import socket
from collections.abc import Mapping


def _get_random_port() -> int:
    # os automatically assigns an available port when binding to port 0, so we can use that to find a free port
    try:
        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
            s.bind(('', 0))
            s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            port = s.getsockname()[1]
            return port
    except Exception as e:
        raise RuntimeError(f"Could not find an available port: {e}")


def _get_service_port(mapping: str | int | Mapping[str, object]) -> int | None:
    if isinstance(mapping, int):
        return mapping

    if isinstance(mapping, Mapping):
        published = mapping.get("published")
        if published is None:
            return None
        try:
            return int(published)
        except (TypeError, ValueError):
            return None

    parts = str(mapping).split(":")
    match parts:
        case [""]:
            return None
        case [port] | [port, _]:
            try:
                return int(port)
            except ValueError:
                return None
        case ["localhost" | "127.0.0.1", _, _]:
            return None
        case [_, port, _]:
            try:
                return int(port)
            except ValueError:
                return None
        case _:
            return None


def _replace_port_in_mapping(
        mapping: str | int | Mapping[str, object],
        port_from: int,
        port_to: int,
) -> str | dict[str, object]:
    if isinstance(mapping, Mapping):
        updated = dict(mapping)
        if _get_service_port(updated) == port_from:
            updated["published"] = str(port_to)
        return updated

    parts = str(mapping).split(":")
    match parts:
        case [_]:
            return str(port_to)
        case [_, container_port]:
            return f"{port_to}:{container_port}"
        case [ip, _, container_port]:
            return f"{ip}:{port_to}:{container_port}"
        case _:
            return str(port_to)


def _get_port_index(mappings: list[str | int | Mapping[str, object]], port: int) -> int | None:
    for i, mapping in enumerate(mappings):
        if _get_service_port(mapping) == port:
            return i
    return None