#import packages
import pandas as pd
from fbprophet import Prophet
import matplotlib.pyplot as plt

# function to calculate compound annual growth rate
def CAGR(first, last, periods):
    return ((last/first)**(1/periods)-1) * 100

# comment either of the following two blocks.

# Block 1 for BSE SENSEX
################################################################################
# read the Indian BSE data file
df = pd.read_csv('D:\\python3\\data\\SensexHistoricalData.csv')
################################################################################

# Block 2 for DOW JONES
################################################################################
## read the US Dow Jones data file
#df_i = pd.read_csv('D:\\python3\\data\\DowJonesHistoricalPrices.csv')

## Dow jones data is in reverse order, i.e. from current date to the past dates.
## We need to correct this before proceeding
#df_i['Date'] = pd.to_datetime(df_i.Date)
#df = df_i.iloc[::-1]
################################################################################

# preparing data. Prophet only understands y and ds columns. Hence we need to rename
# our data frame columns
df.rename(columns={'Close': 'y', 'Date': 'ds'}, inplace=True)

# Model initialization. Create an object of class Prophet.
model = Prophet()

# Fit the data(train the model)
model.fit(df)

# Create a future data frame of future dates. Here 3650 is approximate number of days in 10 yrs time frame.
future = model.make_future_dataframe(periods=3650)

# Prediction for future dates.
forecast = model.predict(future)

# forecast has number of various columns. In this exercise we are considering only two of them.
# ds is a date column and yhat is the median predicated value.
forecast_valid = forecast[['ds','yhat']][:]
forecast_valid.rename(columns={'yhat': 'y'}, inplace=True)

#print the last predicted value
print ("Closing price at 2029 would be around ", forecast_valid[['y']].iloc[-1])

#print CAGR for next ten years.
print ('Your investments will have a CAGR of ',(CAGR(df['y'].iloc[-1], forecast_valid[['y']].iloc[-1], 10)), '%')

# create a date index for input data frame.
df['Date'] = pd.to_datetime(df.ds)
df.index = df['Date']

# Create a date index for forecast data frame.
forecast_valid['Date'] = pd.to_datetime(forecast_valid.ds)
forecast_valid.index = forecast_valid['Date']

# plot the actual data
plt.figure(figsize=(16,8))
plt.plot(df['y'], label='Close Price History')

# plot the prophet predictions
plt.plot(forecast_valid[['y']], label='Future Predictions')

#set the title of the graph
plt.suptitle('Stock Market Predictions "Bse Sensex"', fontsize=16)

#set the title of the graph window
fig = plt.gcf()
fig.canvas.set_window_title('Stock Market Predictions')

#display the legends
plt.legend()

#display the graph
plt.show()