import { useState, useCallback, useRef } from "react";
import { DndContext, closestCenter, PointerSensor, useSensor, useSensors } from "@dnd-kit/core";
import type { DragEndEvent, Modifier } from "@dnd-kit/core";
import { SortableContext, useSortable, horizontalListSortingStrategy } from "@dnd-kit/sortable";
import { CSS } from "@dnd-kit/utilities";

const restrictToHorizontalAxis: Modifier = ({ transform }) => ({ ...transform, y: 0 });
import type { ModuleField } from "../types";

interface Props {
  fields: ModuleField[];
  activeId: number | null;
  onActivate: (id: number) => void;
  onReorder: (activeId: number, overId: number) => void;
  onResize: (id: number, width: number) => void;
}

function SortableColumn({
  field,
  active,
  isLast,
  onActivate,
  onResizeStart,
}: {
  field: ModuleField;
  active: boolean;
  isLast: boolean;
  onActivate: (id: number) => void;
  onResizeStart: (e: React.MouseEvent, id: number) => void;
}) {
  const { attributes, listeners, setNodeRef, transform, transition, isDragging } = useSortable({ id: field.id });
  const style = { transform: CSS.Transform.toString(transform), transition, opacity: isDragging ? 0.4 : 1 };

  return (
    <div
      ref={setNodeRef}
      style={{ ...style, width: field.listW, flexShrink: 0, position: "relative" }}
      className={`px-3 py-2 border-r border-slate-200 text-xs font-medium cursor-pointer select-none ${
        active ? "bg-blue-50 text-blue-600" : "text-slate-600 hover:bg-slate-100"
      }`}
      onClick={() => onActivate(field.id)}
    >
      <div className="flex items-center gap-1.5">
        <span
          {...attributes}
          {...listeners}
          className="text-slate-300 hover:text-slate-500 cursor-grab active:cursor-grabbing shrink-0"
          title="拖拽排序"
        >
          <svg className="w-3 h-3" fill="none" stroke="currentColor" viewBox="0 0 24 24">
            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth="2" d="M6 10h12M6 14h12" />
          </svg>
        </span>
        <span className="truncate">{field.label}</span>
        <span className="text-[10px] text-slate-300 ml-auto">{field.listW}</span>
      </div>
      {!isLast && (
        <div
          className="col-resize-handle"
          onMouseDown={(e) => onResizeStart(e, field.id)}
          onClick={(e) => e.stopPropagation()}
        />
      )}
    </div>
  );
}

export default function TablePreview({ fields, activeId, onActivate, onReorder, onResize }: Props) {
  const sensors = useSensors(useSensor(PointerSensor, { activationConstraint: { distance: 5 } }));
  const [resizing, setResizing] = useState<{ id: number; startX: number; startW: number } | null>(null);
  const tableRef = useRef<HTMLDivElement>(null);

  const handleDragEnd = useCallback(
    (event: DragEndEvent) => {
      const { active, over } = event;
      if (over && active.id !== over.id) {
        onReorder(Number(active.id), Number(over.id));
      }
    },
    [onReorder]
  );

  const handleResizeStart = useCallback(
    (e: React.MouseEvent, id: number) => {
      e.preventDefault();
      e.stopPropagation();
      const field = fields.find((f) => f.id === id);
      if (!field) return;
      setResizing({ id, startX: e.clientX, startW: field.listW });
    },
    [fields]
  );

  const handleMouseMove = useCallback(
    (e: MouseEvent) => {
      if (!resizing) return;
      const dx = e.clientX - resizing.startX;
      const w = Math.max(40, Math.min(400, Math.round(resizing.startW + dx)));
      onResize(resizing.id, w);
      setResizing((prev) => (prev ? { ...prev } : null));
    },
    [resizing, onResize]
  );

  const handleMouseUp = useCallback(() => {
    setResizing(null);
  }, []);

  // Attach global listeners for resize
  if (resizing) {
    document.addEventListener("mousemove", handleMouseMove);
    document.addEventListener("mouseup", handleMouseUp);
  }

  const visible = fields.filter((f) => f.listOn).sort((a, b) => a.order - b.order);
  if (!visible.length) {
    return <div className="text-center text-xs text-slate-300 mt-16">暂无可见列 · 请开启字段的列表开关</div>;
  }

  const totalW = visible.reduce((s, f) => s + f.listW, 0);

  return (
    <div ref={tableRef}>
      <DndContext sensors={sensors} collisionDetection={closestCenter} onDragEnd={handleDragEnd} modifiers={[restrictToHorizontalAxis]}>
        <SortableContext items={visible.map((f) => f.id)} strategy={horizontalListSortingStrategy}>
          <div className="overflow-x-auto border border-slate-200 rounded-lg bg-white shadow-sm">
            <div style={{ minWidth: Math.max(totalW, 400) }}>
              <div className="flex bg-slate-50 border-b border-slate-200">
                {visible.map((f, i) => (
                  <SortableColumn
                    key={f.id}
                    field={f}
                    active={f.id === activeId}
                    isLast={i === visible.length - 1}
                    onActivate={onActivate}
                    onResizeStart={handleResizeStart}
                  />
                ))}
              </div>
              {[0, 1].map((r) => (
                <div key={r} className="flex border-b border-slate-50 text-xs text-slate-300">
                  {visible.map((f) => (
                    <div
                      key={f.id}
                      className="shrink-0 px-3 py-2 border-r border-slate-50"
                      style={{ width: f.listW, textAlign: f.listAlign }}
                    >
                      {f.type === "select" ? "—" : f.type === "date" ? "2024-08-12" : f.type === "number" ? "100.00" : "示例"}
                    </div>
                  ))}
                </div>
              ))}
            </div>
          </div>
        </SortableContext>
      </DndContext>
      <div className="mt-2 text-[11px] text-slate-400 text-center">
        拖拽列头排序 · 拖拽右边缘调整宽度 · 点击列头选中字段
      </div>
    </div>
  );
}