import asyncio
import glob
import importlib
import os
import shutil
import sys
from contextlib import asynccontextmanager
from pathlib import Path
from typing import Callable, List, Optional

from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.staticfiles import StaticFiles
from loguru import logger
from slowapi import Limiter
from slowapi.util import get_remote_address
from starlette.middleware.sessions import SessionMiddleware

from lnbits.core.crud import (
    get_dbversions,
    get_installed_extensions,
    update_installed_extension_state,
)
from lnbits.core.helpers import migrate_extension_database
from lnbits.core.tasks import (  # watchdog_task
    killswitch_task,
    wait_for_paid_invoices,
)
from lnbits.exceptions import register_exception_handlers
from lnbits.settings import settings
from lnbits.tasks import (
    cancel_all_tasks,
    create_permanent_task,
    register_invoice_listener,
)
from lnbits.utils.cache import cache
from lnbits.utils.logger import (
    configure_logger,
    initialize_server_websocket_logger,
    log_server_info,
)
from lnbits.wallets import get_funding_source, set_funding_source

from .commands import migrate_databases
from .core import init_core_routers
from .core.db import core_app_extra
from .core.services import check_admin_settings, check_webpush_settings
from .core.views.extension_api import add_installed_extension
from .extension_manager import (
    Extension,
    InstallableExtension,
    get_valid_extensions,
    version_parse,
)
from .middleware import (
    CustomGZipMiddleware,
    ExtensionsRedirectMiddleware,
    InstalledExtensionMiddleware,
    add_first_install_middleware,
    add_ip_block_middleware,
    add_ratelimit_middleware,
)
from .requestvars import g
from .tasks import (
    check_pending_payments,
    create_task,
    internal_invoice_listener,
    invoice_listener,
)


async def startup(app: FastAPI):
    settings.lnbits_running = True

    # wait till migration is done
    await migrate_databases()

    # setup admin settings
    await check_admin_settings()
    await check_webpush_settings()

    log_server_info()

    # initialize WALLET
    try:
        set_funding_source()
    except Exception as e:
        logger.error(f"Error initializing {settings.lnbits_backend_wallet_class}: {e}")
        set_void_wallet_class()

    # initialize funding source
    await check_funding_source()

    # register core routes
    init_core_routers(app)

    # initialize tasks
    register_async_tasks(app)


async def shutdown():
    logger.warning("LNbits shutting down...")
    settings.lnbits_running = False

    # shutdown event
    cancel_all_tasks()

    # wait a bit to allow them to finish, so that cleanup can run without problems
    await asyncio.sleep(0.1)
    funding_source = get_funding_source()
    await funding_source.cleanup()


@asynccontextmanager
async def lifespan(app: FastAPI):
    await startup(app)
    yield
    await shutdown()


def create_app() -> FastAPI:
    configure_logger()
    app = FastAPI(
        title=settings.lnbits_title,
        description=(
            "API for LNbits, the free and open source bitcoin wallet and "
            "accounts system with plugins."
        ),
        version=settings.version,
        lifespan=lifespan,
        license_info={
            "name": "MIT License",
            "url": "https://raw.githubusercontent.com/lnbits/lnbits/main/LICENSE",
        },
    )

    # Allow registering new extensions routes without direct access to the `app` object
    core_app_extra.register_new_ext_routes = register_new_ext_routes(app)
    core_app_extra.register_new_ratelimiter = register_new_ratelimiter(app)

    # register static files
    static_path = Path("lnbits", "static")
    static = StaticFiles(directory=static_path)
    app.mount("/static", static, name="static")

    g().base_url = f"http://{settings.host}:{settings.port}"

    app.add_middleware(
        CORSMiddleware, allow_origins=["*"], allow_methods=["*"], allow_headers=["*"]
    )

    app.add_middleware(
        CustomGZipMiddleware, minimum_size=1000, exclude_paths=["/api/v1/payments/sse"]
    )

    # required for SSO login
    app.add_middleware(SessionMiddleware, secret_key=settings.auth_secret_key)

    # order of these two middlewares is important
    app.add_middleware(InstalledExtensionMiddleware)
    app.add_middleware(ExtensionsRedirectMiddleware)

    register_custom_extensions_path()

    add_first_install_middleware(app)

