"""Process operations."""

from __future__ import annotations

import contextlib
import os
import signal
import sys
from typing import Optional
from urllib.parse import urlparse

import psutil

from pynecone import constants
from pynecone.config import get_config
from pynecone.utils import console, prerequisites


def kill(pid):
    """Kill a process.

    Args:
        pid: The process ID.
    """
    os.kill(pid, signal.SIGTERM)


def get_num_workers() -> int:
    """Get the number of backend worker processes.

    Returns:
        The number of backend worker processes.
    """
    return 1 if prerequisites.get_redis() is None else (os.cpu_count() or 1) * 2 + 1


def get_api_port() -> int:
    """Get the API port.

    Returns:
        The API port.
    """
    port = urlparse(get_config().api_url).port
    if port is None:
        port = urlparse(constants.API_URL).port
    assert port is not None
    return port


def get_process_on_port(port) -> Optional[psutil.Process]:
    """Get the process on the given port.

    Args:
        port: The port.

    Returns:
        The process on the given port.
    """
    for proc in psutil.process_iter(["pid", "name", "cmdline"]):
        try:
            for conns in proc.connections(kind="inet"):
                if conns.laddr.port == int(port):
                    return proc
        except (psutil.NoSuchProcess, psutil.AccessDenied, psutil.ZombieProcess):
            pass
    return None


def is_process_on_port(port) -> bool:
    """Check if a process is running on the given port.

    Args:
        port: The port.

    Returns:
        Whether a process is running on the given port.
    """
    return get_process_on_port(port) is not None


def kill_process_on_port(port):
    """Kill the process on the given port.

    Args:
        port: The port.
    """
    if get_process_on_port(port) is not None:
        with contextlib.suppress(psutil.AccessDenied):
            get_process_on_port(port).kill()  # type: ignore


def change_or_terminate_port(port, _type) -> str:
    """Terminate or change the port.

    Args:
        port: The port.
        _type: The type of the port.

    Returns:
        The new port or the current one.
    """
    console.print(
        f"Something is already running on port [bold underline]{port}[/bold underline]. This is the port the {_type} runs on."
    )
    frontend_action = console.ask("Kill or change it?", choices=["k", "c", "n"])
    if frontend_action == "k":
        kill_process_on_port(port)
        return port
    elif frontend_action == "c":
        new_port = console.ask("Specify the new port")

        # Check if also the new port is used
        if is_process_on_port(new_port):
            return change_or_terminate_port(new_port, _type)
        else:
            console.print(
                f"The {_type} will run on port [bold underline]{new_port}[/bold underline]."
            )
            return new_port
    else:
        console.print("Exiting...")
        sys.exit()