from __future__ import annotations

import os
import sys
from logging.config import fileConfig
from pathlib import Path

from alembic import context
from sqlalchemy import engine_from_config, pool
from sqlalchemy.engine.url import make_url

config = context.config

if config.config_file_name is not None:
    fileConfig(config.config_file_name)

BACKEND_DIR = Path(__file__).resolve().parents[1]
if str(BACKEND_DIR) not in sys.path:
    sys.path.insert(0, str(BACKEND_DIR))

target_metadata = None


def _get_database_url() -> str:
    url = (os.environ.get("DATABASE_URL") or config.get_main_option("sqlalchemy.url") or "").strip()
    if not url:
        raise RuntimeError("DATABASE_URL (or sqlalchemy.url) is required")
    return url.replace("+aiosqlite", "")


def _ensure_sqlite_dir(url: str) -> None:
    parsed = make_url(url)
    if parsed.get_backend_name() != "sqlite":
        return
    db_path = parsed.database
    if not db_path or db_path == ":memory:":
        return
    Path(db_path).expanduser().resolve().parent.mkdir(parents=True, exist_ok=True)


def run_migrations_offline() -> None:
    url = _get_database_url()
    _ensure_sqlite_dir(url)
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        render_as_batch=url.startswith("sqlite"),
    )

    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online() -> None:
    url = _get_database_url()
    _ensure_sqlite_dir(url)

    connectable = engine_from_config(
        config.get_section(config.config_ini_section, {}),
        prefix="sqlalchemy.",
        url=url,
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        context.configure(
            connection=connection,
            target_metadata=target_metadata,
            render_as_batch=url.startswith("sqlite"),
        )

        with context.begin_transaction():
            context.run_migrations()


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