"""
London Tube Lines
=================
This example shows the London tube lines against the background of the
borough boundaries. It is based on the vega-lite example at
https://vega.github.io/vega-lite/examples/geo_layer_line_london.html.
"""
# category: case studies
import altair as alt
from vega_datasets import data

boroughs = alt.topo_feature(data.londonBoroughs.url, "boroughs")
tubelines = alt.topo_feature(data.londonTubeLines.url, "line")
centroids = data.londonCentroids.url

background = (
    alt.Chart(boroughs)
    .mark_geoshape(stroke="white", strokeWidth=2)
    .encode(color=alt.value("#eee"),)
    .properties(width=700, height=500)
)

labels = (
    alt.Chart(centroids)
    .mark_text()
    .encode(
        longitude="cx:Q",
        latitude="cy:Q",
        text="bLabel:N",
        size=alt.value(8),
        opacity=alt.value(0.6),
    )
    .transform_calculate(
        "bLabel",
        "indexof (datum.name,' ') > 0  ? substring(datum.name,0,indexof(datum.name, ' ')) : datum.name",
    )
)

line_scale = alt.Scale(
    domain=[
        "Bakerloo",
        "Central",
        "Circle",
        "District",
        "DLR",
        "Hammersmith & City",
        "Jubilee",
        "Metropolitan",
        "Northern",
        "Piccadilly",
        "Victoria",
        "Waterloo & City",
    ],
    range=[
        "rgb(137,78,36)",
        "rgb(220,36,30)",
        "rgb(255,206,0)",
        "rgb(1,114,41)",
        "rgb(0,175,173)",
        "rgb(215,153,175)",
        "rgb(106,114,120)",
        "rgb(114,17,84)",
        "rgb(0,0,0)",
        "rgb(0,24,168)",
        "rgb(0,160,226)",
        "rgb(106,187,170)",
    ],
)

lines = (
    alt.Chart(tubelines)
    .mark_geoshape(filled=False, strokeWidth=2)
    .encode(
        alt.Color(
            "id:N",
            legend=alt.Legend(title=None, orient="bottom-right", offset=0),
            scale=line_scale,
        )
    )
)

background + labels + lines
