import secrets, hmac, hashlib, time, base64
from datetime import timedelta
import os
import socket
import struct
from functools import wraps
import threading
from flask import Flask, request, Response, session
from flask_basicauth import BasicAuth
import initialize
from python.helpers import files, git, mcp_server, fasta2a_server
from python.helpers.files import get_abs_path
from python.helpers import runtime, dotenv, process
from python.helpers.extract_tools import load_classes_from_folder
from python.helpers.api import ApiHandler
from python.helpers.print_style import PrintStyle
import atexit
import asyncio

CSRF_SECRET = secrets.token_bytes(32)  # or os.environ["CSRF_SECRET"].encode()
TOKEN_TTL = 3600  # 1 hour validity

def generate_csrf_token():
    nonce = secrets.token_hex(16)  # 128-bit random
    timestamp = str(int(time.time()))
    data = f"{nonce}:{timestamp}"
    sig = hmac.new(CSRF_SECRET, data.encode(), hashlib.sha256).hexdigest()
    return f"{data}.{sig}"

def verify_csrf_token(token):
    try:
        data, sig = token.rsplit(".", 1)
        expected_sig = hmac.new(CSRF_SECRET, data.encode(), hashlib.sha256).hexdigest()
        if not hmac.compare_digest(sig, expected_sig):
            return False
        # check TTL
        nonce, timestamp = data.split(":")
        if time.time() - int(timestamp) > TOKEN_TTL:
            return False
        return True
    except Exception:
        return False


# Set the new timezone to 'UTC'
os.environ["TZ"] = "UTC"
os.environ["TOKENIZERS_PARALLELISM"] = "false"
# Apply the timezone change
if hasattr(time, 'tzset'):
    time.tzset()

# initialize the internal Flask server
webapp = Flask("app", static_folder=get_abs_path("./webui"), static_url_path="/")
webapp.secret_key = os.getenv("FLASK_SECRET_KEY") or secrets.token_hex(32)
webapp.config.update(
    JSON_SORT_KEYS=False,
    SESSION_COOKIE_NAME="session_" + runtime.get_runtime_id(),  # bind the session cookie name to runtime id to prevent session collision on same host
    SESSION_COOKIE_SAMESITE="Strict",
    SESSION_PERMANENT=True,
    PERMANENT_SESSION_LIFETIME=timedelta(days=1)
)


lock = threading.Lock()

# Set up basic authentication for UI and API but not MCP
basic_auth = BasicAuth(webapp)


def is_loopback_address(address):
    loopback_checker = {
        socket.AF_INET: lambda x: struct.unpack("!I", socket.inet_aton(x))[0]
        >> (32 - 8)
        == 127,
        socket.AF_INET6: lambda x: x == "::1",
    }
    address_type = "hostname"
    try:
        socket.inet_pton(socket.AF_INET6, address)
        address_type = "ipv6"
    except socket.error:
        try:
            socket.inet_pton(socket.AF_INET, address)
            address_type = "ipv4"
        except socket.error:
            address_type = "hostname"

    if address_type == "ipv4":
        return loopback_checker[socket.AF_INET](address)
    elif address_type == "ipv6":
        return loopback_checker[socket.AF_INET6](address)
    else:
        for family in (socket.AF_INET, socket.AF_INET6):
            try:
                r = socket.getaddrinfo(address, None, family, socket.SOCK_STREAM)
            except socket.gaierror:
                return False
            for family, _, _, _, sockaddr in r:
                if not loopback_checker[family](sockaddr[0]):
                    return False
        return True


def requires_api_key(f):
    @wraps(f)
    async def decorated(*args, **kwargs):
        # Check for Bearer token first (Hugging Face requirement)
        auth_token = os.getenv("AUTHENTICATION_TOKEN")
        if auth_token:
            print(f"DEBUG: AUTHENTICATION_TOKEN is set. Length: {len(auth_token)}")
            auth_header = request.headers.get("Authorization")
            if auth_header and auth_header.startswith("Bearer "):
                bearer_token = auth_header.split(" ", 1)[1]
                if bearer_token == auth_token:
                    return await f(*args, **kwargs)
            # If Bearer token is provided but incorrect, or not provided when AUTHENTICATION_TOKEN is set
            if auth_header:
                 return Response("Invalid Bearer token", 401)

        # Fallback to the default auth token from settings (same as MCP server)
        from python.helpers.settings import get_settings
        valid_api_key = get_settings()["mcp_server_token"]

        if api_key := request.headers.get("X-API-KEY"):
            if api_key != valid_api_key:
                return Response("Invalid API key", 401)
        elif request.json and request.json.get("api_key"):
            api_key = request.json.get("api_key")
            if api_key != valid_api_key:
                return Response("Invalid API key", 401)
        else:
            # If AUTHENTICATION_TOKEN was set but we reached here, it means Bearer was missing/wrong
            if auth_token:
                return Response("Bearer token required", 401)
            return Response("API key required", 401)
        return await f(*args, **kwargs)

    return decorated


# allow only loopback addresses
def requires_loopback(f):
    @wraps(f)
    async def decorated(*args, **kwargs):
        if not is_loopback_address(request.remote_addr):
            return Response(
                "Access denied.",
                403,
                {},
            )
        return await f(*args, **kwargs)

