from flask import request, redirect, url_for, g
from .config import db
import pymysql

def cancel_order():
    order_id = request.args.get('order_id')
    if not g.user:
        return redirect(url_for("login"))
    conn = pymysql.connect(**db)
    cursor = conn.cursor(pymysql.cursors.DictCursor)

    # 检查订单是否存在
    check_order_sql = "SELECT ID FROM Orders WHERE ID = %s"
    cursor.execute(check_order_sql, (order_id,))
    order_exists = cursor.fetchone()

    if not order_exists:
        cursor.close()
        conn.close()
        return redirect(url_for("order_list"))

    # 查询订单中所有机票的航班ID和座位级别
    tickets_sql = "SELECT FlightID, Seat_class FROM Tickets WHERE OrderID = %s"
    cursor.execute(tickets_sql, (order_id,))
    tickets = cursor.fetchall()

    # 恢复航班的对应余座数
    for ticket in tickets:
        flight_id = ticket['FlightID']
        seat_class = ticket['Seat_class']
        seat_column = seat_class.replace(' ', '_').lower() + "_seats_remaining"
        update_seat_sql = f"""
        UPDATE Flights
        SET {seat_column} = {seat_column} + 1
        WHERE ID = %s
        """
        cursor.execute(update_seat_sql, (flight_id,))

    # 删除对应的机票
    delete_tickets_sql = "DELETE FROM Tickets WHERE OrderID = %s"
    cursor.execute(delete_tickets_sql, (order_id,))

    # 删除订单
    delete_order_sql = "DELETE FROM Orders WHERE ID = %s"
    cursor.execute(delete_order_sql, (order_id,))

    conn.commit()
    cursor.close()
    conn.close()

    return redirect(url_for('order_list'))