recommender を更新する (#575)

ルール: 
    タグと授業のかぶっている数それぞれを合計して、それの降順で並べる。

## 具体的な変更内容

## 影響範囲

## 動作要件

## 補足

## レビューリクエストを出す前にチェック！

- [ ] 改めてセルフレビューしたか
- [ ] 手動での動作検証を行ったか
- [ ] server の機能追加ならば、テストを書いたか
  - 理由: 書いた | server の機能追加ではない
- [ ] 間違った使い方が存在するならば、それのドキュメントをコメントで書いたか
  - 理由: 書いた | 間違った使い方は存在しない
- [ ] わかりやすいPRになっているか

<!-- レビューリクエスト後は、Slackでもメンションしてお願いすることを推奨します。 -->

Author: aster-void

server/prisma/sql/recommend.sql

@@ -1,10 +1,17 @@
-SELECT recv.id, 
-    (SELECT COUNT(*) FROM "Enrollment" recv_enroll
-    INNER JOIN "Enrollment" req_enroll
-    ON recv_enroll."courseId" = req_enroll."courseId" 
-    WHERE recv_enroll."userId" = recv.id
-    AND req_enroll."userId" = $1)
-AS overlap FROM "User" recv
+-- $1 = senderId
+SELECT
+    *, 
+    -- course overlap
+    (SELECT COUNT(1) FROM "Course" course
+        WHERE EXISTS (SELECT 1 FROM "Enrollment" e WHERE e."courseId" = course.id AND e."userId" = recv.id)
+        AND EXISTS (SELECT 1 FROM "Enrollment" e WHERE e."courseId" = course.id AND e."userId" = $1)
+    )
+    + -- interest overlap
+    (SELECT COUNT(1) FROM "InterestSubject" subj
+        WHERE EXISTS (SELECT 1 FROM "Interest" i WHERE i."subjectId" = subj.id AND i."userId" = recv.id)
+        AND EXISTS (SELECT 1 FROM "Interest" i WHERE i."subjectId" = subj.id AND i."userId" = $1)
+    ) AS overlap
+FROM "User" recv
 WHERE recv.id <> $1
 
 AND NOT EXISTS (
@@ -21,13 +28,3 @@ AND NOT EXISTS (
 
 ORDER BY overlap DESC
 LIMIT $2 OFFSET $3;
-
--- SELECT recv.id AS recv, COUNT(recv_enroll) AS overlap FROM "User" recv
--- LEFT JOIN "Relationship" rel ON (rel."sendingUserId" = recv.id AND rel."receivingUserId" = $1) OR (rel."sendingUserId" = $1 AND rel."sendingUserId" = recv.id)
--- LEFT JOIN "Enrollment" recv_enroll ON recv_enroll."userId" = recv.id
--- INNER JOIN "Course" course ON recv_enroll."courseId" = course.id
--- INNER JOIN "Enrollment" req_enroll ON req_enroll."courseId" = course.id
--- WHERE req_enroll."userId" = $1 AND recv.id <> $1
--- AND rel.status != 'MATCHED'
--- GROUP BY recv.id
--- ORDER BY overlap DESC LIMIT $2 OFFSET $3;

server/src/functions/engines/recommendation.test.ts

@@ -8,14 +8,14 @@ beforeAll(() => {
 
 test("recommendation engine", async () => {
   const usersFor101 = await recommendedTo(101, 5, 0);
-  if (!usersFor101.ok) throw new Error();
+  if (!usersFor101.ok) throw console.error(usersFor101.error);
   expect(usersFor101.value.map((entry) => entry.u.id)).toEqual([102, 103]);
 
   const usersFor102 = await recommendedTo(102, 5, 0);
-  if (!usersFor102.ok) throw new Error();
+  if (!usersFor102.ok) throw console.error(usersFor102.error);
   expect(usersFor102.value.map((entry) => entry.u.id)).toEqual([103, 101]);
 
   const usersFor103 = await recommendedTo(103, 5, 0);
-  if (!usersFor103.ok) throw new Error();
+  if (!usersFor103.ok) throw console.error(usersFor103.error);
   expect(usersFor103.value.map((entry) => entry.u.id)).toEqual([102, 101]);
 });

server/src/functions/engines/recommendation.ts

@@ -1,8 +1,7 @@
 import { recommend as sql } from "@prisma/client/sql";
 import { Err, Ok, type Result } from "common/lib/result";
-import type { UserID, UserWithCoursesAndSubjects } from "common/types";
+import type { User, UserID, UserWithCoursesAndSubjects } from "common/types";
 import { prisma } from "../../database/client";
-import { getUserByID } from "../../database/users";
 
 export async function recommendedTo(
   user: UserID,
@@ -11,7 +10,7 @@ export async function recommendedTo(
 ): Promise<
   Result<
     Array<{
-      u: UserWithCoursesAndSubjects;
+      u: User; // UserWithCoursesAndSubjects
       count: number;
     }>
   >
@@ -20,17 +19,16 @@ export async function recommendedTo(
     const result = await prisma.$queryRawTyped(sql(user, limit, offset));
     return Promise.all(
       result.map(async (res) => {
-        const user = await getUserByID(res.id);
-        if (!user.ok) throw new Error("not found"); // this shouldn't happen
-        return {
-          count: Number.parseInt(res.overlap?.toString() ?? "0"),
-          u: user.value,
-        };
+        const { overlap: count, ...u } = res;
+        if (count === null)
+          throw new Error("count is null: something is wrong");
+        return { count: Number(count), u };
       }),
     )
       .then((val) => Ok(val))
       .catch((err) => Err(err));
   } catch (err) {
-    return Err(err);
+    console.error("caught error: ", err);
+    return Err(500);
   }
 }