"""Event parser and human readable log generator."""

from collections.abc import Callable, Collection, Generator, Sequence
from dataclasses import dataclass, field
from datetime import datetime as dt
import logging
import time
from typing import TYPE_CHECKING, Any

from lru import LRU
from sqlalchemy.engine import Result
from sqlalchemy.engine.row import Row
from sqlalchemy.orm import Session

from homeassistant.components.recorder import get_instance
from homeassistant.components.recorder.filters import Filters
from homeassistant.components.recorder.models import (
    bytes_to_uuid_hex_or_none,
    extract_event_type_ids,
    extract_metadata_ids,
    process_timestamp_to_utc_isoformat,
)
from homeassistant.components.recorder.util import (
    execute_stmt_lambda_element,
    session_scope,
)
from homeassistant.components.sensor import DOMAIN as SENSOR_DOMAIN
from homeassistant.const import (
    ATTR_DOMAIN,
    ATTR_ENTITY_ID,
    ATTR_FRIENDLY_NAME,
    ATTR_NAME,
    ATTR_SERVICE,
    EVENT_CALL_SERVICE,
    EVENT_LOGBOOK_ENTRY,
)
from homeassistant.core import HomeAssistant, split_entity_id
from homeassistant.helpers import entity_registry as er
from homeassistant.util import dt as dt_util
from homeassistant.util.collection import chunked_or_all
from homeassistant.util.event_type import EventType

from .const import (
    ATTR_MESSAGE,
    CONTEXT_DOMAIN,
    CONTEXT_ENTITY_ID,
    CONTEXT_ENTITY_ID_NAME,
    CONTEXT_EVENT_TYPE,
    CONTEXT_MESSAGE,
    CONTEXT_NAME,
    CONTEXT_SERVICE,
    CONTEXT_SOURCE,
    CONTEXT_STATE,
    CONTEXT_USER_ID,
    DOMAIN,
    LOGBOOK_ENTRY_DOMAIN,
    LOGBOOK_ENTRY_ENTITY_ID,
    LOGBOOK_ENTRY_ICON,
    LOGBOOK_ENTRY_MESSAGE,
    LOGBOOK_ENTRY_NAME,
    LOGBOOK_ENTRY_SOURCE,
    LOGBOOK_ENTRY_STATE,
    LOGBOOK_ENTRY_WHEN,
)
from .helpers import is_sensor_continuous
from .models import (
    CONTEXT_ID_BIN_POS,
    CONTEXT_ONLY_POS,
    CONTEXT_PARENT_ID_BIN_POS,
    CONTEXT_POS,
    CONTEXT_USER_ID_BIN_POS,
    ENTITY_ID_POS,
    EVENT_TYPE_POS,
    ICON_POS,
    ROW_ID_POS,
    STATE_POS,
    TIME_FIRED_TS_POS,
    EventAsRow,
    LazyEventPartialState,
    LogbookConfig,
    async_event_to_row,
)
from .queries import statement_for_request
from .queries.common import (
    PSEUDO_EVENT_STATE_CHANGED,
    select_context_user_ids_for_context_ids,
)

_LOGGER = logging.getLogger(__name__)

# Bound for the parent-context user-id cache — only needs to bridge the
# historical→live handoff, so the in-flight set is realistically ~tens with
# peak bursts of ~100. Ceiling bounds memory in pathological cases.
MAX_CONTEXT_USER_IDS_CACHE = 256


@dataclass(slots=True)
class LogbookRun:
    """A logbook run which may be a long running event stream or single request."""

    context_lookup: dict[bytes | None, Row | EventAsRow | None]
    external_events: dict[
        EventType[Any] | str,
        tuple[str, Callable[[LazyEventPartialState], dict[str, Any]]],
    ]
    event_cache: EventCache
    entity_name_cache: EntityNameCache
    include_entity_name: bool
    timestamp: bool
    memoize_new_contexts: bool = True
    # True when this run will switch to a live stream; gates population of
    # context_user_ids (wasted work for one-shot REST/get_events callers).
    for_live_stream: bool = False
    # context_id -> user_id for parent context attribution; persisted across
    # batches so child rows can inherit user_id from a parent seen earlier.
    context_user_ids: LRU[bytes, bytes] = field(
        default_factory=lambda: LRU(MAX_CONTEXT_USER_IDS_CACHE)
    )


class EventProcessor:
    """Stream into logbook format."""

