import csv
import io

from fastapi import APIRouter, Depends, HTTPException, UploadFile, File
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.deps import require_role
from app.db.database import get_db
from app.db.models import User
from app.schemas.class_ import ClassCreate, ClassUpdate, ClassOut
from app.schemas.user import UserListItem
from app.schemas.roster import RosterOut, RosterImportRequest
from app.schemas.common import PageResponse
from app.services.class_service import (
    create_class,
    update_class,
    delete_class,
    get_class_by_id,
    list_classes,
    get_member_count,
    get_class_members,
)
from app.services.roster_service import (
    ensure_invite_code,
    regenerate_invite_code,
    import_roster,
    get_roster,
    delete_roster_entry,
    clear_unregistered_roster,
)

router = APIRouter(prefix="/api/classes", tags=["classes"])


@router.get("/", response_model=PageResponse[ClassOut])
async def get_classes(
    page: int = 1,
    page_size: int = 50,
    db: AsyncSession = Depends(get_db),
):
    classes, total = await list_classes(db, page, page_size)
    total_pages = (total + page_size - 1) // page_size
    result = []
    for c in classes:
        count = await get_member_count(db, c.id)
        out = ClassOut.model_validate(c)
        out.member_count = count
        result.append(out)
    return PageResponse(
        items=result, total=total, page=page, page_size=page_size, total_pages=total_pages
    )


@router.post("/", response_model=ClassOut)
async def create_new_class(
    data: ClassCreate,
    admin: User = Depends(require_role("super_admin")),
    db: AsyncSession = Depends(get_db),
):
    class_ = await create_class(db, data)
    out = ClassOut.model_validate(class_)
    out.member_count = 0
    return out


@router.put("/{class_id}", response_model=ClassOut)
async def update_existing_class(
    class_id: int,
    data: ClassUpdate,
    admin: User = Depends(require_role("super_admin")),
    db: AsyncSession = Depends(get_db),
):
    class_ = await get_class_by_id(db, class_id)
    if class_ is None:
        raise HTTPException(status_code=404, detail="Class not found")
    updated = await update_class(db, class_, data)
    out = ClassOut.model_validate(updated)
    out.member_count = await get_member_count(db, class_id)
    return out


@router.delete("/{class_id}")
async def delete_existing_class(
    class_id: int,
    admin: User = Depends(require_role("super_admin")),
    db: AsyncSession = Depends(get_db),
):
    class_ = await get_class_by_id(db, class_id)
    if class_ is None:
        raise HTTPException(status_code=404, detail="Class not found")
    await delete_class(db, class_)
    return {"message": "Class deleted"}


@router.get("/{class_id}/members", response_model=PageResponse[UserListItem])
async def get_members(
    class_id: int,
    status: str | None = None,
    page: int = 1,
    page_size: int = 50,
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    if admin.role == "class_admin" and admin.class_id != class_id:
        raise HTTPException(status_code=403, detail="Access denied for this class")

    members, total = await get_class_members(db, class_id, status, page, page_size)
    total_pages = (total + page_size - 1) // page_size
    return PageResponse(
        items=[UserListItem.model_validate(m) for m in members],
        total=total,
        page=page,
        page_size=page_size,
        total_pages=total_pages,
    )


# --- Roster management ---


@router.get("/{class_id}/roster", response_model=PageResponse[RosterOut])
async def get_class_roster(
    class_id: int,
    page: int = 1,
    page_size: int = 50,
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    if admin.role == "class_admin" and admin.class_id != class_id:
        raise HTTPException(status_code=403, detail="Access denied")
    entries, total = await get_roster(db, class_id, page, page_size)
    total_pages = (total + page_size - 1) // page_size
    return PageResponse(
        items=[RosterOut.model_validate(e) for e in entries],
        total=total,
        page=page,
        page_size=page_size,
        total_pages=total_pages,
    )


