feat(classes): optimize teacher dashboard ui and implement grade management

src/modules/textbooks/data-access.ts

@@ -1,7 +1,7 @@
 import "server-only"
 
 import { cache } from "react"
-import { and, asc, eq, inArray, like, or, sql, type SQL } from "drizzle-orm"
+import { and, asc, eq, inArray, like, or, sql, isNull, type SQL } from "drizzle-orm"
 import { createId } from "@paralleldrive/cuid2"
 
 import { db } from "@/shared/db"
@@ -394,3 +394,37 @@ export async function createKnowledgePoint(data: CreateKnowledgePointInput): Pro
 export async function deleteKnowledgePoint(id: string): Promise<void> {
   await db.delete(knowledgePoints).where(eq(knowledgePoints.id, id))
 }
+
+export async function reorderChapters(chapterId: string, newIndex: number, parentId: string | null): Promise<void> {
+  const [target] = await db.select().from(chapters).where(eq(chapters.id, chapterId)).limit(1)
+  if (!target) throw new Error("Chapter not found")
+
+  const siblings = await db
+    .select()
+    .from(chapters)
+    .where(
+      and(
+        eq(chapters.textbookId, target.textbookId),
+        parentId ? eq(chapters.parentId, parentId) : isNull(chapters.parentId)
+      )
+    )
+    .orderBy(asc(chapters.order))
+
+  const currentSiblings = siblings.filter((c) => c.id !== chapterId)
+  currentSiblings.splice(newIndex, 0, target)
+
+  await db.transaction(async (tx) => {
+    for (let i = 0; i < currentSiblings.length; i++) {
+      const ch = currentSiblings[i]
+      if (ch.order !== i || (ch.id === chapterId && ch.parentId !== parentId)) {
+        await tx
+          .update(chapters)
+          .set({ 
+            order: i,
+            parentId: ch.id === chapterId ? parentId : ch.parentId 
+          })
+          .where(eq(chapters.id, ch.id))
+      }
+    }
+  })
+}