import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:go_router/go_router.dart';
import '../../../core/chat/chat_bloc.dart';
import '../../../core/chat/session_closure_bloc.dart';
import '../widgets/pricing_bottom_sheet.dart';

class ChatScreen extends StatefulWidget {
  final String sessionId;
  final String mitraName;

  const ChatScreen({super.key, required this.sessionId, required this.mitraName});

  @override
  State<ChatScreen> createState() => _ChatScreenState();
}

class _ChatScreenState extends State<ChatScreen> {
  final _messageController = TextEditingController();
  final _scrollController = ScrollController();
  Timer? _typingThrottle;

  @override
  void dispose() {
    _messageController.dispose();
    _scrollController.dispose();
    _typingThrottle?.cancel();
    super.dispose();
  }

  void _scrollToBottom() {
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (_scrollController.hasClients) {
        _scrollController.animateTo(
          _scrollController.position.maxScrollExtent,
          duration: const Duration(milliseconds: 200),
          curve: Curves.easeOut,
        );
      }
    });
  }

  void _onTextChanged(String text) {
    if (_typingThrottle?.isActive ?? false) return;
    context.read<ChatBloc>().add(SendTyping());
    _typingThrottle = Timer(const Duration(seconds: 2), () {});
  }

  void _sendMessage() {
    final text = _messageController.text.trim();
    if (text.isEmpty) return;
    context.read<ChatBloc>().add(SendMessage(text));
    _messageController.clear();
    _scrollToBottom();
  }

  @override
  Widget build(BuildContext context) {
    return MultiBlocListener(
      listeners: [
        BlocListener<ChatBloc, ChatState>(
          listenWhen: (prev, curr) {
            if (prev is ChatConnected && curr is ChatConnected) {
              return prev.sessionExpired != curr.sessionExpired ||
                  prev.sessionClosing != curr.sessionClosing ||
                  prev.messages.length != curr.messages.length;
            }
            return true;
          },
          listener: (context, state) {
            if (state is ChatConnected) {
              if (state.sessionClosing) {
                context.read<SessionClosureBloc>().add(DeclineExtension());
              }
              _scrollToBottom();
              // Auto-mark received messages as read
              final unread = state.messages
                  .where((m) => m.senderType == 'mitra' && m.status != 'read')
                  .map((m) => m.id)
                  .toList();
              if (unread.isNotEmpty) {
                context.read<ChatBloc>().add(MarkMessagesRead(unread));
              }
            }
          },
        ),
        BlocListener<SessionClosureBloc, SessionClosureState>(
          listener: (context, state) {
            if (state is ClosureComplete) {
              context.go('/home');
            }
          },
        ),
      ],
      child: Scaffold(
        appBar: AppBar(
          title: Text(widget.mitraName),
          automaticallyImplyLeading: false,
          actions: [
            BlocBuilder<ChatBloc, ChatState>(
              builder: (context, state) {
                if (state is ChatConnected && state.remainingSeconds != null) {
                  return Padding(
                    padding: const EdgeInsets.only(right: 16),
                    child: Center(
                      child: Text(
                        '${state.remainingSeconds}s',
                        style: TextStyle(
                          color: state.remainingSeconds! < 30 ? Colors.red : null,
                          fontWeight: FontWeight.bold,
                        ),
                      ),
                    ),
                  );
                }
                return const SizedBox.shrink();
              },
            ),
          ],
        ),
        body: BlocBuilder<ChatBloc, ChatState>(
          builder: (context, state) {
            if (state is ChatConnecting) {
              return const Center(child: CircularProgressIndicator());
            }
            if (state is ChatError) {
              return Center(child: Text(state.message));
            }
            if (state is ChatConnected) {
              return _buildChatBody(context, state);
            }
            return const SizedBox.shrink();
          },
        ),
      ),
    );
  }

  Widget _buildChatBody(BuildContext context, ChatConnected state) {
    // Show session expired dialog
    if (state.sessionExpired) {
      return _buildExpiredView(context);
    }

    // Show goodbye input
    final closureState = context.watch<SessionClosureBloc>().state;
    if (closureState is ClosureShowGoodbye || closureState is ClosureSubmitting) {
      return _buildGoodbyeView(context, closureState);
    }

    if (state.sessionPaused) {
      return _buildPausedView();
    }

    return Column(
      children: [
        Expanded(
          child: ListView.builder(
            controller: _scrollController,
            padding: const EdgeInsets.all(16),
            itemCount: state.messages.length,
            itemBuilder: (context, index) {
              final msg = state.messages[index];
              final isMe = msg.senderType == 'customer';
              return _buildMessageBubble(msg, isMe);
            },
          ),
        ),
        if (state.isOtherTyping)
          const Padding(
            padding: EdgeInsets.symmetric(horizontal: 16, vertical: 4),
            child: Align(
              alignment: Alignment.centerLeft,
              child: Text('Bestie sedang mengetik...', style: TextStyle(color: Colors.grey, fontSize: 12)),
            ),
          ),
        _buildInputBar(context, state),
      ],
    );
  }