    def __init__(
        self,
        hass: HomeAssistant,
        event_types: Collection[EventType[Any] | str],
        entity_ids: list[str] | None = None,
        device_ids: list[str] | None = None,
        context_id: str | None = None,
        timestamp: bool = False,
        include_entity_name: bool = True,
        for_live_stream: bool = False,
    ) -> None:
        """Init the event stream."""
        assert not (context_id and (entity_ids or device_ids)), (
            "can't pass in both context_id and (entity_ids or device_ids)"
        )
        self.hass = hass
        self.ent_reg = er.async_get(hass)
        self.event_types = event_types
        self.entity_ids = entity_ids
        self.device_ids = device_ids
        self.context_id = context_id
        logbook_config: LogbookConfig = hass.data[DOMAIN]
        self.filters: Filters | None = logbook_config.sqlalchemy_filter
        self.logbook_run = LogbookRun(
            context_lookup={None: None},
            external_events=logbook_config.external_events,
            event_cache=EventCache({}),
            entity_name_cache=EntityNameCache(self.hass),
            include_entity_name=include_entity_name,
            timestamp=timestamp,
            for_live_stream=for_live_stream,
        )
        self.context_augmenter = ContextAugmenter(self.logbook_run)

    @property
    def limited_select(self) -> bool:
        """Check if the stream is limited by entities context or device ids."""
        return bool(self.entity_ids or self.context_id or self.device_ids)

    def switch_to_live(self) -> None:
        """Switch to live stream.

        Clear caches so we can reduce memory pressure.
        """
        self.logbook_run.event_cache.clear()
        self.logbook_run.context_lookup.clear()
        self.logbook_run.memoize_new_contexts = False

    def get_events(
        self,
        start_day: dt,
        end_day: dt,
    ) -> list[dict[str, Any]]:
        """Get events for a period of time."""
        with session_scope(hass=self.hass, read_only=True) as session:
            metadata_ids: list[int] | None = None
            instance = get_instance(self.hass)
            if self.entity_ids:
                metadata_ids = extract_metadata_ids(
                    instance.states_meta_manager.get_many(
                        self.entity_ids, session, False
                    )
                )
            event_type_ids = tuple(
                extract_event_type_ids(
                    instance.event_type_manager.get_many(self.event_types, session)
                )
            )
            stmt = statement_for_request(
                start_day,
                end_day,
                event_type_ids,
                self.entity_ids,
                metadata_ids,
                self.device_ids,
                self.filters,
                self.context_id,
            )
            rows = execute_stmt_lambda_element(session, stmt, orm_rows=False)
            query_parent_user_ids: dict[bytes, bytes] | None = None
            if self.entity_ids or self.device_ids:
                # Filtered queries exclude parent call_service rows for
                # unrelated targets, so child contexts lose user attribution
                # without a pre-pass. all_stmt already includes them.
                rows = list(rows)
                query_parent_user_ids = self._fetch_parent_user_ids(
                    session, rows, instance.max_bind_vars
                )
            return self.humanify(rows, query_parent_user_ids)

    def _fetch_parent_user_ids(
        self,
        session: Session,
        rows: list[Row],
        max_bind_vars: int,
    ) -> dict[bytes, bytes] | None:
        """Resolve parent-context user_ids for rows in a filtered query.

