"""Request-local UI translations. User content and stored identifiers stay unchanged."""

import json
from contextvars import ContextVar
from pathlib import Path
from urllib.parse import urlencode, urlsplit


LANGUAGE_COOKIE = "metalcircle_language"
current_language = ContextVar("current_language", default="de")
current_page = ContextVar("current_page", default="/")
ENGLISH = json.loads((Path(__file__).parent / "locales" / "en.json").read_text())


def gettext(message):
    if not isinstance(message, str):
        return message
    return ENGLISH.get(message, message) if current_language.get() == "en" else message


def format_time(value):
    """Format display times without changing stored or form-submitted values."""
    if current_language.get() == "en":
        period = "AM" if value.hour < 12 else "PM"
        return f"{value.hour % 12 or 12}:{value.minute:02d} {period}"
    return value.strftime("%H:%M")


def format_datetime(value):
    return f"{value.strftime('%d.%m.%Y')} {format_time(value)}"


def safe_return_path(value):
    """Only allow local absolute paths, including their query string and fragment."""
    if not value or not value.startswith("/") or value.startswith("//"):
        return "/"
    if "\\" in value or any(ord(char) < 32 or ord(char) == 127 for char in value):
        return "/"
    parsed = urlsplit(value)
    if parsed.scheme or parsed.netloc or parsed.path.startswith("/language/"):
        return "/"
    return value


def language_url(language):
    return f"/language/{language}?{urlencode({'next': current_page.get()})}"