import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:provider/provider.dart';

import '../services/app_state.dart';
import 'faq_screen.dart';

/// The very first thing shown on a fresh install — before the onboarding
/// tour, before anything else — gating [MainShell] entirely until the user
/// taps "I Agree" (see [AppRoot] in main.dart and
/// [AppState.hasAcceptedUserAgreement]/[AppState.acceptUserAgreement]).
/// Its whole purpose is the liability section below: this app stores data
/// on the user's own device (and, optionally, their own cloud storage
/// account) with no server or backend of ours involved, so we have no
/// ability to recover anything for them if it's lost — plus the privacy
/// section, disclosing that we don't track/log anything ourselves, and
/// that AdMob (only active for users on the free, ad-supported tier) is
/// the sole source of any data collection, governed by Google's own
/// practices rather than anything this app adds.
class UserAgreementScreen extends StatelessWidget {
  /// True when reached from Settings (see [SettingsScreen]) to re-read the
  /// agreement/privacy policy at any time — required so this content stays
  /// reachable in the app beyond the one-time first-launch gate, not just
  /// something a user saw once and can never get back to. Hides the
  /// Decline/I Agree actions (already answered, and "Decline" quitting the
  /// app would be a bizarre side effect of just re-reading this) and shows
  /// a normal back button instead of gating navigation away entirely.
  final bool isReview;

  const UserAgreementScreen({super.key, this.isReview = false});

  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;

    return Scaffold(
      appBar: AppBar(
        title: const Text('User Agreement'),
        automaticallyImplyLeading: isReview,
      ),
      body: SafeArea(
        child: Column(
          children: [
            Expanded(
              child: ListView(
                padding: const EdgeInsets.all(20),
                children: [
                  Text(
                    isReview
                        ? 'This is the agreement you accepted when you first opened Show Me '
                            'The Fuel Refund.'
                        : 'Please read and accept the following before using Show Me The Fuel '
                            'Refund.',
                    style: textTheme.bodyLarge,
                  ),
                  const SizedBox(height: 20),
                  _Section(
                    title: 'Your Data Lives on Your Device',
                    body:
                        'Every vehicle, fuel receipt, and photo you log is stored locally on '
                        'this device. If you connect a cloud storage account (Google Drive, '
                        'Dropbox, OneDrive, or your own WebDAV server) in Settings, a copy is '
                        'also kept there — in storage you control, not on any server we run. '
                        "We don't operate a backend, and we don't have a copy of your data.\n\n"
                        "This is also how sharing works: if the folder you connect to is one "
                        "you share with someone else, anyone else who connects the app to "
                        "that same folder sees and can edit the same vehicles, fuel entries, "
                        "and receipt photos you do. Data in a shared folder isn't private to "
                        "just you.",
                  ),
                  _Section(
                    title: 'Privacy',
                    body:
                        "We don't track or log your data in any way — there's no analytics, no "
                        "crash reporting, and no server of ours receiving anything you enter. If "
                        'you haven\'t purchased "Remove Ads for a Year" and are using the free, '
                        'ad-supported version, the only data collected is whatever Google AdMob '
                        'itself requires to serve ads (e.g. a device advertising identifier) — '
                        "that collection is Google's, governed by its own privacy practices, not "
                        'something this app adds on top of.',
                  ),
                  _Section(
                    title: 'We Are Not Responsible for Your Data or Any Data Loss',
                    body:
                        'The developer is not responsible for your data, or for any loss, '
                        'corruption, or unavailability of it, for any reason — including but '
                        'not limited to device loss, theft, or damage; an uninstall or app/OS '
                        'update; a bug in this app; or an outage or account issue with a cloud '
                        'storage provider you connect. Backing up your data (by connecting a '
                        'cloud storage account, and by keeping it connected and in good '
                        'standing) is entirely your responsibility. If you never connect a '
                        'backup, the only copy of your data is the one on this device.',
                  ),
                  _Section(
                    title: 'Provided As-Is',
                    body:
                        'This app is provided "as is," without warranty of any kind, express or '
                        'implied. Fuel and gallon values are read automatically from your '
                        'receipt photos and may be misread — always review them before relying '
                        'on them, including for a refund claim.',
                  ),
                  _Section(
                    title: 'Not Tax or Legal Advice',
                    body:
                        'This app is purely informational. Missouri actually offers two '
                        'separate fuel tax refunds — up to 12.5¢ per gallon for highway use, '
                        "and up to 29.5¢ per gallon for non-highway use — and it's worth "
                        "evaluating both to see how you could benefit. This app helps you "
                        "organize the receipts you'd need for either one.\n\n"
                        "Nothing here is tax or legal advice, and using this app doesn't "
                        'guarantee your eligibility for either refund. For guidance on your '
                        'specific situation, consult a tax professional. Both refunds are set '
                        'by Missouri law, which can change at any time — always confirm '
                        'current eligibility and rates with the Missouri Department of '
                        'Revenue before filing.',
                  ),
                  Align(
                    alignment: Alignment.centerLeft,
                    child: TextButton.icon(
                      onPressed: () => Navigator.of(context).push(
                        MaterialPageRoute(builder: (_) => const FaqScreen()),
                      ),
                      icon: const Icon(Icons.help_outline),
                      label: const Text('See the FAQ for more'),
                    ),
                  ),
                  const SizedBox(height: 8),
                ],
              ),
            ),
            if (!isReview) ...[
              const Divider(height: 1),
              Padding(
                padding: const EdgeInsets.all(16),
                child: Row(
                  children: [
                    Expanded(
                      child: OutlinedButton(
                        onPressed: () => SystemNavigator.pop(),
                        child: const Text('Decline'),
                      ),
                    ),
                    const SizedBox(width: 12),
                    Expanded(
                      child: FilledButton(
                        onPressed: () => context.read<AppState>().acceptUserAgreement(),
                        child: const Text('I Agree'),
                      ),
                    ),
                  ],
                ),
              ),
            ],
          ],
        ),
      ),
    );
  }
}

class _Section extends StatelessWidget {
  final String title;
  final String body;

  const _Section({required this.title, required this.body});

  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;
    return Padding(
      padding: const EdgeInsets.only(bottom: 20),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(title, style: textTheme.titleMedium?.copyWith(fontWeight: FontWeight.w700)),
          const SizedBox(height: 6),
          Text(body, style: textTheme.bodyMedium),
        ],
      ),
    );
  }
}