import 'dart:async';

import 'package:flutter/material.dart';
import 'package:lucide_icons/lucide_icons.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../core/exceptions.dart';
import '../../data/models/message.dart';
import '../../providers/journal_provider.dart';
import '../../providers/voice_provider.dart';
import '../../widgets/chat_message_bubble.dart';
import '../../widgets/voice_mic_button.dart';
import 'journal_history_screen.dart';

class JournalScreen extends ConsumerStatefulWidget {
  const JournalScreen({super.key});

  @override
  ConsumerState<JournalScreen> createState() => _JournalScreenState();
}

class _JournalScreenState extends ConsumerState<JournalScreen>
    with WidgetsBindingObserver {
  final _controller = TextEditingController();
  final _scrollController = ScrollController();
  bool _refreshing = false;

  Timer? _pollTimer;
  bool _appInForeground = true;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _pollTimer =
        Timer.periodic(const Duration(seconds: 60), (_) => _pollSilently());
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    final wasBackground = !_appInForeground;
    _appInForeground = state == AppLifecycleState.resumed;
    if (_appInForeground && wasBackground && mounted) {
      ref.read(journalProvider.notifier).refreshMessages();
    }
  }

  void _pollSilently() {
    if (!_appInForeground || !mounted) return;
    final isStreaming = ref.read(isJournalStreamingProvider);
    if (isStreaming) return;
    ref.read(journalProvider.notifier).silentRefresh();
  }

  Future<void> _pullToRefresh() async {
    try {
      await ref.read(journalProvider.notifier).refreshMessages();
    } catch (_) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Could not refresh.')),
        );
      }
    }
  }

  @override
  void dispose() {
    _pollTimer?.cancel();
    WidgetsBinding.instance.removeObserver(this);
    _controller.dispose();
    _scrollController.dispose();
    super.dispose();
  }

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

  Future<void> _sendReply() async {
    final text = _controller.text.trim();
    if (text.isEmpty) return;
    _controller.clear();
    try {
      await ref.read(journalProvider.notifier).sendReply(text);
    } on AppException catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context)
            .showSnackBar(SnackBar(content: Text(e.message)));
      }
    } catch (_) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Failed to send reply.')),
        );
      }
    }
  }

  Future<void> _toggleVoiceMode() async {
    final voice = ref.read(voiceProvider);
    if (voice.voiceModeActive) {
      ref.read(voiceProvider.notifier).exitVoiceMode();
      return;
    }
    await ref.read(voiceProvider.notifier).enterVoiceMode(
      onTranscript: (transcript) async {
        await ref.read(journalProvider.notifier).sendReply(transcript);
      },
      enableTts: true,
      onError: (msg) {
        if (mounted) {
          ScaffoldMessenger.of(context)
              .showSnackBar(SnackBar(content: Text(msg)));
        }
      },
    );
  }

  Future<void> _refresh() async {
    setState(() => _refreshing = true);
    try {
      await ref.read(journalProvider.notifier).regeneratePrep();
    } catch (_) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Could not regenerate prep.')),
        );
      }
    } finally {
      if (mounted) setState(() => _refreshing = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final journalAsync = ref.watch(journalProvider);
    final isStreaming = ref.watch(isJournalStreamingProvider);
    final voiceState = ref.watch(voiceProvider);
    final scheme = Theme.of(context).colorScheme;

    ref.listen(journalProvider, (prev, next) => _scrollToBottom());

    // Feed streaming assistant content to VoiceNotifier for TTS.
    ref.listen(journalProvider, (prev, next) {
      if (!voiceState.voiceModeActive) return;
      final day = next.value;
      if (day == null || day.messages.isEmpty) return;
      final last = day.messages.last;
      if (last.role != MessageRole.assistant) return;
      final isComplete = last.status != 'generating';
      ref
          .read(voiceProvider.notifier)
          .feedContent(last.content, isComplete: isComplete);
    });

