"""Alembic environment for DeerFlow application tables.

ONLY manages DeerFlow's tables (runs, threads_meta, cron_jobs, users).
LangGraph's checkpointer tables are managed by LangGraph itself -- they
have their own schema lifecycle and must not be touched by Alembic.
"""

from __future__ import annotations

import asyncio
import logging
import os
from logging.config import fileConfig

from alembic import context
from sqlalchemy import text
from sqlalchemy.ext.asyncio import create_async_engine

from deerflow.persistence.base import Base

# Import all models so metadata is populated.
try:
    import deerflow.persistence.models as models  # register ORM models with Base.metadata

    _ = models
except ImportError:
    # Models not available — migration will work with existing metadata only.
    logging.getLogger(__name__).warning("Could not import deerflow.persistence.models; Alembic may not detect all tables")

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

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,
        render_as_batch=True,
    )
    with context.begin_transaction():
        context.run_migrations()


def do_run_migrations(connection):
    render_as_batch = connection.dialect.name == "sqlite"

    # On MySQL, shrink the session lock waits so a blocked DDL fails fast
    # instead of hanging on the server default (lock_wait_timeout = 31536000s
    # = 1 year; innodb_lock_wait_timeout = 50s). Without this, an idle
    # transaction on another connection can freeze startup indefinitely.
    # Tunable via DEER_FLOW_ALEMBIC_LOCK_WAIT (seconds, default 15).
    if connection.dialect.name == "mysql":
        try:
            lock_wait = int(os.getenv("DEER_FLOW_ALEMBIC_LOCK_WAIT", "15"))
        except ValueError:
            lock_wait = 15
        connection.execute(text(f"SET SESSION lock_wait_timeout = {lock_wait}"))
        connection.execute(text(f"SET SESSION innodb_lock_wait_timeout = {lock_wait}"))

    context.configure(
        connection=connection,
        target_metadata=target_metadata,
        render_as_batch=render_as_batch,  # Required for SQLite ALTER TABLE support
    )
    with context.begin_transaction():
        context.run_migrations()


async def run_migrations_online() -> None:
    connectable = create_async_engine(config.get_main_option("sqlalchemy.url"))
    async with connectable.connect() as connection:
        await connection.run_sync(do_run_migrations)
    await connectable.dispose()


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