@router.post("/{class_id}/roster/import")
async def import_class_roster(
    class_id: int,
    data: RosterImportRequest,
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    if admin.role == "class_admin" and admin.class_id != class_id:
        raise HTTPException(status_code=403, detail="Access denied")
    count = await import_roster(db, class_id, data.entries)
    return {"message": f"成功导入 {count} 条记录"}


@router.post("/{class_id}/roster/upload")
async def upload_roster_file(
    class_id: int,
    file: UploadFile = File(...),
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    if admin.role == "class_admin" and admin.class_id != class_id:
        raise HTTPException(status_code=403, detail="Access denied")

    contents = await file.read()
    filename = file.filename or ""

    entries: list[dict] = []

    if filename.endswith(".csv"):
        text = contents.decode("utf-8-sig")
        reader = csv.DictReader(io.StringIO(text))
        for row in reader:
            sid = row.get("student_id") or row.get("学号") or ""
            name = row.get("name") or row.get("姓名") or ""
            if sid and name:
                entries.append({"student_id": sid.strip(), "name": name.strip()})
    elif filename.endswith((".xlsx", ".xls")):
        try:
            import openpyxl

            wb = openpyxl.load_workbook(io.BytesIO(contents), read_only=True)
            ws = wb.active
            rows = list(ws.iter_rows(values_only=True))
            if len(rows) < 2:
                raise HTTPException(status_code=400, detail="Excel 文件为空")
            header = [str(h).strip() if h else "" for h in rows[0]]
            # Find student_id and name columns
            sid_col = None
            name_col = None
            for i, h in enumerate(header):
                if h in ("student_id", "学号"):
                    sid_col = i
                elif h in ("name", "姓名"):
                    name_col = i
            if sid_col is None or name_col is None:
                raise HTTPException(
                    status_code=400,
                    detail="Excel 需包含 '学号'(student_id) 和 '姓名'(name) 列",
                )
            for row in rows[1:]:
                sid = str(row[sid_col]).strip() if row[sid_col] else ""
                name = str(row[name_col]).strip() if row[name_col] else ""
                if sid and name and sid != "None":
                    entries.append({"student_id": sid, "name": name})
            wb.close()
        except ImportError:
            raise HTTPException(
                status_code=400, detail="服务器未安装 openpyxl，请使用 CSV 格式"
            )
    else:
        raise HTTPException(status_code=400, detail="仅支持 CSV 或 Excel (.xlsx) 文件")

    if not entries:
        raise HTTPException(status_code=400, detail="未找到有效数据")

    count = await import_roster(db, class_id, entries)
    return {"message": f"成功导入 {count} 条记录"}


@router.delete("/{class_id}/roster/{roster_id}")
async def delete_roster_item(
    class_id: int,
    roster_id: int,
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    success = await delete_roster_entry(db, roster_id)
    if not success:
        raise HTTPException(status_code=400, detail="无法删除（已注册或不存在）")
    return {"message": "已删除"}


@router.post("/{class_id}/roster/clear")
async def clear_roster(
    class_id: int,
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    if admin.role == "class_admin" and admin.class_id != class_id:
        raise HTTPException(status_code=403, detail="Access denied")
    count = await clear_unregistered_roster(db, class_id)
    return {"message": f"已清除 {count} 条未注册记录"}


# --- Invite code management ---


@router.get("/{class_id}/invite-code")
async def get_invite_code(
    class_id: int,
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    code = await ensure_invite_code(db, class_id)
    if not code:
        raise HTTPException(status_code=404, detail="Class not found")
    return {"invite_code": code}


@router.post("/{class_id}/invite-code/regenerate")
async def regenerate_invite(
    class_id: int,
    admin: User = Depends(require_role("super_admin", "class_admin")),
    db: AsyncSession = Depends(get_db),
):
    code = await regenerate_invite_code(db, class_id)
    if not code:
        raise HTTPException(status_code=404, detail="Class not found")
    return {"invite_code": code}