"""Storage helpers: versioned stores and per-entry runtime data."""
from __future__ import annotations

import asyncio
import copy
import logging
from collections.abc import Awaitable, Callable
from dataclasses import dataclass, field
from typing import Any

from homeassistant.config_entries import ConfigEntry
from homeassistant.core import HomeAssistant
from homeassistant.helpers.storage import Store

from .const import (
    DOMAIN,
    STORAGE_CONFIG_KEY,
    STORAGE_KEY,
    STORAGE_MINOR_VERSION,
    STORAGE_VERSION,
    STORAGE_VIRTUAL_LIGHTS_KEY,
)
from .coordinate_canonicalization import (
    canonicalize_config_geometry,
    canonicalize_layout_geometry,
)

_LOGGER = logging.getLogger(__name__)
_BG_MODES = frozenset({"static", "daynight"})


def migrate_config_background_mode(old_data: dict[str, Any]) -> dict[str, Any]:
    """Materialize the legacy implicit background mode without changing its view.

    Only the config-store document has a top-level ``config`` object. Layout
    and virtual-light stores pass through this helper unchanged even though
    they share the same Store subclass and minor version.
    """
    config = old_data.get("config")
    if not isinstance(config, dict):
        return old_data
    settings = config.get("settings")
    mode = settings.get("bg_mode") if isinstance(settings, dict) else None
    if mode in _BG_MODES:
        return old_data

    data = copy.deepcopy(old_data)
    migrated_config = data["config"]
    migrated_settings = migrated_config.get("settings")
    if not isinstance(migrated_settings, dict):
        migrated_settings = {}
        migrated_config["settings"] = migrated_settings
    migrated_settings["bg_mode"] = "static"
    return data


class HouseplanStore(Store):
    """Store with a migration hook.

    Bump STORAGE_MINOR_VERSION for backward-compatible schema additions and
    STORAGE_VERSION for breaking changes, then handle them here. Keeping the
    skeleton in place from day one means old installations always pass through
    a single, tested upgrade path.
    """

    async def _async_migrate_func(
        self,
        old_major_version: int,
        old_minor_version: int,
        old_data: dict[str, Any],
    ) -> dict[str, Any]:
        if old_major_version == 1 and old_minor_version < 2:
            return migrate_config_background_mode(old_data)
        return old_data


@dataclass
class HouseplanData:
    """Runtime data of the single config entry (entry.runtime_data)."""

    store: HouseplanStore
    config_store: HouseplanStore
    virtual_light_store: HouseplanStore
    virtual_lights: Any | None = None
    # One lock for every load→modify→save cycle of both stores: prevents
    # lost updates from concurrent WS calls and makes the rev check atomic.
    write_lock: asyncio.Lock = field(default_factory=asyncio.Lock)
    # A separate, narrower lock for the check-quota→write-file pair of an
    # upload. Without it N parallel uploads all measure the store BEFORE any
    # of them writes, and all pass a quota only one of them fits under
    # (HP-1490-02). Separate from write_lock so a slow directory scan does not
    # stall config/layout commits.
    upload_lock: asyncio.Lock = field(default_factory=asyncio.Lock)
    # Collect files nothing references any more. Set during setup, which also
    # runs it once and schedules it daily. Exposed so it can be invoked
    # directly — a test that fakes a 24 h jump proves the timer fires, not that
    # the work happens, and those are different claims.
    sweep: Callable[[], Awaitable[None]] | None = None
    # Stable HA instance id used only through a one-way export fingerprint.
    instance_id: str = ""
    # Parsed import candidates are short-lived, user-bound and memory-only.
    # dict keeps insertion order, which lets the preview service evict oldest.
    import_previews: dict[str, dict[str, Any]] = field(default_factory=dict)
    # #43: already-sanitized support-package bytes only.  Raw config/layout is
    # never retained here; the write lock below is used to take one coherent
    # deep copy and the privacy projection immediately replaces it.
    support_previews: dict[str, dict[str, Any]] = field(default_factory=dict)
    # #330 §4.2: junction-limit violation counts of the STORED document,
    # keyed by its rev — (rev, {space_id: {rule: count}}). One slot,
    # memory-only, invalidated by a rev mismatch; the previous document is
    # not re-judged on every write. Counts only — documents are never held.
    junction_baseline: tuple[int, dict[str, dict[str, int]]] | None = None
    # Runtime-only #485 authority; never serialized by HouseplanStore.
    radar_coordinator: Any | None = None


