import subprocess
import time
import os
import threading
import logging

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

class TN3270Session:
    def __init__(self):
        self.host      = os.environ.get("ZOS_HOST", "192.168.2.243")
        self.port      = os.environ.get("ZOS_PORT", "23")
        self.s3270     = None
        self.lock      = threading.Lock()
        self.connected = False

    def _start_s3270(self):
        self.s3270 = subprocess.Popen(
            ["s3270", "-model", "3279-2", f"{self.host}:{self.port}"],
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            text=True,
            bufsize=1,
        )
        time.sleep(2)

    def _send(self, command):
        self.s3270.stdin.write(command + "\n")
        self.s3270.stdin.flush()
        return self._read_response()

    def _read_response(self):
        lines = []
        while True:
            line = self.s3270.stdout.readline()
            if not line:
                return False, lines
            line = line.rstrip("\n")
            if line == "ok":
                return True, lines
            if line == "error":
                return False, lines
            if line.startswith("data: "):
                line = line[6:]
            lines.append(line)

    def connect(self):
        logger.info(f"Connecting to {self.host}:{self.port}")
        self._start_s3270()
        time.sleep(2)
        self.connected = True
        logger.info("TN3270 connected - waiting for user input")

    def disconnect(self):
        try:
            self.s3270.terminate()
        except Exception:
            pass
        finally:
            self.connected = False

    def get_screen(self):
        with self.lock:
            ok, lines = self._send("Ascii()")
            return "\n".join(lines)

    def send_command(self, command):
        with self.lock:
            self._send(f'String("{command}")')
            self._send("Enter()")
            time.sleep(0.5)
            ok, lines = self._send("Ascii()")
            return "\n".join(lines)

    def send_pf(self, key):
        with self.lock:
            self._send(f"PF({key})")
            time.sleep(0.3)
            ok, lines = self._send("Ascii()")
            return "\n".join(lines)

    def send_tab(self):
        with self.lock:
            self._send("Tab()")
            ok, lines = self._send("Ascii()")
            return "\n".join(lines)

    def send_enter(self):
        with self.lock:
            self._send("Enter()")
            time.sleep(0.5)
            ok, lines = self._send("Ascii()")
            return "\n".join(lines)

    def send_key(self, key):
        with self.lock:
            self._send(key)
            time.sleep(0.1)
            ok, lines = self._send("Ascii()")
            return "\n".join(lines)

    def send_char(self, char):
        with self.lock:
            escaped = char.replace('"', '\"')
            self._send(f'String("{escaped}")')
            ok, lines = self._send("Ascii()")
            return "\n".join(lines)