"""Alembic environment for second-brain — second_brain schema.

Mirrors vault-mcp/alembic/env.py. Reads SECOND_BRAIN_DATABASE_URL (with
HERBYLAB_DATABASE_URL as a fallback) so the same migration tree works
across local dev, CI, and production.

The connection bootstraps the `second_brain` schema and pins alembic's
own version table to that schema; migration scripts themselves set
search_path before issuing unqualified DDL.

The bootstrap-then-commit pattern below is the fix for the "autobegin
trap": running any further statement before context.begin_transaction()
would autobegin a new transaction, causing alembic's begin_transaction()
to nest as a savepoint that silently rolls back when the connection
closes. Do not regress this.
"""

from __future__ import annotations

import os
from logging.config import fileConfig

from dotenv import load_dotenv
from sqlalchemy import engine_from_config, pool

from alembic import context

# Make the project's `src/` importable so `second_brain.models` resolves
# without a `pip install -e .`.
import sys
from pathlib import Path

_PROJECT_ROOT = Path(__file__).resolve().parent.parent
sys.path.insert(0, str(_PROJECT_ROOT / "src"))

from second_brain.models import Base, SCHEMA  # noqa: E402

load_dotenv()

config = context.config

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


def _resolve_db_url() -> str | None:
    """Pick the first usable URL out of the two homelab conventions."""
    for var in ("SECOND_BRAIN_DATABASE_URL", "HERBYLAB_DATABASE_URL"):
        v = os.environ.get(var)
        if v:
            return v
    return None


_db_url = _resolve_db_url()
if _db_url:
    config.set_main_option("sqlalchemy.url", _db_url)

target_metadata = Base.metadata


def run_migrations_offline() -> None:
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
        version_table_schema=SCHEMA,
        include_schemas=True,
    )

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


def run_migrations_online() -> None:
    connectable = engine_from_config(
        config.get_section(config.config_ini_section, {}),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        # Bootstrap the schema before alembic looks for alembic_version.
        # The runtime role (lovebug) does NOT have CREATE on the petalbrain
        # database — bare `CREATE SCHEMA IF NOT EXISTS` would fail with
        # permission denied even though the schema already exists. So we
        # only attempt to create it when the schema is genuinely missing
        # (operator must have bootstrapped it once as postgres superuser:
        # `CREATE SCHEMA second_brain AUTHORIZATION lovebug`).
        # Commit explicitly so any DDL persists; otherwise the implicit
        # transaction is rolled back when the connection closes. Avoid
        # running any further statement here — it would autobegin a new
        # transaction and cause alembic's `begin_transaction()` to nest as
        # a savepoint, which silently rolls back when the connection closes.
        # The migration script sets search_path itself.
        row = connection.exec_driver_sql(
            "SELECT 1 FROM pg_namespace WHERE nspname = %s",
            (SCHEMA,),
        ).fetchone()
        if row is None:
            connection.exec_driver_sql(f"CREATE SCHEMA {SCHEMA}")
        connection.commit()
        context.configure(
            connection=connection,
            target_metadata=target_metadata,
            version_table_schema=SCHEMA,
            include_schemas=True,
        )

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


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