's'

lib/content/course-utils.ts

@@ -0,0 +1,26 @@
+/**
+ * 课程工具 - 获取上一节/下一节
+ */
+
+export type LessonRef = { moduleIndex: number; lessonIndex: number };
+
+export function getPrevNextLesson(
+  modules: readonly { lessons: readonly unknown[] }[],
+  moduleIndex: number,
+  lessonIndex: number
+): { prev: LessonRef | null; next: LessonRef | null } {
+  const allLessons: LessonRef[] = [];
+  modules.forEach((m, mi) => {
+    m.lessons.forEach((_, li) => {
+      allLessons.push({ moduleIndex: mi, lessonIndex: li });
+    });
+  });
+
+  const idx = allLessons.findIndex((l) => l.moduleIndex === moduleIndex && l.lessonIndex === lessonIndex);
+  if (idx < 0) return { prev: null, next: null };
+
+  return {
+    prev: idx > 0 ? allLessons[idx - 1] : null,
+    next: idx < allLessons.length - 1 ? allLessons[idx + 1] : null,
+  };
+}