        Done in Python rather than as a SQL union branch because the
        context_parent_id_bin column is sparsely populated — scanning the
        States table for non-null parents costs ~40% of the overall query
        on real datasets. Here we collect only the parent ids we actually
        need and fetch them via an indexed point-lookup on context_id_bin.
        """
        cache = self.logbook_run.context_user_ids
        pending: set[bytes] = {
            parent_id
            for row in rows
            if (parent_id := row[CONTEXT_PARENT_ID_BIN_POS]) and parent_id not in cache
        }
        if not pending:
            return None
        query_parent_user_ids: dict[bytes, bytes] = {}
        # The lambda statement unions events and states, so each id appears
        # in two IN clauses — halve the chunk size to stay under the
        # database's max bind variable count.
        for pending_chunk in chunked_or_all(pending, max_bind_vars // 2):
            # Schema allows NULL but the query's WHERE clauses exclude it;
            # explicit checks satisfy the type checker.
            query_parent_user_ids.update(
                {
                    parent_id: user_id
                    for parent_id, user_id in execute_stmt_lambda_element(
                        session,
                        select_context_user_ids_for_context_ids(pending_chunk),
                        orm_rows=False,
                    )
                    if parent_id is not None and user_id is not None
                }
            )
        if self.logbook_run.for_live_stream:
            cache.update(query_parent_user_ids)
        return query_parent_user_ids

    def humanify(
        self,
        rows: Generator[EventAsRow] | Sequence[Row] | Result,
        query_parent_user_ids: dict[bytes, bytes] | None = None,
    ) -> list[dict[str, Any]]:
        """Humanify rows."""
        return list(
            _humanify(
                self.hass,
                rows,
                self.ent_reg,
                self.logbook_run,
                self.context_augmenter,
                query_parent_user_ids,
            )
        )


def _humanify(
    hass: HomeAssistant,
    rows: Generator[EventAsRow] | Sequence[Row] | Result,
    ent_reg: er.EntityRegistry,
    logbook_run: LogbookRun,
    context_augmenter: ContextAugmenter,
    query_parent_user_ids: dict[bytes, bytes] | None,
) -> Generator[dict[str, Any]]:
    """Generate a converted list of events into entries."""
    # Continuous sensors, will be excluded from the logbook
    continuous_sensors: dict[str, bool] = {}
    context_lookup = logbook_run.context_lookup
    external_events = logbook_run.external_events
    event_cache_get = logbook_run.event_cache.get
    entity_name_cache_get = logbook_run.entity_name_cache.get
    include_entity_name = logbook_run.include_entity_name
    timestamp = logbook_run.timestamp
    memoize_new_contexts = logbook_run.memoize_new_contexts
    get_context = context_augmenter.get_context
    context_id_bin: bytes
    data: dict[str, Any]

    context_user_ids = logbook_run.context_user_ids
    # Skip the LRU write on one-shot runs — the LogbookRun is discarded.
    populate_context_user_ids = logbook_run.for_live_stream

    # Process rows
    for row in rows:
        context_id_bin = row[CONTEXT_ID_BIN_POS]
        if memoize_new_contexts and context_id_bin not in context_lookup:
            context_lookup[context_id_bin] = row
        if (
            populate_context_user_ids
            and (context_user_id_bin := row[CONTEXT_USER_ID_BIN_POS])
            and context_id_bin not in context_user_ids
        ):
            context_user_ids[context_id_bin] = context_user_id_bin
        if row[CONTEXT_ONLY_POS]:
            continue
        event_type = row[EVENT_TYPE_POS]
        if event_type == EVENT_CALL_SERVICE:
            continue

        if event_type is PSEUDO_EVENT_STATE_CHANGED:
            entity_id = row[ENTITY_ID_POS]
            if TYPE_CHECKING:
                assert entity_id is not None
            # Skip continuous sensors
            if (
                is_continuous := continuous_sensors.get(entity_id)
            ) is None and split_entity_id(entity_id)[0] == SENSOR_DOMAIN:
                is_continuous = is_sensor_continuous(hass, ent_reg, entity_id)
                continuous_sensors[entity_id] = is_continuous
            if is_continuous:
                continue

            data = {
                LOGBOOK_ENTRY_STATE: row[STATE_POS],
                LOGBOOK_ENTRY_ENTITY_ID: entity_id,
            }
            if include_entity_name:
                data[LOGBOOK_ENTRY_NAME] = entity_name_cache_get(entity_id)
            if icon := row[ICON_POS]:
                data[LOGBOOK_ENTRY_ICON] = icon

