"use client";

/**
 * TableColumnDropZone — 테이블 데이터 연결 탭의 드롭 영역
 *
 * 탭1에서 설정한 열 개수만큼 슬롯을 표시하고,
 * TableColumnPalette에서 드래그한 컬럼을 드롭하여 배치.
 * 이미 배치된 컬럼은 다른 슬롯으로 드래그하여 위치 교환 가능.
 * 배치된 컬럼에는 인라인으로 헤더명/숫자형식 설정 가능.
 */

import React from "react";
import { useDrag, useDrop } from "react-dnd";
import { Input } from "@/components/ui/input";
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select";
import { X, Columns, GripVertical } from "lucide-react";
import { TABLE_COLUMN_DND_TYPE } from "./TableColumnPalette";
import type { ComponentConfig } from "@/types/report";

type TableColumn = NonNullable<ComponentConfig["tableColumns"]>[number];

export const TABLE_SLOT_DND_TYPE = "table-slot";

interface TableColumnDropZoneProps {
  columns: TableColumn[];
  onUpdate: (idx: number, updates: Partial<TableColumn>) => void;
  onDrop: (slotIndex: number, columnName: string, dataType: string) => void;
  onClear: (slotIndex: number) => void;
  onMove: (fromIndex: number, toIndex: number) => void;
}

interface SlotDragItem {
  type: typeof TABLE_SLOT_DND_TYPE;
  sourceIndex: number;
}

interface PaletteDragItem {
  columnName: string;
  dataType: string;
}

interface SlotProps {
  col: TableColumn;
  idx: number;
  onUpdate: (idx: number, updates: Partial<TableColumn>) => void;
  onDrop: (slotIndex: number, columnName: string, dataType: string) => void;
  onClear: (slotIndex: number) => void;
  onMove: (fromIndex: number, toIndex: number) => void;
}

function DropSlot({ col, idx, onUpdate, onDrop, onClear, onMove }: SlotProps) {
  const isEmpty = !col.field;

  const [{ isDragging }, drag, preview] = useDrag(() => ({
    type: TABLE_SLOT_DND_TYPE,
    item: { type: TABLE_SLOT_DND_TYPE, sourceIndex: idx } as SlotDragItem,
    canDrag: !isEmpty,
    collect: (monitor) => ({
      isDragging: monitor.isDragging(),
    }),
  }), [idx, isEmpty]);

  const [{ isOver, canDrop: canDropHere }, drop] = useDrop(() => ({
    accept: [TABLE_COLUMN_DND_TYPE, TABLE_SLOT_DND_TYPE],
    drop: (item: PaletteDragItem | SlotDragItem, monitor) => {
      const itemType = monitor.getItemType();
      if (itemType === TABLE_SLOT_DND_TYPE) {
        const slotItem = item as SlotDragItem;
        if (slotItem.sourceIndex !== idx) {
          onMove(slotItem.sourceIndex, idx);
        }
      } else {
        const paletteItem = item as PaletteDragItem;
        onDrop(idx, paletteItem.columnName, paletteItem.dataType);
      }
    },
    canDrop: (item, monitor) => {
      if (monitor.getItemType() === TABLE_SLOT_DND_TYPE) {
        return (item as SlotDragItem).sourceIndex !== idx;
      }
      return true;
    },
    collect: (monitor) => ({
      isOver: monitor.isOver(),
      canDrop: monitor.canDrop(),
    }),
  }), [idx, onDrop, onMove]);

  const isActive = isOver && canDropHere;

  const ref = (node: HTMLDivElement | null) => {
    preview(drop(node));
  };

