"""Standard conversation implementation for Home Assistant."""
from __future__ import annotations

import asyncio
from collections import defaultdict
from collections.abc import Awaitable, Callable, Iterable
from dataclasses import dataclass
import functools
import logging
from pathlib import Path
import re
from typing import IO, Any

from hassil.expression import Expression, ListReference, Sequence
from hassil.intents import (
    Intents,
    ResponseType,
    SlotList,
    TextSlotList,
    WildcardSlotList,
)
from hassil.recognize import RecognizeResult, recognize_all
from hassil.util import merge_dict
from home_assistant_intents import get_domains_and_languages, get_intents
import yaml

from homeassistant import core, setup
from homeassistant.components.homeassistant.exposed_entities import (
    async_listen_entity_updates,
    async_should_expose,
)
from homeassistant.const import MATCH_ALL
from homeassistant.helpers import (
    area_registry as ar,
    device_registry as dr,
    entity_registry as er,
    intent,
    start,
    template,
    translation,
)
from homeassistant.helpers.event import (
    EventStateChangedData,
    async_track_state_added_domain,
)
from homeassistant.helpers.typing import EventType
from homeassistant.util.json import JsonObjectType, json_loads_object

from .agent import AbstractConversationAgent, ConversationInput, ConversationResult
from .const import DEFAULT_EXPOSED_ATTRIBUTES, DOMAIN

_LOGGER = logging.getLogger(__name__)
_DEFAULT_ERROR_TEXT = "Sorry, I couldn't understand that"
_ENTITY_REGISTRY_UPDATE_FIELDS = ["aliases", "name", "original_name"]

REGEX_TYPE = type(re.compile(""))
TRIGGER_CALLBACK_TYPE = Callable[[str, RecognizeResult], Awaitable[str | None]]


def json_load(fp: IO[str]) -> JsonObjectType:
    """Wrap json_loads for get_intents."""
    return json_loads_object(fp.read())


@dataclass(slots=True)
class LanguageIntents:
    """Loaded intents for a language."""

    intents: Intents
    intents_dict: dict[str, Any]
    intent_responses: dict[str, Any]
    error_responses: dict[str, Any]
    loaded_components: set[str]


@dataclass(slots=True)
class TriggerData:
    """List of sentences and the callback for a trigger."""

    sentences: list[str]
    callback: TRIGGER_CALLBACK_TYPE


def _get_language_variations(language: str) -> Iterable[str]:
    """Generate language codes with and without region."""
    yield language

    parts = re.split(r"([-_])", language)
    if len(parts) == 3:
        lang, sep, region = parts
        if sep == "_":
            # en_US -> en-US
            yield f"{lang}-{region}"

        # en-US -> en
        yield lang


@core.callback
def async_setup(hass: core.HomeAssistant) -> None:
    """Set up entity registry listener for the default agent."""
    entity_registry = er.async_get(hass)
    for entity_id in entity_registry.entities:
        async_should_expose(hass, DOMAIN, entity_id)

    @core.callback
    def async_entity_state_listener(event: EventType[EventStateChangedData]) -> None:
        """Set expose flag on new entities."""
        async_should_expose(hass, DOMAIN, event.data["entity_id"])

    @core.callback
    def async_hass_started(hass: core.HomeAssistant) -> None:
        """Set expose flag on all entities."""
        for state in hass.states.async_all():
            async_should_expose(hass, DOMAIN, state.entity_id)
        async_track_state_added_domain(hass, MATCH_ALL, async_entity_state_listener)

    start.async_at_started(hass, async_hass_started)


class DefaultAgent(AbstractConversationAgent):
    """Default agent for conversation agent."""

    def __init__(self, hass: core.HomeAssistant) -> None:
        """Initialize the default agent."""
        self.hass = hass
        self._lang_intents: dict[str, LanguageIntents] = {}
        self._lang_lock: dict[str, asyncio.Lock] = defaultdict(asyncio.Lock)

        # intent -> [sentences]
        self._config_intents: dict[str, Any] = {}
        self._slot_lists: dict[str, SlotList] | None = None

        # Sentences that will trigger a callback (skipping intent recognition)
        self._trigger_sentences: list[TriggerData] = []
        self._trigger_intents: Intents | None = None

    @property
    def supported_languages(self) -> list[str]:
        """Return a list of supported languages."""
        return get_domains_and_languages()["homeassistant"]

    async def async_initialize(self, config_intents):
        """Initialize the default agent."""
        if "intent" not in self.hass.config.components:
            await setup.async_setup_component(self.hass, "intent", {})

