buy route pset7 Finance

@app.route("/buy", methods=["GET", "POST"])
@login_required
def buy():
    """Buy shares of stock."""

    if request.method == "POST":
        # ensure a symbol was submitted
        if not request.form.get("symbol"):
            return apology("symbol required")

        # check if symbol is valid
        stock = lookup(request.form.get("symbol"))
        if not stock:
            return apology("symbol does not exist")

        # ensure that number of shares entered is not negative
        user_input_shares = int(request.form.get("shares"))
        if user_input_shares < 0:
            return apology("number of shares cannot be negative!")

        # check how much cash user has
        cash = db.execute("SELECT cash FROM users WHERE id=:uid", uid=session["user_id"])
        if not cash:
            return apology("something went wrong when looking up cash amount")

        # calculate total price of stock
        total = stock["price"] * user_input_shares
        if total > cash[0]["cash"]:
            return apology("You don't have enough money!")

        # update user's information and total amount of cash in database and send user to Portfolio
        total_cash = cash[0]["cash"] - total
        db.execute("UPDATE users SET cash=:cash WHERE id=:uid", cash=total_cash, uid=session["user_id"])

        transactions_info = db.execute("SELECT * FROM transactions WHERE user_id=:uid", uid=session["user_id"])
        total_shares = 0
        if len(transactions_info) != 0:
            for i in range(len(transactions_info)):
                if transactions_info[i]["stock_symbol"] == request.form.get("symbol") and transactions_info[i]["no_of_shares"] > 0:
                    total_shares = db.execute("UPDATE transactions SET no_of_shares=:shares WHERE user_id=:uid AND stock_symbol=:ssymbol AND time=:t",
                    shares=transactions_info["no_of_shares"] + user_input_shares, uid=session["user_id"], stock_symbol=request.form.get("symbol"),
                    t=time.time())
                elif transactions_info[i]["stock_symbol"] != request.form.get("symbol"):
                    db.execute("INSERT INTO transactions (stock_name, stock_price, stock_symbol, time, no_of_shares, user_id) VALUES(:sname, :sprice, :ssymbol, :t, :shares, :uid)",
        sname=stock["name"], sprice=stock["price"], ssymbol=stock["symbol"], t=time.time(), shares=user_input_shares, uid=session["user_id"])

        cash = db.execute("SELECT cash FROM users WHERE id=:uid", uid=session["user_id"])

        grand_total = 0
        total = 0
        for i in range(len(transactions_info)):
            grand_total = (transactions_info[i]["no_of_shares"] * transactions_info[i]["stock_price"]) + cash
            if transactions_info[i]["stock_symbol"] == stock["symbol"]:
                total = transactions_info["stock_price"] * transactions_info[i]["no_of_shares"]

        return render_template("index.html", transactions_info=transactions_info, total_shares=total_shares,
        grand_total=grand_total, cash=cash, total=total)
    elif request.method == "GET":
        return render_template("buy.html")