"""Ticket #18: one-time legacy Vocalinux import into the Voculinux locations.

Seams under test (all offline, no hardware):
- A fresh run with a legacy install present imports ``config.json``, the
  custom dictionary, and the portal restore token exactly once and logs it;
  a second run imports nothing.
- A fresh run with an existing new configuration never imports, merges, or
  writes to the legacy location.
- A fresh run with no legacy install starts from defaults (nothing imported).
- Models are not migrated.
"""

import json
from pathlib import Path

from vocalinux import legacy_import
from vocalinux.legacy_import import import_legacy_once


def _isolate(monkeypatch, tmp_path: Path) -> tuple[Path, Path]:
    """Point XDG roots at scratch dirs; return (config_root, data_root)."""
    config_root = tmp_path / "config"
    data_root = tmp_path / "data"
    monkeypatch.setenv("XDG_CONFIG_HOME", str(config_root))
    monkeypatch.setenv("XDG_DATA_HOME", str(data_root))
    return config_root, data_root


def _seed_legacy(config_root: Path, data_root: Path) -> dict[str, Path]:
    """Create a legacy install's payload; return the created files."""
    legacy_config = config_root / "vocalinux"
    legacy_data = data_root / "vocalinux"
    legacy_config.mkdir(parents=True)
    legacy_data.mkdir(parents=True)
    created = {}
    for name, content in (
        ("config.json", '{"general": {"first_run": false}}'),
        ("dictionary.txt", "Supabase\n"),
        ("custom-dictionary-corrections.json", json.dumps({"version": 1, "corrections": []})),
    ):
        target = legacy_config / name
        target.write_text(content, encoding="utf-8")
        created[name] = target
    token = legacy_data / "remote_desktop_restore_token"
    token.write_text("legacy-token\n", encoding="utf-8")
    created["remote_desktop_restore_token"] = token
    return created


def test_fresh_run_with_legacy_install_imports_once(monkeypatch, tmp_path, caplog) -> None:
    """Legacy config, dictionary, and restore token copy over exactly once."""
    config_root, data_root = _isolate(monkeypatch, tmp_path)
    _seed_legacy(config_root, data_root)

    with caplog.at_level("INFO", logger="vocalinux.legacy_import"):
        imported = import_legacy_once()

    assert len(imported) == 4
    assert (
        config_root / "voculinux" / "config.json"
    ).read_text() == '{"general": {"first_run": false}}'
    assert (config_root / "voculinux" / "dictionary.txt").read_text() == "Supabase\n"
    assert json.loads(
        (config_root / "voculinux" / "custom-dictionary-corrections.json").read_text()
    ) == {
        "version": 1,
        "corrections": [],
    }
    assert (
        data_root / "voculinux" / "remote_desktop_restore_token"
    ).read_text() == "legacy-token\n"
    assert any("Legacy Vocalinux import complete" in r.message for r in caplog.records)

    # A second run imports nothing.
    assert import_legacy_once() == []


def test_existing_new_config_never_imports_or_touches_legacy(monkeypatch, tmp_path) -> None:
    """An existing new configuration always wins: no merge, no write-back."""
    config_root, data_root = _isolate(monkeypatch, tmp_path)
    seeded = _seed_legacy(config_root, data_root)
    before = {name: path.read_bytes() for name, path in seeded.items()}

    new_config = config_root / "voculinux"
    new_config.mkdir(parents=True)
    (new_config / "config.json").write_text('{"general": {"first_run": true}}', encoding="utf-8")

    assert import_legacy_once() == []
    assert (new_config / "config.json").read_text() == '{"general": {"first_run": true}}'
    assert not (new_config / "dictionary.txt").exists()
    assert not (data_root / "voculinux").exists()
    for name, path in seeded.items():
        assert path.read_bytes() == before[name], name


def test_no_legacy_install_starts_from_defaults(monkeypatch, tmp_path) -> None:
    """No legacy directories means nothing is imported."""
    _isolate(monkeypatch, tmp_path)
    assert import_legacy_once() == []


def test_models_are_not_migrated(monkeypatch, tmp_path) -> None:
    """A legacy models directory is left alone; rung files re-download."""
    config_root, data_root = _isolate(monkeypatch, tmp_path)
    _seed_legacy(config_root, data_root)
    legacy_models = data_root / "vocalinux" / "models"
    legacy_models.mkdir(parents=True)
    (legacy_models / "ggml-large-v3-turbo-q8_0.bin").write_bytes(b"fake-model")

    imported = import_legacy_once()

    assert not (data_root / "voculinux" / "models").exists()
    assert {Path(p).name for p in imported} == {
        "config.json",
        "dictionary.txt",
        "custom-dictionary-corrections.json",
        "remote_desktop_restore_token",
    }


def test_partial_legacy_payload_imports_what_exists(monkeypatch, tmp_path) -> None:
    """A legacy install with only a config still imports just that file."""
    config_root, _data_root = _isolate(monkeypatch, tmp_path)
    legacy_config = config_root / "vocalinux"
    legacy_config.mkdir(parents=True)
    (legacy_config / "config.json").write_text("{}", encoding="utf-8")

    imported = import_legacy_once()

    assert imported == [str(config_root / "voculinux" / "config.json")]
    assert import_legacy_once() == []


def test_new_dictionary_never_overwritten_by_legacy(monkeypatch, tmp_path) -> None:
    """A new dictionary file is never clobbered even when config is absent."""
    config_root, data_root = _isolate(monkeypatch, tmp_path)
    _seed_legacy(config_root, data_root)
    new_config = config_root / "voculinux"
    new_config.mkdir(parents=True)
    (new_config / "dictionary.txt").write_text("Mine\n", encoding="utf-8")

    import_legacy_once()

    # No new config.json exists, so the import ran — but the existing new
    # dictionary file must survive untouched.
    assert (new_config / "dictionary.txt").read_text() == "Mine\n"
    assert legacy_import.CONFIG_FILENAME == "config.json"