import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import '../../../core/chat/chat_notifier.dart';
import '../../../core/chat/session_closure_notifier.dart';
import '../../../core/constants.dart';
import '../widgets/pricing_bottom_sheet.dart';

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

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

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

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

  @override
  void initState() {
    super.initState();
    ref.read(chatProvider.notifier).connect(widget.sessionId);
  }

  @override
  void dispose() {
    ref.read(chatProvider.notifier).disconnect();
    _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;
    ref.read(chatProvider.notifier).sendTyping();
    _typingThrottle = Timer(const Duration(seconds: 2), () {});
  }

  void _sendMessage() {
    final text = _messageController.text.trim();
    if (text.isEmpty) return;
    ref.read(chatProvider.notifier).sendMessage(text);
    _messageController.clear();
    _scrollToBottom();
  }

  @override
  Widget build(BuildContext context) {
    final chatState = ref.watch(chatProvider);
    final closureState = ref.watch(sessionClosureProvider);

    // Listen for closure complete to navigate home
    ref.listen(sessionClosureProvider, (prev, next) {
      if (next is ClosureCompleteData) {
        context.go('/home');
      }
    });

    // Listen for chat state changes to manage closure state
    ref.listen(chatProvider, (prev, next) {
      if (next is ChatConnectedData) {
        if (next.sessionClosing && !next.sessionExpired) {
          final closure = ref.read(sessionClosureProvider);
          if (closure is ClosureInitialData) {
            ref.read(sessionClosureProvider.notifier).declineExtension();
          }
        }
        if (!next.sessionPaused && !next.sessionExpired && !next.sessionClosing) {
          final closure = ref.read(sessionClosureProvider);
          if (closure is! ClosureInitialData) {
            ref.read(sessionClosureProvider.notifier).reset();
          }
        }
        _scrollToBottom();
        final unread = next.messages
            .where((m) => m.senderType == UserType.mitra && m.status != MessageStatus.read)
            .map((m) => m.id)
            .toList();
        if (unread.isNotEmpty) {
          ref.read(chatProvider.notifier).markRead(unread);
        }
      }
    });

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.mitraName),
        automaticallyImplyLeading: false,
        actions: [
          if (chatState is ChatConnectedData && chatState.remainingSeconds != null)
            Padding(
              padding: const EdgeInsets.only(right: 16),
              child: Center(
                child: Text(
                  '${chatState.remainingSeconds}s',
                  style: TextStyle(
                    color: chatState.remainingSeconds! < 30 ? Colors.red : null,
                    fontWeight: FontWeight.bold,
                  ),
                ),
              ),
            ),
        ],
      ),
      body: _buildBody(chatState, closureState),
    );
  }

  Widget _buildBody(ChatData chatState, SessionClosureData closureState) {
    if (chatState is ChatConnectingData) {
      return const Center(child: CircularProgressIndicator());
    }
    if (chatState is ChatErrorData) {
      return Center(child: Text(chatState.message));
    }
    if (chatState is ChatConnectedData) {
      return _buildChatBody(chatState, closureState);
    }
    return const SizedBox.shrink();
  }

  Widget _buildChatBody(ChatConnectedData state, SessionClosureData closureState) {
    if (closureState is ClosureShowGoodbyeData || closureState is ClosureSubmittingData) {
      return _buildGoodbyeView(closureState);
    }

    if (state.sessionExpired) {
      return _buildExpiredView();
    }

    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 == UserType.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(),
      ],
    );
  }

  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 MessageStatus.sent:
        return const Icon(Icons.check, size: 14, color: Colors.grey);
      case MessageStatus.delivered:
        return const Icon(Icons.done_all, size: 14, color: Colors.grey);
      case MessageStatus.read:
        return const Icon(Icons.done_all, size: 14, color: Colors.blue);
      default:
        return const SizedBox.shrink();
    }
  }

  Widget _buildInputBar() {
    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() {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(32),
        child: TweenAnimationBuilder<int>(
          tween: IntTween(begin: 300, end: 0),
          duration: const Duration(seconds: 300),
          builder: (context, remaining, _) {
            if (remaining <= 0) {
              WidgetsBinding.instance.addPostFrameCallback((_) {
                ref.read(sessionClosureProvider.notifier).declineExtension();
              });
            }
            final minutes = remaining ~/ 60;
            final seconds = remaining % 60;
            return 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: 12),
                Text(
                  '$minutes:${seconds.toString().padLeft(2, '0')}',
                  style: TextStyle(
                    fontSize: 32,
                    fontWeight: FontWeight.bold,
                    color: remaining < 60 ? Colors.red : Colors.orange,
                  ),
                ),
                const SizedBox(height: 24),
                ElevatedButton(
                  onPressed: () => PricingBottomSheet.showForExtension(context, sessionId: widget.sessionId),
                  child: const Text('Perpanjang Sesi'),
                ),
                const SizedBox(height: 12),
                TextButton(
                  onPressed: () => ref.read(sessionClosureProvider.notifier).declineExtension(),
                  child: const Text('Tidak, akhiri sesi'),
                ),
              ],
            );
          },
        ),
      ),
    );
  }

  Widget _buildGoodbyeView(SessionClosureData closureState) {
    final controller = TextEditingController();
    return SingleChildScrollView(
      padding: const EdgeInsets.all(32),
      child: Column(
        children: [
          const SizedBox(height: 48),
          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 ClosureSubmittingData
                  ? null
                  : () {
                      final text = controller.text.trim();
                      if (text.isNotEmpty) {
                        ref.read(sessionClosureProvider.notifier).submitGoodbye(
                          widget.sessionId, text,
                        );
                      }
                    },
              child: closureState is ClosureSubmittingData
                  ? 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)),
          ],
        ),
      ),
    );
  }
}