import 'package:flutter/cupertino.dart';
import 'package:please_pay_me/core/format/formatters.dart';
import 'package:please_pay_me/data/models/budget.dart';
import 'package:please_pay_me/data/models/job.dart';
import 'package:please_pay_me/features/budgets/budget_form_sheet.dart';
import 'package:please_pay_me/features/budgets/budgets_controller.dart';
import 'package:please_pay_me/features/expenses/expense_actions.dart';
import 'package:please_pay_me/features/journal/journal_controller.dart';
import 'package:please_pay_me/features/work/jobs_controller.dart';
import 'package:please_pay_me/theme/theme.dart';
import 'package:please_pay_me/ui/ui.dart';
import 'package:provider/provider.dart';

/// Home tab: current envelope, today's allowance and quick actions.
class OverviewScreen extends StatelessWidget {
  const OverviewScreen({super.key});

  @override
  Widget build(BuildContext context) {
    final budgets = context.watch<BudgetsController>();

    return CupertinoPageScaffold(
      backgroundColor: AppColors.of(context, AppColors.groupedBackground),
      child: CustomScrollView(
        physics: const BouncingScrollPhysics(parent: AlwaysScrollableScrollPhysics()),
        slivers: [
          const AppLargeNavBar(title: 'Обзор'),
          CupertinoSliverRefreshControl(
            onRefresh: () async {
              await Future.wait([
                budgets.load(silent: true),
                context.read<JobsController>().load(silent: true),
                context.read<JournalController>().load(silent: true),
              ]);
            },
          ),
          SliverToBoxAdapter(
            child: budgets.state.map(
              loading: () => const AppLoadingView(),
              error: (message) => AppErrorView(message: message, onRetry: budgets.load),
              data: (_) {
                final selected = budgets.selected;
                if (selected == null) return _NoBudgets(controller: budgets);
                return _OverviewBody(status: selected);
              },
            ),
          ),
          const SliverToBoxAdapter(child: SizedBox(height: AppSpacing.s7)),
        ],
      ),
    );
  }
}

class _NoBudgets extends StatelessWidget {
  const _NoBudgets({required this.controller});

  final BudgetsController controller;

  @override
  Widget build(BuildContext context) {
    return AppEmptyState(
      icon: CupertinoIcons.money_rubl_circle,
      title: 'Бюджета пока нет',
      message: 'Создайте конверт до следующей зарплаты — приложение посчитает дневной лимит.',
      actionLabel: 'Создать бюджет',
      onAction: () => showBudgetFormSheet(context: context, controller: controller),
    );
  }
}

class _OverviewBody extends StatelessWidget {
  const _OverviewBody({required this.status});

  final BudgetStatus status;

  @override
  Widget build(BuildContext context) {
    final budgets = context.watch<BudgetsController>();
    final currency = status.budget.currency;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        AppCard(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Row(
                children: [
                  Expanded(child: AppText.headline(status.budget.name)),
                  AppChip(
                    label: status.isExpired
                        ? 'Завершён'
                        : formatDaysLeft(status.daysLeft).replaceFirst('осталось ', ''),
                    selected: !status.isExpired,
                  ),
                ],
              ),
              const SizedBox(height: AppSpacing.s3),
              const AppText.footnote('Остаток бюджета'),
              AppText.largeTitle(
                formatMoney(status.remaining, currency: currency),
                color: status.isOverBudget ? AppColors.systemRed : AppColors.label,
              ),
              const SizedBox(height: AppSpacing.s4),
              AppProgressBar(
                value: status.spentProgress,
                color: status.isOverBudget ? AppColors.systemRed : AppColors.accent,
              ),
              const SizedBox(height: AppSpacing.s2),
              AppText.footnote(
                'Потрачено ${formatMoney(status.totalSpent, currency: currency)} '
                'из ${formatMoney(status.budget.totalAmount, currency: currency)}',
              ),
            ],
          ),
        ),
        const SizedBox(height: AppSpacing.s4),
        _TodayCard(status: status),
        const SizedBox(height: AppSpacing.s4),
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: AppSpacing.gutter),
          child: Row(
            children: [
              Expanded(
                child: AppButton(
                  label: 'Добавить трату',
                  icon: CupertinoIcons.plus,
                  onPressed: budgets.isMutating
                      ? null
                      : () => showExpenseFormSheet(context: context, controller: budgets),
                ),
              ),
              const SizedBox(width: AppSpacing.s3),
              AppButton(
                label: 'Отменить',
                style: AppButtonStyle.gray,
                expanded: false,
                onPressed: budgets.isMutating
                    ? null
                    : () => undoLastExpense(context: context, controller: budgets),
              ),
            ],
          ),
        ),
        const SizedBox(height: AppSpacing.s5),
        const _NextPaySection(),
        const _RecentOperations(),
      ],
    );
  }
}

