feat(teacher): 题库模块（QuestionBank）

工作内容

- 新增 /teacher/questions 页面，支持 Suspense/空状态/加载态

- 题库 CRUD Server Actions：创建/更新/递归删除子题，变更后 revalidatePath

- getQuestions 支持 q/type/difficulty/knowledgePointId 筛选与分页返回 meta

- UI：表格列/筛选器/创建编辑弹窗，content JSON 兼容组卷

- 更新中文设计文档：docs/design/004_question_bank_implementation.md

src/modules/questions/actions.ts

@@ -2,18 +2,18 @@
 
 import { db } from "@/shared/db";
 import { questions, questionsToKnowledgePoints } from "@/shared/db/schema";
-import { CreateQuestionInput, CreateQuestionSchema } from "./schema";
+import { CreateQuestionSchema } from "./schema";
+import type { CreateQuestionInput } from "./schema";
 import { ActionState } from "@/shared/types/action-state";
 import { revalidatePath } from "next/cache";
 import { createId } from "@paralleldrive/cuid2";
+import { and, eq } from "drizzle-orm";
+import { z } from "zod";
 
-// --- Mock Auth Helper (Replace with actual Auth.js call) ---
 async function getCurrentUser() {
-  // In production: const session = await auth(); return session?.user;
-  // Mocking a teacher user for this demonstration
   return {
     id: "user_teacher_123",
-    role: "teacher", // or "admin"
+    role: "teacher",
   };
 }
 
@@ -25,17 +25,14 @@ async function ensureTeacher() {
   return user;
 }
 
-// --- Recursive Insert Helper ---
-// We pass 'tx' to ensure all operations run within the same transaction
 type Tx = Parameters<Parameters<typeof db.transaction>[0]>[0]
 
 async function insertQuestionWithRelations(
   tx: Tx,
-  input: CreateQuestionInput,
+  input: z.infer<typeof CreateQuestionSchema>,
   authorId: string,
   parentId: string | null = null
 ) {
-  // We generate ID explicitly here.
   const newQuestionId = createId();
 
   await tx.insert(questions).values({
@@ -47,7 +44,6 @@ async function insertQuestionWithRelations(
     parentId: parentId,
   });
 
-  // 2. Link Knowledge Points
   if (input.knowledgePointIds && input.knowledgePointIds.length > 0) {
     await tx.insert(questionsToKnowledgePoints).values(
       input.knowledgePointIds.map((kpId) => ({
@@ -57,7 +53,6 @@ async function insertQuestionWithRelations(
     );
   }
 
-  // 3. Handle Sub-Questions (Recursion)
   if (input.subQuestions && input.subQuestions.length > 0) {
     for (const subQ of input.subQuestions) {
       await insertQuestionWithRelations(tx, subQ, authorId, newQuestionId);
@@ -67,25 +62,16 @@ async function insertQuestionWithRelations(
   return newQuestionId;
 }
 
-// --- Main Server Action ---
-
 export async function createNestedQuestion(
   prevState: ActionState<string> | undefined,
-  formData: FormData | CreateQuestionInput // Support both FormData and JSON input
+  formData: FormData | CreateQuestionInput
 ): Promise<ActionState<string>> {
   try {
-    // 1. Auth Check
     const user = await ensureTeacher();
 
-    // 2. Parse Input
-    // If formData is actual FormData, we need to convert it. 
-    // For complex nested structures, frontend usually sends JSON string or pure JSON object if using `useServerAction` with arguments.
-    // Here we assume the client might send a raw object (if using direct function call) or we parse FormData.
     let rawInput: unknown = formData;
     
     if (formData instanceof FormData) {
-       // Parsing complex nested JSON from FormData is messy. 
-       // We assume one field 'data' contains the JSON, or we expect direct object usage (common in modern Next.js RPC).
        const jsonString = formData.get("json");
        if (typeof jsonString === "string") {
          rawInput = JSON.parse(jsonString) as unknown;
@@ -106,13 +92,11 @@ export async function createNestedQuestion(
 
     const input = validatedFields.data;
 
-    // 3. Database Transaction
     await db.transaction(async (tx) => {
       await insertQuestionWithRelations(tx, input, user.id, null);
     });
 
