refactor: P0-1/2/4 解耦修复 - 拆分过耦合文件 + dashboard 解耦

src/modules/exams/data-access.ts

@@ -1,6 +1,6 @@
 import { db } from "@/shared/db"
 import { exams, examQuestions, questions, subjects, grades, classes } from "@/shared/db/schema"
-import { eq, desc, like, and, or, inArray } from "drizzle-orm"
+import { count, eq, desc, like, and, or, inArray } from "drizzle-orm"
 import { cache } from "react"
 
 import type { Exam, ExamDifficulty, ExamStatus } from "./types"
@@ -337,3 +337,37 @@ export const persistAiGeneratedExamDraft = async (input: {
     }
   })
 }
+
+export type ExamsDashboardStats = {
+  examCount: number
+}
+
+export const getExamsDashboardStats = cache(async (scope?: DataScope): Promise<ExamsDashboardStats> => {
+  const conditions = []
+
+  if (scope && scope.type !== "all") {
+    if (scope.type === "owned") {
+      conditions.push(eq(exams.creatorId, scope.userId))
+    }
+    if (scope.type === "grade_managed" && scope.gradeIds.length > 0) {
+      conditions.push(inArray(exams.gradeId, scope.gradeIds))
+    }
+    if (scope.type === "class_taught" && scope.classIds.length > 0) {
+      const teacherGradeIds = await db
+        .selectDistinct({ gradeId: classes.gradeId })
+        .from(classes)
+        .where(inArray(classes.id, scope.classIds))
+      const gradeIds = teacherGradeIds.map((g) => g.gradeId).filter(Boolean) as string[]
+      if (gradeIds.length > 0) {
+        conditions.push(inArray(exams.gradeId, gradeIds))
+      }
+    }
+  }
+
+  const [row] = await db
+    .select({ value: count() })
+    .from(exams)
+    .where(conditions.length ? and(...conditions) : undefined)
+
+  return { examCount: Number(row?.value ?? 0) }
+})