    # adds security middleware
    add_ip_block_middleware(app)
    add_ratelimit_middleware(app)

    register_exception_handlers(app)

    return app


async def check_funding_source() -> None:
    funding_source = get_funding_source()

    max_retries = settings.funding_source_max_retries
    retry_counter = 0

    while settings.lnbits_running:
        try:
            logger.info(f"Connecting to backend {funding_source.__class__.__name__}...")
            error_message, balance = await funding_source.status()
            if not error_message:
                retry_counter = 0
                logger.success(
                    f"✔️ Backend {funding_source.__class__.__name__} connected "
                    f"and with a balance of {balance} msat."
                )
                break
            logger.error(
                f"The backend for {funding_source.__class__.__name__} isn't "
                f"working properly: '{error_message}'",
                RuntimeWarning,
            )
        except Exception as e:
            logger.error(
                f"Error connecting to {funding_source.__class__.__name__}: {e}"
            )

        if retry_counter >= max_retries:
            set_void_wallet_class()
            funding_source = get_funding_source()
            break

        retry_counter += 1
        sleep_time = min(0.25 * (2**retry_counter), 60)
        logger.warning(
            f"Retrying connection to backend in {sleep_time} seconds... "
            f"({retry_counter}/{max_retries})"
        )
        await asyncio.sleep(sleep_time)


def set_void_wallet_class():
    logger.warning(
        "Fallback to VoidWallet, because the backend for "
        f"{settings.lnbits_backend_wallet_class} isn't working properly"
    )
    set_funding_source("VoidWallet")


async def check_installed_extensions(app: FastAPI):
    """
    Check extensions that have been installed, but for some reason no longer present in
    the 'lnbits/extensions' directory. One reason might be a docker-container that was
    re-created. The 'data' directory (where the '.zip' files live) is expected to
    persist state. Zips that are missing will be re-downloaded.
    """
    shutil.rmtree(os.path.join("lnbits", "upgrades"), True)
    installed_extensions = await build_all_installed_extensions_list(False)

    for ext in installed_extensions:
        try:
            installed = await check_installed_extension_files(ext)
            if not installed:
                await restore_installed_extension(app, ext)
                logger.info(
                    "✔️ Successfully re-installed extension: "
                    f"{ext.id} ({ext.installed_version})"
                )
        except Exception as e:
            logger.warning(e)
            logger.warning(
                f"Failed to re-install extension: {ext.id} ({ext.installed_version})"
            )

    logger.info(f"Installed Extensions ({len(installed_extensions)}):")
    for ext in installed_extensions:
        logger.info(f"{ext.id} ({ext.installed_version})")


async def build_all_installed_extensions_list(
    include_deactivated: Optional[bool] = True,
) -> List[InstallableExtension]:
    """
    Returns a list of all the installed extensions plus the extensions that
    MUST be installed by default (see LNBITS_EXTENSIONS_DEFAULT_INSTALL).
    """
    installed_extensions = await get_installed_extensions()
    settings.lnbits_all_extensions_ids = {e.id for e in installed_extensions}

    for ext_id in settings.lnbits_extensions_default_install:
        if ext_id in settings.lnbits_all_extensions_ids:
            continue

        ext_releases = await InstallableExtension.get_extension_releases(ext_id)
        ext_releases = sorted(
            ext_releases, key=lambda r: version_parse(r.version), reverse=True
        )

        release = next((e for e in ext_releases if e.is_version_compatible), None)

        if release:
            ext_info = InstallableExtension(
                id=ext_id, name=ext_id, installed_release=release, icon=release.icon
            )
            installed_extensions.append(ext_info)

    if include_deactivated:
        return installed_extensions

    if settings.lnbits_extensions_deactivate_all:
        return []

    return [
        e
        for e in installed_extensions
        if e.id not in settings.lnbits_deactivated_extensions
    ]


async def check_installed_extension_files(ext: InstallableExtension) -> bool:
    if ext.has_installed_version:
        return True

    zip_files = glob.glob(os.path.join(settings.lnbits_data_folder, "zips", "*.zip"))

    if f"./{ext.zip_path!s}" not in zip_files:
        await ext.download_archive()
    ext.extract_archive()

    return False


async def restore_installed_extension(app: FastAPI, ext: InstallableExtension):
    await add_installed_extension(ext)
    await update_installed_extension_state(ext_id=ext.id, active=True)

    extension = Extension.from_installable_ext(ext)
    register_ext_routes(app, extension)

    current_version = (await get_dbversions()).get(ext.id, 0)
    await migrate_extension_database(extension, current_version)

