// Author: fruit.com.cn

import 'dart:async';
import 'dart:math' as math;

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

import '../../../core/data/models/comment.dart';
import '../../../core/data/services/auth_controller.dart';
import '../../../core/data/services/comment_controller.dart';
import '../../../core/platform/haptics.dart';
import '../../../core/platform/keyboard_inset.dart';
import '../../../core/theme/app_colors.dart';
import '../../../core/widgets/auth_gate.dart';
import '../../../l10n/app_localizations.dart';

const double _sheetRadius = 20;
const double _inputRadius = 12;
const double _postButtonHeight = 32;
const int _maxCommentLength = 300;
const Duration _keyboardSettleDelay = Duration(milliseconds: 80);
const double _maxKeyboardInsetRatio = 0.6;

/// 独立评论输入弹窗，复用原评论控制器的发布与列表更新能力。
class CommentComposerSheet extends StatefulWidget {
  const CommentComposerSheet({
    super.key,
    required this.controller,
    required this.onDismiss,
    required this.onPosted,
    this.replyTo,
  });

  final CommentController controller;
  final VoidCallback onDismiss;
  final VoidCallback onPosted;
  final DramaComment? replyTo;

  @override
  State<CommentComposerSheet> createState() => _CommentComposerSheetState();
}

class _CommentComposerSheetState extends State<CommentComposerSheet> {
  final _input = TextEditingController();
  final _inputFocus = FocusNode();
  final _keyboardInset = KeyboardInsetNotifier.instance;
  Timer? _keyboardSettleTimer;
  double _pinnedKeyboardInset = 0;
  int _insetBaseline = 0;
  bool _pinnedInitialized = false;
  bool _insetReady = false;
  bool _useChannelInset = false;
  bool _keyboardVisible = false;

  @override
  void initState() {
    super.initState();
    _input.addListener(_onInputChanged);
    _keyboardInset.addListener(_onKeyboardInsetChanged);
    widget.controller.addListener(_onControllerChanged);
    unawaited(_prepareInput());
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    if (!_pinnedInitialized) {
      _pinnedInitialized = true;
      _pinnedKeyboardInset =
          _normalizeKeyboardInset(MediaQuery.viewInsetsOf(context).bottom) ?? 0;
    }
    _trackKeyboardInset(_keyboardHeight(context));
  }

  Future<void> _prepareInput() async {
    await _keyboardInset.start();
    if (!mounted) return;
    _insetBaseline = _keyboardInset.value;
    _insetReady = true;
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      _inputFocus.requestFocus();
      WidgetsBinding.instance.addPostFrameCallback((_) {
        if (!mounted || _keyboardHeight(context) > 0) return;
        unawaited(
          SystemChannels.textInput.invokeMethod<void>('TextInput.show'),
        );
      });
    });
  }

  @override
  void dispose() {
    _input.removeListener(_onInputChanged);
    _keyboardInset.removeListener(_onKeyboardInsetChanged);
    widget.controller.removeListener(_onControllerChanged);
    _keyboardSettleTimer?.cancel();
    _inputFocus.unfocus();
    _input.dispose();
    _inputFocus.dispose();
    super.dispose();
  }

  void _onInputChanged() {
    if (mounted) setState(() {});
  }

  void _onControllerChanged() {
    if (mounted) setState(() {});
  }

  void _onKeyboardInsetChanged() {
    if (!mounted || !_insetReady) return;
    if (_keyboardInset.value != _insetBaseline) {
      _useChannelInset = true;
    }
    _trackKeyboardInset(_keyboardHeight(context));
  }

  double _keyboardHeight(BuildContext context) {
    final viewInset = MediaQuery.viewInsetsOf(context).bottom;
    final channelInset = _useChannelInset
        ? _keyboardInset.value / MediaQuery.devicePixelRatioOf(context)
        : 0.0;
    return math.max(viewInset, channelInset);
  }

  double? _normalizeKeyboardInset(double inset) {
    final maxInset = MediaQuery.sizeOf(context).height * _maxKeyboardInsetRatio;
    if (!inset.isFinite || inset > maxInset) return null;
    return math.max(0, inset).roundToDouble();
  }

  void _trackKeyboardInset(double inset) {
    final visible = inset > 0;
    if (visible == _keyboardVisible) return;
    _keyboardVisible = visible;
    _keyboardSettleTimer?.cancel();
    _keyboardSettleTimer = null;
    if (!visible) return;
    _keyboardSettleTimer = Timer(
      _keyboardSettleDelay,
      _captureSettledKeyboardInset,
    );
  }

  void _captureSettledKeyboardInset() {
    _keyboardSettleTimer = null;
    if (!mounted) return;
    final inset = _keyboardHeight(context);
    if (inset <= 0) {
      _keyboardVisible = false;
      return;
    }
    final next = _normalizeKeyboardInset(inset);
    if (next == null || next == _pinnedKeyboardInset) return;
    setState(() => _pinnedKeyboardInset = next);
  }

  Future<void> _submit() async {
    if (widget.controller.submitting) return;
    final text = _input.text.trim();
    if (text.isEmpty) return;
    unawaited(context.read<Haptics>().lightImpact());
    final result = await widget.controller.publish(
      text,
      replyTo: widget.replyTo,
    );
    if (!mounted) return;
    if (result.isSuccess) {
      _input.clear();
      widget.onPosted();
      return;
    }
    final l10n = AppLocalizations.of(context)!;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text(result.errorMessage ?? l10n.commentPostFailed)),
    );
  }

