Add CodeMirror extension to display find match count in the editor. (#390)

src-web/components/core/Editor/searchMatchCount.ts

@@ -0,0 +1,115 @@
+import { getSearchQuery, searchPanelOpen } from '@codemirror/search';
+import type { Extension } from '@codemirror/state';
+import { type EditorView, ViewPlugin, type ViewUpdate } from '@codemirror/view';
+
+/**
+ * A CodeMirror extension that displays the total number of search matches
+ * inside the built-in search panel.
+ */
+export function searchMatchCount(): Extension {
+  return ViewPlugin.fromClass(
+    class {
+      private countEl: HTMLElement | null = null;
+
+      constructor(private view: EditorView) {
+        this.updateCount();
+      }
+
+      update(update: ViewUpdate) {
+        // Recompute when doc changes, search state changes, or selection moves
+        const query = getSearchQuery(update.state);
+        const prevQuery = getSearchQuery(update.startState);
+        const open = searchPanelOpen(update.state);
+        const prevOpen = searchPanelOpen(update.startState);
+
+        if (update.docChanged || update.selectionSet || !query.eq(prevQuery) || open !== prevOpen) {
+          this.updateCount();
+        }
+      }
+
+      private updateCount() {
+        const state = this.view.state;
+        const open = searchPanelOpen(state);
+        const query = getSearchQuery(state);
+
+        if (!open) {
+          this.removeCountEl();
+          return;
+        }
+
+        this.ensureCountEl();
+
+        if (!query.search) {
+          if (this.countEl) {
+            this.countEl.textContent = '0/0';
+          }
+          return;
+        }
+
+        const selection = state.selection.main;
+        let count = 0;
+        let currentIndex = 0;
+        const MAX_COUNT = 9999;
+        const cursor = query.getCursor(state);
+        while (!cursor.next().done) {
+          count++;
+          if (cursor.value.from <= selection.from && cursor.value.to >= selection.to) {
+            currentIndex = count;
+          }
+          if (count > MAX_COUNT) break;
+        }
+
+        if (this.countEl) {
+          if (count > MAX_COUNT) {
+            this.countEl.textContent = `${MAX_COUNT}+`;
+          } else if (count === 0) {
+            this.countEl.textContent = '0/0';
+          } else if (currentIndex > 0) {
+            this.countEl.textContent = `${currentIndex}/${count}`;
+          } else {
+            this.countEl.textContent = `0/${count}`;
+          }
+        }
+      }
+
+      private ensureCountEl() {
+        // Find the search panel in the editor DOM
+        const panel = this.view.dom.querySelector('.cm-search');
+        if (!panel) {
+          this.countEl = null;
+          return;
+        }
+
+        if (this.countEl && this.countEl.parentElement === panel) {
+          return; // Already attached
+        }
+
+        this.countEl = document.createElement('span');
+        this.countEl.className = 'cm-search-match-count';
+
+        // Reorder: insert prev button, then next button, then count after the search input
+        const searchInput = panel.querySelector('input');
+        const prevBtn = panel.querySelector('button[name="prev"]');
+        const nextBtn = panel.querySelector('button[name="next"]');
+        if (searchInput && searchInput.parentElement === panel) {
+          searchInput.after(this.countEl);
+          if (prevBtn) this.countEl.after(prevBtn);
+          if (nextBtn && prevBtn) prevBtn.after(nextBtn);
+        } else {
+          panel.prepend(this.countEl);
+        }
+      }
+
+      private removeCountEl() {
+        if (this.countEl) {
+          this.countEl.remove();
+          this.countEl = null;
+        }
+      }
+
+      destroy() {
+        this.removeCountEl();
+      }
+    },
+  );
+}