# migrations/env.py
from __future__ import annotations

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

from alembic import context
from sqlalchemy import pool
from sqlalchemy.engine import Connection
from sqlalchemy.ext.asyncio import AsyncEngine, create_async_engine

# ----------------------------------------------------------------------
# Alembic Grund-Setup (Logging etc.)
# ----------------------------------------------------------------------
config = context.config
if config.config_file_name is not None:
    fileConfig(config.config_file_name)

# ----------------------------------------------------------------------
# Projekt-Root auf sys.path, damit "from app ..." klappt
# ----------------------------------------------------------------------
ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", ".."))
if ROOT not in sys.path:
    sys.path.insert(0, ROOT)

# ----------------------------------------------------------------------
# ORM-Base & Modelle importieren (wichtig: Modelle registrieren Tabellen)
# ----------------------------------------------------------------------
from app.db import Base
from app import models  # noqa: F401

target_metadata = Base.metadata

# ----------------------------------------------------------------------
# Async-DB-URL (z. B. postgresql+asyncpg://...)
# ----------------------------------------------------------------------
DATABASE_URL = os.getenv("DATABASE_URL")
if not DATABASE_URL:
    raise RuntimeError(
        "DATABASE_URL ist nicht gesetzt (z. B. postgresql+asyncpg://user:pass@host:5432/db)"
    )

# ----------------------------------------------------------------------
# (Optional) Leere Autogenerate-Revisionen unterdrücken
# ----------------------------------------------------------------------
def process_revision_directives(context, revision, directives):
    cmd_opts = getattr(config, "cmd_opts", None)
    if cmd_opts and getattr(cmd_opts, "autogenerate", False):
        script = directives[0]
        if hasattr(script, "upgrade_ops") and script.upgrade_ops.is_empty():
            directives[:] = []  # keine 'pass'-Revision erzeugen

# ----------------------------------------------------------------------
# Offline-Pfad (bewusst deaktiviert, damit Autogenerate immer online läuft)
# ----------------------------------------------------------------------
def run_migrations_offline() -> None:
    raise RuntimeError("Offline-Modus deaktiviert – bitte Online-Modus verwenden.")

# ----------------------------------------------------------------------
# Online-Pfad (AsyncEngine + run_sync)
# ----------------------------------------------------------------------
async def run_migrations_online() -> None:
    connectable: AsyncEngine = create_async_engine(
        DATABASE_URL,
        poolclass=pool.NullPool,
        future=True,
    )

    async with connectable.connect() as async_conn:

        def do_run_migrations(connection: Connection) -> None:
            # WICHTIG: connection + target_metadata -> nötige Voraussetzung
            # damit Alembic den DB-Ist gegen ORM-Soll vergleicht (Autogenerate)
            context.configure(
                connection=connection,
                target_metadata=target_metadata,
                compare_type=True,
                compare_server_default=True,
                include_schemas=True,
                process_revision_directives=process_revision_directives,
            )
            with context.begin_transaction():
                context.run_migrations()

        # run_sync ruft do_run_migrations(connection) auf
        await async_conn.run_sync(do_run_migrations)

    await connectable.dispose()

# ----------------------------------------------------------------------
# WICHTIG: beim Import starten – KEIN __main__-Guard
# ----------------------------------------------------------------------
def run_migrations() -> None:
    if context.is_offline_mode():
        run_migrations_offline()
    else:
        asyncio.run(run_migrations_online())

run_migrations()