import 'package:flutter/material.dart';

// --- Data Structure for Sidebar Menu Items ---
class SidebarItem {
  final IconData? icon; // Now nullable, as we might use an image
  final String label;
  final String? route; // Null if it's a parent category
  final List<SidebarItem>? children; // Sub-items
  final bool isParent;
  final String? imagePath; // New: Optional path to an image asset

  SidebarItem({
    this.icon,
    required this.label,
    this.route,
    this.children,
    this.isParent = false,
    this.imagePath, // Initialize the new property
  }) : assert(icon != null || imagePath != null, 'Either icon or imagePath must be provided'); // Ensure one is present
}

// --- Collapsible Sidebar Widget ---
class CollapsibleSidebar extends StatefulWidget {
  final Function(String route) onNavigate;
  final bool isCollapsed; // Receive collapse state from HomePage
  final VoidCallback onToggle; // Receive toggle callback from HomePage (for AppBar button)

  const CollapsibleSidebar({
    super.key,
    required this.onNavigate,
    required this.isCollapsed,
    required this.onToggle,
  });

  @override
  State<CollapsibleSidebar> createState() => _CollapsibleSidebarState();
}

class _CollapsibleSidebarState extends State<CollapsibleSidebar> {
  // Define your menu items here based on the routes you provided
  late final List<SidebarItem> _menuItems;

