"""Render the installed command wrapper with persistent application paths."""

from __future__ import annotations

import argparse
import os
from pathlib import Path
import sys
from typing import Sequence


APP_ROOT_TOKEN = "@PTLINUX_APP_ROOT@"
INSTALL_DIRECTORY_TOKEN = "@PTLINUX_INSTALL_DIR@"


class LauncherWrapperError(ValueError):
	"""Raised when a safe launcher wrapper cannot be rendered."""


def quote_shell_word(value: str) -> str:
	"""Quote one value as a literal POSIX shell word."""

	if not value or any(character in value for character in ("\x00", "\n", "\r")):
		raise LauncherWrapperError("launcher path contains invalid characters")
	return "'" + value.replace("'", "'\"'\"'") + "'"


def _absolute_directory(path: Path, label: str) -> Path:
	directory = path.expanduser()
	if not directory.is_absolute():
		raise LauncherWrapperError(f"{label} must be absolute")
	return directory


def render_launcher_wrapper(
	template: str,
	app_root: Path,
	install_directory: Path,
) -> str:
	"""Embed the selected install layout in one command-wrapper template."""

	for token in (APP_ROOT_TOKEN, INSTALL_DIRECTORY_TOKEN):
		if template.count(token) != 1:
			raise LauncherWrapperError(
				f"launcher template must contain exactly one {token} token"
			)
	application = _absolute_directory(app_root, "application directory")
	installation = _absolute_directory(install_directory, "install directory")
	if not any(
		(candidate / "ptlinux").is_dir()
		for candidate in (
			application / "current",
			application / "previous",
			application,
		)
	):
		raise LauncherWrapperError(f"application files are missing: {application}")
	rendered = template.replace(APP_ROOT_TOKEN, quote_shell_word(str(application)))
	rendered = rendered.replace(
		INSTALL_DIRECTORY_TOKEN,
		quote_shell_word(str(installation)),
	)
	return rendered if rendered.endswith("\n") else rendered + "\n"


def install_launcher_wrapper(
	template: Path,
	app_root: Path,
	install_directory: Path,
	destination: Path,
) -> None:
	"""Render and atomically install one executable command wrapper."""

	rendered = render_launcher_wrapper(
		template.read_text(encoding="utf-8"),
		app_root,
		install_directory,
	)
	destination.parent.mkdir(parents=True, exist_ok=True)
	temporary = destination.with_name(f".{destination.name}.{os.getpid()}.tmp")
	try:
		temporary.write_text(rendered, encoding="utf-8")
		temporary.chmod(0o755)
		temporary.replace(destination)
	except BaseException:
		temporary.unlink(missing_ok=True)
		raise


def main(argv: Sequence[str] | None = None) -> int:
	parser = argparse.ArgumentParser(
		description="install the PristonTale EU command wrapper"
	)
	parser.add_argument("template", type=Path)
	parser.add_argument("app_root", type=Path)
	parser.add_argument("install_directory", type=Path)
	parser.add_argument("destination", type=Path)
	arguments = parser.parse_args(argv)
	try:
		install_launcher_wrapper(
			arguments.template,
			arguments.app_root,
			arguments.install_directory,
			arguments.destination,
		)
	except (LauncherWrapperError, OSError) as exc:
		print(f"Could not install command wrapper: {exc}", file=sys.stderr)
		return 1
	return 0


if __name__ == "__main__":
	raise SystemExit(main())