// Author: fruit.com.cn

import 'dart:async';

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

import '../../core/data/remote/api_client.dart';
import '../../core/data/services/auth_controller.dart';
import '../../core/platform/haptics.dart';
import '../../core/platform/keyboard_inset.dart';
import '../../core/theme/app_colors.dart';
import '../../core/widgets/centered_toast.dart';
import '../../l10n/app_localizations.dart';

const double _fieldHeight = 52;
const double _fieldRadius = 14;
const double _sheetRadius = 28;
const double _buttonHeight = 52;
const int _resendSeconds = 60;
const int _phoneMinLength = 8;
const int _codeMinLength = 4;

/// 打开手机号 OTP 登录/注册表单；成功登录后返回 true。
Future<bool?> showPhoneAuthSheet(BuildContext context, {bool signUp = false}) {
  return showModalBottomSheet<bool>(
    context: context,
    isScrollControlled: true,
    useSafeArea: true,
    backgroundColor: Colors.transparent,
    barrierColor: Colors.black.withValues(alpha: 0.62),
    builder: (_) => PhoneAuthSheet(initialSignUp: signUp),
  );
}

class PhoneAuthSheet extends StatefulWidget {
  const PhoneAuthSheet({super.key, this.initialSignUp = false});

  final bool initialSignUp;

  @override
  State<PhoneAuthSheet> createState() => _PhoneAuthSheetState();
}

class _PhoneAuthSheetState extends State<PhoneAuthSheet> {
  late final TextEditingController _phone;
  late final TextEditingController _code;
  late final FocusNode _phoneFocus;
  late final FocusNode _codeFocus;
  late final ScrollController _scrollController;
  final _keyboardInset = KeyboardInsetNotifier.instance;
  Timer? _countdown;
  double _lastKeyboardInset = 0;
  bool _signUp = false;
  bool _sending = false;
  bool _submitting = false;
  int _remaining = 0;
  String? _error;

  @override
  void initState() {
    super.initState();
    _signUp = widget.initialSignUp;
    _phone = TextEditingController();
    _code = TextEditingController();
    _phoneFocus = FocusNode(debugLabel: 'phone-auth-number');
    _codeFocus = FocusNode(debugLabel: 'phone-auth-code');
    _scrollController = ScrollController();
    _phoneFocus.addListener(_onFocusChanged);
    _codeFocus.addListener(_onFocusChanged);
    _keyboardInset.addListener(_onKeyboardInsetChanged);
    unawaited(_keyboardInset.start());
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    final inset = effectiveKeyboardInset(context, _keyboardInset);
    if ((inset - _lastKeyboardInset).abs() >= 1) {
      _lastKeyboardInset = inset;
      _scheduleRevealFocusedField();
    }
  }

  @override
  void dispose() {
    _keyboardInset.removeListener(_onKeyboardInsetChanged);
    _phoneFocus.removeListener(_onFocusChanged);
    _codeFocus.removeListener(_onFocusChanged);
    _countdown?.cancel();
    _phone.dispose();
    _code.dispose();
    _phoneFocus.dispose();
    _codeFocus.dispose();
    _scrollController.dispose();
    super.dispose();
  }

  void _onKeyboardInsetChanged() {
    if (!mounted) return;
    setState(() {});
    _scheduleRevealFocusedField();
  }

  void _onFocusChanged() {
    if (_phoneFocus.hasFocus || _codeFocus.hasFocus) {
      _scheduleRevealFocusedField();
    }
  }

  void _scheduleRevealFocusedField() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) _revealFocusedField();
    });
  }

  void _revealFocusedField() {
    if (!_scrollController.hasClients) return;
    final focus = _codeFocus.hasFocus
        ? _codeFocus
        : _phoneFocus.hasFocus
        ? _phoneFocus
        : null;
    final fieldContext = focus?.context;
    final renderObject = fieldContext?.findRenderObject();
    if (renderObject is! RenderBox || !renderObject.hasSize) return;
    final keyboardInset = effectiveKeyboardInset(context, _keyboardInset);
    if (keyboardInset <= 0) return;
    final fieldBottom = renderObject
        .localToGlobal(Offset(0, renderObject.size.height))
        .dy;
    final visibleBottom =
        MediaQuery.sizeOf(context).height - keyboardInset - 24;
    final overlap = fieldBottom - visibleBottom;
    if (overlap <= 0) return;
    final position = _scrollController.position;
    final target = (position.pixels + overlap)
        .clamp(position.minScrollExtent, position.maxScrollExtent)
        .toDouble();
    if (target <= position.pixels + 0.5) return;
    unawaited(
      _scrollController.animateTo(
        target,
        duration: const Duration(milliseconds: 200),
        curve: Curves.easeOutCubic,
      ),
    );
  }

