import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../../app/providers.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/theme/app_dimens.dart';
import '../../../core/theme/app_layout.dart';
import '../../../core/theme/app_typography.dart';
import '../../../core/utils/formatters.dart';
import '../../auth/providers/auth_controller.dart';
import '../../sync/widgets/sign_out_dialog.dart';
import '../providers/cart_controller.dart';
import '../../sync/providers/sync_controller.dart';
import '../providers/navigation_provider.dart';

/// Left navigation rail.
///
/// Renders in three widths: full labels on desktop, icons only on tablet
/// landscape, and off-canvas below that. The same widget serves all three so
/// the active state and badges never drift apart.
class AppSidebar extends ConsumerWidget {
  const AppSidebar({
    super.key,
    required this.mode,
    this.onDestinationTap,
  });

  final SidebarMode mode;

  /// Lets the drawer close itself after a tap.
  final VoidCallback? onDestinationTap;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    // The drawer presentation uses the expanded layout at full width.
    final expanded = mode != SidebarMode.rail;
    final width = mode == SidebarMode.rail
        ? PosLayout.railWidth
        : PosLayout.expandedWidth;

    return AnimatedContainer(
      duration: AppMotion.normal,
      curve: AppMotion.emphasized,
      width: width,
      decoration: const BoxDecoration(
        color: AppColors.surface,
        border: Border(right: BorderSide(color: AppColors.border)),
      ),
      child: SafeArea(
        right: false,
        child: Column(
          children: [
            _Brand(expanded: expanded),
            const Divider(height: 1),
            _Profile(expanded: expanded),
            const Divider(height: 1),
            Expanded(
              child: SingleChildScrollView(
                padding: const EdgeInsets.symmetric(vertical: AppSpacing.md),
                child: Column(
                  children: [
                    for (final section in NavSection.values)
                      _Section(
                        section: section,
                        expanded: expanded,
                        onDestinationTap: onDestinationTap,
                      ),
                  ],
                ),
              ),
            ),
            const Divider(height: 1),
            _LogoutTile(expanded: expanded),
          ],
        ),
      ),
    );
  }
}

class _Brand extends StatelessWidget {
  const _Brand({required this.expanded});

  final bool expanded;

  @override
  Widget build(BuildContext context) {
    return Container(
      height: AppSizes.headerHeight,
      padding: EdgeInsets.symmetric(
        horizontal: expanded ? AppSpacing.xl : AppSpacing.md,
      ),
      alignment: expanded ? Alignment.centerLeft : Alignment.center,
      child: Row(
        mainAxisSize: MainAxisSize.min,
        children: [
          Container(
            width: 36,
            height: 36,
            decoration: BoxDecoration(
              gradient: AppColors.primaryGradient,
              borderRadius: BorderRadius.circular(10),
            ),
            alignment: Alignment.center,
            child: const Text(
              'N',
              style: TextStyle(
                color: Colors.white,
                fontSize: 20,
                fontWeight: FontWeight.w800,
              ),
            ),
          ),
          if (expanded) ...[
            const SizedBox(width: AppSpacing.md),
            Flexible(
              child: Column(
                mainAxisSize: MainAxisSize.min,
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  const Text(
                    'Nearle',
                    style: TextStyle(
                      fontSize: 17,
                      fontWeight: FontWeight.w700,
                      letterSpacing: -0.3,
                      color: AppColors.textPrimary,
                      height: 1.1,
                    ),
                  ),
                  Text(
                    'POS',
                    style: AppTypography.sectionLabel()
                        .copyWith(color: AppColors.primary),
                  ),
                ],
              ),
            ),
          ],
        ],
      ),
    );
  }
}

class _Profile extends ConsumerWidget {
  const _Profile({required this.expanded});

  final bool expanded;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final user = ref.watch(currentUserProvider);
    final name = user?.name ?? ref.watch(cashierSessionProvider).name;
    final role = user?.role.label ?? ref.watch(cashierSessionProvider).role;

