from __future__ import annotations

from sqlalchemy import text
from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.orm import DeclarativeBase

from app.config import Settings


class Base(DeclarativeBase):
    pass


_engine: AsyncEngine | None = None
_session_factory: async_sessionmaker[AsyncSession] | None = None


def init_db(settings: Settings) -> None:
    global _engine, _session_factory
    if _engine is not None and _session_factory is not None:
        return

    _engine = create_async_engine(
        settings.pg_dsn,
        pool_pre_ping=True,
        pool_size=20,
        max_overflow=40,
    )
    _session_factory = async_sessionmaker(_engine, expire_on_commit=False)


def get_engine() -> AsyncEngine:
    if _engine is None:
        raise RuntimeError("Database engine has not been initialized.")
    return _engine


def get_session_factory() -> async_sessionmaker[AsyncSession]:
    if _session_factory is None:
        raise RuntimeError("Database session factory has not been initialized.")
    return _session_factory


async def ensure_schema_compatibility() -> None:
    engine = get_engine()
    statements = [
        "DROP INDEX IF EXISTS idx_token_bindings_ip",
        "ALTER TABLE token_bindings ALTER COLUMN bound_ip TYPE TEXT USING bound_ip::text",
        "ALTER TABLE intercept_logs ALTER COLUMN bound_ip TYPE TEXT USING bound_ip::text",
        "ALTER TABLE token_bindings ADD COLUMN IF NOT EXISTS binding_mode VARCHAR(16) DEFAULT 'single'",
        "ALTER TABLE token_bindings ADD COLUMN IF NOT EXISTS allowed_ips JSONB DEFAULT '[]'::jsonb",
        "UPDATE token_bindings SET binding_mode = 'single' WHERE binding_mode IS NULL OR binding_mode = ''",
        """
        UPDATE token_bindings
        SET allowed_ips = jsonb_build_array(bound_ip)
        WHERE allowed_ips IS NULL OR allowed_ips = '[]'::jsonb
        """,
        "ALTER TABLE token_bindings ALTER COLUMN binding_mode SET NOT NULL",
        "ALTER TABLE token_bindings ALTER COLUMN allowed_ips SET NOT NULL",
        "ALTER TABLE token_bindings ALTER COLUMN binding_mode SET DEFAULT 'single'",
        "ALTER TABLE token_bindings ALTER COLUMN allowed_ips SET DEFAULT '[]'::jsonb",
        "CREATE INDEX IF NOT EXISTS idx_token_bindings_ip ON token_bindings(bound_ip)",
    ]
    async with engine.begin() as connection:
        for statement in statements:
            await connection.execute(text(statement))


async def close_db() -> None:
    global _engine, _session_factory
    if _engine is not None:
        await _engine.dispose()
    _engine = None
    _session_factory = None