"""
===========================================
Drawing the AIA limb on a STEREO EUVI image
===========================================

In this example we use a STEREO-B and an SDO image to demonstrate how to
overplot the limb as seen by AIA on an EUVI-B image. Then we overplot the AIA
coordinate grid on the STEREO image.
"""
import matplotlib.pyplot as plt

import astropy.units as u
from astropy.coordinates import SkyCoord

import sunpy.coordinates.wcs_utils
import sunpy.map
from sunpy.data.sample import AIA_193_JUN2012, STEREO_B_195_JUN2012

##############################################################################
# Let's create a dictionary with the two maps, which we crop to full disk.

maps = {m.detector: m.submap(SkyCoord([-1100, 1100], [-1100, 1100],
                                      unit=u.arcsec, frame=m.coordinate_frame))
        for m in sunpy.map.Map([AIA_193_JUN2012, STEREO_B_195_JUN2012])}
maps['AIA'].plot_settings['vmin'] = 0  # set the minimum plotted pixel value

##############################################################################
# Now, let's plot both maps, and we draw the limb as seen by AIA onto the
# EUVI image. We remove the part of the limb that is hidden because it is on
# the far side of the Sun from STEREO's point of view.

fig = plt.figure(figsize=(10, 4))
ax1 = fig.add_subplot(121, projection=maps['AIA'])
maps['AIA'].plot(axes=ax1)
maps['AIA'].draw_limb(axes=ax1)

ax2 = fig.add_subplot(122, projection=maps['EUVI'])
maps['EUVI'].plot(axes=ax2)
visible, hidden = maps['AIA'].draw_limb(axes=ax2)
hidden.remove()

##############################################################################
# Let's plot the helioprojective coordinate grid as seen by SDO on the STEREO
# image in a cropped view. Note that only those grid lines that intersect the
# edge of the plot will have corresponding ticks and tick labels.

fig = plt.figure()
ax = fig.add_subplot(projection=maps['EUVI'])

maps['EUVI'].plot(axes=ax)

# Crop the view using pixel coordinates
ax.set_xlim(500, 1300)
ax.set_ylim(100, 900)

# Shrink the plot slightly and move the title up to make room for new labels.
ax.set_position([0.1, 0.1, 0.8, 0.7])
ax.set_title(ax.get_title(), pad=45)

# Change the default grid labels and line properties.
stereo_x, stereo_y = ax.coords
stereo_x.set_axislabel("Helioprojective Longitude (STEREO B) [arcsec]")
stereo_y.set_axislabel("Helioprojective Latitude (STEREO B) [arcsec]")
ax.coords.grid(color='white', linewidth=1)

# Add a new coordinate overlay in the SDO frame.
overlay = ax.get_coords_overlay(maps['AIA'].coordinate_frame)
overlay.grid()

# Configure the grid:
x, y = overlay

# Wrap the longitude at 180 deg rather than the default 360.
x.set_coord_type('longitude', 180*u.deg)

# Set the tick spacing
x.set_ticks(spacing=250*u.arcsec)
y.set_ticks(spacing=250*u.arcsec)

# Set the ticks to be on the top and left axes.
x.set_ticks_position('tr')
y.set_ticks_position('tr')

# Change the defaults to arcseconds
x.set_major_formatter('s.s')
y.set_major_formatter('s.s')

# Add axes labels
x.set_axislabel("Helioprojective Longitude (SDO) [arcsec]")
y.set_axislabel("Helioprojective Latitude (SDO) [arcsec]")

plt.show()