
+
+  let hidden = true;
+
+  const show = () => {
+    info.iconsContainer.classList.add('visible');
+    info.iconsContainer.inert = false;
+    hidden = false;
+  };
+
+  const hide = () => {
+    info.iconsContainer.classList.remove('visible');
+    info.iconsContainer.inert = true;
+    hidden = true;
+  };
+
+  const considerHiding = () => {
+    if (hoverElements.some(el => el.matches(':hover'))) {
+      return;
+    }
+
+    if (<document.activeElement is inside tooltip>) {
+      return;
+    }
+
+    if (justTouched) {
+      return;
+    }
+
+    hide();
+  };
+
+  // Hover (pointer)
+
+  let hoverTimeout;
+
+  info.mainLink.addEventListener('mouseenter', () => {
+    if (hidden) {
+      hoverTimeout = setTimeout(show, 250);
+    }
+  });
+
+  info.mainLink.addEventListener('mouseout', () => {
+    if (hidden) {
+      clearTimeout(hoverTimeout);
+    } else {
+      considerHiding();
+    }
+  });
+
+  info.iconsContainer.addEventListener('mouseout', () => {
+    if (!hidden) {
+      considerHiding();
+    }
+  });
+
+  // Focus (keyboard)
+
+  let focusTimeout;
+
+  info.mainLink.addEventListener('focus', () => {
+    focusTimeout = setTimeout(show, 750);
+  });
+
+  info.mainLink.addEventListener('blur', () => {
+    clearTimeout(focusTimeout);
+  });
+
+  info.iconsContainer.addEventListener('focusout', () => {
+    requestAnimationFrame(considerHiding);
+  });
+
+  info.mainLink.addEventListener('blur', () => {
+    requestAnimationFrame(considerHiding);
+  });
+}
+*/
+
 // Sticky commentary sidebar ------------------------------
 
 const albumCommentarySidebarInfo = clientInfo.albumCommentarySidebarInfo = {