refactor STAC extensions and validation outside of populator logic

.github/CODEOWNERS

@@ -0,0 +1,4 @@
+# see documentation
+# https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners
+
+*       @fmigneault @huard @dchandan

STACpopulator/extensions/cmip6.py

@@ -0,0 +1,356 @@
+import json
+from datetime import datetime
+from typing import (
+    Any,
+    Generic,
+    Iterable,
+    List,
+    Literal,
+    MutableMapping,
+    Type,
+    TypeVar,
+    Union,
+    Optional,
+    cast,
+    get_args
+)
+
+import pystac
+import pyessv
+from pydantic import AnyHttpUrl, BaseModel, ConfigDict, Field, FieldValidationInfo, field_validator
+from pydantic.fields import FieldInfo
+from pystac.extensions import item_assets
+from pystac.extensions.base import (
+    ExtensionManagementMixin,
+    PropertiesExtension,
+    SummariesExtension,
+)
+
+from STACpopulator.models import AnyGeometry
+from STACpopulator.stac_utils import ServiceType, collection2literal, ncattrs_to_bbox, ncattrs_to_geometry
+
+T = TypeVar("T", pystac.Collection, pystac.Item, pystac.Asset, item_assets.AssetDefinition)
+
+SchemaName = Literal["cmip6"]
+SCHEMA_URI: str = "https://stac-extensions.github.io/cmip6/v1.0.0/schema.json"
+PREFIX = f"{get_args(SchemaName)[0]}:"
+
+# CMIP6 controlled vocabulary (CV)
+CV = pyessv.WCRP.CMIP6  # noqa
+
+# Enum classes built from the pyessv' CV
+ActivityID = collection2literal(CV.activity_id)
+ExperimentID = collection2literal(CV.experiment_id)
+Frequency = collection2literal(CV.frequency)
+GridLabel = collection2literal(CV.grid_label)
+InstitutionID = collection2literal(CV.institution_id)
+NominalResolution = collection2literal(CV.nominal_resolution)
+Realm = collection2literal(CV.realm)
+SourceID = collection2literal(CV.source_id, "source_id")
+SourceType = collection2literal(CV.source_type)
+SubExperimentID = collection2literal(CV.sub_experiment_id)
+TableID = collection2literal(CV.table_id)
+
+
+def add_cmip6_prefix(name: str) -> str:
+    return PREFIX + name if "datetime" not in name else name
+
+
+class CMIP6Properties(BaseModel, validate_assignment=True):
+    """Data model for CMIP6 Controlled Vocabulary."""
+
+    Conventions: str
+    activity_id: ActivityID
+    creation_date: datetime
+    data_specs_version: str
+    experiment: str
+    experiment_id: ExperimentID
+    frequency: Frequency
+    further_info_url: AnyHttpUrl
+    grid_label: GridLabel
+    institution: str
+    institution_id: InstitutionID
+    nominal_resolution: NominalResolution
+    realm: List[Realm]
+    source: str
+    source_id: SourceID
+    source_type: List[SourceType]
+    sub_experiment: Union[str, Literal["none"]]
+    sub_experiment_id: SubExperimentID | Literal["none"]
+    table_id: TableID
+    variable_id: str
+    variant_label: str
+    initialization_index: int
+    physics_index: int
+    realization_index: int
+    forcing_index: int
+    tracking_id: str = Field("")
+    version: str = Field("")
+    product: str
+    license: str
+    grid: str
+    mip_era: str
+
+    model_config = ConfigDict(alias_generator=add_cmip6_prefix, populate_by_name=True, extra="ignore")
+
+    @field_validator("initialization_index", "physics_index", "realization_index", "forcing_index", mode="before")
+    @classmethod
+    def only_item(cls, v: list[int], info: FieldValidationInfo):
+        """Pick single item from list."""
+        assert len(v) == 1, f"{info.field_name} must have one item only."
+        return v[0]
+
+    @field_validator("realm", "source_type", mode="before")
+    @classmethod
+    def split(cls, v: str, __info: FieldValidationInfo):
+        """Split string into list."""
+        return v.split(" ")
+
+    @field_validator("version")
+    @classmethod
+    def validate_version(cls, v: str, __info: FieldValidationInfo):
+        assert v[0] == "v", "Version string should begin with a lower case 'v'"
+        assert v[1:].isdigit(), "All characters in version string, except first, should be digits"
+        return v
+
+
+class CMIP6Helper:
+    def __init__(self, attrs: MutableMapping[str, Any], geometry_model: Type[AnyGeometry]):
+        self.attrs = attrs
+        self.cmip6_attrs = attrs["attributes"]
+        self.cfmeta = attrs["groups"]["CFMetadata"]["attributes"]
+        self.geometry_model = geometry_model
+
+    @property
+    def uid(self) -> str:
+        """Return a unique ID for CMIP6 data item."""
