fix: sync server-rendered watchlist state to client

internal/anime/handler/handler.go

@@ -316,8 +316,8 @@ func (h *AnimeHandler) HandleScheduleSection(c *gin.Context) {
 	watchlistMap := h.watchlistMapForAnimes(c.Request.Context(), userID, animes)
 
 	c.HTML(http.StatusOK, "schedule.gohtml", gin.H{
-		"_fragment":   "schedule_section",
-		"Animes":      animes,
+		"_fragment":    "schedule_section",
+		"Animes":       animes,
 		"WatchlistMap": watchlistMap,
 	})
 }

static/assets/style.css

@@ -58,3 +58,13 @@ body {
   background-color: var(--color-background);
   color: var(--text);
 }
+
+[data-watchlist-toggle] .watchlist-icon,
+[data-watchlist-toggle] .watchlist-icon path {
+  fill: none;
+}
+
+[data-watchlist-toggle][data-watchlist-state='in'] .watchlist-icon,
+[data-watchlist-toggle][data-watchlist-state='in'] .watchlist-icon path {
+  fill: currentColor;
+}

static/watchlist.ts

@@ -66,6 +66,7 @@ const syncIconsForId = (id: number): void => {
     const malId = toInt(button.dataset.malId);
     if (malId !== id) return;
     button.classList.toggle('in-watchlist', shouldBeInWatchlist);
+    button.dataset.watchlistState = shouldBeInWatchlist ? 'in' : 'out';
     button.setAttribute(
       'aria-label',
       shouldBeInWatchlist ? 'Remove from Watchlist' : 'Add to Watchlist'
@@ -109,8 +110,18 @@ const closeClosestDropdown = (from: HTMLElement): void => {
   });
 };
 
-const toggleWatchlist = async (id: number, title: string): Promise<void> => {
+const toggleWatchlist = async (
+  id: number,
+  title: string,
+  renderedState: string | undefined
+): Promise<void> => {
   if (inflight.has(id)) return;
+  if (renderedState === 'in') {
+    watchlistIds.add(id);
+  } else if (renderedState === 'out') {
+    watchlistIds.delete(id);
+  }
+
   const isInWatchlist = watchlistIds.has(id);
 
   setBusy(id, true);
@@ -250,6 +261,20 @@ const initWatchlist = (ids: number[]): void => {
   });
 };
 
+const getRenderedWatchlistIds = (): number[] => {
+  const ids = new Set<number>();
+
+  document
+    .querySelectorAll<HTMLElement>('[data-watchlist-toggle][data-watchlist-state="in"][data-mal-id]')
+    .forEach(button => {
+      const id = toInt(button.dataset.malId);
+      if (id === null) return;
+      ids.add(id);
+    });
+
+  return Array.from(ids);
+};
+
 const onReady = (fn: () => void): void => {
   if (document.readyState === 'loading') {
     document.addEventListener('DOMContentLoaded', fn, { once: true });
@@ -272,7 +297,7 @@ const installDelegatedHandlers = (): void => {
       const id = toInt(toggleButton.getAttribute('data-mal-id') ?? undefined);
       if (id === null) return;
       const title = toggleButton.getAttribute('data-watchlist-title') ?? 'anime';
-      void toggleWatchlist(id, title);
+      void toggleWatchlist(id, title, toggleButton.dataset.watchlistState);
       return;
     }
 
@@ -322,5 +347,10 @@ onReady(() => {
     }
   }
 
+  const renderedWatchlistIds = getRenderedWatchlistIds();
+  if (renderedWatchlistIds.length > 0) {
+    initWatchlist(renderedWatchlistIds);
+  }
+
   installDelegatedHandlers();
 });

templates/components/anime_card.gohtml

@@ -43,6 +43,7 @@
             data-watchlist-toggle
             data-mal-id="{{$anime.MalID}}"
             data-watchlist-title="{{$anime.DisplayTitle}}"
+            data-watchlist-state="{{if $isWatchlist}}in{{else}}out{{end}}"
             class="text-accent hover:text-accent/80 transition-colors focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-accent disabled:opacity-50 {{if $isWatchlist}}in-watchlist{{end}}"
             aria-label="{{if $isWatchlist}}Remove from Watchlist{{else}}Add to Watchlist{{end}}"
           >

templates/schedule.gohtml

@@ -55,6 +55,7 @@
                   data-watchlist-toggle
                   data-mal-id="{{$anime.MalID}}"
                   data-watchlist-title="{{$anime.DisplayTitle}}"
+                  data-watchlist-state="{{if (index $.WatchlistMap $anime.MalID)}}in{{else}}out{{end}}"
                   class="shrink-0 text-accent hover:text-accent/80 transition-colors focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-accent disabled:opacity-50 {{if (index $.WatchlistMap $anime.MalID)}}in-watchlist{{end}}"
                   aria-label="{{if (index $.WatchlistMap $anime.MalID)}}Remove from Watchlist{{else}}Add to Watchlist{{end}}"
                 >