  String get _target => _phone.text.replaceAll(RegExp(r'[\s-]'), '');

  bool get _phoneValid => _target.length >= _phoneMinLength;

  Future<void> _sendCode() async {
    if (_sending || _remaining > 0) return;
    final l10n = AppLocalizations.of(context)!;
    if (!_phoneValid) {
      setState(() => _error = l10n.authPhoneInvalid);
      return;
    }
    setState(() {
      _sending = true;
      _error = null;
    });
    final haptics = context.read<Haptics>();
    final auth = context.read<AuthController>();
    String? failureMessage;
    await haptics.lightImpact();
    try {
      await auth.sendOtp(
        target: _target,
        scene: _signUp ? 'REGISTER' : 'LOGIN',
      );
      if (!mounted) return;
      _startCountdown();
      setState(() => _error = null);
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(SnackBar(content: Text(l10n.authCodeSent)));
      _codeFocus.requestFocus();
    } on ApiException catch (error) {
      failureMessage = error.message;
    } catch (_) {
      failureMessage = l10n.authNetworkError;
    } finally {
      if (mounted) setState(() => _sending = false);
    }
    if (mounted && failureMessage != null) {
      showCenteredToast(context, failureMessage);
    }
  }

  void _startCountdown() {
    _countdown?.cancel();
    _remaining = _resendSeconds;
    _countdown = Timer.periodic(const Duration(seconds: 1), (timer) {
      if (!mounted) return timer.cancel();
      setState(() => _remaining--);
      if (_remaining <= 0) timer.cancel();
    });
  }

  Future<void> _submit() async {
    if (_submitting) return;
    final l10n = AppLocalizations.of(context)!;
    if (!_phoneValid) {
      setState(() => _error = l10n.authPhoneInvalid);
      return;
    }
    if (_code.text.trim().length < _codeMinLength) {
      setState(() => _error = l10n.authCodeRequired);
      return;
    }
    setState(() {
      _submitting = true;
      _error = null;
    });
    final haptics = context.read<Haptics>();
    final auth = context.read<AuthController>();
    String? failureMessage;
    await haptics.lightImpact();
    try {
      if (_signUp) {
        await auth.registerWithPhone(target: _target, code: _code.text.trim());
      } else {
        await auth.signInWithPhone(target: _target, code: _code.text.trim());
      }
      if (mounted) Navigator.of(context).pop(true);
    } on ApiException catch (error) {
      failureMessage = error.message;
    } catch (_) {
      failureMessage = l10n.authNetworkError;
    } finally {
      if (mounted) setState(() => _submitting = false);
    }
    if (mounted && failureMessage != null) {
      showCenteredToast(context, failureMessage);
    }
  }

  void _switchMode() {
    setState(() {
      _signUp = !_signUp;
      _error = null;
    });
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final bottom = effectiveKeyboardInset(context, _keyboardInset);
    return Padding(
      padding: EdgeInsets.only(bottom: bottom),
      child: Container(
        key: const Key('phone-auth-sheet'),
        decoration: const BoxDecoration(
          color: AppColors.card,
          borderRadius: BorderRadius.vertical(
            top: Radius.circular(_sheetRadius),
          ),
        ),
        child: SingleChildScrollView(
          controller: _scrollController,
          padding: const EdgeInsets.fromLTRB(22, 10, 22, 26),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Center(child: _grabber()),
              const SizedBox(height: 16),
              Text(
                _signUp ? l10n.authPhoneSignUp : l10n.authPhoneTitle,
                style: const TextStyle(
                  color: AppColors.onSurface,
                  fontSize: 22,
                  fontWeight: FontWeight.w800,
                ),
              ),
              const SizedBox(height: 6),
              Text(
                l10n.authSubtitle,
                style: const TextStyle(color: AppColors.subtle, fontSize: 12),
              ),
              const SizedBox(height: 20),
              _phoneField(l10n),
              const SizedBox(height: 12),
              _codeField(l10n),
              if (_error != null) ...[
                const SizedBox(height: 10),
                Text(
                  _error!,
                  key: const Key('auth-phone-error'),
                  style: const TextStyle(color: AppColors.accent, fontSize: 12),
                ),
              ],
              const SizedBox(height: 18),
              _submitButton(l10n),
              const SizedBox(height: 8),
              Center(
                child: TextButton(
                  key: const Key('auth-phone-switch'),
                  onPressed: _submitting ? null : _switchMode,
                  style: TextButton.styleFrom(
                    foregroundColor: AppColors.blueSoft,
                    minimumSize: const Size(48, 48),
                  ),
                  child: Text(
                    _signUp ? l10n.authSwitchToSignIn : l10n.authSwitchToSignUp,
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _grabber() => Container(
    width: 40,
    height: 4,
    decoration: BoxDecoration(
      color: AppColors.subtle.withValues(alpha: 0.4),
      borderRadius: BorderRadius.circular(2),
    ),
  );

