"""ScrollRow — a horizontally-scrolling row of id-keyed cards, diffed in place
on every refresh instead of torn down and rebuilt. That matters here for two
reasons: rebuilding would fight an in-progress VolumeMeter drag (see that
widget's own drag-guard), and it would tear down/respawn each card's live
`parec` peak-monitor process on every single `pactl subscribe` event instead
of only when a device/app actually appears or disappears.
"""

from __future__ import annotations

import gi

gi.require_version("Gtk", "4.0")
from gi.repository import Gtk  # noqa: E402


class ScrollRow(Gtk.ScrolledWindow):
    def __init__(self, make_card, empty_text: str = "Nothing here") -> None:
        super().__init__()
        self.set_policy(Gtk.PolicyType.EXTERNAL, Gtk.PolicyType.NEVER)
        self.add_css_class("sb-scroll-row")
        self._make_card = make_card
        self._row = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL, spacing=14)
        self._row.add_css_class("sb-row")
        self.set_child(self._row)
        self._cards: dict = {}
        self._empty_label = Gtk.Label(label=empty_text)
        self._empty_label.add_css_class("sb-empty")
        self._active = False

    def sync(self, items: list[dict], *extra) -> None:
        seen = set()
        for item in items:
            iid = item["id"]
            seen.add(iid)
            card = self._cards.get(iid)
            if card is None:
                card = self._make_card(item, *extra)
                self._cards[iid] = card
                self._row.append(card)
                if self._active:
                    card.start_peak()
            else:
                card.update(item, *extra)
        for iid in [i for i in self._cards if i not in seen]:
            card = self._cards.pop(iid)
            card.stop_peak()
            self._row.remove(card)
        self._sync_empty_state()

    def _sync_empty_state(self) -> None:
        empty = not self._cards
        if empty and self._empty_label.get_parent() is None:
            self._row.append(self._empty_label)
        elif not empty and self._empty_label.get_parent() is not None:
            self._row.remove(self._empty_label)

    def activate(self) -> None:
        self._active = True
        for card in self._cards.values():
            card.start_peak()

    def deactivate(self) -> None:
        self._active = False
        for card in self._cards.values():
            card.stop_peak()