'use client';

import { useState, useSyncExternalStore } from 'react';
import { CloseIcon } from './icons/CloseIcon';

export type SidebarPanel = {
  id: string;
  label: string;
  icon: React.ReactNode;
  component: React.ReactNode;
};

function useIsWide(): boolean {
  return useSyncExternalStore(
    (cb) => {
      window.addEventListener('resize', cb);
      return () => window.removeEventListener('resize', cb);
    },
    () => window.innerWidth >= 768,
    () => false,
  );
}

/* -----------------------------
   Shared sidebar logic
------------------------------*/
function useSidebarState(panels: SidebarPanel[], isWide: boolean) {
  const [activeId, setActiveId] = useState<string | null>(null);

  // open first panel by default ONLY on first mount (desktop only)
  const [initialized, setInitialized] = useState(false);

  if (!initialized && isWide) {
    setActiveId(panels[0]?.id ?? null);
    setInitialized(true);
  }

  const setClosed = () => setActiveId(null);

  const toggle = (id: string) => {
    setActiveId((prev) => (prev === id ? null : id));
  };

  return {
    activeId,
    setActiveId,
    setClosed,
    toggle,
  };
}

/* -----------------------------
   Desktop UI
------------------------------*/
function DesktopSidebar({
  activePanel,
  isOpen,
  setClosed,
}: {
  activePanel?: SidebarPanel;
  isOpen: boolean;
  setClosed: () => void;
}) {
  return (
    <div
      className={`
        flex transition-[transform,opacity] duration-300 ease-in-out overflow-hidden
        ${isOpen ? 'w-64 opacity-100' : 'w-0 opacity-0'}
      `}
    >
      {activePanel && (
        <div className="w-64 flex flex-col border-r border-muted transition-theme">
          <div className="flex items-center justify-between px-4 py-3 border-b border-muted shrink-0">
            <span className="text-sm font-semibold text-accent">
              {activePanel.label}
            </span>
            <button onClick={setClosed}>
              <CloseIcon className="w-4 h-4" />
            </button>
          </div>
          <div className="flex-1 overflow-y-auto p-3 min-h-0">
            {activePanel.component}
          </div>
        </div>
      )}
    </div>
  );
}

/* -----------------------------
   Mobile UI (drawer)
------------------------------*/
function MobileSidebar({
  activePanel,
  setClosed,
}: {
  activePanel?: SidebarPanel;
  setClosed: () => void;
}) {
  if (!activePanel) return null;

  return (
    <>
      {/* Backdrop */}
      <div className="fixed inset-0 bg-black/40 z-20" onClick={setClosed} />

      {/* Drawer */}
      <div className="fixed left-14 top-[var(--header-height)] bottom-0 z-30 bg-primary overflow-y-auto border border-muted w-64">
        <div className="flex items-center justify-between px-4 py-3 border-b border-muted">
          <span className="text-sm font-semibold text-accent">
            {activePanel.label}
          </span>

          <button onClick={setClosed}>
            <CloseIcon className="w-4 h-4" />
          </button>
        </div>

        <div className="p-3">{activePanel.component}</div>
      </div>
    </>
  );
}

/* -----------------------------
   Icon rail (shared)
------------------------------*/
function IconRail({
  panels,
  effectiveId,
  toggle,
}: {
  panels: SidebarPanel[];
  effectiveId: string | null;
  toggle: (id: string, effectiveId: string | null) => void;
}) {
  return (
    <div className="w-12 flex flex-col items-center py-3 gap-1 z-30">
      {panels.map((panel) => (
        <button
          key={panel.id}
          onClick={() => toggle(panel.id, effectiveId)}
          title={panel.label}
          className={`w-8 h-8 rounded-lg flex items-center justify-center transition-theme ${
            effectiveId === panel.id ? 'bg-accent2' : ''
          }`}
        >
          {panel.icon}
        </button>
      ))}
    </div>
  );
}

/* -----------------------------
   Main Sidebar (controller)
------------------------------*/
export default function Sidebar({ panels }: { panels: SidebarPanel[] }) {
  const isWide = useIsWide();

  const { activeId, setClosed, toggle } = useSidebarState(panels, isWide);

  const effectiveId = activeId;
  const activePanel = panels.find((p) => p.id === effectiveId);
  const isOpen = !!activePanel;

  return (
    <div className="flex border-r border-t border-muted transition-theme">
      {/* Desktop */}
      {isWide && (
        <DesktopSidebar
          activePanel={activePanel}
          isOpen={isOpen}
          setClosed={setClosed}
        />
      )}

      {/* Mobile */}
      {!isWide && (
        <MobileSidebar activePanel={activePanel} setClosed={setClosed} />
      )}

      {/* Icon rail */}
      <IconRail panels={panels} effectiveId={effectiveId} toggle={toggle} />
    </div>
  );
}