    return decorated


# require authentication for handlers
def requires_auth(f):
    @wraps(f)
    async def decorated(*args, **kwargs):
        user = dotenv.get_dotenv_value("AUTH_LOGIN")
        password = dotenv.get_dotenv_value("AUTH_PASSWORD")
        if user and password:
            auth = request.authorization
            if not auth or not (auth.username == user and auth.password == password):
                return Response(
                    "Could not verify your access level for that URL.\n"
                    "You have to login with proper credentials",
                    401,
                    {"WWW-Authenticate": 'Basic realm="Login Required"'},
                )
        return await f(*args, **kwargs)

    return decorated


def csrf_protect(f):
    @wraps(f)
    async def decorated(*args, **kwargs):
        header = request.headers.get("X-CSRF-Token")
        if not header or not verify_csrf_token(header):
            print("Invalid or missing CSRF token!")
            return Response("CSRF token missing or invalid", 403)
        print("CSRF token OK.")
        return await f(*args, **kwargs)

    return decorated


# handle default address, load index
@webapp.route("/", methods=["GET"])
@requires_auth
async def serve_index():
    PrintStyle().print("Serving index.html")
    gitinfo = None
    try:
        gitinfo = git.get_git_info()
    except Exception as e:
        PrintStyle().error(f"Error getting git info: {e}")
        gitinfo = {
            "version": "unknown",
            "commit_time": "unknown",
        }
    index_content = files.read_file("webui/index.html")
    index_content = files.replace_placeholders_text(
        _content=index_content,
        version_no=gitinfo["version"],
        version_time=gitinfo["commit_time"]
    )

    # Generate and inject CSRF token and runtime_id into meta tags
    csrf_token = generate_csrf_token()
    runtime_id = runtime.get_runtime_id()
    meta_tags = f'''<meta name="csrf-token" content="{csrf_token}">
    <meta name="runtime-id" content="{runtime_id}">'''
    index_content = index_content.replace("</head>", f"{meta_tags}</head>")
    PrintStyle().print("Finished serving index.html")
    return index_content

def run():
    PrintStyle().print("Initializing framework...")

    # Suppress only request logs but keep the startup messages
    from werkzeug.serving import WSGIRequestHandler
    from werkzeug.serving import make_server
    from werkzeug.middleware.dispatcher import DispatcherMiddleware
    from a2wsgi import ASGIMiddleware

    PrintStyle().print("Starting server...")

    class NoRequestLoggingWSGIRequestHandler(WSGIRequestHandler):
        def log_request(self, code="-", size="-"):
            pass  # Override to suppress request logging

    # Get configuration from environment
    port = runtime.get_web_ui_port()
    host = (
        runtime.get_arg("host") or dotenv.get_dotenv_value("WEB_UI_HOST") or "localhost"
    )
    server = None

    def register_api_handler(app, handler: type[ApiHandler]):
        name = handler.__module__.split(".")[-1]
        instance = handler(app, lock)

        async def handler_wrap():
            return await instance.handle_request(request=request)

        if handler.requires_loopback():
            handler_wrap = requires_loopback(handler_wrap)
        if handler.requires_auth():
            handler_wrap = requires_auth(handler_wrap)
        if handler.requires_api_key():
            handler_wrap = requires_api_key(handler_wrap)
        if handler.requires_csrf():
            handler_wrap = csrf_protect(handler_wrap)

        app.add_url_rule(
            f"/{name}",
            f"/{name}",
            handler_wrap,
            methods=handler.get_methods(),
        )

    # initialize and register API handlers
    handlers = load_classes_from_folder("python/api", "*.py", ApiHandler)
    for handler in handlers:
        register_api_handler(webapp, handler)

    # add the webapp, mcp, and a2a to the app
    middleware_routes = {
        "/mcp": ASGIMiddleware(app=mcp_server.DynamicMcpProxy.get_instance()),  # type: ignore
        "/a2a": ASGIMiddleware(app=fasta2a_server.DynamicA2AProxy.get_instance()),  # type: ignore
    }

    app = DispatcherMiddleware(webapp, middleware_routes)  # type: ignore

    PrintStyle().debug(f"Starting server at http://{host}:{port} ...")

    server = make_server(
        host=host,
        port=port,
        app=app,
        request_handler=NoRequestLoggingWSGIRequestHandler,
        threaded=True,
    )
    process.set_server(server)
    server.log_startup()

    # Start init_a0 in a background thread when server starts
    # threading.Thread(target=init_a0, daemon=True).start()
    init_a0()

    # run the server
    server.serve_forever()


def init_a0():
    # initialize contexts and MCP
    init_chats = initialize.initialize_chats()
    # only wait for init chats, otherwise they would seem to disappear for a while on restart
    init_chats.result_sync()

    initialize.initialize_mcp()
    # start job loop
    initialize.initialize_job_loop()
    # preload
    initialize.initialize_preload()


def shutdown_mcp():
    proxy = mcp_server.DynamicMcpProxy.get_instance()
    if proxy:
        asyncio.run(proxy.close())

atexit.register(shutdown_mcp)


# run the internal server
if __name__ == "__main__":
    runtime.initialize()
    dotenv.load_dotenv()
    run()