"""Utility functions for HAProxy MCP Server."""

from typing import Dict, Generator
from .config import StatField, StateField, STATE_MIN_COLUMNS
from .haproxy_client import haproxy_cmd_batch


def parse_servers_state(state_output: str) -> dict[str, dict[str, dict[str, str]]]:
    """Parse 'show servers state' output.

    Args:
        state_output: Raw output from HAProxy 'show servers state' command

    Returns:
        Nested dict: {backend: {server: {addr: str, port: str, state: str}}}

    Example:
        state = haproxy_cmd("show servers state")
        parsed = parse_servers_state(state)
        # parsed["pool_1"]["pool_1_1"] == {"addr": "10.0.0.1", "port": "8080", "state": "2"}
    """
    result: dict[str, dict[str, dict[str, str]]] = {}
    for line in state_output.split("\n"):
        parts = line.split()
        if len(parts) >= STATE_MIN_COLUMNS:
            backend = parts[StateField.BE_NAME]
            server = parts[StateField.SRV_NAME]
            addr = parts[StateField.SRV_ADDR]
            port = parts[StateField.SRV_PORT]
            state = parts[StateField.SRV_OP_STATE] if len(parts) > StateField.SRV_OP_STATE else ""

            if backend not in result:
                result[backend] = {}
            result[backend][server] = {
                "addr": addr,
                "port": port,
                "state": state,
            }
    return result


def disable_server_slot(backend: str, server: str) -> None:
    """Disable a server slot (set to maint and clear address).

    Args:
        backend: Backend name (e.g., 'pool_1')
        server: Server name (e.g., 'pool_1_1')

    Raises:
        HaproxyError: If HAProxy command fails
    """
    haproxy_cmd_batch([
        f"set server {backend}/{server} state maint",
        f"set server {backend}/{server} addr 0.0.0.0 port 0"
    ])


def parse_stat_csv(stat_output: str) -> Generator[Dict[str, str], None, None]:
    """Parse HAProxy stat CSV output into structured data.

    Args:
        stat_output: Raw output from 'show stat' command

    Yields:
        Dictionaries with parsed stat fields for each row
    """
    for line in stat_output.split("\n"):
        if not line or line.startswith("#"):
            continue
        parts = line.split(",")
        if len(parts) > StatField.STATUS:
            yield {
                "pxname": parts[StatField.PXNAME],
                "svname": parts[StatField.SVNAME],
                "scur": parts[StatField.SCUR] if len(parts) > StatField.SCUR else "0",
                "smax": parts[StatField.SMAX] if len(parts) > StatField.SMAX else "0",
                "status": parts[StatField.STATUS],
                "weight": parts[StatField.WEIGHT] if len(parts) > StatField.WEIGHT else "0",
                "check_status": parts[StatField.CHECK_STATUS] if len(parts) > StatField.CHECK_STATUS else "",
            }