"""Stable desktop identity shared by the launcher and Wine game window."""

from __future__ import annotations

import os
from pathlib import Path
from typing import Mapping


APPLICATION_NAME = "PristonTale EU"
APPLICATION_WM_CLASS = "PristonTaleEU"
APPLICATION_WM_INSTANCE = "pristontale-eu"
APPLICATION_ICON_FILENAME = "eu.pristontale.PTLinux.png"
APPLICATION_ICON_VARIABLE = "PTLINUX_ICON_PATH"


def find_application_icon(
	environment: Mapping[str, str] | None = None,
) -> Path | None:
	"""Find the installed icon, with source-tree fallbacks for development."""

	env = os.environ if environment is None else environment
	candidates: list[Path] = []
	explicit = env.get(APPLICATION_ICON_VARIABLE)
	if explicit:
		candidates.append(Path(explicit).expanduser())

	# Some distributions bundle the icon beside this module. The installer
	# publishes the same asset through the user's XDG data directory.
	candidates.append(Path(__file__).with_name(APPLICATION_ICON_FILENAME))
	home_value = env.get("HOME")
	if home_value:
		home = Path(home_value).expanduser()
		data_home_value = env.get("XDG_DATA_HOME")
		data_home = (
			Path(data_home_value).expanduser()
			if data_home_value
			else home / ".local/share"
		)
		candidates.append(data_home / "pixmaps" / APPLICATION_ICON_FILENAME)
		default_icon = home / ".local/share/pixmaps" / APPLICATION_ICON_FILENAME
		if default_icon not in candidates:
			candidates.append(default_icon)

	# The source checkout keeps installer assets under packaging/.
	candidates.append(
		Path(__file__).resolve().parent.parent
		/ "packaging"
		/ APPLICATION_ICON_FILENAME
	)
	seen: set[Path] = set()
	for candidate in candidates:
		resolved = candidate.resolve(strict=False)
		if resolved in seen:
			continue
		seen.add(resolved)
		if resolved.is_file():
			return resolved
	return None