tm_app/lib/views/tenders/widgets/windowed_pagination.dart

import 'package:flutter/material.dart';
import 'package:tm_app/core/theme/colors.dart';

/// A windowed numbered pagination widget that mirrors the Next.js
/// implementation: ±10 page-button window around the current page,
/// 1-based labels, prev/next chevrons.
class WindowedPagination extends StatelessWidget {
  const WindowedPagination({
    super.key,
    required this.currentPage,
    required this.totalPages,
    required this.onPageChanged,
    this.maxPageJump = 10,
    this.compact = false,
  });

  /// 0-based absolute current page index.
  final int currentPage;

  /// Total number of pages (1-based count).
  final int totalPages;

  /// Called with the 0-based target page index.
  final ValueChanged<int> onPageChanged;

  /// Half-width of the page-button window (web uses 10).
  final int maxPageJump;

  /// If true, renders smaller buttons (for mobile).
  final bool compact;

  @override
  Widget build(BuildContext context) {
    if (totalPages <= 1) {
      return const SizedBox.shrink();
    }

    final clampedCurrent = currentPage.clamp(0, totalPages - 1);
    final windowStart = (clampedCurrent - maxPageJump).clamp(0, totalPages - 1);
    final windowEnd = (clampedCurrent + maxPageJump).clamp(0, totalPages - 1);

    final buttons = <Widget>[];

    buttons.add(
      _NavButton(
        icon: Icons.chevron_left,
        enabled: clampedCurrent > 0,
        compact: compact,
        onTap: () => onPageChanged(clampedCurrent - 1),
      ),
    );

    if (windowStart > 0) {
      buttons.add(_buildPageButton(0, clampedCurrent));
      if (windowStart > 1) {
        buttons.add(const _Ellipsis());
      }
    }

    for (var i = windowStart; i <= windowEnd; i++) {
      buttons.add(_buildPageButton(i, clampedCurrent));
    }

    if (windowEnd < totalPages - 1) {
      if (windowEnd < totalPages - 2) {
        buttons.add(const _Ellipsis());
      }
      buttons.add(_buildPageButton(totalPages - 1, clampedCurrent));
    }

    buttons.add(
      _NavButton(
        icon: Icons.chevron_right,
        enabled: clampedCurrent < totalPages - 1,
        compact: compact,
        onTap: () => onPageChanged(clampedCurrent + 1),
      ),
    );

    final gap = compact ? 4.0 : 6.0;
    return Padding(
      padding: EdgeInsets.symmetric(vertical: compact ? 8 : 12),
      child: LayoutBuilder(
        builder: (context, constraints) {
          return SingleChildScrollView(
            scrollDirection: Axis.horizontal,
            child: ConstrainedBox(
              constraints: BoxConstraints(minWidth: constraints.maxWidth),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: _withSpacing(buttons, gap),
              ),
            ),
          );
        },
      ),
    );
  }

  Widget _buildPageButton(int pageIndex, int currentPageIndex) {
    final isActive = pageIndex == currentPageIndex;
    return _PageButton(
      label: '${pageIndex + 1}',
      isActive: isActive,
      compact: compact,
      onTap: isActive ? null : () => onPageChanged(pageIndex),
    );
  }

  static List<Widget> _withSpacing(List<Widget> items, double gap) {
    final result = <Widget>[];
    for (var i = 0; i < items.length; i++) {
      result.add(items[i]);
      if (i != items.length - 1) {
        result.add(SizedBox(width: gap));
      }
    }
    return result;
  }
}

class _PageButton extends StatelessWidget {
  const _PageButton({
    required this.label,
    required this.isActive,
    required this.compact,
    this.onTap,
  });

  final String label;
  final bool isActive;
  final bool compact;
  final VoidCallback? onTap;

  @override
  Widget build(BuildContext context) {
    final size = compact ? 32.0 : 38.0;
    return SizedBox(
      width: size,
      height: size,
      child: Material(
        color: Colors.transparent,
        child: InkWell(
          borderRadius: BorderRadius.circular(12),
          onTap: onTap,
          child: Container(
            alignment: Alignment.center,
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(12),
              gradient: isActive
                  ? const LinearGradient(
                      begin: Alignment.topLeft,
                      end: Alignment.bottomRight,
                      colors: [AppColors.mainBlue, AppColors.primaryColor],
                    )
                  : null,
              color: isActive ? null : AppColors.grey0,
              border: Border.all(
                color: isActive ? Colors.transparent : AppColors.grey30,
                width: 1,
              ),
              boxShadow: isActive
                  ? [
                      BoxShadow(
                        color: AppColors.mainBlue.withValues(alpha: 0.25),
                        blurRadius: 8,
                        offset: const Offset(0, 2),
                      ),
                    ]
                  : null,
            ),
            child: Text(
              label,
              style: TextStyle(
                fontSize: compact ? 12 : 13,
                fontWeight: isActive ? FontWeight.w600 : FontWeight.w500,
                color: isActive ? Colors.white : AppColors.grey70,
              ),
            ),
          ),
        ),
      ),
    );
  }
}

class _NavButton extends StatelessWidget {
  const _NavButton({
    required this.icon,
    required this.enabled,
    required this.compact,
    required this.onTap,
  });

  final IconData icon;
  final bool enabled;
  final bool compact;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final size = compact ? 32.0 : 38.0;
    return SizedBox(
      width: size,
      height: size,
      child: Material(
        color: Colors.transparent,
        child: InkWell(
          borderRadius: BorderRadius.circular(12),
          onTap: enabled ? onTap : null,
          child: Container(
            alignment: Alignment.center,
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(12),
              color: AppColors.grey0,
              border: Border.all(
                color: enabled ? AppColors.grey30 : AppColors.grey20,
                width: 1,
              ),
            ),
            child: Icon(
              icon,
              size: compact ? 18 : 20,
              color: enabled ? AppColors.grey70 : AppColors.grey40,
            ),
          ),
        ),
      ),
    );
  }
}

class _Ellipsis extends StatelessWidget {
  const _Ellipsis();

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 2),
      child: Text(
        '…',
        style: TextStyle(
          fontSize: 14,
          color: AppColors.grey60,
          fontWeight: FontWeight.w500,
        ),
      ),
    );
  }
}