        elif event_type in external_events:
            domain, describe_event = external_events[event_type]
            try:
                data = describe_event(event_cache_get(row))
            except Exception:
                _LOGGER.exception(
                    "Error with %s describe event for %s", domain, event_type
                )
                continue
            data[LOGBOOK_ENTRY_DOMAIN] = domain

        elif event_type == EVENT_LOGBOOK_ENTRY:
            event = event_cache_get(row)
            if not (event_data := event.data):
                continue
            entry_domain = event_data.get(ATTR_DOMAIN)
            entry_entity_id = event_data.get(ATTR_ENTITY_ID)
            if entry_domain is None and entry_entity_id is not None:
                entry_domain = split_entity_id(str(entry_entity_id))[0]
            data = {
                LOGBOOK_ENTRY_NAME: event_data.get(ATTR_NAME),
                LOGBOOK_ENTRY_MESSAGE: event_data.get(ATTR_MESSAGE),
                LOGBOOK_ENTRY_DOMAIN: entry_domain,
                LOGBOOK_ENTRY_ENTITY_ID: entry_entity_id,
            }

        else:
            continue

        row_time_fired_ts = row[TIME_FIRED_TS_POS]
        # Explicit None check: 0.0 is a valid epoch.
        time_fired_ts: float = (
            row_time_fired_ts if row_time_fired_ts is not None else time.time()
        )
        if timestamp:
            when: str | float = time_fired_ts
        else:
            when = process_timestamp_to_utc_isoformat(
                dt_util.utc_from_timestamp(time_fired_ts)
            )
        data[LOGBOOK_ENTRY_WHEN] = when

        if context_user_id_bin := row[CONTEXT_USER_ID_BIN_POS]:
            data[CONTEXT_USER_ID] = bytes_to_uuid_hex_or_none(context_user_id_bin)

        # Augment context if its available but not if the context is the same as the row
        # or if the context is the parent of the row
        if (context_row := get_context(context_id_bin, row)) and not (
            (row is context_row or _rows_ids_match(row, context_row))
            and (
                not (context_parent := row[CONTEXT_PARENT_ID_BIN_POS])
                or not (context_row := get_context(context_parent, context_row))
                or row is context_row
                or _rows_ids_match(row, context_row)
            )
        ):
            context_augmenter.augment(data, context_row)

        # Fall back to the parent context for child contexts that inherit
        # user attribution (e.g., generic_thermostat -> switch turn_on).
        # Read from context_lookup directly instead of get_context() to
        # avoid the origin_event fallback which would return the *child*
        # row's origin event, not the parent's.
        if CONTEXT_USER_ID not in data and (
            context_parent_id_bin := row[CONTEXT_PARENT_ID_BIN_POS]
        ):
            parent_user_id_bin: bytes | None = context_user_ids.get(
                context_parent_id_bin
            )
            if parent_user_id_bin is None and query_parent_user_ids is not None:
                parent_user_id_bin = query_parent_user_ids.get(context_parent_id_bin)
            if (
                parent_user_id_bin is None
                and (parent_row := context_lookup.get(context_parent_id_bin))
                is not None
            ):
                parent_user_id_bin = parent_row[CONTEXT_USER_ID_BIN_POS]
            if parent_user_id_bin:
                data[CONTEXT_USER_ID] = bytes_to_uuid_hex_or_none(parent_user_id_bin)

        yield data


class ContextAugmenter:
    """Augment data with context trace."""

    def __init__(self, logbook_run: LogbookRun) -> None:
        """Init the augmenter."""
        self.context_lookup = logbook_run.context_lookup
        self.entity_name_cache = logbook_run.entity_name_cache
        self.external_events = logbook_run.external_events
        self.event_cache = logbook_run.event_cache
        self.include_entity_name = logbook_run.include_entity_name

    def get_context(
        self, context_id_bin: bytes | None, row: Row | EventAsRow | None
    ) -> Row | EventAsRow | None:
        """Get the context row from the id or row context."""
        if context_id_bin is not None and (
            context_row := self.context_lookup.get(context_id_bin)
        ):
            return context_row
        if (
            type(row) is EventAsRow
            and (context := row[CONTEXT_POS]) is not None
            and (origin_event := context.origin_event) is not None
        ):
            return async_event_to_row(origin_event)
        return None

