"""Config flow for Denon AVR Bluetooth integration."""
from __future__ import annotations

import logging
import re
from typing import Any

import voluptuous as vol

from homeassistant import config_entries
from homeassistant.data_entry_flow import FlowResult

from .const import DOMAIN
from .protocol import find_denon_devices

_LOGGER = logging.getLogger(__name__)

_MAC_RE = re.compile(r"^([0-9A-F]{2}:){5}[0-9A-F]{2}$", re.IGNORECASE)

MANUAL_SCHEMA = vol.Schema(
    {
        vol.Required("mac"): str,
        vol.Optional("name", default="Denon AVR-S540BT"): str,
    }
)


class DenonBTConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
    """Handle a config flow for Denon AVR Bluetooth."""

    VERSION = 1

    def __init__(self) -> None:
        self._discovered: list[dict[str, Any]] = []

    async def async_step_user(
        self, user_input: dict[str, Any] | None = None
    ) -> FlowResult:
        """Entry point — try D-Bus discovery, fall back to manual."""
        self._discovered = await self.hass.async_add_executor_job(
            find_denon_devices
        )
        if self._discovered:
            return await self.async_step_select()
        return await self.async_step_manual()

    # ── Device selection ─────────────────────────────────────────────────────

    async def async_step_select(
        self, user_input: dict[str, Any] | None = None
    ) -> FlowResult:
        """Let the user pick a discovered device or go manual."""
        if user_input is not None:
            chosen = user_input["device"]
            if chosen == "_manual":
                return await self.async_step_manual()

            for dev in self._discovered:
                if dev["mac"] == chosen:
                    await self.async_set_unique_id(dev["mac"].upper())
                    self._abort_if_unique_id_configured()
                    return self.async_create_entry(
                        title=dev["name"],
                        data={"mac": dev["mac"], "name": dev["name"]},
                    )

        options = {
            dev["mac"]: f"{dev['name']} ({dev['mac']})"
            for dev in self._discovered
        }
        options["_manual"] = "Enter MAC address manually\u2026"

        return self.async_show_form(
            step_id="select",
            data_schema=vol.Schema(
                {vol.Required("device"): vol.In(options)}
            ),
        )

    # ── Manual MAC entry ─────────────────────────────────────────────────────

    async def async_step_manual(
        self, user_input: dict[str, Any] | None = None
    ) -> FlowResult:
        """Handle manual MAC address entry."""
        errors: dict[str, str] = {}

        if user_input is not None:
            mac = user_input["mac"].strip().upper()
            name = user_input.get("name", "Denon AVR")

            if not _MAC_RE.match(mac):
                errors["base"] = "invalid_mac"
            else:
                await self.async_set_unique_id(mac)
                self._abort_if_unique_id_configured()
                return self.async_create_entry(
                    title=name,
                    data={"mac": mac, "name": name},
                )

        return self.async_show_form(
            step_id="manual",
            data_schema=MANUAL_SCHEMA,
            errors=errors,
        )