"""StackPilot backend — FastAPI application entry point."""
from __future__ import annotations

import asyncio
import logging
from concurrent.futures import ThreadPoolExecutor
from contextlib import asynccontextmanager

from fastapi import FastAPI, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse
from sqlmodel import Session

from config import settings
from version import APP_VERSION
from database import engine, init_db
import docker_client
from docker_client import DockerError
from routers import (
    audit,
    auth,
    backups,
    containers,
    dashboard,
    destinations,
    editor,
    files,
    git,
    images,
    networks,
    oidc,
    ports,
    registries,
    schedules,
    secrets,
    settings as settings_router,
    stacks,
    system,
    templates,
    tokens,
    volumes,
    ws,
)
from services import (
    backup_destination_service,
    git_service,
    image_status_store,
    logo_service,
    registry_service,
    schedule_service,
    secret_service,
    stack_cleanup_service,
    stack_lock_service,
    template_service,
    update_service,
)

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger("stackpilot")


#: Workers for ``asyncio.to_thread``. The default (CPU count + 4, so six on a
#: two-core VM) is shared by everything that leaves the event loop — a backup
#: streaming several volumes, the dashboard, NFS and SFTP destinations — and
#: running out of it does not fail, it waits. Long-lived readers (the event
#: stream, terminals) have threads of their own; this is headroom for the rest.
DEFAULT_EXECUTOR_WORKERS = 64


@asynccontextmanager
async def lifespan(app: FastAPI):
    asyncio.get_running_loop().set_default_executor(
        ThreadPoolExecutor(max_workers=DEFAULT_EXECUTOR_WORKERS, thread_name_prefix="sp-worker")
    )
    init_db()
    # Register stacks that already exist on disk.
    try:
        with Session(engine) as session:
            stacks.sync_discovered_stacks(session)
            orphans = stack_cleanup_service.prune_orphans(session)
        if orphans:
            logger.info("Forgot Git sources/policies of deleted stack(s): %s", ", ".join(orphans))
    except Exception as exc:  # noqa: BLE001
        logger.warning("Stack discovery failed: %s", exc)
    # One-off: encrypt backup-destination credentials written before they were
    # stored encrypted (see services/crypto_service.py).
    try:
        with Session(engine) as session:
            encrypted = backup_destination_service.migrate_plaintext_configs(session)
        if encrypted:
            logger.info("Encrypted %d backup destination config(s) at rest", encrypted)
    except Exception as exc:  # noqa: BLE001
        logger.warning("Destination config encryption migration failed: %s", exc)
    try:
        fixed = secret_service.fix_permissions()
        if fixed:
            logger.info("Made %d stack secret file(s) readable for non-root containers", fixed)
    except Exception as exc:  # noqa: BLE001
        logger.warning("Could not fix secret permissions: %s", exc)
    try:
        moved = template_service.migrate_legacy_db_templates()
        if moved:
            logger.info("Migrated %d custom template(s) from the database to folders", moved)
    except Exception as exc:  # noqa: BLE001
        logger.warning("Legacy template migration failed: %s", exc)
    # Throwaway containers a previous run left behind (a helper whose start
    # failed, e.g. on an NFS mount, used to stay in "Created" and keep its
    # volume in use). Nothing of ours is in flight yet, so all can go.
    try:
        client = docker_client.get_client()
        cleared = docker_client.remove_stale_helpers(client)
        cleared += backup_destination_service.clear_nfs_leftovers(client)
        if cleared:
            logger.info("Removed %d leftover helper container(s)", cleared)
    except Exception as exc:  # noqa: BLE001 - Docker may not be up yet
        logger.warning("Could not clean up helper containers: %s", exc)
    # Runtime state that used to live in module dicts and was lost on restart.
    # Stack locks mean "an operation is running"; after a restart none is, so
    # all of them go — not just the expired ones. A backup holds its lock for
    # twelve hours, and one that died with its process used to leave the stack
    # un-startable for the rest of them.
    try:
        with Session(engine) as session:
            stale = stack_lock_service.clear_all(session)
        if stale:
            logger.info(
                "Cleared %d stack lock(s) left over from a previous run: %s",
                len(stale), ", ".join(sorted(stale)),
            )
    except Exception as exc:  # noqa: BLE001
        logger.warning("Could not clear stack locks: %s", exc)
    try:
        restored = image_status_store.install()
        logger.info("Restored %d cached image update status(es)", restored)
    except Exception as exc:  # noqa: BLE001
        logger.warning("Could not restore the image update cache: %s", exc)
    # Private registry credentials: into the in-memory cache the update checker
    # reads, and into the config.json the Docker CLI reads.
    try:
        with Session(engine) as session:
            known = registry_service.reload(session)
        if known:
            logger.info("Loaded credentials for %d registr%s", known, "y" if known == 1 else "ies")
    except Exception as exc:  # noqa: BLE001
        logger.warning("Could not load registry credentials: %s", exc)

    update_task = asyncio.create_task(update_service.background_loop())
    schedule_task = asyncio.create_task(schedule_service.scheduler_loop())
    # App logos. Deliberately a task and not awaited: the catalog is a network
    # download, and a box with no outbound internet must still start instantly
    # (it just keeps the built-in glyphs).
    logo_task = asyncio.create_task(logo_service.catalog_loop())
    git_service.ensure_cache_root()
    git_task = asyncio.create_task(git_service.poll_loop())
    logger.info("StackPilot backend ready on port %s", settings.PORT)
    yield
    update_task.cancel()
    schedule_task.cancel()
    logo_task.cancel()
    git_task.cancel()


app = FastAPI(title="StackPilot", version=APP_VERSION, lifespan=lifespan)

app.add_middleware(
    CORSMiddleware,
    allow_origins=settings.CORS_ORIGINS,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.exception_handler(DockerError)
async def docker_error_handler(_request: Request, exc: DockerError):
    return JSONResponse(
        status_code=502,
        content={"error": exc.error, "detail": exc.detail},
    )


app.include_router(auth.router)
app.include_router(stacks.router)
app.include_router(git.router)
app.include_router(git.hook_router)
app.include_router(oidc.router)
app.include_router(tokens.router)
app.include_router(registries.router)
app.include_router(secrets.router)
app.include_router(containers.router)
app.include_router(dashboard.router)
app.include_router(system.router)
app.include_router(volumes.router)
app.include_router(editor.router)
app.include_router(files.router)
app.include_router(images.router)
app.include_router(ports.router)
app.include_router(templates.router)
app.include_router(audit.router)
app.include_router(settings_router.router)
app.include_router(backups.router)
app.include_router(destinations.router)
app.include_router(schedules.router)
app.include_router(networks.router)
app.include_router(ws.router)


@app.get("/api/health")
def health() -> dict:
    return {"status": "ok", "version": APP_VERSION}