"""Database configuration and session management for Homelab Automation.
Uses SQLAlchemy 2.x async engine with SQLite + aiosqlite driver.
"""
from __future__ import annotations

import asyncio
import os
from pathlib import Path
from typing import AsyncGenerator
from urllib.parse import urlparse

from alembic import command
from alembic.config import Config
from sqlalchemy import event, MetaData
from sqlalchemy.ext.asyncio import AsyncEngine, AsyncSession, async_sessionmaker, create_async_engine
from sqlalchemy.orm import declarative_base

# Naming convention to keep Alembic happy with constraints
NAMING_CONVENTION = {
    "ix": "ix_%(column_0_label)s",
    "uq": "uq_%(table_name)s_%(column_0_name)s",
    "ck": "ck_%(table_name)s_%(constraint_name)s",
    "fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
    "pk": "pk_%(table_name)s",
}

metadata_obj = MetaData(naming_convention=NAMING_CONVENTION)
Base = declarative_base(metadata=metadata_obj)

# Resolve base path (project root)
ROOT_DIR = Path(__file__).resolve().parents[2]
DEFAULT_DB_PATH = Path(os.environ.get("DB_PATH") or (ROOT_DIR / "data" / "homelab.db"))
DATABASE_URL = os.environ.get("DATABASE_URL", f"sqlite+aiosqlite:///{DEFAULT_DB_PATH}")

# Ensure SQLite directory exists even if DATABASE_URL overrides DB_PATH
def _ensure_sqlite_dir(db_url: str) -> None:
    if not db_url.startswith("sqlite"):
        return
    # Extraire le chemin après sqlite+aiosqlite:///
    # Sur Windows, le chemin peut être C:\... donc on ne peut pas utiliser urlparse
    prefix = "sqlite+aiosqlite:///"
    if db_url.startswith(prefix):
        path_str = db_url[len(prefix):]
        # Sur Windows, le chemin peut commencer par une lettre de lecteur (C:)
        db_path = Path(path_str)
        if db_path.parent and str(db_path.parent) != ".":
            db_path.parent.mkdir(parents=True, exist_ok=True)

DEFAULT_DB_PATH.parent.mkdir(parents=True, exist_ok=True)
_ensure_sqlite_dir(DATABASE_URL)


def _debug_db_paths() -> None:
    try:
        print(
            "[DB] DATABASE_URL=%s, DEFAULT_DB_PATH=%s, parent_exists=%s, parent=%s"
            % (
                DATABASE_URL,
                DEFAULT_DB_PATH,
                DEFAULT_DB_PATH.parent.exists(),
                DEFAULT_DB_PATH.parent,
            )
        )
    except Exception:
        # Debug logging should never break startup
        pass


_debug_db_paths()

engine: AsyncEngine = create_async_engine(
    DATABASE_URL,
    echo=False,
    pool_pre_ping=True,
    future=True,
)

# Ensure SQLite pragmas (WAL + FK) when using SQLite
if DATABASE_URL.startswith("sqlite"):
    @event.listens_for(engine.sync_engine, "connect")
    def _set_sqlite_pragmas(dbapi_connection, connection_record):  # type: ignore[override]
        cursor = dbapi_connection.cursor()
        cursor.execute("PRAGMA foreign_keys=ON")
        # WAL mode can fail on some Docker volume mounts (e.g., NFS, CIFS, overlay issues)
        # Fall back to DELETE mode if WAL fails
        try:
            cursor.execute("PRAGMA journal_mode=WAL")
        except Exception:
            # WAL not supported, use DELETE mode instead
            try:
                cursor.execute("PRAGMA journal_mode=DELETE")
            except Exception:
                pass  # Ignore if this also fails
        cursor.close()

async_session_maker = async_sessionmaker(
    bind=engine,
    autoflush=False,
    expire_on_commit=False,
    class_=AsyncSession,
)


async def get_db() -> AsyncGenerator[AsyncSession, None]:
    """FastAPI dependency that yields an AsyncSession with automatic rollback on error."""
    async with async_session_maker() as session:  # type: AsyncSession
        try:
            yield session
        except Exception:
            await session.rollback()
            raise
        finally:
            await session.close()


async def init_db() -> None:
    """Create all tables (mostly for dev/tests; migrations should be handled by Alembic)."""
    from . import (
        host,
        task,
        schedule,
        schedule_run,
        log,
        alert,
        app_setting,
        docker_container,
        docker_image,
        docker_volume,
        docker_alert,
        playbook_lint,
        favorite_group,
        favorite_container,
    )  # noqa: F401

    def _to_sync_database_url(db_url: str) -> str:
        return db_url.replace("sqlite+aiosqlite:", "sqlite:")

    def _run_alembic_upgrade() -> None:
        # Try multiple locations for alembic.ini (dev vs Docker)
        alembic_ini_paths = [
            ROOT_DIR / "alembic.ini",  # Dev: /path/to/project/alembic.ini
            Path("/alembic.ini"),       # Docker: /alembic.ini
            Path("/app/alembic.ini"),   # Docker alternative
        ]
        
        alembic_ini = None
        for path in alembic_ini_paths:
            if path.exists():
                alembic_ini = path
                print(f"[DB] Found alembic.ini at: {alembic_ini}")
                break
        
        if not alembic_ini:
            print(f"[DB] alembic.ini not found in any of: {[str(p) for p in alembic_ini_paths]}")
            return
        
        try:
            cfg = Config(str(alembic_ini))
            cfg.set_main_option("sqlalchemy.url", _to_sync_database_url(DATABASE_URL))
            print(f"[DB] Running Alembic upgrade to head...")
            command.upgrade(cfg, "head")
            print(f"[DB] Alembic upgrade completed successfully")
        except Exception as e:
            print(f"[DB] Alembic upgrade failed: {e}")
            raise

    try:
        await asyncio.to_thread(_run_alembic_upgrade)
    except Exception as e:
        print(f"[DB] Exception during Alembic migration: {e}")

    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)