  @override
  void initState() {
    super.initState();
    _menuItems = [
      SidebarItem(
        // Reverted to IconData for the top-level 'Air' category
        icon: Icons.cloud,
        label: "Air",
        isParent: true,
        children: [
          // Added Manual sub-category for Air
          SidebarItem(
            icon: Icons.handshake, // Example icon for Manual
            label: "Manual",
            isParent: true,
            children: [
              SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/air/manual/dashboard'),
              SidebarItem(icon: Icons.edit_note, label: "Manual Sampling", route: '/air/manual/manual-sampling'),
              SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/air/manual/report'),
              SidebarItem(icon: Icons.article, label: "Data Log", route: '/air/manual/data-log'),
              SidebarItem(icon: Icons.image, label: "Image Request", route: '/air/manual/image-request'),
            ],
          ),
          SidebarItem(
              icon: Icons.trending_up, label: "Continuous", isParent: true, children: [
            SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/air/continuous/dashboard'),
            SidebarItem(icon: Icons.info, label: "Overview", route: '/air/continuous/overview'),
            SidebarItem(icon: Icons.input, label: "Entry", route: '/air/continuous/entry'),
            SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/air/continuous/report'),
          ]),
          SidebarItem(
              icon: Icons.search, label: "Investigative", isParent: true, children: [
            SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/air/investigative/dashboard'),
            SidebarItem(icon: Icons.info, label: "Overview", route: '/air/investigative/overview'),
            SidebarItem(icon: Icons.input, label: "Entry", route: '/air/investigative/entry'),
            SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/air/investigative/report'),
          ]),
        ],
      ),
      SidebarItem(
        // Reverted to IconData for the top-level 'River' category
        icon: Icons.water,
        label: "River",
        isParent: true,
        children: [
          // Added Manual sub-category for River
          SidebarItem(
            icon: Icons.handshake, // Example icon for Manual
            label: "Manual",
            isParent: true,
            children: [
              SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/river/manual/dashboard'),
              SidebarItem(icon: Icons.pin_drop, label: "In-Situ Sampling", route: '/river/manual/in-situ'),
              SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/river/manual/report'),
              SidebarItem(icon: Icons.date_range, label: "Triennial Sampling", route: '/river/manual/triennial'),
              SidebarItem(icon: Icons.article, label: "Data Log", route: '/river/manual/data-log'),
              SidebarItem(icon: Icons.image, label: "Image Request", route: '/river/manual/image-request'),
            ],
          ),
          SidebarItem(
              icon: Icons.trending_up, label: "Continuous", isParent: true, children: [
            SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/river/continuous/dashboard'),
            SidebarItem(icon: Icons.info, label: "Overview", route: '/river/continuous/overview'),
            SidebarItem(icon: Icons.input, label: "Entry", route: '/river/continuous/entry'),
            SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/river/continuous/report'),
          ]),
          SidebarItem(
              icon: Icons.search, label: "Investigative", isParent: true, children: [
            SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/river/investigative/dashboard'),
            SidebarItem(icon: Icons.info, label: "Overview", route: '/river/investigative/overview'),
            SidebarItem(icon: Icons.input, label: "Entry", route: '/river/investigative/entry'),
            SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/river/investigative/report'),
          ]),
        ],
      ),
      SidebarItem(
        // Reverted to IconData for the top-level 'Marine' category
        icon: Icons.sailing,
        label: "Marine",
        isParent: true,
        children: [
          // Added Manual sub-category for Marine
          SidebarItem(
            icon: Icons.handshake, // Example icon for Manual
            label: "Manual",
            isParent: true,
            children: [
              SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/marine/manual/dashboard'),
              SidebarItem(icon: Icons.description, label: "Info Centre Document", route: '/marine/manual/info'),
              SidebarItem(icon: Icons.assignment, label: "Pre-Sampling", route: '/marine/manual/pre-sampling'),
              SidebarItem(icon: Icons.pin_drop, label: "In-Situ Sampling", route: '/marine/manual/in-situ'),
              SidebarItem(icon: Icons.waves, label: "Tarball Sampling", route: '/marine/manual/tarball'),
              SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/marine/manual/report'),
              SidebarItem(icon: Icons.article, label: "Data Log", route: '/marine/manual/data-log'),
              SidebarItem(icon: Icons.image, label: "Image Request", route: '/marine/manual/image-request'),
            ],
          ),
          SidebarItem(
              icon: Icons.trending_up, label: "Continuous", isParent: true, children: [
            SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/marine/continuous/dashboard'),
            SidebarItem(icon: Icons.info, label: "Overview", route: '/marine/continuous/overview'),
            SidebarItem(icon: Icons.input, label: "Entry", route: '/marine/continuous/entry'),
            SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/marine/continuous/report'),
          ]),
          SidebarItem(
              icon: Icons.search, label: "Investigative", isParent: true, children: [
            SidebarItem(icon: Icons.dashboard, label: "Dashboard", route: '/marine/investigative/dashboard'),
            SidebarItem(icon: Icons.info, label: "Overview", route: '/marine/investigative/overview'),
            SidebarItem(icon: Icons.input, label: "Entry", route: '/marine/investigative/entry'),
            SidebarItem(icon: Icons.receipt_long, label: "Report", route: '/marine/investigative/report'),
          ]),
        ],
      ),
      // Added Settings menu item
      SidebarItem(icon: Icons.settings, label: "Settings", route: '/settings'),
    ];
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      width: widget.isCollapsed ? 70 : 280, // Increased expanded width for sub-menus
      color: Theme.of(context).primaryColor, // Use theme primary color for sidebar
      child: Column(
        children: [
          const SizedBox(height: 16), // Spacing below the (now removed) toggle button area

          Expanded(
            child: ListView(
              padding: EdgeInsets.zero, // Remove default listview padding
              children: [
                if (!widget.isCollapsed) ...[
                  // If sidebar is expanded, show full categories with sub-menus
                  for (var item in _menuItems)
                    _buildExpandableNavItem(item),
                ] else ...[
                  // If sidebar is collapsed, only show icons for top-level items
                  for (var item in _menuItems)
                    _buildCollapsedNavItem(item),
                ],
              ],
            ),
          ),
          const Divider(color: Colors.white24, height: 1), // Separator before logout
          // Logout item, using an icon as it's a standard action
          _buildNavItem(Icons.logout, "Logout", '/logout', isTopLevel: true),
        ],
      ),
    );
  }

  // Helper to build the leading widget (Icon or Image) for a sidebar item
  Widget _buildLeadingWidget(SidebarItem item) {
    // Now only checks for icon, as imagePath is not used for top-level items anymore
    // but the property still exists on SidebarItem for potential future use or other items.
    return Icon(item.icon, color: Colors.white);
  }

