import { type ReactNode } from "react";
import { useTranslation } from "react-i18next";
import { Check, Pencil, Pin, PinOff, RotateCcw } from "lucide-react";
import { useScrollFade } from "../lib/useScrollFade";
import { useHoverFocusWithin } from "../lib/useHoverFocusWithin";

// The shared floating side panel — one shell for the Feed / Plex / Playlists rails so they read as
// one system, and the same peek-open model as the nav rail: unpinned it sits as a small tab docked
// against the rail's right edge (this panel is the flex sibling right after it) and expands into a
// rounded glass card on hover/focus WITHOUT pushing content; pinned it stays expanded in-flow.
// `collapsed` (persisted per-account) therefore means "unpinned".
export default function SidePanel({
  title,
  icon,
  count = 0,
  collapsed,
  onToggleCollapse,
  editing = false,
  onToggleEditing,
  onReset,
  editHint,
  actions,
  iconExpanded,
  onTitleClick,
  titleActionLabel,
  children,
}: {
  title: string;
  icon: ReactNode;
  count?: number;
  collapsed: boolean;
  onToggleCollapse: () => void;
  // Customize (reorder/hide) mode — omit onToggleEditing to hide the pencil entirely.
  editing?: boolean;
  onToggleEditing?: () => void;
  onReset?: () => void;
  editHint?: string;
  // Extra header controls shown when NOT editing (e.g. the feed's Clear all + Share view).
  actions?: ReactNode;
  // Optional override for the icon in the EXPANDED header only (the collapsed tab keeps the plain
  // `icon`) — the feed passes its saved-views popover trigger here so the header icon opens the picker.
  iconExpanded?: ReactNode;
  // When set, the expanded-header title becomes a button (the feed opens its Personal Views modal).
  onTitleClick?: () => void;
  // Accessible name / tooltip describing what onTitleClick does (the plain title text alone doesn't).
  titleActionLabel?: string;
  children: ReactNode;
}) {
  const { t } = useTranslation();
  const fade = useScrollFade();
  const peek = useHoverFocusWithin();
  const pinned = !collapsed;
  const expanded = pinned || peek.active;

  return (
    // Layout slot: reserves only the tab's gutter when unpinned, so the expanded card overlays
    // content instead of pushing it. Pinned reserves --rail-pinned-w: 16.75rem (in-flow, pushes) on a
    // full-width page or a narrow window, but 2.25rem (overlay, doesn't push) when the centred content
    // leaves room for the rail to sit in its left margin — see PageShell. Default 16.75rem = old w-67.
    <div
      // Focus is tracked container-wide (keyboard: tab anywhere inside holds it open). HOVER is NOT
      // on this full-height slot — that made the whole column next to the nav rail a live target, so
      // merely approaching the rail popped the panel open. Hover now lives only on the visible tab
      // handle + the expanded card below, so only pointing AT the tab opens it.
      {...peek.focusHandlers}
      className={`hidden md:block relative shrink-0 transition-[width] ${pinned ? "w-[var(--rail-pinned-w,16.75rem)]" : "w-9"}`}
    >
      {/* The tab: a small handle flush against the nav rail, flat on the docked edge. It stays
          mounted while the card is open — swapping it out from under the pointer would drop the very
          hover that opened the card, and unmounting it while focused would throw keyboard focus to
          nowhere. It only goes transparent: the card's rounded corner cuts away its own pixels, and
          this square-cornered tab sits right under that arc, so it would otherwise bleed through.
          `opacity-0` (not `invisible`/`hidden`) keeps it hoverable and focusable. */}
      <button
        {...peek.hoverHandlers}
        onClick={onToggleCollapse}
        aria-label={pinned ? t("sidebar.unpin") : t("sidebar.pin")}
        className={`glass glass-hover absolute top-3 left-0 z-paneltab flex flex-col items-center gap-2 px-1.5 py-3 rounded-l-none rounded-r-xl transition-opacity ${
          expanded ? "opacity-0" : ""
        } ${count > 0 ? "ring-1 ring-accent/40" : ""}`}
      >
        <span className="text-accent">{icon}</span>
        {count > 0 && (
          <span className="bg-accent text-accent-fg text-3xs font-bold px-1.5 py-0.5 rounded-full tabular-nums">
            {count > 9 ? "9+" : count}
          </span>
        )}
        <span
          className="text-xs font-semibold uppercase tracking-[0.18em] text-muted"
          style={{ writingMode: "vertical-rl", transform: "rotate(180deg)" }}
        >
          {title}
        </span>
      </button>

      {expanded && (
        <aside
          {...peek.hoverHandlers}
          className="glass absolute top-3 bottom-3 left-0 z-panel w-64 rounded-2xl flex flex-col overflow-hidden"
        >
          {/* Row 1 — identity only: pin, icon, title (flexes + truncates last), count, customize.
              Module actions live on their own row below so the title always has room. */}
          <div className="flex items-center gap-1.5 px-3 py-2.5 border-b border-border/60 flex-none">
            <button
              onClick={onToggleCollapse}
              title={pinned ? t("sidebar.unpin") : t("sidebar.pin")}
              aria-label={pinned ? t("sidebar.unpin") : t("sidebar.pin")}
              className="shrink-0 -ml-1 p-1 rounded-md text-muted hover:text-fg hover:bg-card transition"
            >
              {pinned ? <PinOff className="w-4 h-4" /> : <Pin className="w-4 h-4" />}
            </button>
            {iconExpanded ?? <span className="shrink-0 flex text-accent">{icon}</span>}
            {onTitleClick ? (
              <button
                onClick={onTitleClick}
                title={titleActionLabel}
                aria-label={titleActionLabel}
                className="flex-1 min-w-0 truncate text-left text-sm font-bold uppercase tracking-[0.12em] transition hover:text-accent"
              >
                {title}
              </button>
            ) : (
              <span className="flex-1 min-w-0 truncate text-sm font-bold uppercase tracking-[0.12em]">
                {title}
              </span>
            )}
            {count > 0 && (
              <span
                title={t("sidebar.activeCount", { count })}
                className="shrink-0 min-w-4.5 h-4.5 px-1.5 rounded-full bg-accent/15 text-accent text-2xs font-semibold inline-flex items-center justify-center tabular-nums"
              >
                {count}
              </span>
            )}
            {editing && onReset && (
              <button
                onClick={onReset}
                title={t("sidebar.resetDefaults")}
                className="shrink-0 p-1.5 rounded-lg text-muted hover:text-fg hover:bg-card transition"
              >
                <RotateCcw className="w-4 h-4" />
              </button>
            )}
            {onToggleEditing && (
              <button
                onClick={onToggleEditing}
                title={editing ? t("sidebar.done") : t("sidebar.customize")}
                className={`shrink-0 p-1.5 rounded-lg transition hover:bg-card ${
                  editing ? "text-accent" : "text-muted hover:text-fg"
                }`}
              >
                {editing ? <Check className="w-4 h-4" /> : <Pencil className="w-4 h-4" />}
              </button>
            )}
          </div>

          {/* Row 2 — module actions (e.g. Clear all / Share), only when not customizing. */}
          {!editing && actions && (
            <div className="flex items-center justify-between gap-2 px-3 py-1.5 border-b border-border/60 flex-none">
              {actions}
            </div>
          )}

          <div
            ref={fade.ref}
            style={fade.style}
            className="flex-1 min-h-0 overflow-y-auto no-scrollbar"
          >
            <div className="p-3 space-y-3">
              {editing && editHint && <div className="text-2xs text-muted">{editHint}</div>}
              {children}
            </div>
          </div>
        </aside>
      )}
    </div>
  );
}