from __future__ import annotations
from typing import Any
import rasterio
from fastmcp import Context
from fastmcp.exceptions import ToolError
def extract_raster_info(
path: str,
band: int | None = None,
ctx: Context | None = None,
) -> dict[str, Any]:
"""Extract raster metadata using Rasterio.
Returns a plain dict suitable for constructing the Raster Info model
or direct JSON serialization from a Resource.
"""
try:
with rasterio.Env():
with rasterio.open(path) as ds:
if band is not None:
if band < 1 or band > ds.count:
raise ToolError(
f"Band index {band} is out of range. Valid range: 1 to {ds.count}. "
f"This raster has {ds.count} band(s)."
)
ov_levels = ds.overviews(band)
else:
ov_levels = ds.overviews(1) if ds.count >= 1 else []
crs_str = str(ds.crs) if ds.crs else None
transform = [
ds.transform.a,
ds.transform.b,
ds.transform.c,
ds.transform.d,
ds.transform.e,
ds.transform.f,
]
dtype_str = ds.dtypes[0] if ds.dtypes else None
bounds = (ds.bounds.left, ds.bounds.bottom, ds.bounds.right, ds.bounds.top)
return {
"path": path,
"driver": ds.driver,
"crs": crs_str,
"width": ds.width,
"height": ds.height,
"count": ds.count,
"dtype": dtype_str,
"transform": transform,
"bounds": bounds,
"nodata": ds.nodata,
"overview_levels": ov_levels,
"tags": ds.tags() or {},
}
except rasterio.errors.RasterioIOError as e:
msg = (
f"Cannot open raster at '{path}'. "
"Please ensure the file exists and is a valid raster format."
)
raise ToolError(msg) from e
except Exception as e:
raise ToolError(f"Unexpected error while reading raster metadata: {str(e)}") from e