        # Intents from config may only contains sentences for HA config's language
        if config_intents:
            self._config_intents = config_intents

        self.hass.bus.async_listen(
            ar.EVENT_AREA_REGISTRY_UPDATED,
            self._async_handle_area_registry_changed,
            run_immediately=True,
        )
        self.hass.bus.async_listen(
            er.EVENT_ENTITY_REGISTRY_UPDATED,
            self._async_handle_entity_registry_changed,
            run_immediately=True,
        )
        self.hass.bus.async_listen(
            core.EVENT_STATE_CHANGED,
            self._async_handle_state_changed,
            run_immediately=True,
        )
        async_listen_entity_updates(
            self.hass, DOMAIN, self._async_exposed_entities_updated
        )

    async def async_recognize(
        self, user_input: ConversationInput
    ) -> RecognizeResult | None:
        """Recognize intent from user input."""
        language = user_input.language or self.hass.config.language
        lang_intents = self._lang_intents.get(language)

        # Reload intents if missing or new components
        if lang_intents is None or (
            lang_intents.loaded_components - self.hass.config.components
        ):
            # Load intents in executor
            lang_intents = await self.async_get_or_load_intents(language)

        if lang_intents is None:
            # No intents loaded
            _LOGGER.warning("No intents were loaded for language: %s", language)
            return None

        slot_lists = self._make_slot_lists()
        result = await self.hass.async_add_executor_job(
            self._recognize,
            user_input,
            lang_intents,
            slot_lists,
        )

        return result

    async def async_process(self, user_input: ConversationInput) -> ConversationResult:
        """Process a sentence."""
        if trigger_result := await self._match_triggers(user_input.text):
            return trigger_result

        language = user_input.language or self.hass.config.language
        conversation_id = None  # Not supported

        result = await self.async_recognize(user_input)
        lang_intents = self._lang_intents.get(language)

        if result is None:
            _LOGGER.debug("No intent was matched for '%s'", user_input.text)
            return _make_error_result(
                language,
                intent.IntentResponseErrorCode.NO_INTENT_MATCH,
                self._get_error_text(ResponseType.NO_INTENT, lang_intents),
                conversation_id,
            )

        # Will never happen because result will be None when no intents are
        # loaded in async_recognize.
        assert lang_intents is not None

        try:
            intent_response = await intent.async_handle(
                self.hass,
                DOMAIN,
                result.intent.name,
                {
                    entity.name: {"value": entity.value}
                    for entity in result.entities_list
                },
                user_input.text,
                user_input.context,
                language,
                assistant=DOMAIN,
            )
        except intent.IntentHandleError:
            _LOGGER.exception("Intent handling error")
            return _make_error_result(
                language,
                intent.IntentResponseErrorCode.FAILED_TO_HANDLE,
                self._get_error_text(ResponseType.HANDLE_ERROR, lang_intents),
                conversation_id,
            )
        except intent.IntentUnexpectedError:
            _LOGGER.exception("Unexpected intent error")
            return _make_error_result(
                language,
                intent.IntentResponseErrorCode.UNKNOWN,
                self._get_error_text(ResponseType.HANDLE_ERROR, lang_intents),
                conversation_id,
            )

        if (
            (not intent_response.speech)
            and (intent_response.intent is not None)
            and (response_key := result.response)
        ):
            # Use response template, if available
            response_template_str = lang_intents.intent_responses.get(
                result.intent.name, {}
            ).get(response_key)
            if response_template_str:
                response_template = template.Template(response_template_str, self.hass)
                speech = await self._build_speech(
                    language, response_template, intent_response, result
                )
                intent_response.async_set_speech(speech)

        return ConversationResult(
            response=intent_response, conversation_id=conversation_id
        )

    def _recognize(
        self,
        user_input: ConversationInput,
        lang_intents: LanguageIntents,
        slot_lists: dict[str, SlotList],
    ) -> RecognizeResult | None:
        """Search intents for a match to user input."""
        # Prioritize matches with entity names above area names
        maybe_result: RecognizeResult | None = None
        for result in recognize_all(
            user_input.text, lang_intents.intents, slot_lists=slot_lists
        ):
            if "name" in result.entities:
                return result

