from __future__ import annotations

import sqlite3

import pytest

from backend.database import MIGRATIONS, Database, Migration, MigrationError, MigrationRunner
from backend.database.repositories import DatabaseStatusRepository


def create_example(connection: sqlite3.Connection) -> None:
    connection.execute("CREATE TABLE example (id INTEGER PRIMARY KEY, value TEXT NOT NULL)")


def drop_example(connection: sqlite3.Connection) -> None:
    connection.execute("DROP TABLE example")


def example_migration(signature: str = "example:v1") -> Migration:
    return Migration(1, "create_example", signature, create_example, drop_example)


def table_names(database: Database) -> set[str]:
    with database.read() as connection:
        return {
            str(row["name"])
            for row in connection.execute("SELECT name FROM sqlite_master WHERE type='table'")
        }


def test_connection_enables_wal_foreign_keys_and_busy_timeout(tmp_path) -> None:
    database = Database(tmp_path / "app.db")

    with database.read() as connection:
        assert connection.execute("PRAGMA journal_mode").fetchone()[0] == "wal"
        assert connection.execute("PRAGMA foreign_keys").fetchone()[0] == 1
        assert connection.execute("PRAGMA busy_timeout").fetchone()[0] == 20_000


def test_migration_can_upgrade_idempotently_and_downgrade(tmp_path) -> None:
    database = Database(tmp_path / "app.db")
    runner = MigrationRunner(database)
    migration = example_migration()

    assert runner.upgrade((migration,)) == (1,)
    assert runner.upgrade((migration,)) == ()
    assert "example" in table_names(database)
    assert DatabaseStatusRepository(database).get().schema_version == 1

    assert runner.downgrade((migration,), target_version=0) == (1,)
    assert "example" not in table_names(database)
    assert DatabaseStatusRepository(database).get().schema_version == 0


def test_failed_migration_is_atomic_and_not_recorded(tmp_path) -> None:
    database = Database(tmp_path / "app.db")

    def fail(connection: sqlite3.Connection) -> None:
        connection.execute("CREATE TABLE should_rollback (id INTEGER)")
        raise RuntimeError("stop")

    migration = Migration(1, "failure", "failure:v1", fail, lambda connection: None)
    with pytest.raises(MigrationError, match="upgrade failed"):
        MigrationRunner(database).upgrade((migration,))

    assert "should_rollback" not in table_names(database)
    assert DatabaseStatusRepository(database).get().schema_version == 0


def test_applied_migration_checksum_cannot_change(tmp_path) -> None:
    database = Database(tmp_path / "app.db")
    runner = MigrationRunner(database)
    runner.upgrade((example_migration(),))

    with pytest.raises(MigrationError, match="checksum changed"):
        runner.upgrade((example_migration("example:v2"),))
    with pytest.raises(MigrationError, match="checksum changed"):
        runner.downgrade((example_migration("example:v2"),), target_version=0)


def test_unknown_database_migration_is_rejected(tmp_path) -> None:
    database = Database(tmp_path / "app.db")
    runner = MigrationRunner(database)
    runner.upgrade((example_migration(),))

    with pytest.raises(MigrationError, match="unknown migrations"):
        runner.upgrade(())


def test_non_contiguous_database_history_is_rejected(tmp_path) -> None:
    database = Database(tmp_path / "app.db")
    first = example_migration()
    second = Migration(
        2,
        "second",
        "second:v1",
        lambda connection: None,
        lambda connection: None,
    )
    runner = MigrationRunner(database)
    runner.upgrade((first, second))
    with database.transaction() as connection:
        connection.execute("DELETE FROM schema_migrations WHERE version = 1")

    with pytest.raises(MigrationError, match="not contiguous"):
        runner.upgrade((first, second))


def test_real_account_schema_can_upgrade_and_rollback(tmp_path) -> None:
    database = Database(tmp_path / "app.db")
    runner = MigrationRunner(database)

    assert runner.upgrade(MIGRATIONS) == (1, 2, 3, 4, 5, 6, 7, 8, 9)
    assert {
        "users",
        "memberships",
        "sessions",
        "birth_profiles",
        "llm_usage_daily",
        "system_credentials",
        "llm_models",
        "llm_configuration",
        "trading_days",
        "market_entities",
        "market_summaries",
        "chart_series",
        "sector_member_snapshots",
        "market_insight_snapshots",
        "seat_aliases",
        "watchlist_entries",
        "screener_factor_snapshots",
        "screener_factor_values",
        "screener_runs",
        "custom_screener_strategies",
        "strategy_tracks",
        "strategy_track_bars",
        "strategy_track_events",
        "mentor_preferences",
        "mentor_messages",
        "llm_requests",
        "llm_attempts",
        "heaven_readings",
    } <= table_names(database)

    assert runner.downgrade(MIGRATIONS, target_version=0) == (9, 8, 7, 6, 5, 4, 3, 2, 1)
    assert "users" not in table_names(database)
    assert "llm_models" not in table_names(database)