HouseplanConfigEntry = ConfigEntry[HouseplanData]


def create_data(hass: HomeAssistant) -> HouseplanData:
    """Create the stores for a config entry."""
    data = HouseplanData(
        store=HouseplanStore(hass, STORAGE_VERSION, STORAGE_KEY, minor_version=STORAGE_MINOR_VERSION),
        config_store=HouseplanStore(
            hass, STORAGE_VERSION, STORAGE_CONFIG_KEY, minor_version=STORAGE_MINOR_VERSION
        ),
        virtual_light_store=HouseplanStore(
            hass,
            STORAGE_VERSION,
            STORAGE_VIRTUAL_LIGHTS_KEY,
            minor_version=STORAGE_MINOR_VERSION,
        ),
    )
    from .virtual_lights import VirtualLightController

    data.virtual_lights = VirtualLightController(data.virtual_light_store)
    return data


def get_data(hass: HomeAssistant) -> HouseplanData | None:
    """Runtime data of the loaded entry, or None when not set up."""
    entries = hass.config_entries.async_loaded_entries(DOMAIN)
    return entries[0].runtime_data if entries else None


def get_entry(hass: HomeAssistant) -> ConfigEntry | None:
    """The loaded config entry, or None."""
    entries = hass.config_entries.async_loaded_entries(DOMAIN)
    return entries[0] if entries else None


OPTIMIZE_BACKUP = "optimize_backup"
OPTIMIZE_PENDING = "optimize_pending"
LAYOUT_STORE_CORE_KEYS = frozenset({"layout", "rev"})


def layout_store_payload(
    stored: dict[str, Any],
    layout: dict[str, Any],
    rev: int,
    *,
    metadata: dict[str, Any] | None = None,
    remove: tuple[str, ...] = (),
    replace_metadata: bool = False,
) -> dict[str, Any]:
    """Build one layout-store write without silently dropping metadata.

    Layout used to be saved by several independent dict comprehensions.  Every
    new metadata key therefore had to be added to every caller or was lost on
    the next drag.  All writers now express only the metadata they intentionally
    add/remove and this helper preserves the rest.
    """
    excluded = {*LAYOUT_STORE_CORE_KEYS, *remove}
    out = {} if replace_metadata else {
        key: value for key, value in stored.items() if key not in excluded
    }
    if metadata:
        out.update(metadata)
    out["layout"] = canonicalize_layout_geometry(layout)
    out["rev"] = rev
    return out


async def async_save_layout_state(
    runtime: HouseplanData,
    stored: dict[str, Any],
    layout: dict[str, Any],
    rev: int,
    *,
    metadata: dict[str, Any] | None = None,
    remove: tuple[str, ...] = (),
    replace_metadata: bool = False,
) -> dict[str, Any]:
    """Persist layout and return the exact store document written."""
    payload = layout_store_payload(
        stored,
        layout,
        rev,
        metadata=metadata,
        remove=remove,
        replace_metadata=replace_metadata,
    )
    await runtime.store.async_save(payload)
    return payload


async def async_save_config_state(
    runtime: HouseplanData,
    config: dict[str, Any],
    rev: int,
    *,
    previous_rev: int | None = None,
) -> dict[str, Any]:
    """Persist configuration and reconcile dependent operational state.

    Callers already hold ``runtime.write_lock``.  Reading the previous
    revision here keeps less common writers (import recovery and undo) on the
    same path as ordinary editor saves without duplicating lifecycle rules.
    """
    if previous_rev is None:
        previous = await runtime.config_store.async_load() or {}
        try:
            previous_rev = int(previous.get("rev", 0))
        except (TypeError, ValueError):
            previous_rev = 0

    canonical_config = canonicalize_config_geometry(config)
    payload = {"config": canonical_config, "rev": rev}
    await runtime.config_store.async_save(payload)

    # The config is already durable at this point.  Reconciliation remains a
    # separate Store write; an interrupted pair is detected from config_rev on
    # the next read and fails safe to the compatibility default (all on).
    from .virtual_lights import async_reconcile_virtual_lights

    try:
        controller = getattr(runtime, "virtual_lights", None)
        if controller is not None:
            await controller.async_flush()
        await async_reconcile_virtual_lights(
            runtime.virtual_light_store,
            canonical_config,
            rev,
            previous_config_rev=previous_rev,
        )
        if controller is not None:
            controller.reset()
    except Exception:  # noqa: BLE001 - config commit already stands
        _LOGGER.exception("House Plan: virtual-light state reconciliation failed")
    return payload


@dataclass(frozen=True)
class ResolvedStorePair:
    """One coherent config/layout read, optionally after pending recovery."""

    config_data: dict[str, Any]
    layout_data: dict[str, Any]
    recovered_kind: str | None = None


def _pending_target(
    layout_data: dict[str, Any],
) -> dict[str, Any] | None:
    """Return a structurally usable paired-write intent, if one is present."""
    pending = layout_data.get(OPTIMIZE_PENDING)
    if not isinstance(pending, dict):
        return None
    if not isinstance(pending.get("config"), dict):
        return None
    if not isinstance(pending.get("layout"), dict):
        return None
    return pending


async def async_converge_store_pair(
    runtime: HouseplanData,
    pending: dict[str, Any],
    *,
    config_data: dict[str, Any] | None = None,
    layout_data: dict[str, Any] | None = None,
) -> ResolvedStorePair:
    """Converge both stores on one durable paired-write intent.

