"""Миграция схемы checks: идемпотентность и сохранение старых NULL."""
import sqlite3


def _cols(db_path):
    con = sqlite3.connect(db_path)
    cols = [r[1] for r in con.execute("PRAGMA table_info(checks)").fetchall()]
    con.close()
    return cols


def _make_old_db(db_path, with_error_col=False):
    """БД со старой схемой checks (до учёта usage) и живыми данными."""
    con = sqlite3.connect(db_path)
    con.execute("""CREATE TABLE checks (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        model_id TEXT NOT NULL,
        checked_at TEXT NOT NULL,
        ok INTEGER NOT NULL,
        latency_ms INTEGER)""")
    if with_error_col:
        con.execute("ALTER TABLE checks ADD COLUMN error TEXT")
    con.execute(
        "INSERT INTO checks (model_id, checked_at, ok, latency_ms, error) VALUES (?,?,?,?,?)"
        if with_error_col else
        "INSERT INTO checks (model_id, checked_at, ok, latency_ms) VALUES (?,?,?,?)",
        ("zai/old-model", "2026-01-01T00:00:00+00:00", 1, 123, None)
        if with_error_col else ("zai/old-model", "2026-01-01T00:00:00+00:00", 1, 123),
    )
    con.commit()
    con.close()


def test_migration_old_schema_preserves_null(fresh_main):
    _make_old_db(fresh_main.DB_PATH, with_error_col=True)
    fresh_main.init_db()

    cols = _cols(fresh_main.DB_PATH)
    for c in ("input_tokens", "output_tokens", "total_tokens", "usage_json"):
        assert c in cols, f"колонка {c} не добавлена"

    con = sqlite3.connect(fresh_main.DB_PATH)
    con.row_factory = sqlite3.Row
    row = con.execute("SELECT * FROM checks WHERE model_id='zai/old-model'").fetchone()
    con.close()
    assert row["ok"] == 1 and row["latency_ms"] == 123
    # старые данные: неизвестное потребление = NULL, не нули
    assert row["input_tokens"] is None
    assert row["output_tokens"] is None
    assert row["total_tokens"] is None
    assert row["usage_json"] is None


def test_migration_from_ancient_schema_without_error(fresh_main):
    _make_old_db(fresh_main.DB_PATH, with_error_col=False)
    fresh_main.init_db()  # не должен падать: добавит и error, и usage-колонки
    cols = _cols(fresh_main.DB_PATH)
    assert "error" in cols
    assert "usage_json" in cols


def test_migration_idempotent(fresh_main):
    _make_old_db(fresh_main.DB_PATH, with_error_col=True)
    fresh_main.init_db()
    fresh_main.init_db()  # повторный запуск — no-op без ошибок

    con = sqlite3.connect(fresh_main.DB_PATH)
    n = con.execute("SELECT COUNT(*) FROM checks").fetchone()[0]
    con.close()
    assert n == 1  # данные не задвоились и не потерялись


def test_fresh_db_has_usage_columns(fresh_main):
    fresh_main.init_db()
    cols = _cols(fresh_main.DB_PATH)
    for c in ("input_tokens", "output_tokens", "total_tokens", "usage_json"):
        assert c in cols