"""The discovery flow helper."""
from __future__ import annotations

from collections.abc import Coroutine
from typing import Any, NamedTuple

from homeassistant.const import EVENT_HOMEASSISTANT_STARTED
from homeassistant.core import CoreState, Event, HomeAssistant, callback
from homeassistant.data_entry_flow import FlowResult
from homeassistant.loader import bind_hass
from homeassistant.util.async_ import gather_with_concurrency

FLOW_INIT_LIMIT = 2
DISCOVERY_FLOW_DISPATCHER = "discovery_flow_disptacher"


@bind_hass
@callback
def async_create_flow(
    hass: HomeAssistant, domain: str, context: dict[str, Any], data: Any
) -> None:
    """Create a discovery flow."""
    dispatcher: FlowDispatcher | None = None
    if DISCOVERY_FLOW_DISPATCHER in hass.data:
        dispatcher = hass.data[DISCOVERY_FLOW_DISPATCHER]
    elif hass.state != CoreState.running:
        dispatcher = hass.data[DISCOVERY_FLOW_DISPATCHER] = FlowDispatcher(hass)
        dispatcher.async_setup()

    if not dispatcher or dispatcher.started:
        if init_coro := _async_init_flow(hass, domain, context, data):
            hass.async_create_task(init_coro)
        return

    return dispatcher.async_create(domain, context, data)


@callback
def _async_init_flow(
    hass: HomeAssistant, domain: str, context: dict[str, Any], data: Any
) -> Coroutine[None, None, FlowResult] | None:
    """Create a discovery flow."""
    # Avoid spawning flows that have the same initial discovery data
    # as ones in progress as it may cause additional device probing
    # which can overload devices since zeroconf/ssdp updates can happen
    # multiple times in the same minute
    if hass.config_entries.flow.async_has_matching_flow(domain, context, data):
        return None

    return hass.config_entries.flow.async_init(domain, context=context, data=data)


class PendingFlowKey(NamedTuple):
    """Key for pending flows."""

    domain: str
    source: str


class PendingFlowValue(NamedTuple):
    """Value for pending flows."""

    context: dict[str, Any]
    data: Any


class FlowDispatcher:
    """Dispatch discovery flows."""

    def __init__(self, hass: HomeAssistant) -> None:
        """Init the discovery dispatcher."""
        self.hass = hass
        self.started = False
        self.pending_flows: dict[PendingFlowKey, list[PendingFlowValue]] = {}

    @callback
    def async_setup(self) -> None:
        """Set up the flow disptcher."""
        self.hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STARTED, self._async_start)

    async def _async_start(self, event: Event) -> None:
        """Start processing pending flows."""
        pending_flows = self.pending_flows
        self.pending_flows = {}
        self.started = True
        init_coros = [
            _async_init_flow(
                self.hass, flow_key.domain, flow_values.context, flow_values.data
            )
            for flow_key, flows in pending_flows.items()
            for flow_values in flows
        ]
        await gather_with_concurrency(
            FLOW_INIT_LIMIT,
            *[init_coro for init_coro in init_coros if init_coro is not None],
        )

    @callback
    def async_create(self, domain: str, context: dict[str, Any], data: Any) -> None:
        """Create and add or queue a flow."""
        key = PendingFlowKey(domain, context["source"])
        values = PendingFlowValue(context, data)
        existing = self.pending_flows.setdefault(key, [])
        if not any(existing_values.data == data for existing_values in existing):
            existing.append(values)