    return Padding(
      padding: EdgeInsets.symmetric(
        horizontal: expanded ? AppSpacing.lg : AppSpacing.sm,
        vertical: AppSpacing.md,
      ),
      child: Row(
        mainAxisAlignment:
            expanded ? MainAxisAlignment.start : MainAxisAlignment.center,
        children: [
          Container(
            width: 38,
            height: 38,
            decoration: BoxDecoration(
              color: AppColors.primarySurface,
              borderRadius: AppRadius.brSm,
              border: Border.all(color: AppColors.primaryBorder),
            ),
            alignment: Alignment.center,
            child: Text(
              Formatters.initials(name),
              style: const TextStyle(
                color: AppColors.primary,
                fontSize: 13,
                fontWeight: FontWeight.w700,
              ),
            ),
          ),
          if (expanded) ...[
            const SizedBox(width: AppSpacing.md),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    name,
                    overflow: TextOverflow.ellipsis,
                    style: const TextStyle(
                      fontSize: 14,
                      fontWeight: FontWeight.w600,
                      color: AppColors.textPrimary,
                      height: 1.2,
                    ),
                  ),
                  Text(
                    role,
                    style: const TextStyle(
                      fontSize: 11.5,
                      color: AppColors.textTertiary,
                      height: 1.3,
                    ),
                  ),
                ],
              ),
            ),
          ],
        ],
      ),
    );
  }
}

class _Section extends ConsumerWidget {
  const _Section({
    required this.section,
    required this.expanded,
    this.onDestinationTap,
  });

  final NavSection section;
  final bool expanded;
  final VoidCallback? onDestinationTap;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final active = ref.watch(activeModuleProvider);
    final cartCount = ref.watch(cartItemCountProvider);
    final ready = ref.watch(catalogueReadyProvider);
    final outstanding = ref.watch(unsyncedCountProvider).value ?? 0;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        if (expanded)
          Padding(
            padding: const EdgeInsets.fromLTRB(
              AppSpacing.xl,
              AppSpacing.lg,
              AppSpacing.xl,
              AppSpacing.sm,
            ),
            child: Text(section.label.toUpperCase(),
                style: AppTypography.sectionLabel()),
          )
        else
          const Padding(
            padding: EdgeInsets.symmetric(
              horizontal: AppSpacing.xl,
              vertical: AppSpacing.md,
            ),
            child: Divider(height: 1),
          ),
        for (final module in section.modules)
          _NavTile(
            module: module,
            expanded: expanded,
            selected: active == module,
            badge: switch (module) {
              PosModule.pos => cartCount > 0 ? cartCount : null,
              PosModule.productImport => ready ? null : 1,
              PosModule.events => outstanding > 0 ? outstanding : null,
              _ => null,
            },
            badgeColor: switch (module) {
              PosModule.productImport => AppColors.danger,
              PosModule.events => AppColors.warning,
              _ => AppColors.primary,
            },
            onTap: () {
              ref.read(activeModuleProvider.notifier).state = module;
              onDestinationTap?.call();
            },
          ),
      ],
    );
  }
}

class _NavTile extends StatefulWidget {
  const _NavTile({
    required this.module,
    required this.expanded,
    required this.selected,
    required this.onTap,
    this.badge,
    this.badgeColor,
  });

  final PosModule module;
  final bool expanded;
  final bool selected;
  final VoidCallback onTap;
  final int? badge;
  final Color? badgeColor;

  @override
  State<_NavTile> createState() => _NavTileState();
}

class _NavTileState extends State<_NavTile> {
  bool _hovered = false;

