"use client";

import React, { useMemo } from "react";
import { GripVertical } from "lucide-react";
import { Input } from "@/components/ui/input";
import { Checkbox } from "@/components/ui/checkbox";
import { cn } from "@/lib/utils";
import {
  DndContext,
  closestCenter,
  KeyboardSensor,
  PointerSensor,
  useSensor,
  useSensors,
  type DragEndEvent,
} from "@dnd-kit/core";
import {
  SortableContext,
  verticalListSortingStrategy,
  useSortable,
  arrayMove,
} from "@dnd-kit/sortable";
import { CSS } from "@dnd-kit/utilities";

import { FormatSegment } from "./types";
import { SEGMENT_TYPE_LABELS, buildFormattedString, SAMPLE_VALUES } from "./config";

// 개별 세그먼트 행
interface SortableSegmentRowProps {
  segment: FormatSegment;
  index: number;
  onChange: (index: number, updates: Partial<FormatSegment>) => void;
}

function SortableSegmentRow({ segment, index, onChange }: SortableSegmentRowProps) {
  const {
    attributes,
    listeners,
    setNodeRef,
    transform,
    transition,
    isDragging,
  } = useSortable({ id: `${segment.type}-${index}` });

  const style = {
    transform: CSS.Transform.toString(transform),
    transition,
  };

  return (
    <div
      ref={setNodeRef}
      style={style}
      className={cn(
        "grid grid-cols-[16px_56px_18px_1fr_1fr_1fr] items-center gap-1 rounded border bg-white px-2 py-1.5",
        isDragging && "opacity-50",
      )}
    >
      <div
        {...attributes}
        {...listeners}
        className="cursor-grab text-gray-400 hover:text-gray-600"
      >
        <GripVertical className="h-3.5 w-3.5" />
      </div>

      <span className="truncate text-xs font-medium">
        {SEGMENT_TYPE_LABELS[segment.type]}
      </span>

      <Checkbox
        checked={segment.showLabel}
        onCheckedChange={(checked) =>
          onChange(index, { showLabel: checked === true })
        }
        className="h-3.5 w-3.5"
      />

      <Input
        value={segment.label}
        onChange={(e) => onChange(index, { label: e.target.value })}
        placeholder=""
        className={cn(
          "h-6 px-1 text-xs",
          !segment.showLabel && "text-gray-400 line-through",
        )}
      />

      <Input
        value={segment.separatorAfter}
        onChange={(e) => onChange(index, { separatorAfter: e.target.value })}
        placeholder=""
        className="h-6 px-1 text-center text-xs"
      />

      <Input
        type="number"
        min={0}
        max={5}
        value={segment.pad}
        onChange={(e) =>
          onChange(index, { pad: parseInt(e.target.value) || 0 })
        }
        disabled={segment.type !== "row" && segment.type !== "level"}
        className={cn(
          "h-6 px-1 text-center text-xs",
          segment.type !== "row" && segment.type !== "level" && "bg-gray-100 opacity-50",
        )}
      />
    </div>
  );
}

// FormatSegmentEditor 메인 컴포넌트
interface FormatSegmentEditorProps {
  label: string;
  segments: FormatSegment[];
  onChange: (segments: FormatSegment[]) => void;
  sampleValues?: Record<string, string>;
}

export function FormatSegmentEditor({
  label,
  segments,
  onChange,
  sampleValues = SAMPLE_VALUES,
}: FormatSegmentEditorProps) {
  const sensors = useSensors(
    useSensor(PointerSensor, {
      activationConstraint: { distance: 5 },
    }),
    useSensor(KeyboardSensor),
  );

  const preview = useMemo(
    () => buildFormattedString(segments, sampleValues),
    [segments, sampleValues],
  );

  const sortableIds = useMemo(
    () => segments.map((seg, i) => `${seg.type}-${i}`),
    [segments],
  );

  const handleDragEnd = (event: DragEndEvent) => {
    const { active, over } = event;
    if (!over || active.id === over.id) return;

    const oldIndex = sortableIds.indexOf(active.id as string);
    const newIndex = sortableIds.indexOf(over.id as string);
    if (oldIndex === -1 || newIndex === -1) return;

    onChange(arrayMove([...segments], oldIndex, newIndex));
  };

  const handleSegmentChange = (index: number, updates: Partial<FormatSegment>) => {
    const updated = segments.map((seg, i) =>
      i === index ? { ...seg, ...updates } : seg,
    );
    onChange(updated);
  };

  return (
    <div className="space-y-2">
      <div className="text-xs font-medium text-gray-600">{label}</div>

      <div className="grid grid-cols-[16px_56px_18px_1fr_1fr_1fr] items-center gap-1 px-2 text-[10px] text-gray-500">
        <span />
        <span />
        <span />
        <span>라벨</span>
        <span className="text-center">구분</span>
        <span className="text-center">자릿수</span>
      </div>

      <DndContext
        sensors={sensors}
        collisionDetection={closestCenter}
        onDragEnd={handleDragEnd}
      >
        <SortableContext items={sortableIds} strategy={verticalListSortingStrategy}>
          <div className="space-y-1">
            {segments.map((segment, index) => (
              <SortableSegmentRow
                key={sortableIds[index]}
                segment={segment}
                index={index}
                onChange={handleSegmentChange}
              />
            ))}
          </div>
        </SortableContext>
      </DndContext>

      <div className="rounded bg-gray-50 px-2 py-1.5">
        <span className="text-[10px] text-gray-500">미리보기: </span>
        <span className="text-xs font-medium text-gray-800">
          {preview || "(빈 값)"}
        </span>
      </div>
    </div>
  );
}