Feat: [main] baekjoon-bot-v1

workbook_picker.py

@@ -0,0 +1,62 @@
+from typing import Optional, Tuple
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import AsyncSession
+
+
+async def pick_from_workbook(
+    db: AsyncSession,
+    workbook_id: int,
+    pick: str = "random",   # random | level_asc
+) -> Tuple[Optional[int], Optional[str], Optional[int]]:
+    """
+    workbook_id에서 아직 보내지 않은 문제 1개 선택 + workbook_sends 기록까지 원샷.
+    pick:
+      - random: 기존처럼 랜덤
+      - level_asc: level 낮은 것부터(쉬운 것부터). level NULL은 맨 뒤.
+                  같은 level이면 랜덤으로 섞어서 뽑음.
+    """
+    mode = (pick or "random").lower().strip()
+    if mode not in ("random", "level_asc"):
+        mode = "random"
+
+    # 정렬 기준만 분기
+    if mode == "level_asc":
+        order_sql = "ORDER BY (wp.level IS NULL) ASC, wp.level ASC, random()"
+    else:
+        order_sql = "ORDER BY random()"
+
+    sql = f"""
+    WITH candidate AS (
+      SELECT
+        wp.problem_id,
+        COALESCE(wp.title_ko, wp.title_en, '제목 없음') AS title,
+        wp.level
+      FROM workbook_problems wp
+      LEFT JOIN workbook_sends ws
+             ON ws.workbook_id = wp.workbook_id
+            AND ws.problem_id = wp.problem_id
+      WHERE wp.workbook_id = :wid
+        AND ws.problem_id IS NULL
+      {order_sql}
+      LIMIT 1
+    ),
+    ins AS (
+      INSERT INTO workbook_sends(workbook_id, problem_id)
+      SELECT :wid, problem_id
+      FROM candidate
+      ON CONFLICT DO NOTHING
+      RETURNING problem_id
+    )
+    SELECT problem_id, title, level
+    FROM candidate;
+    """
+
+    row = (await db.execute(text(sql), {"wid": workbook_id})).first()
+    if not row:
+        return None, None, None
+
+    await db.commit()
+    pid = int(row[0])
+    title = str(row[1])
+    level = int(row[2]) if row[2] is not None else None
+    return pid, title, level