Feature/xyz routes

.gitignore

@@ -115,6 +115,9 @@ venv.bak/
 .spyderproject
 .spyproject
 
+# Pycharm project settings
+.idea
+
 # Rope project settings
 .ropeproject
 

xpublish/routers/__init__.py

@@ -1,3 +1,8 @@
 from .base import base_router
 from .common import common_router, dataset_collection_router
 from .zarr import zarr_router
+
+try:
+    from .xyz import xyz_router
+except ImportError:
+    pass

xpublish/routers/xyz.py

@@ -0,0 +1,79 @@
+import xarray as xr
+import cachey
+from fastapi import APIRouter, Depends, Response, Query, Path
+from typing import Optional
+
+from xpublish.utils.cache import CostTimer
+from xpublish.utils.api import DATASET_ID_ATTR_KEY
+from xpublish.dependencies import get_dataset, get_cache
+from xpublish.utils.ows import (
+    get_image_datashader,
+    get_bounds,
+    LayerOptionsMixin,
+    get_tiles,
+)
+
+
+class XYZRouter(APIRouter, LayerOptionsMixin):
+    pass
+
+
+xyz_router = XYZRouter()
+
+
+def query_builder(time, xleft, xright, ybottom, ytop, xlab, ylab):
+    query = {}
+    query.update({xlab: slice(xleft, xright), ylab: slice(ytop, ybottom)})
+    if time:
+        query["time"] = time
+    return query
+
+
+@xyz_router.get("/tiles/{var}/{z}/{x}/{y}")
+@xyz_router.get("/tiles/{var}/{z}/{x}/{y}.{format}")
+async def tiles(
+    var: str = Path(
+        ..., description="Dataset's variable. It defines the map's data layer"
+    ),
+    z: int = Path(..., description="Tiles' zoom level"),
+    x: int = Path(..., description="Tiles' column"),
+    y: int = Path(..., description="Tiles' row"),
+    format: str = Query("PNG", description="Image format. Default to PNG"),
+    time: str = Query(
+        None,
+        description="Filter by time in time-varying datasets. String time format should match dataset's time format",
+    ),
+    xlab: str = Query("x", description="Dataset x coordinate label"),
+    ylab: str = Query("y", description="Dataset y coordinate label"),
+    cache: cachey.Cache = Depends(get_cache),
+    dataset: xr.Dataset = Depends(get_dataset),
+):
+
+    # color mapping settings
+    datashader_settings = getattr(xyz_router, "datashader_settings")
+
+    TMS = getattr(xyz_router, "TMS")
+
+    xleft, xright, ybottom, ytop = get_bounds(TMS, z, x, y)
+
+    query = query_builder(time, xleft, xright, ybottom, ytop, xlab, ylab)
+
+    cache_key = (
+        dataset.attrs.get(DATASET_ID_ATTR_KEY, "")
+        + "/"
+        + f"/tiles/{var}/{z}/{x}/{y}.{format}?{time}"
+    )
+    response = cache.get(cache_key)
+
+    if response is None:
+        with CostTimer() as ct:
+
+            tile = get_tiles(var, dataset, query)
+
+            byte_image = get_image_datashader(tile, datashader_settings, format)
+
+            response = Response(content=byte_image, media_type=f"image/{format}")
+
+        cache.put(cache_key, response, ct.time, len(byte_image))
+
+    return response

xpublish/utils/ows.py

@@ -0,0 +1,89 @@
+from datashader import transfer_functions as tf
+import datashader as ds
+import xarray as xr
+from fastapi import HTTPException
+import morecantile
+
+
+# From Morecantile, morecantile.tms.list()
+WEB_CRS = {
+    3857: "WebMercatorQuad",
+    32631: "UTM31WGS84Quad",
+    3978: "CanadianNAD83_LCC",
+    5482: "LINZAntarticaMapTilegrid",
+    4326: "WorldCRS84Quad",
+    5041: "UPSAntarcticWGS84Quad",
+    3035: "EuropeanETRS89_LAEAQuad",
+    3395: "WorldMercatorWGS84Quad",
+    2193: "NZTM2000",
+}
+
+
+class DataValidationError(KeyError):
+    pass
+
+
+class LayerOptionsMixin:
+    def set_options(self, crs_epsg: int = 3857, color_mapping: dict = {}) -> None:
+
+        self.datashader_settings = color_mapping.get("datashader_settings")
+        self.matplotlib_settings = color_mapping.get("matplotlib_settings")
+
+        if crs_epsg not in WEB_CRS.keys():
+            raise DataValidationError(f"User input {crs_epsg} not supported")
+
+        self.TMS = morecantile.tms.get(WEB_CRS[crs_epsg])
+
+
+def get_bounds(TMS, zoom, x, y):
+
+    bbx = TMS.xy_bounds(morecantile.Tile(int(x), int(y), int(zoom)))
+
+    return bbx.left, bbx.right, bbx.bottom, bbx.top
+
+
+def get_tiles(var, dataset, query) -> xr.DataArray:
+
+    if query.get("time"):
+        tile = dataset[var].sel(query)  # noqa
+    else:
+        tile = dataset[var].sel(query)  # noqa
+
+    if 0 in tile.sizes.values():
+        raise HTTPException(status_code=406, detail=f"Map outside dataset domain")
+
+    return tile
+
+
+def get_image_datashader(tile, datashader_settings, format):
+
+    raster_param = datashader_settings.get("raster", {})
+    shade_param = datashader_settings.get("shade", {"cmap": ["blue", "red"]})
+
+    cvs = ds.Canvas(plot_width=256, plot_height=256)
+
+    agg = cvs.raster(tile, **raster_param)
+
+    img = tf.shade(agg, **shade_param)
+
+    img_io = img.to_bytesio(format)
+
+    return img_io.read()
+
+
+def get_legend():
+    pass
+
+
+def validate_dataset(dataset):
+    dims = dataset.dims
+    if "x" not in dims or "y" not in dims:
+        raise DataValidationError(
+            f" Expected spatial dimension names 'x' and 'y', found: {dims}"
+        )
+    if "time" not in dims and len(dims) >= 3:
+        raise DataValidationError(
+            f" Expected time dimension name 'time', found: {dims}"
+        )
+    if len(dims) > 4:
+        raise DataValidationError(f" Not implemented for dimensions > 4")