  @override
  Widget build(BuildContext context) {
    final selected = widget.selected;
    final fg = selected
        ? AppColors.primary
        : (_hovered ? AppColors.textPrimary : AppColors.textSecondary);

    final tile = AnimatedContainer(
      duration: AppMotion.fast,
      height: AppSizes.navItemHeight,
      padding: EdgeInsets.symmetric(
        horizontal: widget.expanded ? AppSpacing.md : 0,
      ),
      decoration: BoxDecoration(
        color: selected
            ? AppColors.primarySurface
            : (_hovered ? AppColors.surfaceAlt : Colors.transparent),
        borderRadius: AppRadius.brSm,
      ),
      child: Row(
        mainAxisAlignment: widget.expanded
            ? MainAxisAlignment.start
            : MainAxisAlignment.center,
        children: [
          Stack(
            clipBehavior: Clip.none,
            children: [
              Icon(widget.module.icon, size: 20, color: fg),
              // In rail mode the label is gone, so the badge rides the icon.
              if (widget.badge != null && !widget.expanded)
                Positioned(
                  top: -5,
                  right: -8,
                  child: _Badge(
                    value: widget.badge!,
                    color: widget.badgeColor ?? AppColors.primary,
                  ),
                ),
            ],
          ),
          if (widget.expanded) ...[
            const SizedBox(width: AppSpacing.md),
            Expanded(
              child: Text(
                widget.module.label,
                overflow: TextOverflow.ellipsis,
                style: TextStyle(
                  fontSize: 14,
                  fontWeight: selected ? FontWeight.w600 : FontWeight.w500,
                  color: fg,
                ),
              ),
            ),
            if (widget.badge != null)
              _Badge(
                value: widget.badge!,
                color: widget.badgeColor ?? AppColors.primary,
              ),
          ],
        ],
      ),
    );

    return MouseRegion(
      onEnter: (_) => setState(() => _hovered = true),
      onExit: (_) => setState(() => _hovered = false),
      child: Padding(
        padding: EdgeInsets.symmetric(
          horizontal: widget.expanded ? AppSpacing.md : AppSpacing.lg,
          vertical: 2,
        ),
        child: Stack(
          children: [
            Material(
              color: Colors.transparent,
              child: InkWell(
                onTap: widget.onTap,
                borderRadius: AppRadius.brSm,
                child: widget.expanded
                    ? tile
                    : Tooltip(message: widget.module.title, child: tile),
              ),
            ),
            // Accent bar marking the active destination.
            if (selected)
              Positioned(
                left: 0,
                top: 10,
                bottom: 10,
                child: Container(
                  width: 3,
                  decoration: const BoxDecoration(
                    color: AppColors.primary,
                    borderRadius: AppRadius.brPill,
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }
}

class _Badge extends StatelessWidget {
  const _Badge({required this.value, required this.color});

  final int value;
  final Color color;

  @override
  Widget build(BuildContext context) {
    return Container(
      constraints: const BoxConstraints(minWidth: 19),
      height: 19,
      padding: const EdgeInsets.symmetric(horizontal: 5),
      decoration: BoxDecoration(color: color, borderRadius: AppRadius.brPill),
      alignment: Alignment.center,
      child: Text(
        value > 99 ? '99+' : '$value',
        style: const TextStyle(
          color: Colors.white,
          fontSize: 10.5,
          fontWeight: FontWeight.w700,
        ),
      ),
    );
  }
}

class _LogoutTile extends ConsumerWidget {
  const _LogoutTile({required this.expanded});

  final bool expanded;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Padding(
      padding: const EdgeInsets.all(AppSpacing.md),
      child: Material(
        color: Colors.transparent,
        child: InkWell(
          onTap: () => showSignOutDialog(context, ref),
          borderRadius: AppRadius.brSm,
          child: Container(
            height: AppSizes.navItemHeight,
            padding: EdgeInsets.symmetric(
              horizontal: expanded ? AppSpacing.md : 0,
            ),
            alignment: expanded ? Alignment.centerLeft : Alignment.center,
            child: Row(
              mainAxisSize: MainAxisSize.min,
              children: [
                const Icon(Icons.logout_rounded,
                    size: 19, color: AppColors.danger),
                if (expanded) ...[
                  const SizedBox(width: AppSpacing.md),
                  const Text(
                    'Logout',
                    style: TextStyle(
                      fontSize: 14,
                      fontWeight: FontWeight.w500,
                      color: AppColors.danger,
                    ),
                  ),
                ],
              ],
            ),
          ),
        ),
      ),
    );
  }
}