"use client";

import { ChevronLeft, ChevronRight, ChevronsLeft, ChevronsRight } from "lucide-react";
import { Button } from "@/components/ui/button";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { cn } from "@/lib/utils";

export interface PaginationInfo {
  currentPage: number;
  totalPages: number;
  totalItems: number;
  itemsPerPage: number;
  startItem: number;
  endItem: number;
}

export interface PaginationProps {
  paginationInfo: PaginationInfo;
  onPageChange: (page: number) => void;
  onPageSizeChange?: (pageSize: number) => void;
  showPageSizeSelector?: boolean;
  pageSizeOptions?: number[];
  className?: string;
}

/**
 * 재사용 가능한 페이지네이션 컴포넌트
 *
 * @example
 * <Pagination
 *   paginationInfo={{
 *     currentPage: 1,
 *     totalPages: 10,
 *     totalItems: 200,
 *     itemsPerPage: 20,
 *     startItem: 1,
 *     endItem: 20
 *   }}
 *   onPageChange={(page) => console.log('Page changed:', page)}
 *   onPageSizeChange={(size) => console.log('Page size changed:', size)}
 *   showPageSizeSelector={true}
 *   pageSizeOptions={[10, 20, 50, 100]}
 * />
 */
export function Pagination({
  paginationInfo,
  onPageChange,
  onPageSizeChange,
  showPageSizeSelector = false,
  pageSizeOptions = [10, 20, 50, 100],
  className,
}: PaginationProps) {
  const { currentPage, totalPages, totalItems, itemsPerPage, startItem, endItem } = paginationInfo;

  // 페이지 버튼 범위 계산 (현재 페이지 기준으로 앞뒤 2개씩)
  const getPageNumbers = () => {
    const delta = 2;
    const range = [];
    const rangeWithDots = [];

    // 시작과 끝 계산
    let start = Math.max(1, currentPage - delta);
    let end = Math.min(totalPages, currentPage + delta);

    // 범위 조정
    if (end - start < delta * 2) {
      if (start === 1) {
        end = Math.min(totalPages, start + delta * 2);
      } else if (end === totalPages) {
        start = Math.max(1, end - delta * 2);
      }
    }

    // 페이지 번호 배열 생성
    for (let i = start; i <= end; i++) {
      range.push(i);
    }

    // 첫 페이지와 점 추가
    if (start > 1) {
      rangeWithDots.push(1);
      if (start > 2) {
        rangeWithDots.push("...");
      }
    }

    // 중간 범위 추가
    rangeWithDots.push(...range);

    // 마지막 페이지와 점 추가
    if (end < totalPages) {
      if (end < totalPages - 1) {
        rangeWithDots.push("...");
      }
      rangeWithDots.push(totalPages);
    }

    return rangeWithDots;
  };

  const pageNumbers = getPageNumbers();

  // 페이지 변경 핸들러
  const handlePageChange = (page: number) => {
    if (page >= 1 && page <= totalPages && page !== currentPage) {
      onPageChange(page);
    }
  };

  // 페이지 크기 변경 핸들러
  const handlePageSizeChange = (newPageSize: string) => {
    const size = parseInt(newPageSize, 10);
    if (onPageSizeChange && size !== itemsPerPage) {
      onPageSizeChange(size);
    }
  };

  // 항상 페이지네이션을 표시 (1페이지일 때도 표시)

  return (
    <div className={cn("flex flex-col gap-4 lg:flex-row lg:items-center lg:justify-between", className)}>
      {/* 페이지 정보 */}
      <div className="text-muted-foreground text-center text-sm lg:text-left">
        <span className="font-medium">{startItem.toLocaleString()}</span>
        {" - "}
        <span className="font-medium">{endItem.toLocaleString()}</span>
        {" / "}
        <span className="font-medium">{totalItems.toLocaleString()}</span>개 항목
      </div>

      {/* 페이지네이션 컨트롤 */}
      <div className="flex flex-col items-center gap-4 lg:flex-row">
        {/* 페이지 크기 선택 */}
        {showPageSizeSelector && onPageSizeChange && (
          <div className="flex items-center justify-center gap-2">
            <span className="text-muted-foreground text-sm">페이지당</span>
            <Select value={itemsPerPage.toString()} onValueChange={handlePageSizeChange}>
              <SelectTrigger className="w-20">
                <SelectValue />
              </SelectTrigger>
              <SelectContent>
                {pageSizeOptions.map((size) => (
                  <SelectItem key={size} value={size.toString()}>
                    {size}
                  </SelectItem>
                ))}
              </SelectContent>
            </Select>
            <span className="text-muted-foreground text-sm">개</span>
          </div>
        )}

        {/* 페이지 버튼들 */}
        <div className="flex items-center justify-center gap-1">
          {/* 첫 페이지로 */}
          <Button
            variant="ghost"
            size="sm"
            onClick={() => handlePageChange(1)}
            disabled={currentPage === 1}
            className="h-8 w-8 p-0 lg:h-9 lg:w-9"
            title="첫 페이지"
          >
            <ChevronsLeft className="h-3 w-3 lg:h-4 lg:w-4" />
          </Button>

          {/* 이전 페이지 */}
          <Button
            variant="ghost"
            size="sm"
            onClick={() => handlePageChange(currentPage - 1)}
            disabled={currentPage === 1}
            className="h-8 w-8 p-0 lg:h-9 lg:w-9"
            title="이전 페이지"
          >
            <ChevronLeft className="h-3 w-3 lg:h-4 lg:w-4" />
          </Button>

          {/* 페이지 번호들 */}
          {pageNumbers.map((page, index) => (
            <div key={index}>
              {page === "..." ? (
                <span className="text-muted-foreground flex h-8 w-8 items-center justify-center text-sm lg:h-9 lg:w-9">
                  ...
                </span>
              ) : (
                <Button
                  variant={page === currentPage ? "default" : "ghost"}
                  size="sm"
                  onClick={() => handlePageChange(page as number)}
                  className="h-8 w-8 p-0 lg:h-9 lg:w-9"
                >
                  {page}
                </Button>
              )}
            </div>
          ))}

          {/* 다음 페이지 */}
          <Button
            variant="ghost"
            size="sm"
            onClick={() => handlePageChange(currentPage + 1)}
            disabled={currentPage === totalPages}
            className="h-8 w-8 p-0 lg:h-9 lg:w-9"
            title="다음 페이지"
          >
            <ChevronRight className="h-3 w-3 lg:h-4 lg:w-4" />
          </Button>

          {/* 마지막 페이지로 */}
          <Button
            variant="ghost"
            size="sm"
            onClick={() => handlePageChange(totalPages)}
            disabled={currentPage === totalPages}
            className="h-8 w-8 p-0 lg:h-9 lg:w-9"
            title="마지막 페이지"
          >
            <ChevronsRight className="h-3 w-3 lg:h-4 lg:w-4" />
          </Button>
        </div>
      </div>
    </div>
  );
}