# -*- coding: utf-8 -*-
"""
ICON/Triangular grid
==============================================

This example shows how to draw the edges of an ICON triangular mesh with
:py:func:`easyclimate.plot.icon.plot_triangular_grid <easyclimate.plot.icon.plot_triangular_grid>`.

The helper reads ICON cell-center and vertex-boundary coordinates from the
dataset, then draws the triangular edges on either plain Matplotlib axes or
Cartopy map projections.
"""
import xarray as xr
import numpy as np
import cartopy.crs as ccrs
import matplotlib.pyplot as plt
import easyclimate as ecl

from easyclimate.plot.icon import plot_triangular_grid

# %%
# Open a sample ICON pressure-level file. The file contains the native ICON
# cell-center coordinates and triangular cell bounds needed by the mesh helper.
data = ecl.open_tutorial_dataset("icon_native_pl_20080909T000000Z")
data

# %%
# Draw the triangular mesh directly on the current Matplotlib axes.
plot_triangular_grid(data)

# %%
# Plot the global ICON mesh on a shifted PlateCarree projection. Passing a
# Cartopy GeoAxes lets the helper add the mesh with geographic coordinates.
fig = plt.figure(figsize=(12, 6))
ax = plt.axes(projection=ccrs.PlateCarree(180))
ax.coastlines(resolution="110m", linewidth=0.6)

plot_triangular_grid(data, ax = ax, transform=ccrs.PlateCarree());
ax.set_global()
ax.gridlines(draw_labels=True, alpha = 0)

ax.set_title("Global ICON mesh 1")

# %%
# The same native triangular mesh can be displayed with a Robinson projection.
fig = plt.figure(figsize=(12, 6))
ax = plt.axes(projection=ccrs.Robinson(0))
ax.coastlines(resolution="110m", linewidth=0.6)

plot_triangular_grid(data, ax = ax, transform=ccrs.PlateCarree());
ax.set_global()
ax.gridlines(draw_labels=True, alpha = 0)

ax.set_title("Global ICON mesh 2")

# %%
# Orthographic projection is useful for inspecting the global grid from a
# regional viewing angle.
fig = plt.figure(figsize=(12, 6))
ax = plt.axes(projection=ccrs.Orthographic(central_longitude=110.0, central_latitude=70.0))
ax.coastlines(resolution="110m", linewidth=0.6)

plot_triangular_grid(data, ax = ax, transform=ccrs.PlateCarree())
ax.set_global()
ax.gridlines(draw_labels=True, alpha = 0)

ax.set_global()
ax.set_title("Global ICON mesh 3")

# %%
# Restrict the plotted cells to a regional longitude-latitude window. The
# helper selects cells by their centers and draws only the visible triangular
# edges.

# sphinx_gallery_thumbnail_number = -1
fig = plt.figure(figsize=(12, 6))
ax = plt.axes(projection=ccrs.PlateCarree(180))
ax.coastlines(resolution="50m", linewidth=0.6, color="b")

plot_triangular_grid(
    data,
    ax = ax,
    transform=ccrs.PlateCarree(),
    lon_min = 90,
    lon_max = 150,
    lat_min = 10,
    lat_max = 50,
);
ax.set_extent([90, 150, 10, 50], crs = ccrs.PlateCarree())
ax.gridlines(draw_labels=True, alpha = 0)

ax.set_title("East Asia ICON mesh 1")