  Widget _phoneField(AppLocalizations l10n) => SizedBox(
    height: _fieldHeight,
    child: TextField(
      key: const Key('auth-phone-number'),
      controller: _phone,
      focusNode: _phoneFocus,
      enabled: !_submitting,
      keyboardType: TextInputType.phone,
      textInputAction: TextInputAction.next,
      autofillHints: const [AutofillHints.telephoneNumber],
      inputFormatters: [
        FilteringTextInputFormatter.allow(RegExp(r'[0-9+\s-]')),
        LengthLimitingTextInputFormatter(20),
      ],
      onSubmitted: (_) => _codeFocus.requestFocus(),
      onChanged: (_) => setState(() => _error = null),
      style: const TextStyle(color: AppColors.onSurface, fontSize: 15),
      decoration: _decoration(l10n.authPhoneLabel, l10n.authPhoneHint),
    ),
  );

  Widget _codeField(AppLocalizations l10n) => SizedBox(
    height: _fieldHeight,
    child: TextField(
      key: const Key('auth-phone-code'),
      controller: _code,
      focusNode: _codeFocus,
      enabled: !_submitting,
      keyboardType: TextInputType.number,
      textInputAction: TextInputAction.done,
      autofillHints: const [AutofillHints.oneTimeCode],
      inputFormatters: [
        FilteringTextInputFormatter.digitsOnly,
        LengthLimitingTextInputFormatter(6),
      ],
      onSubmitted: (_) => _submit(),
      onChanged: (_) => setState(() => _error = null),
      style: const TextStyle(color: AppColors.onSurface, fontSize: 15),
      decoration: _decoration(
        l10n.authCodeLabel,
        l10n.authCodeHint,
      ).copyWith(suffixIcon: _sendButton(l10n)),
    ),
  );

  Widget _sendButton(AppLocalizations l10n) => Padding(
    padding: const EdgeInsets.only(right: 6),
    child: TextButton(
      key: const Key('auth-send-code'),
      onPressed: _sending || _remaining > 0 ? null : _sendCode,
      style: TextButton.styleFrom(
        foregroundColor: AppColors.blueSoft,
        minimumSize: const Size(48, 48),
        padding: const EdgeInsets.symmetric(horizontal: 10),
      ),
      child: _sending
          ? const SizedBox(
              width: 16,
              height: 16,
              child: CircularProgressIndicator(strokeWidth: 2),
            )
          : Text(
              _remaining > 0
                  ? l10n.authResendCode(_remaining)
                  : l10n.authSendCode,
              style: const TextStyle(fontSize: 12, fontWeight: FontWeight.w700),
            ),
    ),
  );

  Widget _submitButton(AppLocalizations l10n) => SizedBox(
    width: double.infinity,
    height: _buttonHeight,
    child: FilledButton(
      key: const Key('auth-phone-submit'),
      onPressed: _submitting ? null : _submit,
      style: FilledButton.styleFrom(
        backgroundColor: AppColors.blue,
        foregroundColor: AppColors.onPrimary,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(_buttonHeight / 2),
        ),
      ),
      child: _submitting
          ? const SizedBox(
              width: 20,
              height: 20,
              child: CircularProgressIndicator(
                strokeWidth: 2,
                color: AppColors.onPrimary,
              ),
            )
          : Text(
              _signUp ? l10n.authPhoneSignUpAction : l10n.authPhoneSignInAction,
              style: const TextStyle(fontSize: 15, fontWeight: FontWeight.w800),
            ),
    ),
  );

  InputDecoration _decoration(String label, String hint) => InputDecoration(
    labelText: label,
    hintText: hint,
    labelStyle: const TextStyle(color: AppColors.subtle),
    hintStyle: const TextStyle(color: AppColors.subtle),
    filled: true,
    fillColor: AppColors.input,
    contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 14),
    border: OutlineInputBorder(
      borderRadius: BorderRadius.circular(_fieldRadius),
      borderSide: BorderSide.none,
    ),
    focusedBorder: OutlineInputBorder(
      borderRadius: BorderRadius.circular(_fieldRadius),
      borderSide: const BorderSide(color: AppColors.blue, width: 1.5),
    ),
  );
}