  // Builds an expandable item for parent categories (only when sidebar is expanded)
  Widget _buildExpandableNavItem(SidebarItem item) {
    if (item.children == null || item.children!.isEmpty) {
      // This case handles a top-level item that is NOT a parent,
      // but if you have such an item, it should probably go through _buildNavItem directly.
      // For this structure, all top-level items are parents.
      return _buildNavItem(item.icon, item.label, item.route ?? '', isTopLevel: true, imagePath: item.imagePath);
    }

    return Theme(
      data: Theme.of(context).copyWith(dividerColor: Colors.transparent), // Hide divider in expansion tile
      child: ExpansionTile(
        initiallyExpanded: false, // You can set this to true if you want some categories open by default
        leading: _buildLeadingWidget(item), // Use the helper for leading widget
        title: Text(item.label, style: const TextStyle(color: Colors.white)),
        iconColor: Colors.white,
        collapsedIconColor: Colors.white,
        childrenPadding: const EdgeInsets.only(left: 20.0), // Indent sub-items
        children: item.children!.map((childItem) {
          if (childItem.isParent) {
            // Nested expansion tiles for sub-categories like "Manual", "Continuous"
            return _buildExpandableNavItem(childItem);
          } else {
            // Leaf item (actual navigation link)
            return _buildNavItem(childItem.icon, childItem.label, childItem.route ?? '', imagePath: childItem.imagePath);
          }
        }).toList(),
      ),
    );
  }

  // Builds a regular navigation item (for sub-items when expanded, or top-level when collapsed)
  Widget _buildNavItem(IconData? icon, String label, String route, {bool isTopLevel = false, String? imagePath}) {
    return InkWell(
      onTap: () {
        if (route.isNotEmpty) {
          widget.onNavigate(route);
        }
      },
      child: Padding(
        padding: EdgeInsets.symmetric(
          vertical: 12,
          horizontal: isTopLevel && widget.isCollapsed ? 0 : 8, // Center icon if top-level and collapsed
        ),
        child: isTopLevel && widget.isCollapsed
            ? Center(
          child: icon != null
              ? Icon(icon, color: Colors.white)
              : const SizedBox.shrink(), // Fallback if no icon or imagePath
        ) // Only icon when collapsed
            : Row(
          children: [
            icon != null
                ? Icon(icon, color: Colors.white)
                : const SizedBox.shrink(), // Fallback if no icon or imagePath
            const SizedBox(width: 12),
            Expanded( // Use Expanded to prevent text overflow
              child: Text(label, style: const TextStyle(color: Colors.white)),
            ),
          ],
        ),
      ),
    );
  }

  // Builds a collapsed navigation item (only icon/image) for top-level categories
  Widget _buildCollapsedNavItem(SidebarItem item) {
    return InkWell(
      onTap: () {
        if (item.route != null && item.route!.isNotEmpty) {
          widget.onNavigate(item.route!);
        } else {
          // If a parent item is tapped when collapsed, expand the sidebar
          widget.onToggle();
        }
      },
      child: Padding(
        padding: const EdgeInsets.symmetric(vertical: 8.0, horizontal: 0), // Adjusted vertical padding
        child: Column(
          mainAxisSize: MainAxisSize.min, // Use minimum space
          children: [
            item.icon != null
                ? Icon(item.icon, color: Colors.white, size: 24) // Icon size
                : const SizedBox.shrink(), // Fallback if no icon
            const SizedBox(height: 4), // Small space between icon and text
            Text(
              item.label,
              style: const TextStyle(
                color: Colors.white,
                fontSize: 10, // Smaller font size to fit
              ),
              overflow: TextOverflow.ellipsis, // Handle long labels
              maxLines: 1, // Ensure it stays on one line
              textAlign: TextAlign.center, // Center the text
            ),
          ],
        ),
      ),
    );
  }
}
