trail

from math import atan2, cos, radians, sin, sqrt

import numpy as np
import scipy.ndimage as im

from bokeh.document import Document
from bokeh.embed import file_html
from bokeh.models import (Column, ColumnDataSource, GMapOptions, GMapPlot,
                          Grid, Label, Line, LinearAxis, PanTool, Patches,
                          Plot, Range1d, ResetTool, WheelZoomTool)
from bokeh.sampledata.mtb import obiszow_mtb_xcm
from bokeh.util.browser import view


def haversin(theta):
    return sin(0.5 * theta) ** 2


def distance(p1, p2):
    """Distance between (lat1, lon1) and (lat2, lon2). """
    R = 6371

    lat1, lon1 = p1
    lat2, lon2 = p2

    phi1 = radians(lat1)
    phi2 = radians(lat2)
    delta_lat = radians(lat2 - lat1)
    delta_lon = radians(lon2 - lon1)

    a = haversin(delta_lat) + cos(phi1) * cos(phi2) * haversin(delta_lon)
    return 2 * R * atan2(sqrt(a), sqrt(1 - a))


def prep_data(dataset):
    df = dataset.copy()

    latlon = list(zip(df.lat, df.lon))
    dist = np.array([distance(latlon[i + 1], latlon[i]) for i in range(len(latlon[:-1]))])

    df["dist"] = np.concatenate(([0], np.cumsum(dist)))

    slope = np.abs(100 * np.diff(df.alt) / (1000 * dist))
    slope[np.where(                 slope <  4) ] = 0 # "green"
    slope[np.where((slope >=  4) & (slope <  6))] = 1 # "yellow"
    slope[np.where((slope >=  6) & (slope < 10))] = 2 # "pink"
    slope[np.where((slope >= 10) & (slope < 15))] = 3 # "orange"
    slope[np.where( slope >= 15                )] = 4 # "red"
    slope = im.median_filter(slope, 6)

    colors = np.empty_like(slope, dtype=object)
    colors[np.where(slope == 0)] = "green"
    colors[np.where(slope == 1)] = "yellow"
    colors[np.where(slope == 2)] = "pink"
    colors[np.where(slope == 3)] = "orange"
    colors[np.where(slope == 4)] = "red"
    df["colors"] = [*colors, None] # NOTE: add None just make pandas happy

    return df

name = "Obiszów MTB XCM"

# Google Maps now requires an API key. You can find out how to get one here:
# https://developers.google.com/maps/documentation/javascript/get-api-key
API_KEY = "GOOGLE_API_KEY"

def trail_map(data):
    lon = (min(data.lon) + max(data.lon)) / 2
    lat = (min(data.lat) + max(data.lat)) / 2

    map_options = GMapOptions(lng=lon, lat=lat, zoom=13)
    plot = GMapPlot(width=800, height=800, map_options=map_options, api_key=API_KEY)
    plot.title.text = "%s - Trail Map" % name
    plot.x_range = Range1d()
    plot.y_range = Range1d()
    plot.add_tools(PanTool(), WheelZoomTool(), ResetTool())

    line_source = ColumnDataSource(dict(x=data.lon, y=data.lat, dist=data.dist))
    line = Line(x="x", y="y", line_color="blue", line_width=2)
    plot.add_glyph(line_source, line)

    if plot.api_key == "GOOGLE_API_KEY":
        plot.add_layout(Label(x=240, y=700, x_units='screen', y_units='screen',
                              text='Replace GOOGLE_API_KEY with your own key',
                              text_color='red'))

    return plot


def altitude_profile(data):
    plot = Plot(width=800, height=400)
    plot.title.text = "%s - Altitude Profile" % name
    plot.y_range.range_padding = 0

    xaxis = LinearAxis(axis_label="Distance (km)")
    plot.add_layout(xaxis, 'below')

    yaxis = LinearAxis(axis_label="Altitude (m)")
    plot.add_layout(yaxis, 'left')

    plot.add_layout(Grid(dimension=0, ticker=xaxis.ticker))  # x grid
    plot.add_layout(Grid(dimension=1, ticker=yaxis.ticker))  # y grid

    plot.add_tools(PanTool(), WheelZoomTool(), ResetTool())

    X, Y = data.dist, data.alt
    y0 = min(Y)

    patches_source = ColumnDataSource(dict(
        xs=[[X[i], X[i+1], X[i+1], X[i]] for i in range(len(X[:-1])) ],
        ys=[[y0,   y0,     Y[i+1], Y[i]] for i in range(len(Y[:-1])) ],
        color=data.colors[:-1],
    ))
    patches = Patches(xs="xs", ys="ys", fill_color="color", line_color="color")
    plot.add_glyph(patches_source, patches)

    line_source = ColumnDataSource(dict(x=data.dist, y=data.alt))
    line = Line(x='x', y='y', line_color="black", line_width=1)
    plot.add_glyph(line_source, line)

    return plot

data = prep_data(obiszow_mtb_xcm)

trail = trail_map(data)

altitude = altitude_profile(data)

layout = Column(children=[altitude, trail])

doc = Document()
doc.add_root(layout)

if __name__ == "__main__":
    doc.validate()
    filename = "trail.html"
    with open(filename, "w") as f:
        f.write(file_html(doc, title="Trail map and altitude profile"))
    print(f"Wrote {filename}")
    view(filename)