from flask import Blueprint, request, redirect, url_for, flash, g
from app.models.book import Book
from app.models.borrow import BorrowRecord
from app.models.inventory import InventoryLog
from app.models.user import db  # 修正：从 user 模型导入 db
from app.utils.auth import login_required
import datetime

# 创建借阅蓝图
borrow_bp = Blueprint('borrow', __name__, url_prefix='/borrow')


@borrow_bp.route('/book', methods=['POST'])
@login_required
def borrow_book():
    book_id = request.form.get('book_id', type=int)
    borrow_days = request.form.get('borrow_days', type=int, default=14)

    if not book_id:
        flash('请选择要借阅的图书', 'danger')
        return redirect(url_for('book.book_list'))

    book = Book.query.get_or_404(book_id)

    # 检查库存
    if book.stock <= 0:
        flash(f'《{book.title}》当前无库存，无法借阅', 'danger')
        return redirect(url_for('book.book_detail', book_id=book_id))

    # 检查当前用户是否已借阅此书
    existing_borrow = BorrowRecord.query.filter_by(
        user_id=g.user.id,
        book_id=book_id,
        status=1  # 1表示借阅中
    ).first()

    if existing_borrow:
        flash(f'您已借阅《{book.title}》，请勿重复借阅', 'warning')
        return redirect(url_for('book.book_detail', book_id=book_id))

    try:
        # 创建借阅记录
        now = datetime.datetime.now()
        due_date = now + datetime.timedelta(days=borrow_days)

        borrow_record = BorrowRecord(
            user_id=g.user.id,
            book_id=book_id,
            borrow_date=now,
            due_date=due_date,
            status=1,  # 1表示借阅中
            created_at=now,
            updated_at=now
        )

        # 更新图书库存
        book.stock -= 1
        book.updated_at = now

        db.session.add(borrow_record)
        db.session.commit()

        # 添加库存变更日志
        inventory_log = InventoryLog(
            book_id=book_id,
            change_type='借出',
            change_amount=-1,
            after_stock=book.stock,
            operator_id=g.user.id,
            remark='用户借书',
            changed_at=now
        )
        db.session.add(inventory_log)
        db.session.commit()

        flash(f'成功借阅《{book.title}》，请在 {due_date.strftime("%Y-%m-%d")} 前归还', 'success')

    except Exception as e:
        db.session.rollback()
        flash(f'借阅失败: {str(e)}', 'danger')

    return redirect(url_for('book.book_detail', book_id=book_id))