  Widget _buildMessageBubble(ChatMessage msg, bool isMe) {
    return Align(
      alignment: isMe ? Alignment.centerRight : Alignment.centerLeft,
      child: Container(
        margin: const EdgeInsets.symmetric(vertical: 4),
        padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
        constraints: BoxConstraints(maxWidth: MediaQuery.of(context).size.width * 0.75),
        decoration: BoxDecoration(
          color: isMe ? Colors.blue.shade100 : Colors.grey.shade200,
          borderRadius: BorderRadius.circular(16),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.end,
          children: [
            Text(msg.content, style: const TextStyle(fontSize: 15)),
            const SizedBox(height: 4),
            Row(
              mainAxisSize: MainAxisSize.min,
              children: [
                Text(
                  '${msg.createdAt.hour.toString().padLeft(2, '0')}:${msg.createdAt.minute.toString().padLeft(2, '0')}',
                  style: const TextStyle(fontSize: 10, color: Colors.grey),
                ),
                if (isMe) ...[
                  const SizedBox(width: 4),
                  _buildStatusIcon(msg.status),
                ],
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildStatusIcon(String status) {
    switch (status) {
      case 'sending':
        return const Icon(Icons.access_time, size: 14, color: Colors.grey);
      case 'sent':
        return const Icon(Icons.check, size: 14, color: Colors.grey);
      case 'delivered':
        return const Icon(Icons.done_all, size: 14, color: Colors.grey);
      case 'read':
        return const Icon(Icons.done_all, size: 14, color: Colors.blue);
      default:
        return const SizedBox.shrink();
    }
  }

  Widget _buildInputBar(BuildContext context, ChatConnected state) {
    return SafeArea(
      child: Padding(
        padding: const EdgeInsets.all(8),
        child: Row(
          children: [
            Expanded(
              child: TextField(
                controller: _messageController,
                onChanged: _onTextChanged,
                textInputAction: TextInputAction.send,
                onSubmitted: (_) => _sendMessage(),
                decoration: InputDecoration(
                  hintText: 'Ketik pesan...',
                  border: OutlineInputBorder(borderRadius: BorderRadius.circular(24)),
                  contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
                ),
              ),
            ),
            const SizedBox(width: 8),
            IconButton(
              icon: const Icon(Icons.send, color: Colors.blue),
              onPressed: _sendMessage,
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildExpiredView(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(32),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(Icons.timer_off, size: 64, color: Colors.orange),
            const SizedBox(height: 16),
            const Text('Waktu sesi habis', style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
            const SizedBox(height: 8),
            const Text('Apakah kamu ingin memperpanjang sesi?', textAlign: TextAlign.center),
            const SizedBox(height: 24),
            ElevatedButton(
              onPressed: () => PricingBottomSheet.show(context),
              child: const Text('Perpanjang Sesi'),
            ),
            const SizedBox(height: 12),
            TextButton(
              onPressed: () => context.read<SessionClosureBloc>().add(DeclineExtension()),
              child: const Text('Tidak, akhiri sesi'),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildGoodbyeView(BuildContext context, SessionClosureState closureState) {
    final controller = TextEditingController();
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(32),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            const Icon(Icons.waving_hand, size: 64, color: Colors.amber),
            const SizedBox(height: 16),
            const Text('Pesan Penutup', style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
            const SizedBox(height: 8),
            const Text('Tuliskan pesan terakhirmu untuk Bestie', textAlign: TextAlign.center),
            const SizedBox(height: 24),
            TextField(
              controller: controller,
              maxLines: 3,
              decoration: InputDecoration(
                hintText: 'Terima kasih, Bestie...',
                border: OutlineInputBorder(borderRadius: BorderRadius.circular(12)),
              ),
            ),
            const SizedBox(height: 16),
            ElevatedButton(
              onPressed: closureState is ClosureSubmitting
                  ? null
                  : () {
                      final text = controller.text.trim();
                      if (text.isNotEmpty) {
                        context.read<SessionClosureBloc>().add(
                          SubmitGoodbye(sessionId: widget.sessionId, message: text),
                        );
                      }
                    },
              child: closureState is ClosureSubmitting
                  ? const SizedBox(width: 20, height: 20, child: CircularProgressIndicator(strokeWidth: 2))
                  : const Text('Kirim & Selesai'),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildPausedView() {
    return const Center(
      child: Padding(
        padding: EdgeInsets.all(32),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            CircularProgressIndicator(),
            SizedBox(height: 24),
            Text('Menunggu konfirmasi Bestie...', style: TextStyle(fontSize: 18)),
            SizedBox(height: 8),
            Text('Chat dijeda sementara', style: TextStyle(color: Colors.grey)),
          ],
        ),
      ),
    );
  }
}