from contextlib import asynccontextmanager

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from sqlalchemy import text

from .config import get_settings
from .database import Base, SessionLocal, engine
from .routers import (
    api_tokens,
    auth,
    branding,
    categories,
    dashboard,
    groups,
    locations,
    maintenance,
    products,
    settings as settings_router,
    stock,
    transfer,
    units,
    users,
    views,
)
from .seed import ensure_builtin_categories, ensure_builtin_units, ensure_first_admin
from .services.group_codes import backfill as backfill_group_codes

settings = get_settings()


def _ensure_schema() -> None:
    """Schonende Migration: fehlende Spalten auf bestehenden Tabellen nachziehen.

    create_all() legt nur fehlende Tabellen an, ändert aber keine bestehenden.
    Auf Postgres holen wir neue nullable-Spalten per ADD COLUMN IF NOT EXISTS nach,
    damit vorhandene Installationen ihre Daten behalten. Auf SQLite (Tests) sind
    die Spalten bereits durch create_all vorhanden.
    """
    if engine.dialect.name != "postgresql":
        return
    stmts = [
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS display_unit_id INTEGER "
        "REFERENCES units(id) ON DELETE SET NULL",
        "ALTER TABLE groups ADD COLUMN IF NOT EXISTS min_stock_unit_id INTEGER "
        "REFERENCES units(id) ON DELETE SET NULL",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS min_stock_unit_id INTEGER "
        "REFERENCES units(id) ON DELETE SET NULL",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS min_stock_in_packages BOOLEAN "
        "NOT NULL DEFAULT FALSE",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS package_label VARCHAR(32)",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS date_precision VARCHAR(8) "
        "NOT NULL DEFAULT 'day'",
        "ALTER TABLE lots ADD COLUMN IF NOT EXISTS best_before_precision VARCHAR(8) "
        "NOT NULL DEFAULT 'day'",
        "ALTER TABLE products ADD COLUMN IF NOT EXISTS category_id INTEGER "
        "REFERENCES categories(id) ON DELETE SET NULL",
    ]
    with engine.begin() as conn:
        for stmt in stmts:
            conn.execute(text(stmt))


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Tabellen anlegen (MVP: create_all statt Alembic-Migrationen).
    Base.metadata.create_all(bind=engine)
    _ensure_schema()
    db = SessionLocal()
    try:
        ensure_builtin_units(db)
        ensure_builtin_categories(db)
        ensure_first_admin(db)
        # Codes bestehender Gruppen-Zuordnungen nachziehen.
        backfill_group_codes(db)
    finally:
        db.close()
    yield


app = FastAPI(title="Vorrania – Lebensmittel-Lagerverwaltung", version="1.0.0", lifespan=lifespan)

origins = ["*"] if settings.cors_origins.strip() == "*" else [
    o.strip() for o in settings.cors_origins.split(",") if o.strip()
]
app.add_middleware(
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.get("/health", tags=["meta"])
def health() -> dict:
    return {"status": "ok"}


app.include_router(auth.router)
app.include_router(users.router)
app.include_router(products.router)
app.include_router(stock.router)
app.include_router(locations.router)
app.include_router(groups.router)
app.include_router(units.router)
app.include_router(views.router)
app.include_router(transfer.router)
app.include_router(api_tokens.router)
app.include_router(settings_router.router)
app.include_router(branding.router)
app.include_router(categories.router)
app.include_router(maintenance.router)
app.include_router(dashboard.router)