import React, { useRef, useState, useCallback } from 'react';

interface HeaderProps {
  title:    string;
  onEdit:   () => void;
  onDelete: () => void;
}

export function Header({ title, onEdit, onDelete }: HeaderProps) {
  return (
    <div className="flex items-center justify-between px-3 py-1.5 border-b border-gray-700 shrink-0">
      <span className="text-sm font-medium text-gray-200 truncate">{title}</span>
      <div className="flex gap-1 ml-2 shrink-0">
        <button onClick={onEdit}   className="text-xs text-gray-400 hover:text-white px-1.5 py-0.5 rounded hover:bg-gray-700">✏️</button>
        <button onClick={onDelete} className="text-xs text-gray-400 hover:text-red-400 px-1.5 py-0.5 rounded hover:bg-gray-700">🗑</button>
      </div>
    </div>
  );
}

export function EmptyState() {
  return (
    <div className="flex-1 flex items-center justify-center text-gray-500 text-sm">No data</div>
  );
}

interface CardShellProps extends HeaderProps {
  empty:              boolean;
  children:           React.ReactNode;
  /** Ref to the div where the uPlot legend will be mounted */
  legendContainerRef?: React.RefObject<HTMLDivElement>;
}

export function CardShell({ title, onEdit, onDelete, empty, children, legendContainerRef }: CardShellProps) {
  const containerRef = useRef<HTMLDivElement>(null);
  const [legendHeight, setLegendHeight] = useState<number | null>(null);
  const dragRef = useRef<{ startY: number; startH: number } | null>(null);

  const handleMouseDown = useCallback((e: React.MouseEvent) => {
    e.preventDefault();
    e.stopPropagation();
    const el = legendContainerRef?.current;
    if (!el) return;
    dragRef.current = { startY: e.clientY, startH: el.offsetHeight };

    function onMove(ev: MouseEvent) {
      if (!dragRef.current) return;
      const delta = dragRef.current.startY - ev.clientY;
      const containerH = containerRef.current?.offsetHeight ?? 400;
      const newH = Math.max(32, Math.min(containerH - 64, dragRef.current.startH + delta));
      setLegendHeight(newH);
    }
    function onUp() {
      dragRef.current = null;
      document.removeEventListener('mousemove', onMove);
      document.removeEventListener('mouseup', onUp);
    }
    document.addEventListener('mousemove', onMove);
    document.addEventListener('mouseup', onUp);
  }, [legendContainerRef]);

  return (
    <div ref={containerRef} className="h-full flex flex-col bg-gray-900 rounded border border-gray-700 overflow-hidden">
      <Header title={title} onEdit={onEdit} onDelete={onDelete} />
      {empty ? (
        <EmptyState />
      ) : (
        <>
          <div className="flex-1 min-h-0">
            {children}
          </div>
          {legendContainerRef && <>
            <div
              onMouseDown={handleMouseDown}
              className="shrink-0 h-1.5 cursor-row-resize bg-gray-800 hover:bg-gray-700 active:bg-gray-600"
            />
            <div
              ref={legendContainerRef}
              className="shrink-0 overflow-y-auto px-2 py-1 text-[10px] text-gray-400 [&_.u-legend]:w-full [&_.u-series]:flex [&_.u-series]:items-center [&_.u-series_th]:flex [&_.u-series_th]:items-center [&_.u-series_th]:gap-1 [&_.u-marker]:w-3 [&_.u-marker]:h-0.5 [&_.u-marker]:shrink-0 [&_.u-label]:truncate [&_.u-value]:ml-auto [&_.u-value]:font-mono [&_.u-value]:shrink-0"
              style={legendHeight != null ? { height: legendHeight, maxHeight: legendHeight } : { maxHeight: '25%' }}
            />
            <style>{'.u-legend .u-series:first-child { display: none; }'}</style>
          </>}
        </>
      )}
    </div>
  );
}