    # mount routes for the new version
    core_app_extra.register_new_ext_routes(extension)
    ext.notify_upgrade(extension.upgrade_hash)


def register_custom_extensions_path():
    if settings.has_default_extension_path:
        return
    default_ext_path = os.path.join("lnbits", "extensions")
    if os.path.isdir(default_ext_path) and len(os.listdir(default_ext_path)) != 0:
        logger.warning(
            "You are using a custom extensions path, "
            + "but the default extensions directory is not empty. "
            + f"Please clean-up the '{default_ext_path}' directory."
        )
        logger.warning(
            f"You can move the existing '{default_ext_path}' directory to: "
            + f" '{settings.lnbits_extensions_path}/extensions'"
        )

    sys.path.append(str(Path(settings.lnbits_extensions_path, "extensions")))
    sys.path.append(str(Path(settings.lnbits_extensions_path, "upgrades")))


def register_new_ext_routes(app: FastAPI) -> Callable:
    # Returns a function that registers new routes for an extension.
    # The returned function encapsulates (creates a closure around)
    # the `app` object but does expose it.
    def register_new_ext_routes_fn(ext: Extension):
        register_ext_routes(app, ext)

    return register_new_ext_routes_fn


def register_new_ratelimiter(app: FastAPI) -> Callable:
    def register_new_ratelimiter_fn():
        limiter = Limiter(
            key_func=get_remote_address,
            default_limits=[
                f"{settings.lnbits_rate_limit_no}/{settings.lnbits_rate_limit_unit}"
            ],
        )
        app.state.limiter = limiter

    return register_new_ratelimiter_fn


def register_ext_routes(app: FastAPI, ext: Extension) -> None:
    """Register FastAPI routes for extension."""
    ext_module = importlib.import_module(ext.module_name)

    ext_route = getattr(ext_module, f"{ext.code}_ext")

    if hasattr(ext_module, f"{ext.code}_start"):
        ext_start_func = getattr(ext_module, f"{ext.code}_start")
        ext_start_func()

    if hasattr(ext_module, f"{ext.code}_static_files"):
        ext_statics = getattr(ext_module, f"{ext.code}_static_files")
        for s in ext_statics:
            static_dir = Path(
                settings.lnbits_extensions_path, "extensions", *s["path"].split("/")
            )
            app.mount(s["path"], StaticFiles(directory=static_dir), s["name"])

    if hasattr(ext_module, f"{ext.code}_redirect_paths"):
        ext_redirects = getattr(ext_module, f"{ext.code}_redirect_paths")
        settings.lnbits_extensions_redirects = [
            r for r in settings.lnbits_extensions_redirects if r["ext_id"] != ext.code
        ]
        for r in ext_redirects:
            r["ext_id"] = ext.code
            settings.lnbits_extensions_redirects.append(r)

    logger.trace(f"adding route for extension {ext_module}")

    prefix = f"/upgrades/{ext.upgrade_hash}" if ext.upgrade_hash != "" else ""
    app.include_router(router=ext_route, prefix=prefix)


async def check_and_register_extensions(app: FastAPI):
    await check_installed_extensions(app)
    for ext in get_valid_extensions(False):
        try:
            register_ext_routes(app, ext)
        except Exception as exc:
            logger.error(f"Could not load extension `{ext.code}`: {exc!s}")


def register_async_tasks(app: FastAPI):

    # check extensions after restart
    if not settings.lnbits_extensions_deactivate_all:
        create_task(check_and_register_extensions(app))

    create_permanent_task(check_pending_payments)
    create_permanent_task(invoice_listener)
    create_permanent_task(internal_invoice_listener)
    create_permanent_task(cache.invalidate_forever)

    # core invoice listener
    invoice_queue: asyncio.Queue = asyncio.Queue(5)
    register_invoice_listener(invoice_queue, "core")
    create_permanent_task(lambda: wait_for_paid_invoices(invoice_queue))

    # TODO: implement watchdog properly
    # create_permanent_task(watchdog_task)
    create_permanent_task(killswitch_task)

    # server logs for websocket
    if settings.lnbits_admin_ui:
        server_log_task = initialize_server_websocket_logger()
        create_permanent_task(server_log_task)