"""Non-public Wn utilities."""

import hashlib
from collections.abc import Hashable, Iterable
from pathlib import Path
from typing import TypeVar
from unicodedata import combining, normalize

from wn._types import VersionInfo


def version_info(version_string: str) -> VersionInfo:
    return tuple(map(int, version_string.split(".")))


def is_url(string: str) -> bool:
    """Return True if *string* appears to be a URL."""
    # TODO: ETags?
    return any(string.startswith(scheme) for scheme in ("http://", "https://"))


def is_gzip(path: Path) -> bool:
    """Return True if the file at *path* appears to be gzipped."""
    return _inspect_file_signature(path, b"\x1f\x8b")


def is_lzma(path: Path) -> bool:
    """Return True if the file at *path* appears to be lzma-compressed."""
    return _inspect_file_signature(path, b"\xfd7zXZ\x00")


def is_xml(path: Path) -> bool:
    """Return True if the file at *path* appears to be an XML file."""
    return _inspect_file_signature(path, b"<?xml ")


def _inspect_file_signature(path: Path, signature: bytes) -> bool:
    if path.is_file():
        with path.open("rb") as f:
            return f.read(len(signature)) == signature
    return False


def short_hash(string: str) -> str:
    """Return a short hash of *string*."""
    b2 = hashlib.blake2b(digest_size=20)
    b2.update(string.encode("utf-8"))
    return b2.hexdigest()


T = TypeVar("T")


def flatten(iterable: Iterable[Iterable[T]]) -> list[T]:
    return [x for xs in iterable for x in xs]


H = TypeVar("H", bound=Hashable)


def unique_list(items: Iterable[H]) -> list[H]:
    # use a dictionary as an order-preserving set
    targets = dict.fromkeys(items, True)
    return list(targets)


def normalize_form(s: str) -> str:
    return "".join(c for c in normalize("NFKD", s.casefold()) if not combining(c))


def format_lexicon_specifier(id: str, version: str) -> str:
    return f"{id}:{version}"


def split_lexicon_specifier(lexicon: str) -> tuple[str, str]:
    id, _, ver = lexicon.partition(":")
    return id, ver