    Callers hold ``runtime.write_lock``.  Store may raise after bytes reached
    disk, so each failed half is reloaded and compared with the exact payload
    before the exception is allowed to escape.
    """
    if config_data is None:
        config_data = await runtime.config_store.async_load() or {}
    if layout_data is None:
        layout_data = await runtime.store.async_load() or {}

    target_config = canonicalize_config_geometry(pending["config"])
    target_layout = canonicalize_layout_geometry(pending["layout"])
    config_rev = int(config_data.get("rev", 0))
    layout_rev = int(layout_data.get("rev", 0))
    target_config_rev = int(pending.get(
        "config_rev", config_rev + (config_data.get("config") != target_config)
    ))
    target_layout_rev = int(pending.get(
        "layout_rev", layout_rev + (layout_data.get("layout", {}) != target_layout)
    ))

    exact_metadata = pending.get("final_metadata")
    replace_metadata = isinstance(exact_metadata, dict)
    config_needs_write = (
        config_data.get("config") != target_config
        or (
            config_rev != target_config_rev
            if replace_metadata
            else config_rev < target_config_rev
        )
    )
    if config_needs_write:
        previous_config_rev = config_rev
        config_rev = (
            target_config_rev
            if replace_metadata
            else max(config_rev, target_config_rev)
        )
        expected_config = {"config": target_config, "rev": config_rev}
        try:
            config_data = await async_save_config_state(
                runtime,
                target_config,
                config_rev,
                previous_rev=previous_config_rev,
            )
        except Exception:
            # A Store write is allowed to fail after its atomic replacement.
            # Exact reload distinguishes that case from a half that never
            # reached disk; no inference is made from the exception itself.
            config_data = await runtime.config_store.async_load() or {}
            if config_data != expected_config:
                raise

    layout_rev = (
        target_layout_rev
        if replace_metadata
        else max(layout_rev, target_layout_rev)
    )
    metadata = dict(exact_metadata) if replace_metadata else None
    if (
        not replace_metadata
        and not pending.get("clear_backup")
        and OPTIMIZE_BACKUP in layout_data
    ):
        metadata = {OPTIMIZE_BACKUP: layout_data[OPTIMIZE_BACKUP]}
    remove_metadata = [OPTIMIZE_PENDING, OPTIMIZE_BACKUP]
    if pending.get("clear_backup"):
        # A recovered whole-plan undo replaces the complete layout; a nested
        # repair snapshot from that replaced layout must not survive it.
        remove_metadata.append("repair_backup")
    expected_layout = layout_store_payload(
        layout_data,
        target_layout,
        layout_rev,
        metadata=metadata,
        remove=tuple(remove_metadata),
        replace_metadata=replace_metadata,
    )
    try:
        layout_data = await async_save_layout_state(
            runtime,
            layout_data,
            target_layout,
            layout_rev,
            metadata=metadata,
            remove=tuple(remove_metadata),
            replace_metadata=replace_metadata,
        )
    except Exception:
        layout_data = await runtime.store.async_load() or {}
        if layout_data != expected_layout:
            raise

    # Return fresh durable documents.  A following writer must never continue
    # with pre-recovery revisions or a pre-recovery layout snapshot.
    config_data = await runtime.config_store.async_load() or {}
    layout_data = await runtime.store.async_load() or {}
    return ResolvedStorePair(
        config_data=config_data,
        layout_data=layout_data,
        recovered_kind=str(pending.get("kind") or "plan optimization"),
    )


async def async_resolve_pending_pair(runtime: HouseplanData) -> ResolvedStorePair:
    """Load a coherent pair, finishing a valid durable intent first."""
    config_data = await runtime.config_store.async_load() or {}
    layout_data = await runtime.store.async_load() or {}
    pending = _pending_target(layout_data)
    if pending is None:
        return ResolvedStorePair(config_data=config_data, layout_data=layout_data)
    return await async_converge_store_pair(
        runtime,
        pending,
        config_data=config_data,
        layout_data=layout_data,
    )