+        keys = [
+            "activity_id",
+            "institution_id",
+            "source_id",
+            "experiment_id",
+            "variant_label",
+            "table_id",
+            "variable_id",
+            "grid_label",
+        ]
+        name = "_".join(self.cmip6_attrs[k] for k in keys)
+        return name
+
+    @property
+    def geometry(self) -> AnyGeometry:
+        return self.geometry_model(**ncattrs_to_geometry(self.attrs))
+
+    @property
+    def bbox(self) -> list[float]:
+        return ncattrs_to_bbox(self.attrs)
+
+    @property
+    def start_datetime(self) -> datetime:
+        return self.cfmeta["time_coverage_start"]
+
+    @property
+    def end_datetime(self) -> datetime:
+        return self.cfmeta["time_coverage_end"]
+
+    @property
+    def properties(self) -> CMIP6Properties:
+        props = CMIP6Properties(**self.cmip6_attrs)
+        return props
+
+    def stac_item(self) -> "pystac.Item":
+        item = pystac.Item(
+            id=self.uid,
+            geometry=self.geometry.model_dump(),
+            bbox=self.bbox,
+            properties={
+                "start_datetime": self.start_datetime,
+                "end_datetime": self.end_datetime,
+            },
+            datetime=None,
+        )
+        item_cmip6 = CMIP6Extension.ext(item, add_if_missing=True)
+        item_cmip6.apply(self.properties)
+        return item
+
+
+class CMIP6Extension(
+    Generic[T],
+    PropertiesExtension,
+    ExtensionManagementMixin[Union[pystac.Asset, pystac.Item, pystac.Collection]],
+):
+    @property
+    def name(self) -> SchemaName:
+        return get_args(SchemaName)[0]
+
+    def apply(
+        self,
+        properties: Union[CMIP6Properties, dict[str, Any]],
+    ) -> None:
+        """Applies CMIP6 Extension properties to the extended
+        :class:`~pystac.Item` or :class:`~pystac.Asset`.
+        """
+        if isinstance(properties, dict):
+            properties = CMIP6Properties(**properties)
+        data_json = json.loads(properties.model_dump_json(by_alias=True))
+        for prop, val in data_json.items():
+            self._set_property(prop, val)
+
+    @classmethod
+    def get_schema_uri(cls) -> str:
+        return SCHEMA_URI
+
+    @classmethod
+    def ext(cls, obj: T, add_if_missing: bool = False) -> "CMIP6Extension[T]":
+        """Extends the given STAC Object with properties from the
+        :stac-ext:`CMIP6 Extension <cmip6>`.
+
+        This extension can be applied to instances of :class:`~pystac.Item` or
+        :class:`~pystac.Asset`.
+
+        Raises:
+
+            pystac.ExtensionTypeError : If an invalid object type is passed.
+        """
+        if isinstance(obj, pystac.Collection):
+            cls.ensure_has_extension(obj, add_if_missing)
+            return cast(CMIP6Extension[T], CollectionCMIP6Extension(obj))
+        elif isinstance(obj, pystac.Item):
+            cls.ensure_has_extension(obj, add_if_missing)
+            return cast(CMIP6Extension[T], ItemCMIP6Extension(obj))
+        elif isinstance(obj, pystac.Asset):
+            cls.ensure_owner_has_extension(obj, add_if_missing)
+            return cast(CMIP6Extension[T], AssetCMIP6Extension(obj))
+        elif isinstance(obj, item_assets.AssetDefinition):
+            cls.ensure_owner_has_extension(obj, add_if_missing)
+            return cast(CMIP6Extension[T], ItemAssetsCMIP6Extension(obj))
+        else:
+            raise pystac.ExtensionTypeError(cls._ext_error_message(obj))
+
+    @classmethod
+    def summaries(
+        cls, obj: pystac.Collection, add_if_missing: bool = False
+    ) -> "SummariesCMIP6Extension":
+        """Returns the extended summaries object for the given collection."""
+        cls.ensure_has_extension(obj, add_if_missing)
+        return SummariesCMIP6Extension(obj)
+
+
+class ItemCMIP6Extension(CMIP6Extension[pystac.Item]):
+    """A concrete implementation of :class:`CMIP6Extension` on an :class:`~pystac.Item`
+    that extends the properties of the Item to include properties defined in the
+    :stac-ext:`CMIP6 Extension <cmip6>`.
