Files
beavergram/backend/src/utils/watch_rules.py
T

146 lines
4.1 KiB
Python

import re
from collections.abc import Iterable, Iterator
from importlib import import_module
from typing import Any, Literal, Self, get_args
from pydantic import BaseModel, Field, ValidationError, model_validator
MAX_PATTERN = 200
MAX_TEXT = 4096
MAX_NAME = 120
WatchKind = Literal[
"keyword", "new_message", "message_deleted", "message_edited", "peer_online"
]
WATCH_KINDS: tuple[str, ...] = get_args(WatchKind)
sre_parser = import_module("re._parser")
_REPEATS = {sre_parser.MAX_REPEAT, sre_parser.MIN_REPEAT, sre_parser.POSSESSIVE_REPEAT}
class WatchParamsError(ValueError):
pass
def _subpatterns(value: object) -> Iterator[Any]:
if isinstance(value, sre_parser.SubPattern):
yield value
elif isinstance(value, tuple | list):
for item in value:
yield from _subpatterns(item)
def _repeat_depth(items: Iterable[tuple[Any, Any]]) -> int:
depth = 0
for op, value in items:
if op in _REPEATS:
low, high, body = value
depth = max(depth, _repeat_depth(body) + (high > max(low, 1)))
else:
inner = (_repeat_depth(sub) for sub in _subpatterns(value))
depth = max(depth, *inner, 0)
return depth
def compile_pattern(pattern: str) -> re.Pattern[str]:
try:
compiled = re.compile(pattern, re.IGNORECASE)
except re.error as exc:
msg = f"invalid regex: {exc}"
raise ValueError(msg) from exc
if _repeat_depth(sre_parser.parse(pattern)) > 1:
msg = "regex repeats inside a repeat, like (a+)+, which can hang"
raise ValueError(msg)
return compiled
class KeywordParams(BaseModel):
pattern: str = Field(min_length=1, max_length=MAX_PATTERN)
regex: bool = False
chat_id: int | None = None
sender_id: int | None = None
@model_validator(mode="before")
@classmethod
def _legacy_keyword(cls, data: object) -> object:
if isinstance(data, dict) and "pattern" not in data and "keyword" in data:
return {**data, "pattern": data["keyword"]}
return data
@model_validator(mode="after")
def _valid_pattern(self) -> Self:
if not self.pattern.strip():
msg = "pattern is blank"
raise ValueError(msg)
if self.regex:
compile_pattern(self.pattern)
return self
class NewMessageParams(BaseModel):
chat_id: int | None = None
sender_id: int | None = None
@model_validator(mode="after")
def _scoped(self) -> Self:
if self.chat_id is None and self.sender_id is None:
msg = "set chat_id, sender_id or both"
raise ValueError(msg)
return self
class DeletedParams(BaseModel):
chat_id: int | None = None
class EditedParams(BaseModel):
chat_id: int | None = None
class PeerOnlineParams(BaseModel):
peer_id: int
WatchParams = (
KeywordParams | NewMessageParams | DeletedParams | EditedParams | PeerOnlineParams
)
PARAMS_BY_KIND: dict[str, type[WatchParams]] = {
"keyword": KeywordParams,
"new_message": NewMessageParams,
"message_deleted": DeletedParams,
"message_edited": EditedParams,
"peer_online": PeerOnlineParams,
}
def _describe(exc: ValidationError) -> str:
parts = []
for error in exc.errors():
where = ".".join(str(part) for part in error["loc"])
message = error["msg"].removeprefix("Value error, ")
parts.append(f"{where}: {message}" if where else message)
return "; ".join(parts)
def parse_params(kind: str, params: dict[str, Any]) -> WatchParams:
model = PARAMS_BY_KIND.get(kind)
if model is None:
msg = f"unknown kind {kind!r}, expected one of {', '.join(WATCH_KINDS)}"
raise WatchParamsError(msg)
try:
return model.model_validate(params)
except ValidationError as exc:
raise WatchParamsError(_describe(exc)) from exc
def normalize_params(kind: str, params: dict[str, Any]) -> dict[str, Any]:
return parse_params(kind, params).model_dump(exclude_none=True)
def clean_name(name: str | None) -> str | None:
if name is None:
return None
name = name.strip()[:MAX_NAME]
return name or None