            # Keep looking in case an entity has the same name
            maybe_result = result

        return maybe_result

    async def _build_speech(
        self,
        language: str,
        response_template: template.Template,
        intent_response: intent.IntentResponse,
        recognize_result: RecognizeResult,
    ) -> str:
        # Make copies of the states here so we can add translated names for responses.
        matched: list[core.State] = []

        for state in intent_response.matched_states:
            state_copy = core.State.from_dict(state.as_dict())
            if state_copy is not None:
                matched.append(state_copy)

        unmatched: list[core.State] = []
        for state in intent_response.unmatched_states:
            state_copy = core.State.from_dict(state.as_dict())
            if state_copy is not None:
                unmatched.append(state_copy)

        all_states = matched + unmatched
        domains = {state.domain for state in all_states}
        translations = await translation.async_get_translations(
            self.hass, language, "entity_component", domains
        )

        # Use translated state names
        for state in all_states:
            device_class = state.attributes.get("device_class", "_")
            key = f"component.{state.domain}.entity_component.{device_class}.state.{state.state}"
            state.state = translations.get(key, state.state)

        # Get first matched or unmatched state.
        # This is available in the response template as "state".
        state1: core.State | None = None
        if intent_response.matched_states:
            state1 = matched[0]
        elif intent_response.unmatched_states:
            state1 = unmatched[0]

        # Render response template
        speech = response_template.async_render(
            {
                # Slots from intent recognizer
                "slots": {
                    entity_name: entity_value.text or entity_value.value
                    for entity_name, entity_value in recognize_result.entities.items()
                },
                # First matched or unmatched state
                "state": template.TemplateState(self.hass, state1)
                if state1 is not None
                else None,
                "query": {
                    # Entity states that matched the query (e.g, "on")
                    "matched": [
                        template.TemplateState(self.hass, state) for state in matched
                    ],
                    # Entity states that did not match the query
                    "unmatched": [
                        template.TemplateState(self.hass, state) for state in unmatched
                    ],
                },
            }
        )

        # Normalize whitespace
        if speech is not None:
            speech = str(speech)
            speech = " ".join(speech.strip().split())

        return speech

    async def async_reload(self, language: str | None = None):
        """Clear cached intents for a language."""
        if language is None:
            language = self.hass.config.language

        self._lang_intents.pop(language, None)
        _LOGGER.debug("Cleared intents for language: %s", language)

    async def async_prepare(self, language: str | None = None):
        """Load intents for a language."""
        if language is None:
            language = self.hass.config.language

        lang_intents = await self.async_get_or_load_intents(language)

        if lang_intents is None:
            # No intents loaded
            _LOGGER.warning("No intents were loaded for language: %s", language)

    async def async_get_or_load_intents(self, language: str) -> LanguageIntents | None:
        """Load all intents of a language with lock."""
        hass_components = set(self.hass.config.components)
        async with self._lang_lock[language]:
            return await self.hass.async_add_executor_job(
                self._get_or_load_intents, language, hass_components
            )

    def _get_or_load_intents(
        self, language: str, hass_components: set[str]
    ) -> LanguageIntents | None:
        """Load all intents for language (run inside executor)."""
        lang_intents = self._lang_intents.get(language)

        if lang_intents is None:
            intents_dict: dict[str, Any] = {}
            loaded_components: set[str] = set()
        else:
            intents_dict = lang_intents.intents_dict
            loaded_components = lang_intents.loaded_components

        # en-US, en_US, en, ...
        language_variations = list(_get_language_variations(language))

        # Check if any new components have been loaded
        intents_changed = False
        for component in hass_components:
            if component in loaded_components:
                continue

            # Don't check component again
            loaded_components.add(component)

            # Check for intents for this component with the target language.
            # Try en-US, en, etc.
            for language_variation in language_variations:
                component_intents = get_intents(
                    component, language_variation, json_load=json_load
                )
                if component_intents:
                    # Merge sentences into existing dictionary
                    merge_dict(intents_dict, component_intents)

                    # Will need to recreate graph
                    intents_changed = True
                    _LOGGER.debug(
                        "Loaded intents component=%s, language=%s (%s)",
                        component,
                        language,
                        language_variation,
                    )
                    break

        # Check for custom sentences in <config>/custom_sentences/<language>/
        if lang_intents is None:
            # Only load custom sentences once, otherwise they will be re-loaded
            # when components change.
            for language_variation in language_variations:
                custom_sentences_dir = Path(
                    self.hass.config.path("custom_sentences", language_variation)
                )
                if custom_sentences_dir.is_dir():
                    for custom_sentences_path in custom_sentences_dir.rglob("*.yaml"):
                        with custom_sentences_path.open(
                            encoding="utf-8"
                        ) as custom_sentences_file:
                            # Merge custom sentences
                            if isinstance(
                                custom_sentences_yaml := yaml.safe_load(
                                    custom_sentences_file
                                ),
                                dict,
                            ):
                                merge_dict(intents_dict, custom_sentences_yaml)
                            else:
                                _LOGGER.warning(
                                    "Custom sentences file does not match expected format path=%s",
                                    custom_sentences_file.name,
                                )

