buzz/mobile/lib/shared/identity_transfer/nsec_import_sheet.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

import '../hosted/account_identity_store.dart';
import '../theme/theme.dart';
import '../utils/string_utils.dart';
import '../widgets/modal_presentation.dart';
import '../widgets/onboarding_step_page.dart';
import 'nsec_transfer.dart';

/// Lets the user inspect the public identity before explicitly importing it.
/// [onImport] is the secure persistence boundary, not an observable UI store.
Future<bool> showNsecImportSheet(
  BuildContext context, {
  required Future<void> Function(String nsec) onImport,
  String? mismatchMessage,
}) async =>
    await showBuzzModalBottomSheet<bool>(
      context: context,
      title: 'Import identity',
      isScrollControlled: true,
      builder: (_) =>
          NsecImportSheet(onImport: onImport, mismatchMessage: mismatchMessage),
    ) ??
    false;

/// Transient secret input; only public preview and safe errors are displayed.
class NsecImportSheet extends HookWidget {
  const NsecImportSheet({
    super.key,
    required this.onImport,
    this.pickFile,
    this.mismatchMessage,
    this.autofocus = true,
    this.fullScreen = false,
    this.onBack,
  });

  final Future<void> Function(String nsec) onImport;
  final Future<String?> Function()? pickFile;
  final String? mismatchMessage;

  /// Allows a containing sheet to finish expanding before opening the keyboard.
  final bool autofocus;
  final bool fullScreen;
  final VoidCallback? onBack;

  @override
  Widget build(BuildContext context) {
    final input = useTextEditingController();
    final focus = useFocusNode();
    final autofocusRef = useRef(autofocus)..value = autofocus;
    useEffect(() {
      if (autofocus && defaultTargetPlatform == TargetPlatform.iOS) {
        WidgetsBinding.instance.addPostFrameCallback((_) {
          if (context.mounted && autofocusRef.value) focus.requestFocus();
        });
      }
      return null;
    }, [autofocus]);
    final publicKey = useState<String?>(null);
    final error = useState<String?>(null);
    final busy = useState(false);
    final cancelled = useRef(false);

    Future<void> chooseFile() async {
      busy.value = true;
      error.value = null;
      try {
        final text = await (pickFile ?? NsecTransfer.pickFile)();
        if (!context.mounted || cancelled.value || text == null) return;
        final preview = NsecTransfer.preview(text);
        input.text = text.trim();
        publicKey.value = preview;
      } catch (_) {
        if (context.mounted && !cancelled.value) {
          error.value = 'Choose a text file containing one valid nsec.';
        }
      } finally {
        if (context.mounted && !cancelled.value) busy.value = false;
      }
    }

    Future<void> submit() async {
      error.value = null;
      try {
        final preview = NsecTransfer.preview(input.text);
        if (publicKey.value != preview) {
          publicKey.value = preview;
          return;
        }
        busy.value = true;
        await onImport(input.text.trim());
        if (!context.mounted || cancelled.value) return;
        input.clear();
        Navigator.of(context).pop(true);
      } catch (failure) {
        if (!context.mounted || cancelled.value) return;
        error.value = switch (failure) {
          AccountIdentityFailure.mismatch =>
            mismatchMessage ??
                'This device already has a different identity. It has not been replaced.',
          AccountIdentityFailure.occupied =>
            'This device already has a different identity. It has not been replaced.',
          AccountIdentityFailure.invalidKey =>
            'Enter a valid nsec private key.',
          _ =>
            'Could not finish importing this identity. Try again with the same key.',
        };
      } finally {
        if (context.mounted && !cancelled.value) busy.value = false;
      }
    }

    final children = <Widget>[
      if (defaultTargetPlatform == TargetPlatform.iOS)
        CupertinoTextField(
          controller: input,
          placeholder: 'Private key (nsec)',
          padding: const EdgeInsets.all(Grid.gutter),
          decoration: BoxDecoration(
            color: CupertinoColors.secondarySystemGroupedBackground.resolveFrom(
              context,
            ),
            borderRadius: BorderRadius.circular(Radii.container),
          ),
          focusNode: focus,
          maxLength: 1024,
          enabled: !busy.value,
          obscureText: true,
          autocorrect: false,
          enableSuggestions: false,
          enableIMEPersonalizedLearning: false,
          onChanged: (_) {
            publicKey.value = null;
            error.value = null;
          },
        )
      else
        TextField(
          controller: input,
          maxLength: 1024,
          enabled: !busy.value,
          obscureText: true,
          autocorrect: false,
          enableSuggestions: false,
          enableIMEPersonalizedLearning: false,
          decoration: const InputDecoration(labelText: 'Private key (nsec)'),
          onChanged: (_) {
            publicKey.value = null;
            error.value = null;
          },
        ),
      const SizedBox(height: Grid.xs),
      TextButton(
        style: TextButton.styleFrom(
          minimumSize: const Size.fromHeight(52),
          shape: const StadiumBorder(),
        ),
        onPressed: busy.value ? null : chooseFile,
        child: const Text('Choose nsec file'),
      ),
      if (publicKey.value != null) ...[
        const Text('Confirm this is the public identity you want to use:'),
        const SizedBox(height: Grid.xs),
        SelectableText(fullNpub(publicKey.value!)!),
        const SizedBox(height: Grid.sm),
      ],
      if (error.value != null)
        Text(error.value!, style: TextStyle(color: context.colors.error)),
      const SizedBox(height: Grid.xs),
      FilledButton(
        style: FilledButton.styleFrom(
          minimumSize: const Size.fromHeight(52),
          shape: const StadiumBorder(),
        ),
        onPressed: busy.value ? null : submit,
        child: Text(
          busy.value
              ? 'Importing…'
              : publicKey.value == null
              ? 'Preview identity'
              : 'Import this identity',
        ),
      ),
    ];
    if (fullScreen) {
      return OnboardingStepPage(
        title: 'Import identity',
        subtitle:
            'Bring your Buzz identity from another device. Check the public identity before continuing.',
        onBack: () {
          if (cancelled.value || (onBack == null && busy.value)) return;
          cancelled.value = true;
          if (onBack != null) {
            onBack!();
          } else {
            Navigator.of(context).pop(false);
          }
        },
        content: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: children.sublist(0, children.length - 1),
        ),
        actions: [children.last],
      );
    }
    return SafeArea(
      child: SingleChildScrollView(
        padding: EdgeInsets.fromLTRB(
          Grid.gutter,
          Grid.xs,
          Grid.gutter,
          Grid.gutter + MediaQuery.viewInsetsOf(context).bottom,
        ),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: children,
        ),
      ),
    );
  }
}