"""
Test utilities for :py:mod:`betty.locale`.
"""

from __future__ import annotations

import difflib
from pathlib import Path
from typing import Iterator

import aiofiles
from aiofiles.tempfile import TemporaryDirectory
from typing_extensions import override

from betty.app import App
from betty.locale.translation import (
    update_project_translations,
)


class PotFileTestBase:
    """
    A base class for testing that a *.pot file is up to date.
    """

    async def _readlines(self, assets_directory_path: Path) -> Iterator[str]:
        async with aiofiles.open(assets_directory_path / "locale" / "betty.pot") as f:
            return filter(
                lambda line: not line.startswith(
                    (
                        "# Copyright (C) ",
                        "# FIRST AUTHOR <EMAIL@ADDRESS>, ",
                        '"POT-Creation-Date: ',
                        '"PO-Revision-Date: ',
                        '"Generated-By: ',
                    )
                ),
                await f.readlines(),
            )

    def assets_directory_path(self) -> Path:
        """
        The assets directory path containing the translations that are being tested.
        """
        raise NotImplementedError(repr(self))

    def command(self) -> str:
        """
        The command to suggest the developer runs in case the translations are out of date.
        """
        raise NotImplementedError(repr(self))

    async def update_translations(
        self, output_assets_directory_path_override: Path
    ) -> None:
        """
        Update the translations into the given directory.
        """
        raise NotImplementedError(repr(self))

    async def test(self) -> None:
        """
        Test the translations.
        """
        async with TemporaryDirectory() as working_directory_path_str:
            working_directory_path = Path(working_directory_path_str)
            await self.update_translations(working_directory_path)
            actual_pot_contents = await self._readlines(self.assets_directory_path())
            expected_pot_contents = await self._readlines(working_directory_path)
            diff = difflib.unified_diff(
                list(actual_pot_contents),
                list(expected_pot_contents),
            )
            assert (
                len(list(diff)) == 0
            ), f"The gettext *.po files are not up to date. Did you run `{self.command()}`?"


class ProjectPotFileTestBase(PotFileTestBase):
    """
    A base class for testing that an end user's project's *.pot file is up to date.
    """

    @override
    def command(self) -> str:
        return "betty update-translations"  # pragma: no cover

    def source_directory_path(self) -> Path | None:
        """
        The path to a source directory to include.
        """
        return None  # pragma: no cover

    def exclude_source_directory_paths(self) -> set[Path]:
        """
        The paths to any descendant source directories to exclude.
        """
        return set()  # pragma: no cover

    @override
    def assets_directory_path(self) -> Path:
        return self.project_directory_path() / "assets"

    def project_directory_path(self) -> Path:
        """
        Get the path to the directory of the project under test.
        """
        raise NotImplementedError(repr(self))

    @override
    async def update_translations(  # pragma: no cover
        self, output_assets_directory_path_override: Path
    ) -> None:
        async with App.new_temporary() as app, app:
            await update_project_translations(
                self.project_directory_path(),
                self.source_directory_path(),
                self.exclude_source_directory_paths(),
                _output_assets_directory_path_override=output_assets_directory_path_override,
            )