    def augment(self, data: dict[str, Any], context_row: Row | EventAsRow) -> None:
        """Augment data from the row and cache."""
        event_type = context_row[EVENT_TYPE_POS]
        # State change
        if context_entity_id := context_row[ENTITY_ID_POS]:
            data[CONTEXT_STATE] = context_row[STATE_POS]
            data[CONTEXT_ENTITY_ID] = context_entity_id
            if self.include_entity_name:
                data[CONTEXT_ENTITY_ID_NAME] = self.entity_name_cache.get(
                    context_entity_id
                )
            return

        # Call service
        if event_type == EVENT_CALL_SERVICE:
            event = self.event_cache.get(context_row)
            event_data = event.data
            data[CONTEXT_DOMAIN] = event_data.get(ATTR_DOMAIN)
            data[CONTEXT_SERVICE] = event_data.get(ATTR_SERVICE)
            data[CONTEXT_EVENT_TYPE] = event_type
            return

        if event_type not in self.external_events:
            return

        domain, describe_event = self.external_events[event_type]
        data[CONTEXT_EVENT_TYPE] = event_type
        data[CONTEXT_DOMAIN] = domain
        event = self.event_cache.get(context_row)
        try:
            described = describe_event(event)
        except Exception:
            _LOGGER.exception("Error with %s describe event for %s", domain, event_type)
            return
        if name := described.get(LOGBOOK_ENTRY_NAME):
            data[CONTEXT_NAME] = name
        if message := described.get(LOGBOOK_ENTRY_MESSAGE):
            data[CONTEXT_MESSAGE] = message
        # In 2022.12 and later drop `CONTEXT_MESSAGE` if `CONTEXT_SOURCE` is available
        if source := described.get(LOGBOOK_ENTRY_SOURCE):
            data[CONTEXT_SOURCE] = source
        if not (attr_entity_id := described.get(LOGBOOK_ENTRY_ENTITY_ID)):
            return
        data[CONTEXT_ENTITY_ID] = attr_entity_id
        if self.include_entity_name:
            data[CONTEXT_ENTITY_ID_NAME] = self.entity_name_cache.get(attr_entity_id)


def _rows_ids_match(row: Row | EventAsRow, other_row: Row | EventAsRow) -> bool:
    """Check of rows match by using the same method as Events __hash__."""
    return bool((row_id := row[ROW_ID_POS]) and row_id == other_row[ROW_ID_POS])


class EntityNameCache:
    """A cache to lookup the name for an entity.

    This class should not be used to lookup attributes
    that are expected to change state.
    """

    def __init__(self, hass: HomeAssistant) -> None:
        """Init the cache."""
        self._hass = hass
        self._names: dict[str, str] = {}

    def get(self, entity_id: str) -> str:
        """Lookup an the friendly name."""
        if entity_id in self._names:
            return self._names[entity_id]
        if (current_state := self._hass.states.get(entity_id)) and (
            friendly_name := current_state.attributes.get(ATTR_FRIENDLY_NAME)
        ):
            self._names[entity_id] = friendly_name
        else:
            return split_entity_id(entity_id)[1].replace("_", " ")

        return self._names[entity_id]


class EventCache:
    """Cache LazyEventPartialState by row."""

    def __init__(self, event_data_cache: dict[str, dict[str, Any]]) -> None:
        """Init the cache."""
        self._event_data_cache = event_data_cache
        self.event_cache: dict[Row | EventAsRow, LazyEventPartialState] = {}

    def get(self, row: EventAsRow | Row) -> LazyEventPartialState:
        """Get the event from the row."""
        if type(row) is EventAsRow:  # - this is never subclassed
            return LazyEventPartialState(row, self._event_data_cache)
        if event := self.event_cache.get(row):
            return event
        self.event_cache[row] = lazy_event = LazyEventPartialState(
            row, self._event_data_cache
        )
        return lazy_event

    def clear(self) -> None:
        """Clear the event cache."""
        self._event_data_cache = {}
        self.event_cache = {}