#!/usr/bin/env python3
"""
FTP server using Twisted's FTP server infrastructure.
Accepts any credentials, logs all commands and file requests,
forwards events as JSON to LOG_TARGET if set.
"""

import json
import os
import socket
import sys
from datetime import datetime, timezone

from twisted.internet import defer, protocol, reactor
from twisted.protocols.ftp import FTP, FTPFactory
from twisted.python import log as twisted_log
from decnet_logging import syslog_line, write_syslog_file, forward_syslog

NODE_NAME = os.environ.get("NODE_NAME", "ftpserver")
SERVICE_NAME   = "ftp"
LOG_TARGET = os.environ.get("LOG_TARGET", "")




def _log(event_type: str, severity: int = 6, **kwargs) -> None:
    line = syslog_line(SERVICE_NAME, NODE_NAME, event_type, severity, **kwargs)
    print(line, flush=True)
    write_syslog_file(line)
    forward_syslog(line, LOG_TARGET)


class ServerFTP(FTP):
    def connectionMade(self):
        peer = self.transport.getPeer()
        _log("connection", src_ip=peer.host, src_port=peer.port)
        super().connectionMade()

    def ftp_USER(self, username):
        self._server_user = username
        _log("user", username=username)
        return super().ftp_USER(username)

    def ftp_PASS(self, password):
        _log("auth_attempt", username=getattr(self, "_server_user", "?"), password=password)
        # Accept everything — we're a server
        self.state = self.AUTHED
        self._user = getattr(self, "_server_user", "anonymous")
        return defer.succeed((230, "Login successful."))

    def ftp_RETR(self, path):
        _log("download_attempt", path=path)
        self.sendLine(b"550 File unavailable.")
        return defer.succeed(None)

    def connectionLost(self, reason):
        peer = self.transport.getPeer()
        _log("disconnect", src_ip=peer.host, src_port=peer.port)
        super().connectionLost(reason)


class ServerFTPFactory(FTPFactory):
    protocol = ServerFTP


if __name__ == "__main__":
    twisted_log.startLogging(sys.stdout)
    _log("startup", msg=f"FTP server starting as {NODE_NAME} on port 21")
    reactor.listenTCP(21, ServerFTPFactory())
    reactor.run()