from typing import List, Union
import numpy as np
import pandas_datareader as pdr
import pandas as pd
import matplotlib.pyplot as plt


def rsi(symbol :str ,name :str, date :str) -> None :
    """
    Calculates and visualises the Relative Stock Index on a Stock of the company.

    Parameters:
        symbol(str) : Symbol of the company from  https://in.finance.yahoo.com/
        name(str) : Name of the company
        date(str) : start date of historical data in the format (YYYY,M,D)
    Returns:
        Return type: void  
    Example:
        rsi('GOOG','Google','2020,01,01')     

    """
    ticker : str = pdr.get_data_yahoo(symbol, date)
    delta : List[float]  = ticker['Close'].diff()
    up : int   = delta.clip(lower=0)
    down : int = -1*delta.clip(upper=0)
    ema_up : Union[bool,float]= up.ewm(com=13, adjust=False).mean()
    ema_down : Union[bool,float] = down.ewm(com=13, adjust=False).mean()
    rs : float = ema_up/ema_down
    ticker['RSI'] = 100 - (100/(1 + rs))
    ticker : list = ticker.iloc[14:]
    print(ticker)
    fig, (ax1, ax2) = plt.subplots(2)
    ax1.get_xaxis().set_visible(False)
    fig.suptitle(name)
    ticker['Close'].plot(ax=ax1)
    ax1.set_ylabel('Price ($)')
    ticker['RSI'].plot(ax=ax2)
    ax2.set_ylim(0,100)
    ax2.axhline(30, color='r', linestyle='--')
    ax2.axhline(70, color='r', linestyle='--')
    ax2.set_ylabel('RSI')
    plt.show()


def volatility(symbol :str, date :str) ->None:
    """
    Measures and visualizes the Volatility of a Stock by calculating the Average True Range(ATR)
    Parameters:
        symbol(str) : Symbol of the company from  https://in.finance.yahoo.com/
        date(str) : start date of historical data in the format (YYYY,M,D)        
    Returns:
        Return type: void
    Example:
        volatility('GOOG','2020,01,01')    

    """
    
    data : str = pdr.get_data_yahoo(symbol,date)
    data.head()
    high_low : Union[int,float]= data['High'] - data['Low']
    high_cp : List[float] = np.abs(data['High'] - data['Close'].shift())
    low_cp : List[float]= np.abs(data['Low'] - data['Close'].shift())
    df : List[str] = pd.concat([high_low, high_cp, low_cp], axis=1)
    true_range : float= np.max(df, axis=1)
    average_true_range : float= true_range.rolling(14).mean()
    average_true_range
    true_range.rolling(14).sum()/14
    
    fig, ax = plt.subplots()
    average_true_range.plot(ax=ax)
    ax2 : Union[bool,float]= data['Close'].plot(ax=ax, secondary_y=True, alpha=.3)
    ax.set_ylabel("ATR")
    ax2.set_ylabel("Price")
    plt.show()
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