'use client';

import { ReactNode, useCallback } from 'react';
import { format, startOfYear, endOfYear, subMonths, startOfMonth, endOfMonth, subDays } from 'date-fns';
import { Button } from '@/components/ui/button';
import { DatePicker } from '@/components/ui/date-picker';
import { DateRangePicker } from '@/components/ui/date-range-picker';
import { ScrollableButtonGroup } from '@/components/atoms/ScrollableButtonGroup';

/**
 * 날짜 범위 프리셋 타입
 */
export type DatePreset = 'thisYear' | 'fiveMonthsAgo' | 'fourMonthsAgo' | 'threeMonthsAgo' | 'twoMonthsAgo' | 'lastMonth' | 'thisMonth' | 'yesterday' | 'today';

/**
 * 프리셋 레이블 (한국어)
 */
const PRESET_LABELS: Record<DatePreset, string> = {
  thisYear: '당해년도',
  fiveMonthsAgo: 'D-5월',
  fourMonthsAgo: 'D-4월',
  threeMonthsAgo: 'D-3월',
  twoMonthsAgo: '전전월',
  lastMonth: '전월',
  thisMonth: '당월',
  yesterday: '어제',
  today: '오늘',
};

/**
 * 기본 프리셋 순서
 */
const DEFAULT_PRESETS: DatePreset[] = ['today', 'yesterday', 'thisMonth', 'lastMonth', 'twoMonthsAgo', 'thisYear' ];

interface DateRangeSelectorProps {
  /** 시작 날짜 (yyyy-MM-dd 형식) */
  startDate: string;
  /** 종료 날짜 (yyyy-MM-dd 형식) */
  endDate: string;
  /** 시작 날짜 변경 핸들러 */
  onStartDateChange: (date: string) => void;
  /** 종료 날짜 변경 핸들러 */
  onEndDateChange: (date: string) => void;
  /** 표시할 프리셋 목록 (기본: 전체) */
  presets?: DatePreset[];
  /** 프리셋 레이블 커스텀 오버라이드 */
  presetLabels?: Partial<Record<DatePreset, string>>;
  /** 추가 액션 (엑셀 다운로드, 등록 버튼 등) */
  extraActions?: ReactNode;
  /** 프리셋 버튼 숨김 */
  hidePresets?: boolean;
  /** 날짜 입력 숨김 */
  hideDateInputs?: boolean;
  /** 날짜 입력 너비 */
  dateInputWidth?: string;
  /** 프리셋 버튼 위치: 'inline' (날짜 옆), 'below' (별도 줄) */
  presetsPosition?: 'inline' | 'below';
  /** 날짜 입력 변형: 'split' (DatePicker 2개), 'combined' (DateRangePicker 1개) */
  variant?: 'split' | 'combined';
}

/**
 * 날짜 범위 선택 컴포넌트
 *
 * 달력(날짜 입력) + 기간 프리셋 버튼 (당해년도, 전전월, 전월, 당월, 어제, 오늘)
 *
 * @example
 * ```tsx
 * <DateRangeSelector
 *   startDate={startDate}
 *   endDate={endDate}
 *   onStartDateChange={setStartDate}
 *   onEndDateChange={setEndDate}
 *   extraActions={
 *     <>
 *       <Button variant="outline">엑셀 다운로드</Button>
 *       <Button>등록</Button>
 *     </>
 *   }
 * />
 * ```
 */
export function DateRangeSelector({
  startDate,
  endDate,
  onStartDateChange,
  onEndDateChange,
  presets = DEFAULT_PRESETS,
  presetLabels: customLabels,
  extraActions,
  hidePresets = false,
  hideDateInputs = false,
  dateInputWidth = 'w-[140px]',
  presetsPosition = 'inline',
  variant = 'combined',
}: DateRangeSelectorProps) {

  // 프리셋 클릭 핸들러
  const handlePresetClick = useCallback((preset: DatePreset) => {
    const today = new Date();

