import pandas as pd

def calculate_rsi(df, period=14):
    delta = df['close'].diff()
    gain = delta.where(delta > 0, 0)
    loss = -delta.where(delta < 0, 0)

    avg_gain = gain.rolling(window=period).mean()
    avg_loss = loss.rolling(window=period).mean()

    rs = avg_gain / avg_loss
    rsi = 100 - (100 / (1 + rs))
    return rsi

def calculate_macd(df):
    ema12 = df['close'].ewm(span=12, adjust=False).mean()
    ema26 = df['close'].ewm(span=26, adjust=False).mean()
    macd = ema12 - ema26
    signal = macd.ewm(span=9, adjust=False).mean()
    return macd, signal

def generate_signal(df):
    rsi = calculate_rsi(df)
    macd, signal = calculate_macd(df)

    if len(rsi) < 1 or len(macd) < 1 or len(signal) < 1:
        return "Not enough data"

    latest_rsi = rsi.iloc[-1]
    latest_macd = macd.iloc[-1]
    latest_signal = signal.iloc[-1]

    if latest_rsi < 30 and latest_macd > latest_signal:
        return "BUY"
    elif latest_rsi > 70 and latest_macd < latest_signal:
        return "SELL"
    else:
        return "HOLD"