from __future__ import annotations

import importlib
import os
from logging.config import fileConfig
from typing import Any

from alembic import context
from sqlalchemy import create_engine, event, pool
from sqlalchemy.engine import URL, make_url

models = importlib.import_module("backup_tool.db.models")
sqlite_runtime = importlib.import_module("backup_tool.db.sqlite")

config = context.config
if config.config_file_name is not None:
    fileConfig(config.config_file_name)
target_metadata = models.Base.metadata


def configured_url() -> str:
    raw_url = os.environ.get("BACKUP_TOOL_DATABASE_URL") or config.get_main_option("sqlalchemy.url")
    if raw_url is None:
        raise RuntimeError("sqlalchemy.url is required")
    return raw_url


def busy_timeout_ms() -> int:
    raw_value = os.environ.get(
        "BACKUP_TOOL_SQLITE_BUSY_TIMEOUT_MS", str(sqlite_runtime.DEFAULT_BUSY_TIMEOUT_MS)
    )
    try:
        value = int(raw_value)
    except ValueError as error:
        raise RuntimeError("SQLite busy timeout must be an integer") from error
    if value < 1_000 or value > 120_000:
        raise RuntimeError("SQLite busy timeout must be between 1000 and 120000 ms")
    return value


def synchronous_url(raw_url: str) -> URL:
    url = make_url(raw_url)
    if url.drivername != "sqlite+aiosqlite":
        raise RuntimeError("v2 migrations require sqlite+aiosqlite")
    return url.set(drivername="sqlite")


def run_migrations_offline() -> None:
    url = synchronous_url(configured_url())
    context.configure(
        url=url.render_as_string(hide_password=False),
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        compare_type=True,
    )
    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online() -> None:
    timeout = busy_timeout_ms()
    engine = create_engine(
        synchronous_url(configured_url()),
        poolclass=pool.NullPool,
        connect_args=sqlite_runtime.sqlite_connect_args(timeout),
    )

    @event.listens_for(engine, "connect")
    def configure_sqlite(dbapi_connection: Any, _connection_record: Any) -> None:
        sqlite_runtime.configure_sqlite_connection(dbapi_connection)

    with engine.connect() as connection:
        context.configure(connection=connection, target_metadata=target_metadata, compare_type=True)
        with context.begin_transaction():
            context.run_migrations()
    engine.dispose()


if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online()