"""Kodi-style NFO sidecars.

Video descriptions are hostile input — they contain ampersands, angle brackets,
emoji, ASCII art and control characters — so these are always built with
ElementTree's serialiser and never by string formatting.
"""

from __future__ import annotations

import re
import xml.etree.ElementTree as ET
from pathlib import Path

# XML 1.0 forbids most control characters outright; ElementTree will happily
# serialise them and produce a document no parser will read back. Written as a
# raw string so `re` interprets the escapes, not Python.
_ILLEGAL_XML = re.compile(
    r"[^\x09\x0a\x0d\x20-퟿-�\U00010000-\U0010ffff]"
)


def clean_text(value: str | None) -> str:
    return _ILLEGAL_XML.sub("", value or "")


def _child(parent: ET.Element, tag: str, text: str | None) -> ET.Element:
    element = ET.SubElement(parent, tag)
    element.text = clean_text(text)
    return element


def _serialise(root: ET.Element) -> bytes:
    ET.indent(root, space="  ")
    return ET.tostring(root, encoding="utf-8", xml_declaration=True)


def tvshow_nfo(title: str, plot: str | None, channel_id: str) -> bytes:
    root = ET.Element("tvshow")
    _child(root, "title", title)
    _child(root, "plot", plot)
    _child(root, "studio", "YouTube")
    unique = _child(root, "uniqueid", channel_id)
    unique.set("type", "youtube")
    unique.set("default", "true")
    return _serialise(root)


def episode_nfo(
    *,
    title: str,
    show_title: str,
    season: int,
    episode: int,
    plot: str | None,
    aired: str,
    duration_seconds: int | None,
    video_id: str,
) -> bytes:
    root = ET.Element("episodedetails")
    _child(root, "title", title)
    _child(root, "showtitle", show_title)
    _child(root, "season", str(season))
    _child(root, "episode", str(episode))
    _child(root, "plot", plot)
    _child(root, "aired", aired)
    if duration_seconds:
        # Kodi/Jellyfin expect <runtime> in whole minutes.
        _child(root, "runtime", str(max(1, round(duration_seconds / 60))))
    _child(root, "studio", "YouTube")
    unique = _child(root, "uniqueid", video_id)
    unique.set("type", "youtube")
    unique.set("default", "true")
    return _serialise(root)


def write(path: Path, payload: bytes) -> None:
    """Write atomically so a crash never leaves Jellyfin a half-written NFO."""
    path.parent.mkdir(parents=True, exist_ok=True)
    temporary = path.with_name(path.name + ".tmp")
    temporary.write_bytes(payload)
    temporary.replace(path)