Add start to filters

src/stac_auth_proxy/config.py

@@ -48,4 +48,10 @@ class Settings(BaseSettings):
     public_endpoints: EndpointMethods = {"/api.html": ["GET"], "/api": ["GET"]}
     openapi_spec_endpoint: Optional[str] = None
 
+    collections_filter: Optional[ClassInput] = {
+        "cls": "stac_auth_proxy.filters.Template",
+        "args": ["""A_CONTAINEDBY(id, ( '{{ token.collections | join("', '") }}' ))"""],
+    }
+    items_filter: Optional[ClassInput] = None
+
     model_config = SettingsConfigDict(env_prefix="STAC_AUTH_PROXY_")

src/stac_auth_proxy/filters/__init__.py

@@ -0,0 +1,3 @@
+from .template import Template
+
+__all__ = ["Template"]

src/stac_auth_proxy/filters/template.py

@@ -0,0 +1,44 @@
+from typing import Any, Callable
+
+from cql2 import Expr
+from jinja2 import Environment, BaseLoader
+from fastapi import Request, Security
+
+from ..utils import extract_variables
+
+from dataclasses import dataclass, field
+
+
+@dataclass
+class Template:
+    template_str: str
+    token_dependency: Callable[..., Any]
+
+    # Generated attributes
+    env: Environment = field(init=False)
+
+    def __post_init__(self):
+        self.env = Environment(loader=BaseLoader).from_string(self.template_str)
+        self.render.__annotations__["auth_token"] = Security(self.token_dependency)
+
+    async def cql2(self, request: Request, auth_token=Security(...)) -> Expr:
+        # TODO: How to handle the case where auth_token is null?
+        context = {
+            "req": {
+                "path": request.url.path,
+                "method": request.method,
+                "query_params": dict(request.query_params),
+                "path_params": extract_variables(request.url.path),
+                "headers": dict(request.headers),
+                "body": (
+                    await request.json()
+                    if request.headers.get("content-type") == "application/json"
+                    else (await request.body()).decode()
+                ),
+            },
+            "token": auth_token,
+        }
+        cql2_str = self.env.render(**context)
+        cql2_expr = Expr(cql2_str)
+        cql2_expr.validate()
+        return cql2_expr