"""
============================
Plotting a solar cycle index
============================

This example demonstrates how to plot the solar cycle in terms of
the number of sunspots and a prediction for the next few years.
"""
import matplotlib.pyplot as plt

import astropy.units as u
from astropy.time import Time, TimeDelta
from astropy.visualization import time_support

import sunpy.timeseries as ts
from sunpy.net import Fido
from sunpy.net import attrs as a
from sunpy.time import TimeRange

###############################################################################
# The U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center (SWPC)
# provides recent solar cycle indices which includes different sunspot numbers,
# radio flux, and geomagnetic index. They also provide predictions for how the
# sunspot number and radio flux will evolve. Predicted values are based on the
# consensus of the Solar Cycle 24 Prediction Panel.
#
# We will first search for and then download the data.

time_range = TimeRange("2008-06-01 00:00", Time.now())
result = Fido.search(a.Time(time_range), a.Instrument('noaa-indices'))
f_noaa_indices = Fido.fetch(result)
result = Fido.search(a.Time(time_range.end, time_range.end + TimeDelta(4 * u.year)),
                     a.Instrument('noaa-predict'))
f_noaa_predict = Fido.fetch(result)

###############################################################################
#  We then load them into individual `~sunpy.timeseries.TimeSeries` objects.

noaa = ts.TimeSeries(f_noaa_indices, source='noaaindices').truncate(time_range)
noaa_predict = ts.TimeSeries(f_noaa_predict, source='noaapredictindices')

###############################################################################
# Finally, we plot both ``noaa`` and ``noaa_predict`` for the sunspot number.
# In this case we use the S.I.D.C. Brussels International Sunspot Number (RI).
# The predictions provide both a high and low values, which we plot below as
# ranges.

time_support()
fig, ax = plt.subplots()
ax.plot(noaa.time, noaa.quantity('sunspot RI'), label='Sunspot Number')
ax.plot(
    noaa_predict.time, noaa_predict.quantity('sunspot'),
    color='grey', label='Near-term Prediction'
)
ax.fill_between(
    noaa_predict.time, noaa_predict.quantity('sunspot low'),
    noaa_predict.quantity('sunspot high'), alpha=0.3, color='grey'
)
ax.set_ylim(bottom=0)
ax.set_ylabel('Sunspot Number')
ax.set_xlabel('Year')
ax.legend()

plt.show()