class _TodayCard extends StatelessWidget {
  const _TodayCard({required this.status});

  final BudgetStatus status;

  @override
  Widget build(BuildContext context) {
    final currency = status.budget.currency;
    final overspent = status.isOverDaily;

    return AppCard(
      title: 'Сегодня',
      subtitle: formatDay(status.today),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Expanded(
                child: _Metric(
                  label: 'Дневной лимит',
                  value: formatMoney(status.dailyLimit, currency: currency),
                ),
              ),
              Expanded(
                child: _Metric(
                  label: 'Потрачено',
                  value: formatMoney(status.spentToday, currency: currency),
                  color: overspent ? AppColors.systemRed : AppColors.label,
                ),
              ),
            ],
          ),
          const SizedBox(height: AppSpacing.s4),
          AppProgressBar(
            value: status.dailyProgress,
            color: overspent ? AppColors.systemRed : AppColors.systemGreen,
          ),
          const SizedBox(height: AppSpacing.s2),
          AppText.footnote(
            overspent
                ? 'Лимит превышен на ${formatMoney(status.spentToday - status.dailyLimit, currency: currency)}'
                : 'Можно потратить ещё ${formatMoney(status.remainingToday, currency: currency)}',
            color: overspent ? AppColors.systemRed : AppColors.secondaryLabel,
          ),
        ],
      ),
    );
  }
}

class _Metric extends StatelessWidget {
  const _Metric({required this.label, required this.value, this.color = AppColors.label});

  final String label;
  final String value;
  final Color color;

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        AppText.footnote(label),
        const SizedBox(height: 2),
        AppText.title(value, color: color),
      ],
    );
  }
}

class _NextPaySection extends StatelessWidget {
  const _NextPaySection();

  @override
  Widget build(BuildContext context) {
    final jobs = context.watch<JobsController>();
    final pay = jobs.nextPay;
    if (pay == null) return const SizedBox.shrink();

    return Padding(
      padding: const EdgeInsets.only(bottom: AppSpacing.s5),
      child: AppListSection(
        header: 'Ближайшая выплата',
        separatorIndent: 60,
        children: [
          AppListTile(
            leading: const AppIconBadge(
              icon: CupertinoIcons.money_rubl_circle_fill,
              color: AppColors.systemGreen,
            ),
            title: formatMoney(pay.amount),
            subtitle: '${formatDay(pay.date)} · ${pay.percent.round()}% оклада',
            value: _daysUntil(pay),
            showChevron: false,
          ),
        ],
      ),
    );
  }

  String _daysUntil(UpcomingPay pay) {
    final now = DateTime.now();
    final days = pay.date.difference(DateTime(now.year, now.month, now.day)).inDays;
    return switch (days) {
      <= 0 => 'сегодня',
      1 => 'завтра',
      _ => 'через ${plural(days, 'день', 'дня', 'дней')}',
    };
  }
}

class _RecentOperations extends StatelessWidget {
  const _RecentOperations();

  @override
  Widget build(BuildContext context) {
    final journal = context.watch<JournalController>();
    final recent = journal.items.take(3).toList();
    if (recent.isEmpty) return const SizedBox.shrink();

    return AppListSection(
      header: 'Последние операции',
      children: [
        for (final expense in recent)
          AppListTile(
            title: expense.note ?? 'Без комментария',
            subtitle: formatRelativeDay(expense.spentAt),
            value: formatSignedMoney(expense.amount),
            showChevron: false,
          ),
      ],
    );
  }
}