    return Scaffold(
      appBar: AppBar(
        title: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('Journal', style: Theme.of(context).textTheme.titleLarge),
            Text(
              _todayLabel(),
              style: Theme.of(context).textTheme.labelSmall?.copyWith(
                    color: scheme.onSurfaceVariant,
                  ),
            ),
          ],
        ),
        actions: [
          if (_refreshing)
            const Padding(
              padding: EdgeInsets.symmetric(horizontal: 12),
              child: SizedBox(
                width: 20,
                height: 20,
                child: CircularProgressIndicator(strokeWidth: 2),
              ),
            )
          else
            IconButton(
              icon: const Icon(LucideIcons.refreshCw),
              tooltip: 'Regenerate prep',
              onPressed: _refresh,
            ),
          PopupMenuButton<String>(
            onSelected: (value) {
              if (value == 'history') {
                Navigator.of(context).push(MaterialPageRoute(
                  builder: (_) => const JournalHistoryScreen(),
                ));
              }
            },
            itemBuilder: (_) => const [
              PopupMenuItem(
                value: 'history',
                child: Text('Past days'),
              ),
            ],
          ),
        ],
      ),
      body: journalAsync.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (err, stack) => Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              const Text("Could not load today's journal."),
              const SizedBox(height: 12),
              FilledButton.tonal(
                onPressed: () => ref.invalidate(journalProvider),
                child: const Text('Retry'),
              ),
            ],
          ),
        ),
        data: (day) {
          final isWide = MediaQuery.of(context).size.width >= 600;
          Widget body = Column(
            children: [
              Expanded(
                child: RefreshIndicator(
                  onRefresh: _pullToRefresh,
                  child: CustomScrollView(
                    controller: _scrollController,
                    physics: const AlwaysScrollableScrollPhysics(),
                    slivers: [
                      if (day.messages.isEmpty)
                        SliverFillRemaining(
                          child: Center(
                            child: Column(
                              mainAxisSize: MainAxisSize.min,
                              children: [
                                Text(
                                  'No prep yet today.',
                                  style: Theme.of(context)
                                      .textTheme
                                      .bodyMedium
                                      ?.copyWith(color: scheme.onSurfaceVariant),
                                ),
                                const SizedBox(height: 12),
                                FilledButton.tonal(
                                  onPressed: _refresh,
                                  child: const Text('Generate now'),
                                ),
                              ],
                            ),
                          ),
                        )
                      else
                        SliverPadding(
                          padding: const EdgeInsets.symmetric(
                              horizontal: 8, vertical: 8),
                          sliver: SliverList.builder(
                            itemCount: day.messages.length,
                            itemBuilder: (_, i) =>
                                _JournalMessageItem(message: day.messages[i]),
                          ),
                        ),
                    ],
                  ),
                ),
              ),
              if (isStreaming)
                LinearProgressIndicator(
                  minHeight: 2,
                  color: scheme.primary,
                ),
              if (voiceState.voiceModeActive)
                Container(
                  width: double.infinity,
                  color: const Color(0xFFEF4444).withValues(alpha: 0.12),
                  padding: const EdgeInsets.symmetric(
                      horizontal: 16, vertical: 6),
                  child: const Text(
                    '🎤 Listening… tap mic to exit voice mode',
                    style: TextStyle(
                      fontSize: 12,
                      color: Color(0xFFF87171),
                    ),
                  ),
                ),
              const Divider(height: 1),
              SafeArea(
                child: Padding(
                  padding: const EdgeInsets.fromLTRB(8, 6, 8, 6),
                  child: Row(
                    children: [
                      Expanded(
                        child: TextField(
                          controller: _controller,
                          decoration: InputDecoration(
                            hintText: voiceState.voiceModeActive
                                ? 'Listening…'
                                : 'Tell your journal…',
                            hintStyle: voiceState.voiceModeActive
                                ? const TextStyle(fontStyle: FontStyle.italic)
                                : null,
                            border: const OutlineInputBorder(),
                            isDense: true,
                            contentPadding: const EdgeInsets.symmetric(
                                horizontal: 12, vertical: 10),
                          ),
                          minLines: 1,
                          maxLines: 4,
                          textInputAction: TextInputAction.newline,
                          enabled: !isStreaming && !voiceState.voiceModeActive,
                        ),
                      ),
                      const SizedBox(width: 8),
                      VoiceMicButton(
                        mode: voiceState.mode,
                        voiceModeActive: voiceState.voiceModeActive,
                        amplitude: voiceState.amplitude,
                        onTap: _toggleVoiceMode,
                      ),
                      const SizedBox(width: 6),
                      _GradientSendButton(
                        onPressed: (isStreaming || voiceState.voiceModeActive)
                            ? null
                            : _sendReply,
                        isStreaming: isStreaming,
                      ),
                    ],
                  ),
                ),
              ),
            ],
          );
          if (isWide) {
            body = Center(
              child: ConstrainedBox(
                constraints: const BoxConstraints(maxWidth: 700),
                child: body,
              ),
            );
          }
          return body;
        },
      ),
    );
  }

  String _todayLabel() {
    final now = DateTime.now();
    const days = [
      'Monday', 'Tuesday', 'Wednesday', 'Thursday',
      'Friday', 'Saturday', 'Sunday'
    ];
    const months = [
      'January', 'February', 'March', 'April', 'May', 'June',
      'July', 'August', 'September', 'October', 'November', 'December'
    ];
    return '${days[now.weekday - 1]}, ${months[now.month - 1]} ${now.day}';
  }
}

/// Renders a single journal message. The daily-prep prose itself already
/// covers weather ("Weather at home will reach a high of 15.9° ..."), so
/// the journal screen leaves rendering to the message bubble — no separate
/// weather card on top.
class _JournalMessageItem extends StatelessWidget {
  final Message message;

  const _JournalMessageItem({required this.message});

  @override
  Widget build(BuildContext context) {
    return ChatMessageBubble(message: message);
  }
}

class _GradientSendButton extends StatelessWidget {
  final VoidCallback? onPressed;
  final bool isStreaming;

  const _GradientSendButton({
    required this.onPressed,
    required this.isStreaming,
  });

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    final disabled = onPressed == null;

    return DecoratedBox(
      decoration: BoxDecoration(
        gradient: disabled
            ? null
            : const LinearGradient(
                begin: Alignment.topLeft,
                end: Alignment.bottomRight,
                colors: [Color(0xFF5B4A8A), Color(0xFF3F3560)],
              ),
        color: disabled ? scheme.onSurface.withValues(alpha: 0.12) : null,
        borderRadius: BorderRadius.circular(10),
      ),
      child: IconButton(
        icon: isStreaming
            ? const SizedBox(
                width: 20,
                height: 20,
                child: CircularProgressIndicator(
                  strokeWidth: 2,
                  color: Colors.white,
                ),
              )
            : Icon(
                LucideIcons.send,
                color: disabled
                    ? scheme.onSurface.withValues(alpha: 0.38)
                    : Colors.white,
              ),
        onPressed: onPressed,
      ),
    );
  }
}