import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:on_field_work/controller/project_controller.dart';
import 'package:on_field_work/controller/expense/expense_screen_controller.dart';
import 'package:on_field_work/controller/permission_controller.dart';
import 'package:on_field_work/helpers/widgets/my_text.dart';
import 'package:on_field_work/helpers/widgets/my_custom_skeleton.dart';
import 'package:on_field_work/model/expense/expense_list_model.dart';
import 'package:on_field_work/model/expense/add_expense_bottom_sheet.dart';
import 'package:on_field_work/view/expense/expense_filter_bottom_sheet.dart';
import 'package:on_field_work/helpers/widgets/expense/expense_main_components.dart';
import 'package:on_field_work/helpers/utils/permission_constants.dart';
import 'package:on_field_work/helpers/widgets/my_refresh_indicator.dart';
import 'package:on_field_work/helpers/utils/mixins/ui_mixin.dart';
import 'package:on_field_work/helpers/widgets/custom_app_bar.dart';

class ExpenseMainScreen extends StatefulWidget {
  const ExpenseMainScreen({super.key});

  @override
  State<ExpenseMainScreen> createState() => _ExpenseMainScreenState();
}

class _ExpenseMainScreenState extends State<ExpenseMainScreen>
    with SingleTickerProviderStateMixin, UIMixin {
  late TabController _tabController;
  final searchController = TextEditingController();
  final expenseController = Get.put(ExpenseController());
  final projectController = Get.find<ProjectController>();
  final permissionController = Get.put(PermissionController());

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: 2, vsync: this);

    // Defer expense fetch to after first build
    WidgetsBinding.instance.addPostFrameCallback((_) {
      expenseController.fetchExpenses();
    });
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }

  Future<void> _refreshExpenses() async {
    await expenseController.fetchExpenses();
  }

  void _openFilterBottomSheet() {
    showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      backgroundColor: Colors.transparent,
      builder: (_) => ExpenseFilterBottomSheet(
        expenseController: expenseController,
        scrollController: ScrollController(),
      ),
    );
  }

  List<ExpenseModel> _getFilteredExpenses({required bool isHistory}) {
    final query = searchController.text.trim().toLowerCase();
    final now = DateTime.now();

    final filtered = expenseController.expenses.where((e) {
      return query.isEmpty ||
          e.expenseCategory.name.toLowerCase().contains(query) ||
          e.supplerName.toLowerCase().contains(query) ||
          e.paymentMode.name.toLowerCase().contains(query);
    }).toList()
      ..sort((a, b) => b.transactionDate.compareTo(a.transactionDate));

    return isHistory
        ? filtered
            .where((e) =>
                e.transactionDate.isBefore(DateTime(now.year, now.month)))
            .toList()
        : filtered
            .where((e) =>
                e.transactionDate.month == now.month &&
                e.transactionDate.year == now.year)
            .toList();
  }

  @override
  Widget build(BuildContext context) {
    final Color appBarColor = contentTheme.primary;

    return Scaffold(
      backgroundColor: Colors.white,
      appBar: CustomAppBar(
        title: "Expense & Reimbursement",
        backgroundColor: appBarColor,
        onBackPressed: () => Get.toNamed('/dashboard/finance'),
      ),
      body: Stack(
        children: [
          // === FULL GRADIENT BEHIND APPBAR & TABBAR ===
          Positioned.fill(
            child: Column(
              children: [
                Container(
                  height: 80,
                  decoration: BoxDecoration(
                    gradient: LinearGradient(
                      begin: Alignment.topCenter,
                      end: Alignment.bottomCenter,
                      colors: [
                        appBarColor,
                        appBarColor.withOpacity(0.0),
                      ],
                    ),
                  ),
                ),
                Expanded(
                  child:
                      Container(color: Colors.grey[100]), 
                ),
              ],
            ),
          ),

          // === MAIN CONTENT ===
          SafeArea(
            top: false, 
            bottom: true,
            child: Column(
              children: [
                // TAB BAR WITH TRANSPARENT BACKGROUND
                Container(
                  decoration: const BoxDecoration(color: Colors.transparent),
                  child: TabBar(
                    controller: _tabController,
                    labelColor: Colors.white,
                    unselectedLabelColor: Colors.white70,
                    indicatorColor: Colors.white,
                    indicatorWeight: 3,
                    tabs: const [
                      Tab(text: "Current Month"),
                      Tab(text: "History"),
                    ],
                  ),
                ),

                // CONTENT AREA
                Expanded(
                  child: Container(
                    color: Colors.transparent, 
                    child: Column(
                      children: [
                        // SEARCH & FILTER
                        Padding(
                          padding: const EdgeInsets.symmetric(horizontal: 0),
                          child: SearchAndFilter(
                            controller: searchController,
                            onChanged: (_) => setState(() {}),
                            onFilterTap: _openFilterBottomSheet,
                            expenseController: expenseController,
                          ),
                        ),

                        // TABBAR VIEW
                        Expanded(
                          child: TabBarView(
                            controller: _tabController,
                            children: [
                              _buildExpenseList(isHistory: false),
                              _buildExpenseList(isHistory: true),
                            ],
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
      floatingActionButton: Obx(() {
        if (permissionController.permissions.isEmpty)
          return const SizedBox.shrink();

        final canUpload =
            permissionController.hasPermission(Permissions.expenseUpload);

        return canUpload
            ? FloatingActionButton.extended(
                backgroundColor: contentTheme.primary,
                onPressed: showAddExpenseBottomSheet,
                icon: const Icon(Icons.add, color: Colors.white),
                label: const Text(
                  "Add Expense",
                  style: TextStyle(color: Colors.white, fontSize: 16),
                ),
              )
            : const SizedBox.shrink();
      }),
    );
  }

  Widget _buildExpenseList({required bool isHistory}) {
    return Obx(() {
      if (expenseController.isLoading.value &&
          expenseController.expenses.isEmpty) {
        return SkeletonLoaders.expenseListSkeletonLoader();
      }

      final filteredList = _getFilteredExpenses(isHistory: isHistory);

      return MyRefreshIndicator(
        onRefresh: _refreshExpenses,
        child: filteredList.isEmpty
            ? ListView(
                physics: const AlwaysScrollableScrollPhysics(),
                children: [
                  SizedBox(
                    height: MediaQuery.of(context).size.height * 0.5,
                    child: Center(
                      child: MyText.bodyMedium(
                        expenseController.errorMessage.isNotEmpty
                            ? expenseController.errorMessage.value
                            : "No expenses found",
                        color: expenseController.errorMessage.isNotEmpty
                            ? Colors.red
                            : Colors.grey,
                      ),
                    ),
                  ),
                ],
              )
            : NotificationListener<ScrollNotification>(
                onNotification: (scrollInfo) {
                  if (scrollInfo.metrics.pixels ==
                          scrollInfo.metrics.maxScrollExtent &&
                      !expenseController.isLoading.value) {
                    expenseController.loadMoreExpenses();
                  }
                  return false;
                },
                child: ExpenseList(
                  expenseList: filteredList,
                  onViewDetail: () => expenseController.fetchExpenses(),
                ),
              ),
      );
    });
  }
}