  Future<void> _authenticate() async {
    await ensureSignedIn(context);
    if (!mounted || !context.read<AuthController>().isSignedIn) return;
    _inputFocus.requestFocus();
  }

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context)!;
    final signedIn = context.watch<AuthController>().isSignedIn;
    final hasContent = _input.text.trim().isNotEmpty;
    final canPost = signedIn && hasContent && !widget.controller.submitting;
    final multiline = _input.text.contains('\n');

    return FocusScope(
      key: const Key('comment-composer-focus-scope'),
      autofocus: true,
      child: Stack(
        key: const Key('comment-composer-overlay'),
        fit: StackFit.expand,
        children: [
          Positioned.fill(
            child: GestureDetector(
              key: const Key('comment-composer-dismiss-layer'),
              behavior: HitTestBehavior.opaque,
              onTap: widget.onDismiss,
            ),
          ),
          Positioned(
            left: 0,
            right: 0,
            bottom: 0,
            child: GestureDetector(
              behavior: HitTestBehavior.opaque,
              onTap: () {},
              child: Material(
                key: const Key('comment-composer-panel'),
                color: AppColors.card,
                clipBehavior: Clip.antiAlias,
                borderRadius: const BorderRadius.vertical(
                  top: Radius.circular(_sheetRadius),
                ),
                child: SafeArea(
                  top: false,
                  bottom: false,
                  child: Padding(
                    padding: EdgeInsets.only(bottom: _pinnedKeyboardInset),
                    child: Padding(
                      key: const Key('comment-composer-sheet'),
                      padding: const EdgeInsets.fromLTRB(16, 12, 16, 12),
                      child: TextFieldTapRegion(
                        child: Column(
                          mainAxisSize: MainAxisSize.min,
                          crossAxisAlignment: CrossAxisAlignment.stretch,
                          children: [
                            if (widget.replyTo != null)
                              Padding(
                                padding: const EdgeInsets.only(bottom: 8),
                                child: Text(
                                  l10n.replyingTo(
                                    widget.replyTo!.nickname.isEmpty
                                        ? l10n.anonymousUser
                                        : widget.replyTo!.nickname,
                                  ),
                                  style: const TextStyle(
                                    color: AppColors.muted,
                                    fontSize: 12,
                                  ),
                                ),
                              ),
                            Container(
                              decoration: BoxDecoration(
                                color: AppColors.commentInput,
                                borderRadius: BorderRadius.circular(
                                  _inputRadius,
                                ),
                              ),
                              child: TextField(
                                key: const Key('comment-composer-input'),
                                controller: _input,
                                focusNode: _inputFocus,
                                readOnly: !signedIn,
                                canRequestFocus: signedIn,
                                minLines: 1,
                                maxLines: 4,
                                maxLength: _maxCommentLength,
                                textAlignVertical: multiline
                                    ? TextAlignVertical.top
                                    : TextAlignVertical.center,
                                style: TextStyle(
                                  color: AppColors.cream,
                                  fontSize: 15,
                                  height: multiline ? 1.4 : null,
                                ),
                                cursorColor: AppColors.blue,
                                decoration: InputDecoration(
                                  hintText: signedIn
                                      ? l10n.writeComment
                                      : l10n.commentLoginHint,
                                  hintStyle: const TextStyle(
                                    color: AppColors.muted,
                                    fontSize: 14,
                                  ),
                                  counterText: '',
                                  contentPadding: const EdgeInsets.symmetric(
                                    horizontal: 16,
                                    vertical: 12,
                                  ),
                                  border: InputBorder.none,
                                  enabledBorder: InputBorder.none,
                                  focusedBorder: InputBorder.none,
                                ),
                                onTap: signedIn ? null : _authenticate,
                              ),
                            ),
                            const SizedBox(height: 12),
                            Align(
                              alignment: Alignment.centerRight,
                              child: SizedBox(
                                height: _postButtonHeight,
                                child: TextButton(
                                  key: const Key('comment-composer-post'),
                                  onPressed: canPost ? _submit : null,
                                  style: TextButton.styleFrom(
                                    minimumSize: const Size(
                                      0,
                                      _postButtonHeight,
                                    ),
                                    padding: const EdgeInsets.symmetric(
                                      horizontal: 16,
                                    ),
                                    tapTargetSize:
                                        MaterialTapTargetSize.shrinkWrap,
                                    backgroundColor: hasContent
                                        ? AppColors.blue.withValues(alpha: 0.12)
                                        : AppColors.raised,
                                    foregroundColor: AppColors.blue,
                                    disabledForegroundColor: AppColors.muted,
                                    disabledBackgroundColor: AppColors.raised,
                                    shape: RoundedRectangleBorder(
                                      borderRadius: BorderRadius.circular(8),
                                    ),
                                  ),
                                  child: Text(
                                    l10n.postComment,
                                    style: const TextStyle(
                                      fontSize: 14,
                                      fontWeight: FontWeight.w600,
                                    ),
                                  ),
                                ),
                              ),
                            ),
                          ],
                        ),
                      ),
                    ),
                  ),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}