fix(anki): regenerate sentence furigana from the final sentence (#268)

src/anki-integration/sentence-furigana.ts

@@ -0,0 +1,87 @@
+type Segment = { text: string; reading?: string };
+
+function readGroups(value: unknown): Segment[][] | null {
+  if (!Array.isArray(value)) return null;
+  const groups: Segment[][] = [];
+  const rawGroups: unknown[] = value;
+  for (const group of rawGroups) {
+    if (!Array.isArray(group)) return null;
+    const segments: Segment[] = [];
+    const rawSegments: unknown[] = group;
+    for (const segment of rawSegments) {
+      if (
+        typeof segment !== 'object' ||
+        segment === null ||
+        !('text' in segment) ||
+        typeof segment.text !== 'string' ||
+        ('reading' in segment &&
+          segment.reading !== undefined &&
+          typeof segment.reading !== 'string')
+      )
+        return null;
+      segments.push({
+        text: segment.text,
+        reading:
+          'reading' in segment && typeof segment.reading === 'string' ? segment.reading : undefined,
+      });
+    }
+    groups.push(segments);
+  }
+  return groups;
+}
+
+function escapeText(text: string): string {
+  return text
+    .replace(/&/g, '&')
+    .replace(/</g, '&lt;')
+    .replace(/>/g, '&gt;')
+    .replace(/\[/g, '&#91;')
+    .replace(/\]/g, '&#93;');
+}
+
+// Only accept a complete parse, so a lookup of just the headword cannot replace sentence context.
+export function formatSentenceFurigana(
+  text: string,
+  results: unknown[] | null,
+  highlightedText?: string,
+): string | null {
+  for (const result of results ?? []) {
+    if (typeof result !== 'object' || result === null || !('content' in result)) continue;
+    const groups = readGroups(result.content);
+    if (
+      !groups ||
+      groups
+        .flat()
+        .map((segment) => segment.text)
+        .join('') !== text
+    )
+      continue;
+    const highlights: number[] = [];
+    if (highlightedText) {
+      let start = text.indexOf(highlightedText);
+      while (start >= 0) {
+        highlights.push(start);
+        start = text.indexOf(highlightedText, start + highlightedText.length);
+      }
+    }
+    let offset = 0;
+    let bold = false;
+    let output = '';
+    for (const { text: surface, reading } of groups.flat()) {
+      const start = offset;
+      offset += surface.length;
+      const highlighted = highlights.some(
+        (position) => position < offset && position + (highlightedText?.length ?? 0) > start,
+      );
+      if (highlighted !== bold) output += highlighted ? '<b>' : '</b>';
+      bold = highlighted;
+      const escaped = escapeText(surface);
+      output +=
+        reading && reading !== surface && /[\p{Script=Han}々]/u.test(surface)
+          ? ` ${escaped}[${escapeText(reading)}]`
+          : escaped;
+    }
+    return output + (bold ? '</b>' : '');
+  }
+  return null;
+}