                        # Will need to recreate graph
                        intents_changed = True
                        _LOGGER.debug(
                            "Loaded custom sentences language=%s (%s), path=%s",
                            language,
                            language_variation,
                            custom_sentences_path,
                        )

                    # Stop after first matched language variation
                    break

            # Load sentences from HA config for default language only
            if self._config_intents and (language == self.hass.config.language):
                merge_dict(
                    intents_dict,
                    {
                        "intents": {
                            intent_name: {"data": [{"sentences": sentences}]}
                            for intent_name, sentences in self._config_intents.items()
                        }
                    },
                )
                intents_changed = True
                _LOGGER.debug(
                    "Loaded intents from configuration.yaml",
                )

        if not intents_dict:
            return None

        if not intents_changed and lang_intents is not None:
            return lang_intents

        # This can be made faster by not re-parsing existing sentences.
        # But it will likely only be called once anyways, unless new
        # components with sentences are often being loaded.
        intents = Intents.from_dict(intents_dict)

        # Load responses
        responses_dict = intents_dict.get("responses", {})
        intent_responses = responses_dict.get("intents", {})
        error_responses = responses_dict.get("errors", {})

        if lang_intents is None:
            lang_intents = LanguageIntents(
                intents,
                intents_dict,
                intent_responses,
                error_responses,
                loaded_components,
            )
            self._lang_intents[language] = lang_intents
        else:
            lang_intents.intents = intents
            lang_intents.intent_responses = intent_responses
            lang_intents.error_responses = error_responses

        return lang_intents

    @core.callback
    def _async_handle_area_registry_changed(self, event: core.Event) -> None:
        """Clear area area cache when the area registry has changed."""
        self._slot_lists = None

    @core.callback
    def _async_handle_entity_registry_changed(self, event: core.Event) -> None:
        """Clear names list cache when an entity registry entry has changed."""
        if event.data["action"] != "update" or not any(
            field in event.data["changes"] for field in _ENTITY_REGISTRY_UPDATE_FIELDS
        ):
            return
        self._slot_lists = None

    @core.callback
    def _async_handle_state_changed(self, event: core.Event) -> None:
        """Clear names list cache when a state is added or removed from the state machine."""
        if event.data.get("old_state") and event.data.get("new_state"):
            return
        self._slot_lists = None

    @core.callback
    def _async_exposed_entities_updated(self) -> None:
        """Handle updated preferences."""
        self._slot_lists = None

    def _make_slot_lists(self) -> dict[str, SlotList]:
        """Create slot lists with areas and entity names/aliases."""
        if self._slot_lists is not None:
            return self._slot_lists

        area_ids_with_entities: set[str] = set()
        entity_registry = er.async_get(self.hass)
        states = [
            state
            for state in self.hass.states.async_all()
            if async_should_expose(self.hass, DOMAIN, state.entity_id)
        ]
        devices = dr.async_get(self.hass)

        # Gather exposed entity names
        entity_names = []
        for state in states:
            # Checked against "requires_context" and "excludes_context" in hassil
            context = {"domain": state.domain}
            if state.attributes:
                # Include some attributes
                for attr in DEFAULT_EXPOSED_ATTRIBUTES:
                    if attr not in state.attributes:
                        continue
                    context[attr] = state.attributes[attr]

            entity = entity_registry.async_get(state.entity_id)

            if not entity:
                # Default name
                entity_names.append((state.name, state.name, context))
                continue

            if entity.aliases:
                for alias in entity.aliases:
                    entity_names.append((alias, alias, context))

            # Default name
            entity_names.append((state.name, state.name, context))

            if entity.area_id:
                # Expose area too
                area_ids_with_entities.add(entity.area_id)
            elif entity.device_id:
                # Check device for area as well
                device = devices.async_get(entity.device_id)
                if (device is not None) and device.area_id:
                    area_ids_with_entities.add(device.area_id)

        # Gather areas from exposed entities
        areas = ar.async_get(self.hass)
        area_names = []
        for area_id in area_ids_with_entities:
            area = areas.async_get_area(area_id)
            if area is None:
                continue

            area_names.append((area.name, area.id))
            if area.aliases:
                for alias in area.aliases:
                    area_names.append((alias, area.id))

