import { useCallback, type ReactNode } from 'react';
import { Group, Panel, Separator } from 'react-resizable-panels';
import { X, PanelRightOpen, PanelRightClose } from 'lucide-react';

/**
 * Resizable dual-panel layout for chat + artifact/detail panel.
 *
 * Uses react-resizable-panels v4 API:
 * - Left panel: Chat area (always visible)
 * - Right panel: Artifact/detail viewer (collapsible)
 * - Draggable resize handle between panels
 * - Persisted panel sizes via localStorage
 *
 * Side-panel toggle is injected into the chat header via `headerAction`
 * so it sits cleanly in the top-right corner (Trae Solo style).
 */

interface ResizableChatLayoutProps {
  chatPanel: ReactNode;
  rightPanel?: ReactNode;
  rightPanelTitle?: string;
  rightPanelOpen?: boolean;
  onRightPanelToggle?: (open: boolean) => void;
}

const STORAGE_KEY = 'zclaw-layout-panels';
const LEFT_PANEL_ID = 'chat-panel';
const RIGHT_PANEL_ID = 'detail-panel';

function loadPanelSizes(): { left: string; right: string } {
  try {
    const stored = localStorage.getItem(STORAGE_KEY);
    if (stored) {
      const parsed = JSON.parse(stored);
      if (parsed.left && parsed.right) {
        return { left: parsed.left, right: parsed.right };
      }
    }
  } catch { /* ignore */ }
  return { left: '65%', right: '35%' };
}

function savePanelSizes(layout: Record<string, number>) {
  try {
    const left = layout[LEFT_PANEL_ID];
    const right = layout[RIGHT_PANEL_ID];
    if (left !== undefined && right !== undefined) {
      localStorage.setItem(STORAGE_KEY, JSON.stringify({ left, right }));
    }
  } catch { /* ignore */ }
}

export function ResizableChatLayout({
  chatPanel,
  rightPanel,
  rightPanelTitle = '详情',
  rightPanelOpen = false,
  onRightPanelToggle,
}: ResizableChatLayoutProps) {
  const sizes = loadPanelSizes();

  const handleToggle = useCallback(() => {
    onRightPanelToggle?.(!rightPanelOpen);
  }, [rightPanelOpen, onRightPanelToggle]);

  if (!rightPanelOpen || !rightPanel) {
    // Panel closed: just render chat panel, no floating button
    return (
      <div className="h-full flex flex-col overflow-hidden">
        {chatPanel}
      </div>
    );
  }

  return (
    <div className="h-full flex flex-col overflow-hidden">
      <Group
        orientation="horizontal"
        onLayoutChanged={(layout) => savePanelSizes(layout)}
      >
        {/* Left panel: Chat */}
        <Panel
          id={LEFT_PANEL_ID}
          defaultSize={sizes.left}
          minSize="40%"
        >
          <div className="h-full flex flex-col">
            {chatPanel}
          </div>
        </Panel>

        {/* Resize handle */}
        <Separator className="w-1.5 flex items-center justify-center group cursor-col-resize hover:bg-orange-100 dark:hover:bg-orange-900/20 transition-colors">
          <div className="w-0.5 h-8 rounded-full bg-gray-300 dark:bg-gray-600 group-hover:bg-orange-400 dark:group-hover:bg-orange-500 transition-colors" />
        </Separator>

        {/* Right panel: Artifact/Detail */}
        <Panel
          id={RIGHT_PANEL_ID}
          defaultSize={sizes.right}
          minSize="25%"
        >
          <div className="h-full flex flex-col bg-gray-50 dark:bg-gray-900 border-l border-gray-200 dark:border-gray-800">
            {/* Panel header */}
            <div className="h-12 flex items-center justify-between px-4 border-b border-gray-200 dark:border-gray-800 flex-shrink-0">
              <span className="text-xs font-medium text-gray-600 dark:text-gray-400 uppercase tracking-wide">
                {rightPanelTitle}
              </span>
              <button
                onClick={handleToggle}
                className="p-1 rounded text-gray-400 hover:text-gray-600 dark:hover:text-gray-200 transition-colors"
                title="关闭面板"
              >
                <X className="w-4 h-4" />
              </button>
            </div>
            {/* Panel content */}
            <div className="flex-1 overflow-y-auto custom-scrollbar">
              {rightPanel}
            </div>
          </div>
        </Panel>
      </Group>
    </div>
  );
}

/**
 * Toggle button for embedding in chat header.
 * Renders PanelRightOpen/PanelRightClose icon — Trae Solo style.
 */
export function PanelToggleButton({
  panelOpen,
  onToggle,
}: {
  panelOpen: boolean;
  onToggle: () => void;
}) {
  return (
    <button
      onClick={onToggle}
      className="p-1.5 rounded-md text-gray-500 dark:text-gray-400 hover:text-gray-700 dark:hover:text-gray-200 hover:bg-gray-100 dark:hover:bg-gray-800 transition-colors"
      title={panelOpen ? '关闭侧面板' : '查看产物文件'}
    >
      {panelOpen
        ? <PanelRightClose className="w-4 h-4" />
        : <PanelRightOpen className="w-4 h-4" />
      }
    </button>
  );
}