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

import asyncio
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


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]:
        data = old_data
        # if old_major_version == 1 and old_minor_version < 2:
        #     ...migrate...
        return data


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

    store: HouseplanStore
    config_store: HouseplanStore
    # 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)


HouseplanConfigEntry = ConfigEntry[HouseplanData]


def create_data(hass: HomeAssistant) -> HouseplanData:
    """Create the stores for a config entry."""
    return 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
        ),
    )


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"] = 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