        _LOGGER.debug("Exposed areas: %s", area_names)
        _LOGGER.debug("Exposed entities: %s", entity_names)

        self._slot_lists = {
            "area": TextSlotList.from_tuples(area_names, allow_template=False),
            "name": TextSlotList.from_tuples(entity_names, allow_template=False),
        }

        return self._slot_lists

    def _get_error_text(
        self, response_type: ResponseType, lang_intents: LanguageIntents | None
    ) -> str:
        """Get response error text by type."""
        if lang_intents is None:
            return _DEFAULT_ERROR_TEXT

        response_key = response_type.value
        response_str = lang_intents.error_responses.get(response_key)
        return response_str or _DEFAULT_ERROR_TEXT

    def register_trigger(
        self,
        sentences: list[str],
        callback: TRIGGER_CALLBACK_TYPE,
    ) -> core.CALLBACK_TYPE:
        """Register a list of sentences that will trigger a callback when recognized."""
        trigger_data = TriggerData(sentences=sentences, callback=callback)
        self._trigger_sentences.append(trigger_data)

        # Force rebuild on next use
        self._trigger_intents = None

        unregister = functools.partial(self._unregister_trigger, trigger_data)
        return unregister

    def _rebuild_trigger_intents(self) -> None:
        """Rebuild the HassIL intents object from the current trigger sentences."""
        intents_dict = {
            "language": self.hass.config.language,
            "intents": {
                # Use trigger data index as a virtual intent name for HassIL.
                # This works because the intents are rebuilt on every
                # register/unregister.
                str(trigger_id): {"data": [{"sentences": trigger_data.sentences}]}
                for trigger_id, trigger_data in enumerate(self._trigger_sentences)
            },
        }

        self._trigger_intents = Intents.from_dict(intents_dict)

        # Assume slot list references are wildcards
        wildcard_names: set[str] = set()
        for trigger_intent in self._trigger_intents.intents.values():
            for intent_data in trigger_intent.data:
                for sentence in intent_data.sentences:
                    _collect_list_references(sentence, wildcard_names)

        for wildcard_name in wildcard_names:
            self._trigger_intents.slot_lists[wildcard_name] = WildcardSlotList()

        _LOGGER.debug("Rebuilt trigger intents: %s", intents_dict)

    def _unregister_trigger(self, trigger_data: TriggerData) -> None:
        """Unregister a set of trigger sentences."""
        self._trigger_sentences.remove(trigger_data)

        # Force rebuild on next use
        self._trigger_intents = None

    async def _match_triggers(self, sentence: str) -> ConversationResult | None:
        """Try to match sentence against registered trigger sentences.

        Calls the registered callbacks if there's a match and returns a positive
        conversation result.
        """
        if not self._trigger_sentences:
            # No triggers registered
            return None

        if self._trigger_intents is None:
            # Need to rebuild intents before matching
            self._rebuild_trigger_intents()

        assert self._trigger_intents is not None

        matched_triggers: dict[int, RecognizeResult] = {}
        for result in recognize_all(sentence, self._trigger_intents):
            trigger_id = int(result.intent.name)
            if trigger_id in matched_triggers:
                # Already matched a sentence from this trigger
                break

            matched_triggers[trigger_id] = result

        if not matched_triggers:
            # Sentence did not match any trigger sentences
            return None

        _LOGGER.debug(
            "'%s' matched %s trigger(s): %s",
            sentence,
            len(matched_triggers),
            list(matched_triggers),
        )

        # Gather callback responses in parallel
        trigger_responses = await asyncio.gather(
            *(
                self._trigger_sentences[trigger_id].callback(sentence, result)
                for trigger_id, result in matched_triggers.items()
            )
        )

        # Use last non-empty result as speech response
        speech: str | None = None
        for trigger_response in trigger_responses:
            speech = speech or trigger_response

        response = intent.IntentResponse(language=self.hass.config.language)
        response.response_type = intent.IntentResponseType.ACTION_DONE
        response.async_set_speech(speech or "")

        return ConversationResult(response=response)


def _make_error_result(
    language: str,
    error_code: intent.IntentResponseErrorCode,
    response_text: str,
    conversation_id: str | None = None,
) -> ConversationResult:
    """Create conversation result with error code and text."""
    response = intent.IntentResponse(language=language)
    response.async_set_error(error_code, response_text)

    return ConversationResult(response, conversation_id)


def _collect_list_references(expression: Expression, list_names: set[str]) -> None:
    """Collect list reference names recursively."""
    if isinstance(expression, Sequence):
        seq: Sequence = expression
        for item in seq.items:
            _collect_list_references(item, list_names)
    elif isinstance(expression, ListReference):
        # {list}
        list_ref: ListReference = expression
        list_names.add(list_ref.slot_name)
