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';

// Chat theme colors
const _kUserBubbleColor = Color(0xFFD4929A);
const _kBgTint = Color(0xFFF5D0D6);
const _kBannerColor = Color(0xFFC4868F);
const _kAccentPink = Color(0xFFBE7C8A);

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;
  bool _showBestieBanner = true;
  bool _showUserBanner = true;

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

  @override
  void dispose() {
    final notifier = ref.read(chatProvider.notifier);
    _messageController.dispose();
    _scrollController.dispose();
    _typingThrottle?.cancel();
    super.dispose();
    Future.microtask(() => notifier.disconnect());
  }

  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();
  }

  void _exitChat() {
    if (context.canPop()) {
      context.pop();
    } else {
      context.go('/home');
    }
  }

  @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 PopScope(
      canPop: false,
      onPopInvokedWithResult: (didPop, _) {
        if (!didPop) _exitChat();
      },
      child: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.white,
          foregroundColor: Colors.black,
          elevation: 0.5,
          centerTitle: true,
          leading: IconButton(
            icon: const Icon(Icons.chevron_left, size: 28),
            onPressed: _exitChat,
          ),
          title: Text(widget.mitraName),
          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 : Colors.black,
                      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.sessionPaused) {
      return _buildPausedView();
    }

    return Stack(
      children: [
        // Background pattern
        Positioned.fill(
          child: Container(
            color: _kBgTint,
            child: Image.asset(
              'assets/images/chat_pattern.png',
              repeat: ImageRepeat.repeat,
              fit: BoxFit.none,
            ),
          ),
        ),
        // Content
        Column(
          children: [
            // Entry banners
            if (_showBestieBanner)
              _buildEntryBanner(
                '[Bestie] Sudah Memasuki Ruangan',
                () => setState(() => _showBestieBanner = false),
              ),
            if (_showUserBanner)
              _buildEntryBanner(
                '[User] Sudah Memasuki Ruangan',
                () => setState(() => _showUserBanner = false),
              ),
            // Messages
            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);
                },
              ),
            ),
            // Typing indicator
            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)),
                ),
              ),
            // Input bar or session ended bar
            if (state.sessionExpired)
              _buildSessionEndedBar()
            else
              _buildInputBar(),
          ],
        ),
      ],
    );
  }

  Widget _buildEntryBanner(String text, VoidCallback onDismiss) {
    return Container(
      color: _kBannerColor,
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
      child: Row(
        children: [
          const Icon(Icons.volume_up, color: Colors.white, size: 18),
          const SizedBox(width: 8),
          Expanded(
            child: Text(text, style: const TextStyle(color: Colors.white, fontSize: 13)),
          ),
          GestureDetector(
            onTap: onDismiss,
            child: const Icon(Icons.close, color: Colors.white, size: 18),
          ),
        ],
      ),
    );
  }

  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 ? _kUserBubbleColor : Colors.white,
          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: TextStyle(fontSize: 10, color: isMe ? Colors.white70 : 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.white70);
      case MessageStatus.sent:
        return const Icon(Icons.check, size: 14, color: Colors.white70);
      case MessageStatus.delivered:
        return const Icon(Icons.done_all, size: 14, color: Colors.white70);
      case MessageStatus.read:
        return const Icon(Icons.done_all, size: 14, color: Colors.white);
      default:
        return const SizedBox.shrink();
    }
  }

  Widget _buildInputBar() {
    return SafeArea(
      child: Container(
        padding: const EdgeInsets.all(8),
        color: Colors.white,
        child: Row(
          children: [
            Expanded(
              child: TextField(
                controller: _messageController,
                onChanged: _onTextChanged,
                textInputAction: TextInputAction.send,
                onSubmitted: (_) => _sendMessage(),
                decoration: InputDecoration(
                  hintText: 'Ketik Pesan',
                  hintStyle: TextStyle(color: Colors.grey.shade400),
                  filled: true,
                  fillColor: Colors.grey.shade100,
                  border: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(24),
                    borderSide: BorderSide.none,
                  ),
                  contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 10),
                ),
              ),
            ),
            const SizedBox(width: 8),
            Container(
              decoration: const BoxDecoration(
                color: _kAccentPink,
                shape: BoxShape.circle,
              ),
              child: IconButton(
                icon: const Icon(Icons.send, color: Colors.white, size: 20),
                onPressed: _sendMessage,
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildSessionEndedBar() {
    return SafeArea(
      child: Container(
        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
        decoration: BoxDecoration(
          color: _kBgTint,
          border: Border(top: BorderSide(color: Colors.grey.shade300)),
        ),
        child: Row(
          children: [
            const Icon(Icons.access_time, color: Colors.red, size: 18),
            const SizedBox(width: 8),
            const Expanded(
              child: Text(
                'Waktu Curhat Berakhir',
                style: TextStyle(color: Colors.red, fontWeight: FontWeight.w500),
              ),
            ),
            GestureDetector(
              onTap: () => PricingBottomSheet.showForExtension(context, sessionId: widget.sessionId),
              child: const Text(
                'Curhat Lagi',
                style: TextStyle(color: _kAccentPink, fontWeight: FontWeight.bold),
              ),
            ),
          ],
        ),
      ),
    );
  }

  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)),
          ],
        ),
      ),
    );
  }
}