-    // 4. Revalidate Cache
-    revalidatePath("/questions");
+    revalidatePath("/teacher/questions");
 
     return {
       success: true,
@@ -122,10 +106,7 @@ export async function createNestedQuestion(
   } catch (error) {
     console.error("Failed to create question:", error);
 
-    // Drizzle/DB Error Handling (Generic)
     if (error instanceof Error) {
-       // Check for specific DB errors (constraints, etc.)
-       // e.g., if (error.message.includes("Duplicate entry")) ...
        return {
          success: false,
          message: error.message || "Database error occurred",
@@ -138,3 +119,122 @@ export async function createNestedQuestion(
     };
   }
 }
+
+const UpdateQuestionSchema = z.object({
+  id: z.string().min(1),
+  type: z.enum(["single_choice", "multiple_choice", "text", "judgment", "composite"]),
+  difficulty: z.number().min(1).max(5),
+  content: z.any(),
+  knowledgePointIds: z.array(z.string()).optional(),
+});
+
+export async function updateQuestionAction(
+  prevState: ActionState<string> | undefined,
+  formData: FormData
+): Promise<ActionState<string>> {
+  try {
+    const user = await ensureTeacher();
+    const canEditAll = user.role === "admin";
+
+    const jsonString = formData.get("json");
+    if (typeof jsonString !== "string") {
+      return { success: false, message: "Invalid submission format. Expected JSON." };
+    }
+
+    const parsed = UpdateQuestionSchema.safeParse(JSON.parse(jsonString));
+    if (!parsed.success) {
+      return {
+        success: false,
+        message: "Validation failed",
+        errors: parsed.error.flatten().fieldErrors,
+      };
+    }
+
+    const input = parsed.data;
+
+    await db.transaction(async (tx) => {
+      await tx
+        .update(questions)
+        .set({
+          type: input.type,
+          difficulty: input.difficulty,
+          content: input.content,
+          updatedAt: new Date(),
+        })
+        .where(canEditAll ? eq(questions.id, input.id) : and(eq(questions.id, input.id), eq(questions.authorId, user.id)));
+
+      await tx
+        .delete(questionsToKnowledgePoints)
+        .where(eq(questionsToKnowledgePoints.questionId, input.id));
+
+      if (input.knowledgePointIds && input.knowledgePointIds.length > 0) {
+        await tx.insert(questionsToKnowledgePoints).values(
+          input.knowledgePointIds.map((kpId) => ({
+            questionId: input.id,
+            knowledgePointId: kpId,
+          }))
+        );
+      }
+    });
+
+    revalidatePath("/teacher/questions");
+
+    return { success: true, message: "Question updated successfully" };
+  } catch (error) {
+    if (error instanceof Error) {
+      return { success: false, message: error.message };
+    }
+    return { success: false, message: "An unexpected error occurred" };
+  }
+}
+
+async function deleteQuestionRecursive(tx: Tx, questionId: string) {
+  const children = await tx
+    .select({ id: questions.id })
+    .from(questions)
+    .where(eq(questions.parentId, questionId));
+
+  for (const child of children) {
+    await deleteQuestionRecursive(tx, child.id);
+  }
+
+  await tx.delete(questions).where(eq(questions.id, questionId));
+}
+
+export async function deleteQuestionAction(
+  prevState: ActionState<string> | undefined,
+  formData: FormData
+): Promise<ActionState<string>> {
+  try {
+    const user = await ensureTeacher();
+    const canEditAll = user.role === "admin";
+
+    const id = formData.get("id");
+    if (typeof id !== "string" || id.length === 0) {
+      return { success: false, message: "Missing question id" };
+    }
+
+    await db.transaction(async (tx) => {
+      const [owned] = await tx
+        .select({ id: questions.id })
+        .from(questions)
+        .where(canEditAll ? eq(questions.id, id) : and(eq(questions.id, id), eq(questions.authorId, user.id)))
+        .limit(1);
+
+      if (!owned) {
+        throw new Error("Unauthorized");
+      }
+
+      await deleteQuestionRecursive(tx, id);
+    });
+
+    revalidatePath("/teacher/questions");
+
+    return { success: true, message: "Question deleted successfully" };
+  } catch (error) {
+    if (error instanceof Error) {
+      return { success: false, message: error.message };
+    }
+    return { success: false, message: "An unexpected error occurred" };
+  }
+}