    switch (preset) {
      case 'thisYear':
        onStartDateChange(format(startOfYear(today), 'yyyy-MM-dd'));
        onEndDateChange(format(endOfYear(today), 'yyyy-MM-dd'));
        break;
      case 'twoMonthsAgo': {
        const twoMonthsAgo = subMonths(today, 2);
        onStartDateChange(format(startOfMonth(twoMonthsAgo), 'yyyy-MM-dd'));
        onEndDateChange(format(endOfMonth(twoMonthsAgo), 'yyyy-MM-dd'));
        break;
      }
      case 'lastMonth': {
        const lastMonth = subMonths(today, 1);
        onStartDateChange(format(startOfMonth(lastMonth), 'yyyy-MM-dd'));
        onEndDateChange(format(endOfMonth(lastMonth), 'yyyy-MM-dd'));
        break;
      }
      case 'thisMonth':
        onStartDateChange(format(startOfMonth(today), 'yyyy-MM-dd'));
        onEndDateChange(format(endOfMonth(today), 'yyyy-MM-dd'));
        break;
      case 'yesterday': {
        const yesterday = subDays(today, 1);
        onStartDateChange(format(yesterday, 'yyyy-MM-dd'));
        onEndDateChange(format(yesterday, 'yyyy-MM-dd'));
        break;
      }
      case 'today':
        onStartDateChange(format(today, 'yyyy-MM-dd'));
        onEndDateChange(format(today, 'yyyy-MM-dd'));
        break;
      case 'threeMonthsAgo': {
        const threeMonthsAgo = subMonths(today, 3);
        onStartDateChange(format(startOfMonth(threeMonthsAgo), 'yyyy-MM-dd'));
        onEndDateChange(format(endOfMonth(threeMonthsAgo), 'yyyy-MM-dd'));
        break;
      }
      case 'fourMonthsAgo': {
        const fourMonthsAgo = subMonths(today, 4);
        onStartDateChange(format(startOfMonth(fourMonthsAgo), 'yyyy-MM-dd'));
        onEndDateChange(format(endOfMonth(fourMonthsAgo), 'yyyy-MM-dd'));
        break;
      }
      case 'fiveMonthsAgo': {
        const fiveMonthsAgo = subMonths(today, 5);
        onStartDateChange(format(startOfMonth(fiveMonthsAgo), 'yyyy-MM-dd'));
        onEndDateChange(format(endOfMonth(fiveMonthsAgo), 'yyyy-MM-dd'));
        break;
      }
    }
  }, [onStartDateChange, onEndDateChange]);

  // 프리셋 버튼 렌더링
  const renderPresets = () => {
    if (hidePresets || presets.length === 0) return null;
    return (
      <ScrollableButtonGroup>
        {presets.map((preset) => (
          <Button
            key={preset}
            variant="outline"
            size="sm"
            onClick={() => handlePresetClick(preset)}
            className="shrink-0 text-xs sm:text-sm px-2 sm:px-3"
          >
            {customLabels?.[preset] || PRESET_LABELS[preset]}
          </Button>
        ))}
      </ScrollableButtonGroup>
    );
  };

  // 날짜 입력 영역 렌더링
  const renderDateInputs = () => {
    if (hideDateInputs) return null;

    if (variant === 'combined') {
      return (
        <div className="w-full xl:w-auto xl:shrink-0">
          <DateRangePicker
            startDate={startDate}
            endDate={endDate}
            onStartDateChange={onStartDateChange}
            onEndDateChange={onEndDateChange}
            className="w-full xl:w-auto"
            size="sm"
          />
        </div>
      );
    }

    return (
      <div className="flex items-center gap-1 w-full xl:w-auto xl:shrink-0">
        <DatePicker
          value={startDate}
          onChange={onStartDateChange}
          className="flex-1 xl:flex-none xl:w-[170px]"
          size="sm"
          displayFormat="yyyy년 MM월 dd일"
        />
        <span className="text-muted-foreground shrink-0">~</span>
        <DatePicker
          value={endDate}
          onChange={onEndDateChange}
          className="flex-1 xl:flex-none xl:w-[170px]"
          size="sm"
          displayFormat="yyyy년 MM월 dd일"
        />
      </div>
    );
  };

  // presetsPosition이 'below'일 때: 달력+extraActions 같은 줄, 프리셋은 아래 줄
  if (presetsPosition === 'below') {
    return (
      <div className="flex flex-col gap-2 w-full">
        {/* 1줄: 날짜 + extraActions */}
        <div className="flex items-center gap-2">
          {renderDateInputs()}
          {extraActions}
        </div>

        {/* 2줄: 프리셋 버튼들 */}
        {renderPresets()}
      </div>
    );
  }

  // presetsPosition이 'inline' (기본값)
  // PC(1280px+): 달력 | 프리셋버튼 | 검색창 (한 줄, 넘치면 줄바꿈)
  // 태블릿: 달력 / 프리셋버튼 / 검색창 (세 줄)
  // Note: w-full 제거 - 부모 컨테이너에서 다른 요소들과 자연스럽게 한 줄에 배치되도록 함
  return (
    <div className="flex flex-col xl:flex-row xl:flex-wrap xl:items-center gap-2">
      {/* 날짜 범위 선택 */}
      {renderDateInputs()}

      {/* 기간 버튼들 - 달력 바로 옆 */}
      {renderPresets()}

      {/* extraActions (검색창 등) - 마지막에 배치 */}
      {extraActions}
    </div>
  );
}