projjson pydantic model

src/eopf_geozarr/data_api/geozarr/common.py

@@ -3,16 +3,64 @@
 import io
 import urllib
 import urllib.request
-from typing import Annotated, Any, Mapping, TypeVar
+from dataclasses import dataclass
+from typing import Annotated, Any, Mapping, Self, TypeVar
 
 from cf_xarray.utils import parse_cf_standard_name_table
-from pydantic import AfterValidator, BaseModel
+from pydantic import AfterValidator, BaseModel, Field, model_validator
 from pydantic.experimental.missing_sentinel import MISSING
-from typing_extensions import Protocol, runtime_checkable
+from typing_extensions import Final, Literal, Protocol, runtime_checkable
 
+from eopf_geozarr.data_api.geozarr.projjson import ProjJSON
 from eopf_geozarr.data_api.geozarr.types import ResamplingMethod
 
 
+@dataclass(frozen=True)
+class UNSET_TYPE:
+    """
+    Sentinel value to indicate that a value is not set.
+    """
+
+    ...
+
+
+UNSET = UNSET_TYPE()
+
+GEO_PROJ_VERSION: Final = "0.1"
+
+
+class ProjAttrs(BaseModel, extra="allow"):
+    """
+    Zarr attributes for coordinate reference system (CRS) encoding.
+
+    Attributes
+    version: str
+        The version of the metadata.
+    code: str | None
+        Authority:Code identifier.
+    wkt2 : str | None
+        WKT2 (ISO 19162) representation of the CRS.
+    projjson: ProjJson | None
+        PROJJSON representation of the CRS.
+    bbox:
+    """
+
+    version: Literal["0.1"] = "0.1"
+    code: str | None = Field(pattern="^[A-Z]+:[0-9]+$")
+    wkt2: str | None = None
+    projjson: ProjJSON | None
+    bbox: tuple[float, float, float, float] | UNSET_TYPE = UNSET
+    transform: tuple[float, float, float, float, float, float] | UNSET_TYPE = UNSET
+    # TODO: enclosing object must validate these properties against the arrays
+    spatial_dimensions: tuple[str, str] | UNSET_TYPE = UNSET
+
+    @model_validator(mode="after")
+    def check_one_of(self) -> Self:
+        if self.code is None and self.wkt2 is None and self.projjson is None:
+            raise ValueError("One of 'code', 'wkt2', or 'projjson' must be provided.")
+        return self
+
+
 class BaseDataArrayAttrs(BaseModel, extra="allow"):
     """
     Base attributes for a  GeoZarr DataArray.