import csv
import io
import uuid

from fastapi import APIRouter, Depends
from fastapi.responses import StreamingResponse
from sqlalchemy.orm import Session, joinedload

from app.core.database import get_db
from app.core.deps import get_current_user
from app.models.user import ExamRecord, SubjectScore, User
from app.services.student_access import get_student_for_user

router = APIRouter(tags=["export"])


@router.get("/students/{student_id}/scores/export")
def export_scores_csv(
    student_id: uuid.UUID,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    student = get_student_for_user(db, student_id, current_user.id)
    exams = (
        db.query(ExamRecord)
        .options(joinedload(ExamRecord.scores).joinedload(SubjectScore.subject))
        .filter(ExamRecord.student_id == student_id)
        .order_by(ExamRecord.exam_date.asc())
        .all()
    )

    output = io.StringIO()
    writer = csv.writer(output)
    writer.writerow(["考试日期", "考试类型", "标题", "科目", "总分", "得分", "占比"])
    type_map = {"weekly": "周考", "monthly": "月考", "final": "期末"}
    for exam in exams:
        for score in exam.scores:
            writer.writerow([
                exam.exam_date.isoformat(),
                type_map.get(exam.exam_type.value, exam.exam_type.value),
                exam.title or "",
                score.subject.name if score.subject else "",
                float(score.total_score),
                float(score.obtained_score),
                f"{float(score.ratio) * 100:.2f}%",
            ])

    output.seek(0)
    filename = f"{student.name}_scores.csv"
    return StreamingResponse(
        iter([output.getvalue().encode("utf-8-sig")]),
        media_type="text/csv",
        headers={"Content-Disposition": f'attachment; filename="{filename}"'},
    )