import React from 'react';
import { useSearchParams } from 'react-router-dom';

interface PaginationProps {
  total: number;
  totalPages: number;
  currentPage: number;
  onPageChange?: (page: number) => void;
  showTotal?: boolean;
  scrollToTop?: boolean;
  pageSize?: number;
  pageSizeOptions?: number[];
  onPageSizeChange?: (size: number) => void;
}

const Pagination: React.FC<PaginationProps> = ({
  total,
  totalPages,
  currentPage,
  onPageChange,
  showTotal = true,
  scrollToTop = true,
  pageSize = 10,
  pageSizeOptions = [],
  onPageSizeChange,
}) => {
  const [searchParams, setSearchParams] = useSearchParams();

  // 更新 URL 页码的辅助函数
  const updatePageInUrl = (page: number) => {
    setSearchParams(prev => {
      const newParams = new URLSearchParams(prev);
      if (page === 1) {
        newParams.delete('page');
      } else {
        newParams.set('page', page.toString());
      }
      return newParams;
    });

    // 如果提供了自定义的 onPageChange 回调，也调用它
    if (onPageChange) onPageChange(page);

    // 滚动到顶部
    if (scrollToTop) {
      const mainElement = document.querySelector('main');
      if (mainElement) {
        mainElement.scrollTop = 0;
      }
    }
  };

  // 如果只有一页，不显示分页
  if (totalPages <= 1 && (!pageSizeOptions || pageSizeOptions.length === 0)) {
    return null;
  }

  // 生成页码数组
  const generatePages = (): (number | string)[] => {
    const pages: (number | string)[] = [];
    
    if (totalPages <= 7) {
      // 如果总页数少于等于7，显示所有页码
      for (let i = 1; i <= totalPages; i++) {
        pages.push(i);
      }
    } else {
      // 如果总页数大于7，显示带省略号的页码
      if (currentPage <= 3) {
        // 当前页在前3页
        for (let i = 1; i <= 4; i++) {
          pages.push(i);
        }
        pages.push('...');
        pages.push(totalPages);
      } else if (currentPage >= totalPages - 2) {
        // 当前页在后3页
        pages.push(1);
        pages.push('...');
        for (let i = totalPages - 3; i <= totalPages; i++) {
          pages.push(i);
        }
      } else {
        // 当前页在中间
        pages.push(1);
        pages.push('...');
        for (let i = currentPage - 1; i <= currentPage + 1; i++) {
          pages.push(i);
        }
        pages.push('...');
        pages.push(totalPages);
      }
    }
    
    return pages;
  };

  const pages = generatePages();

  return (
    <div className="flex items-center justify-center gap-2 mt-6">
      {showTotal && (
        <span className="text-sm text-gray-600 mr-2">
          共{total}条
        </span>
      )}
      {pageSizeOptions && pageSizeOptions.length > 0 && (
        <div className="flex items-center gap-2 mr-4">
          <span className="text-sm text-gray-600">每页</span>
          <select
            value={pageSize}
            onChange={(e) => {
              const size = Number(e.target.value);
              if (onPageSizeChange) onPageSizeChange(size);
              // 重置到第一页
              updatePageInUrl(1);
            }}
            className="border border-gray-200 rounded-lg px-2 py-1 text-sm"
          >
            {pageSizeOptions.map((opt) => (
              <option key={opt} value={opt}>{opt}</option>
            ))}
          </select>
        </div>
      )}
      <div className="flex items-center gap-1">
        {pages.map((page, index) => {
          if (page === '...') {
            return (
              <span key={`ellipsis-${index}`} className="px-2 text-gray-400">
                …
              </span>
            );
          }
          const pageNum = page as number;
          return (
            <button
              key={pageNum}
              onClick={() => updatePageInUrl(pageNum)}
              className={`px-3 py-1.5 text-sm font-bold rounded-lg transition-colors ${
                pageNum === currentPage
                  ? 'bg-blue-600 text-white'
                  : 'bg-white border border-gray-200 text-gray-600 hover:bg-gray-50'
              }`}
            >
              {pageNum}
            </button>
          );
        })}
      </div>
      <button
        onClick={() => {
          if (currentPage > 1) {
            updatePageInUrl(currentPage - 1);
          }
        }}
        disabled={currentPage === 1}
        className="px-4 py-2 bg-white border border-gray-200 rounded-lg text-sm font-bold disabled:opacity-50 disabled:cursor-not-allowed hover:bg-gray-50 transition-colors"
      >
        上一页
      </button>
      <button
        onClick={() => {
          if (currentPage < totalPages) {
            updatePageInUrl(currentPage + 1);
          }
        }}
        disabled={currentPage === totalPages}
        className="px-4 py-2 bg-white border border-gray-200 rounded-lg text-sm font-bold disabled:opacity-50 disabled:cursor-not-allowed hover:bg-gray-50 transition-colors"
      >
        下一页
      </button>
    </div>
  );
};

export default Pagination;