"""Add XYZ basemaps in QGIS with PyQGIS and render them to PNG.

Run headless with the QGIS Python launcher, for example on Windows:
    "C:\\Program Files\\QGIS 3.40.12\\bin\\python-qgis-ltr.bat" pyqgis_xyz_basemaps.py
Tested with QGIS 3.40.12-Bratislava.
"""
from pathlib import Path

from qgis.core import (
    Qgis,
    QgsApplication,
    QgsCoordinateReferenceSystem,
    QgsCoordinateTransform,
    QgsDataSourceUri,
    QgsMapRendererParallelJob,
    QgsMapSettings,
    QgsProject,
    QgsRasterLayer,
    QgsRectangle,
)
from qgis.PyQt.QtCore import QSize
from qgis.PyQt.QtGui import QColor

OUT = Path(__file__).parent / "output"
OUT.mkdir(exist_ok=True)

BASEMAPS = {
    "OpenStreetMap": ("https://tile.openstreetmap.org/{z}/{x}/{y}.png", 19),
    "Sentinel-2 cloudless 2016 (EOX)": (
        "https://tiles.maps.eox.at/wmts/1.0.0/s2cloudless_3857/default/g/{z}/{y}/{x}.jpg",
        14,
    ),
}


def xyz_layer(name: str, url: str, zmax: int = 19) -> QgsRasterLayer:
    uri = QgsDataSourceUri()
    uri.setParam("type", "xyz")
    uri.setParam("url", url)
    uri.setParam("zmin", "0")
    uri.setParam("zmax", str(zmax))
    source = bytes(uri.encodedUri()).decode()
    layer = QgsRasterLayer(source, name, "wms")
    print(f"{name}: valid={layer.isValid()} crs={layer.crs().authid()}")
    print(f"  source={source}")
    return layer


def main() -> None:
    qgs = QgsApplication([], False)
    qgs.initQgis()
    print("QGIS", Qgis.version())

    project = QgsProject.instance()
    layers = [xyz_layer(n, u, z) for n, (u, z) in BASEMAPS.items()]
    project.addMapLayers(layers)

    wgs84 = QgsCoordinateReferenceSystem("EPSG:4326")
    web_merc = QgsCoordinateReferenceSystem("EPSG:3857")
    to_merc = QgsCoordinateTransform(wgs84, web_merc, project)
    # Holderness coast around Withernsea, East Yorkshire
    extent = to_merc.transformBoundingBox(QgsRectangle(-0.10, 53.70, 0.12, 53.80))

    for layer, fname in zip(layers, ["qgis_osm.png", "qgis_eox_2016.png"]):
        settings = QgsMapSettings()
        settings.setLayers([layer])
        settings.setDestinationCrs(web_merc)
        settings.setExtent(extent)
        settings.setOutputSize(QSize(1000, 700))
        settings.setBackgroundColor(QColor("white"))
        job = QgsMapRendererParallelJob(settings)
        job.start()
        job.waitForFinished()
        job.renderedImage().save(str(OUT / fname))
        print(f"saved {fname}; render errors: {len(job.errors())}")

    qgs.exitQgis()


if __name__ == "__main__":
    main()