  return (
    <div
      ref={ref}
      className={`relative rounded-lg border p-3 transition-all ${
        isDragging
          ? "border-blue-300 bg-blue-50/60 opacity-50 shadow-inner"
          : isActive
            ? "border-blue-400 bg-blue-50 shadow-sm ring-2 ring-blue-200"
            : isEmpty
              ? "border-dashed border-gray-300 bg-gray-50/50"
              : "border-gray-200 bg-white hover:border-blue-200 hover:bg-blue-50/20"
      }`}
    >
      {isEmpty ? (
        <div className="flex flex-col items-center justify-center py-4 text-center">
          <Columns className="mb-1 h-5 w-5 text-gray-300" />
          <span className="text-xs text-gray-400">
            {isActive ? "여기에 놓으세요" : "컬럼을 드래그하여 배치"}
          </span>
          <span className="mt-0.5 text-[10px] text-gray-300">열 {idx + 1}</span>
        </div>
      ) : (
        <div className="space-y-2">
          {/* 드래그 핸들 + 컬럼명 배지 + 제거 버튼 */}
          <div className="flex items-center justify-between">
            <div className="flex items-center gap-1">
              <span
                ref={drag}
                className="flex h-5 w-5 cursor-grab items-center justify-center rounded text-gray-400 hover:bg-gray-100 hover:text-gray-600 active:cursor-grabbing"
                title="드래그하여 위치 이동"
              >
                <GripVertical className="h-3.5 w-3.5" />
              </span>
              <span className="inline-flex items-center gap-1 rounded bg-blue-100 px-2 py-0.5 font-mono text-xs font-medium text-blue-700">
                <Columns className="h-3 w-3" />
                {col.field}
              </span>
            </div>
            <button
              onClick={() => onClear(idx)}
              className="flex h-5 w-5 items-center justify-center rounded-full text-gray-400 hover:bg-red-50 hover:text-red-500"
            >
              <X className="h-3 w-3" />
            </button>
          </div>

          {/* 헤더명 */}
          <div>
            <label className="mb-1 block text-[10px] text-gray-500">헤더명</label>
            <Input
              value={col.header}
              onChange={(e) => onUpdate(idx, { header: e.target.value })}
              className="h-7 text-xs"
            />
          </div>

          {/* 숫자형식 */}
          <div>
            <label className="mb-1 block text-[10px] text-gray-500">숫자형식</label>
            <Select
              value={col.numberFormat || "none"}
              onValueChange={(v) => onUpdate(idx, { numberFormat: v as "none" | "comma" | "currency" })}
            >
              <SelectTrigger className="h-7 text-xs">
                <SelectValue />
              </SelectTrigger>
              <SelectContent>
                <SelectItem value="none">없음</SelectItem>
                <SelectItem value="comma">천단위(,)</SelectItem>
                <SelectItem value="currency">통화</SelectItem>
              </SelectContent>
            </Select>
          </div>
        </div>
      )}
    </div>
  );
}

export function TableColumnDropZone({ columns, onUpdate, onDrop, onClear, onMove }: TableColumnDropZoneProps) {
  const filledCount = columns.filter((c) => c.field).length;

  return (
    <div className="rounded-xl border border-border bg-white shadow-sm">
      <div className="border-b border-gray-200 bg-gray-50 px-4 py-2.5">
        <span className="text-sm font-bold text-gray-800">
          테이블 컬럼 배치
        </span>
        <span className="ml-2 text-xs font-normal text-muted-foreground">
          {filledCount}/{columns.length} 배치됨
        </span>
        {filledCount >= 2 && (
          <span className="ml-2 text-[10px] text-gray-400">
            (드래그로 위치 변경 가능)
          </span>
        )}
      </div>
      <div className="p-3">
        {columns.length === 0 ? (
          <p className="py-6 text-center text-xs text-gray-400">
            레이아웃 탭에서 열을 먼저 추가하세요.
          </p>
        ) : (
          <div
            className="grid gap-2"
            style={{ gridTemplateColumns: `repeat(${Math.min(columns.length, 4)}, 1fr)` }}
          >
            {columns.map((col, idx) => (
              <DropSlot
                key={idx}
                col={col}
                idx={idx}
                onUpdate={onUpdate}
                onDrop={onDrop}
                onClear={onClear}
                onMove={onMove}
              />
            ))}
          </div>
        )}
      </div>
    </div>
  );
}