"""The Home Assistant plugin's MCP tools and its get_overview findings.

get_home_assistant reads what the poll stored. update_home_assistant starts an
update as the page's Install does. The token and webhook id are never returned.
"""
from __future__ import annotations

from sqlalchemy import select

from steward.mcp._context import current_caller, mcp_app
from steward.mcp.tools._audit import audit_mcp, mcp_username
from steward.mcp.tools._shape import age_s, db_session, iso, now_utc, redact_url
from steward.mcp.tools.overview import finding
from steward.models.users import UserRole

from .models import HomeAssistantConnection, HomeAssistantUpdate
from .routes import connection_says
from .service import STALE_BACKUP_HOURS, backup_age_hours, backup_verdict, installable, parse_moment
from .updates import CannotStart, start_update

RECENT_UPDATES = 10


def _run_view(r: HomeAssistantUpdate) -> dict:
    return {"update_id": r.id, "entity_id": r.entity_id, "title": r.title, "kind": r.kind,
            "from_version": r.from_version, "to_version": r.to_version, "state": r.state, "message": r.message,
            "started_by": r.started_by, "started_at": iso(r.started_at), "backup_at": iso(r.backup_at),
            "finished_at": iso(r.finished_at)}


async def get_home_assistant() -> dict:
    """Home Assistant as of the last poll: whether it answers, which updates are
    waiting, how old its last backup is, and the updates Steward was asked to install.

    `installable` is what update_home_assistant takes (Core, OS, add-ons);
    `others_waiting` is firmware and custom integrations, which Steward leaves
    to Home Assistant. `automation` is the Steward maintenance automation's
    state: "on" is needed to install, null means it wasn't found.
    """
    now = now_utc()
    async with db_session() as db:
        c = (await db.execute(select(HomeAssistantConnection))).scalars().first()
        runs = list((await db.execute(select(HomeAssistantUpdate).order_by(
            HomeAssistantUpdate.started_at.desc()).limit(RECENT_UPDATES))).scalars())
    if c is None:
        return {"connected": False, "says": "No connection yet: an admin adds it on the Home Assistant page."}
    reach, says = connection_says(c, now)
    backup = c.backup or {}
    age = backup_age_hours(backup, now)
    return {"connected": True, "url": redact_url(c.url), "reach": reach, "says": says,
            "polled_at": iso(c.last_polled_at), "ok_age_s": age_s(c.last_ok_at, now), "automation": c.automation,
            "installable": [{k: u[k] for k in ("entity_id", "title", "kind", "installed", "latest", "in_progress")}
                            for u in installable(c)],
            "others_waiting": [u["title"] for u in c.updates or [] if u["waiting"] and not u["kind"]],
            "backup": {"verdict": backup_verdict(backup, now)[1], "last_ok": iso(parse_moment(backup.get("last_ok"))),
                       "age_hours": round(age, 1) if age is not None else None, "stale_after_hours": STALE_BACKUP_HOURS,
                       "next": iso(parse_moment(backup.get("next"))), "last_result": backup.get("last_result")},
            "updates": [_run_view(r) for r in runs]}


async def update_home_assistant(entity_id: str) -> dict:
    """Install one Core, OS or add-on update, as the page's Install does: Steward
    takes a backup, confirms it landed, installs, and follows it to its end.

    entity_id: from get_home_assistant's `installable`.

    An update restarts Home Assistant or the add-on, and an OS update reboots the
    machine. Refused while another is under way, or if nothing is waiting there.
    Admin only, as on the page. Recorded in the audit log.
    """
    caller = current_caller()
    try:
        run = await start_update(mcp_app(), entity_id, mcp_username(caller.username))
    except CannotStart as exc:
        raise ValueError(f"Nothing was started: {exc}.") from None
    await audit_mcp("homeassistant.update_started", "homeassistant_update", run.id,
                    {"entity_id": entity_id, "title": run.title, "to": run.to_version})
    return {**_run_view(run), "next": "get_home_assistant follows it: `updates` shows its state."}


def overview_findings(c, latest_run, now) -> list[dict]:
    """A connection that isn't answering, stale backups, and a newest update that
    failed. Updates waiting aren't a problem to raise."""
    if c is None:
        return []
    found = []
    reach, says = connection_says(c, now)
    if reach == "down":
        found.append(finding("warning", "home_assistant_down", "Home Assistant",
                             f"Home Assistant isn't answering: {says}", since=c.last_ok_at, next="get_home_assistant()"))
    tone, backup_says = backup_verdict(c.backup, now)
    if c.last_ok_at is not None and tone == "warn":
        found.append(finding("warning", "home_assistant_backup", "Home Assistant", backup_says,
                             since=parse_moment((c.backup or {}).get("last_ok")), next="get_home_assistant()"))
    if latest_run is not None and latest_run.state == "failed":
        found.append(finding("warning", "home_assistant_update_failed", latest_run.title,
                             f"The update of {latest_run.title} failed: {latest_run.message}",
                             since=latest_run.finished_at, next="get_home_assistant()"))
    return found


async def mcp_overview(db) -> list[dict]:
    c = (await db.execute(select(HomeAssistantConnection))).scalars().first()
    latest = (await db.execute(select(HomeAssistantUpdate).order_by(
        HomeAssistantUpdate.started_at.desc()).limit(1))).scalars().first()
    return overview_findings(c, latest, now_utc())


def register_tools(register) -> None:
    register(get_home_assistant, role=UserRole.viewer, read_only=True)
    register(update_home_assistant, role=UserRole.admin)