+
+    This class should generally not be instantiated directly. Instead, call
+    :meth:`CMIP6Extension.ext` on an :class:`~pystac.Item` to extend it.
+    """
+
+    def __init__(self, item: pystac.Item):
+        self.item = item
+        self.properties = item.properties
+
+    def get_assets(
+        self,
+        service_type: Optional[ServiceType] = None,
+    ) -> dict[str, pystac.Asset]:
+        """Get the item's assets where eo:bands are defined.
+
+        Args:
+            service_type: If set, filter the assets such that only those with a
+                matching :class:`~STACpopulator.stac_utils.ServiceType` are returned.
+
+        Returns:
+            Dict[str, Asset]: A dictionary of assets that match ``service_type``
+                if set or else all of this item's assets were service types are defined.
+        """
+        return {
+            key: asset
+            for key, asset in self.item.get_assets().items()
+            if (
+                service_type is ServiceType and service_type.value in asset.extra_fields
+            )
+            or any(
+                ServiceType.from_value(field, default=None) is ServiceType
+                for field in asset.extra_fields
+            )
+        }
+
+    def __repr__(self) -> str:
+        return f"<ItemCMIP6Extension Item id={self.item.id}>"
+
+
+class ItemAssetsCMIP6Extension(CMIP6Extension[item_assets.AssetDefinition]):
+    properties: dict[str, Any]
+    asset_defn: item_assets.AssetDefinition
+
+    def __init__(self, item_asset: item_assets.AssetDefinition):
+        self.asset_defn = item_asset
+        self.properties = item_asset.properties
+
+
+class AssetCMIP6Extension(CMIP6Extension[pystac.Asset]):
+    """A concrete implementation of :class:`CMIP6Extension` on an :class:`~pystac.Asset`
+    that extends the Asset fields to include properties defined in the
+    :stac-ext:`CMIP6 Extension <cmip6>`.
+
+    This class should generally not be instantiated directly. Instead, call
+    :meth:`CMIP6Extension.ext` on an :class:`~pystac.Asset` to extend it.
+    """
+
+    asset_href: str
+    """The ``href`` value of the :class:`~pystac.Asset` being extended."""
+
+    properties: dict[str, Any]
+    """The :class:`~pystac.Asset` fields, including extension properties."""
+
+    additional_read_properties: Optional[Iterable[dict[str, Any]]] = None
+    """If present, this will be a list containing 1 dictionary representing the
+    properties of the owning :class:`~pystac.Item`."""
+
+    def __init__(self, asset: pystac.Asset):
+        self.asset_href = asset.href
+        self.properties = asset.extra_fields
+        if asset.owner and isinstance(asset.owner, pystac.Item):
+            self.additional_read_properties = [asset.owner.properties]
+
+    def __repr__(self) -> str:
+        return f"<AssetCMIP6Extension Asset href={self.asset_href}>"
+
+
+class SummariesCMIP6Extension(SummariesExtension):
+    """A concrete implementation of :class:`~SummariesExtension` that extends
+    the ``summaries`` field of a :class:`~pystac.Collection` to include properties
+    defined in the :stac-ext:`CMIP6 <cmip6>`.
+    """
+    def _check_cmip6_property(self, prop: str) -> FieldInfo:
+        try:
+            return CMIP6Properties.model_fields[prop]
+        except KeyError:
+            raise AttributeError(f"Name '{prop}' is not a valid CMIP6 property.")
+
+    def _validate_cmip6_property(self, prop: str, summaries: list[Any]) -> None:
+        model = CMIP6Properties.model_construct()
+        validator = CMIP6Properties.__pydantic_validator__
+        for value in summaries:
+            validator.validate_assignment(model, prop, value)
+
+    def get_cmip6_property(self, prop: str) -> list[Any]:
+        self._check_cmip6_property(prop)
+        return self.summaries.get_list(prop)
+
+    def set_cmip6_property(self, prop: str, summaries: list[Any]) -> None:
+        self._check_cmip6_property(prop)
+        self._validate_cmip6_property(prop, summaries)
+        self._set_summary(prop, summaries)
+
+    def __getattr__(self, prop):
+        return self.get_cmip6_property(prop)
+
+    def __setattr__(self, prop, value):
+        self.set_cmip6_property(prop, value)
+
+
+class CollectionCMIP6Extension(CMIP6Extension[pystac.Collection]):
+
+    def __init__(self, collection: pystac.Collection):
+        self.collection = collection