Sergey Antropoff
187 lines
6.9 KiB
Python
187 lines
6.9 KiB
Python
"""Contract-driven dynamic route and semantic handler registry."""
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from __future__ import annotations
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from collections.abc import Awaitable, Callable
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from dataclasses import dataclass, field
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from typing import Any, Literal
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from urllib.parse import parse_qsl
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from fastapi import FastAPI, Request
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from fastapi.responses import JSONResponse
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from app.api.errors import ContractValidationError
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from app.contracts.model import Method, Schema, Snapshot
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Handler = Callable[[Request, dict[str, Any]], Awaitable[Any]]
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FallbackMode = Literal["error", "schema-default", "fixture"]
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class RouteCollisionError(ValueError):
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pass
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@dataclass(slots=True)
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class HandlerRegistry:
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_handlers: dict[tuple[str, str], Handler] = field(default_factory=dict)
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def register(self, path: str, verb: str, handler: Handler) -> None:
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key = (path, verb.upper())
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if key in self._handlers:
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raise RouteCollisionError(f"duplicate semantic handler: {verb} {path}")
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self._handlers[key] = handler
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def get(self, path: str, verb: str) -> Handler | None:
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return self._handlers.get((path, verb.upper()))
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def register_contract_routes(
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app: FastAPI,
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snapshot: Snapshot,
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handlers: HandlerRegistry,
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fallback: FallbackMode = "error",
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) -> None:
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seen: set[tuple[str, str, str]] = set()
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for contract_path in snapshot.paths:
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for contract_method in contract_path.methods:
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for renderer in ("json", "extjs"):
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route = f"/api2/{renderer}{contract_path.path}"
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key = (route, contract_method.verb, renderer)
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if key in seen:
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raise RouteCollisionError(
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f"duplicate contract route: {contract_method.verb} {route}"
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)
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seen.add(key)
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endpoint = _endpoint(
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contract_path.path,
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contract_method,
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renderer,
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handlers,
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fallback,
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)
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app.add_api_route(
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route,
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endpoint,
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methods=[contract_method.verb],
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name=f"contract:{renderer}:{contract_method.verb}:{contract_path.path}",
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openapi_extra={"x-proxmox-method-checksum": contract_method.checksum},
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)
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def _endpoint(
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semantic_path: str,
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method: Method,
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renderer: str,
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handlers: HandlerRegistry,
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fallback: FallbackMode,
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) -> Callable[[Request], Awaitable[JSONResponse]]:
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async def dispatch(request: Request) -> JSONResponse:
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handler = handlers.get(semantic_path, method.verb)
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inputs = await _parse_inputs(request, method)
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if handler is not None:
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data = await handler(request, inputs)
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elif fallback == "schema-default":
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data = _schema_default(method.returns)
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elif fallback == "fixture" and "fixture" in method.extra:
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data = method.extra["fixture"]
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else:
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return JSONResponse(
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status_code=501,
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content={"data": None, "errors": "method semantics are not implemented"},
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)
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if renderer == "extjs":
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return JSONResponse({"data": data, "success": True})
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return JSONResponse({"data": data})
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return dispatch
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async def _parse_inputs(request: Request, method: Method) -> dict[str, Any]:
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supplied: dict[str, Any] = dict(request.query_params)
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supplied.update(request.path_params)
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if request.method not in {"GET", "DELETE"}:
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content_type = request.headers.get("content-type", "").split(";", 1)[0].strip()
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if content_type == "application/json":
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try:
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body = await request.json()
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except ValueError as exc:
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raise ContractValidationError({"body": "invalid JSON"}) from exc
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if not isinstance(body, dict):
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raise ContractValidationError({"body": "expected an object"})
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supplied.update(body)
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elif content_type == "application/x-www-form-urlencoded":
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supplied.update(dict(parse_qsl((await request.body()).decode())))
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definitions = {parameter.name: parameter.definition for parameter in method.parameters}
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errors: dict[str, str] = {}
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parsed: dict[str, Any] = {}
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for name, definition in definitions.items():
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if name not in supplied:
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if definition.optional:
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if definition.default is not None:
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parsed[name] = definition.default
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continue
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errors[name] = "property is missing and it is not optional"
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continue
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try:
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parsed[name] = _coerce(supplied[name], definition)
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except (TypeError, ValueError) as exc:
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errors[name] = str(exc)
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for name in supplied.keys() - definitions.keys():
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if name not in request.path_params:
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errors[name] = "property is not defined in schema"
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if errors:
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raise ContractValidationError(dict(sorted(errors.items())))
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return {"values": parsed, "path": dict(request.path_params)}
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def _coerce(value: Any, schema: Schema) -> Any:
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if schema.type == "integer":
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parsed: Any = int(value)
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elif schema.type == "number":
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parsed = float(value)
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elif schema.type == "boolean":
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if isinstance(value, bool):
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parsed = value
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elif str(value).lower() in {"1", "true", "yes", "on"}:
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parsed = True
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elif str(value).lower() in {"0", "false", "no", "off"}:
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parsed = False
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else:
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raise ValueError("expected a boolean")
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elif schema.type == "string" or schema.type is None:
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parsed = str(value)
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else:
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parsed = value
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if schema.enum and parsed not in schema.enum:
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raise ValueError("value is not in the allowed enumeration")
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if isinstance(parsed, int | float):
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if schema.minimum is not None and parsed < schema.minimum:
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raise ValueError(f"value must be at least {schema.minimum}")
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if schema.maximum is not None and parsed > schema.maximum:
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raise ValueError(f"value must be at most {schema.maximum}")
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if isinstance(parsed, str):
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if schema.min_length is not None and len(parsed) < schema.min_length:
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raise ValueError(f"value is shorter than {schema.min_length}")
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if schema.max_length is not None and len(parsed) > schema.max_length:
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raise ValueError(f"value is longer than {schema.max_length}")
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return parsed
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def _schema_default(schema: Schema) -> Any:
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if schema.default is not None:
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return schema.default
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if schema.type == "array":
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return []
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if schema.type == "object":
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return {
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name: _schema_default(definition)
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for name, definition in schema.properties.items()
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if not definition.optional
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}
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if schema.type == "boolean":
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return False
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if schema.type in {"integer", "number"}:
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return 0
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return None
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