/// Page liste des conversations v4
library conversations_page;

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

import '../../../../shared/design_system/unionflow_design_system.dart';
import '../../domain/entities/conversation.dart';
import '../bloc/messaging_bloc.dart';
import '../bloc/messaging_event.dart';
import '../bloc/messaging_state.dart';
import '../widgets/conversation_tile.dart';
import 'conversation_detail_page.dart';

class ConversationsPage extends StatelessWidget {
  const ConversationsPage({super.key});

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

    return Scaffold(
      backgroundColor: scheme.surface,
      appBar: UFAppBar(
        title: 'Messages',
        moduleGradient: ModuleColors.communicationGradient,
        automaticallyImplyLeading: true,
      ),
      body: BlocConsumer<MessagingBloc, MessagingState>(
        listener: (context, state) {
          if (state is MessagingError) {
            ScaffoldMessenger.of(context).showSnackBar(
              SnackBar(
                content: Text(state.message),
                backgroundColor: ColorTokens.error,
              ),
            );
          }
          if (state is ConversationCreee) {
            _openDetail(context, state.conversation.id);
          }
        },
        builder: (context, state) {
          if (state is MessagingLoading) {
            return const Center(child: CircularProgressIndicator());
          }

          if (state is MesConversationsLoaded) {
            return _buildList(context, state.conversations);
          }

          // État initial ou erreur non fatale — afficher liste vide
          return _buildEmpty(context);
        },
      ),
    );
  }

  Widget _buildList(BuildContext context, List<ConversationSummary> conversations) {
    if (conversations.isEmpty) {
      return _buildEmpty(context);
    }

    // Tri : non lus d'abord, puis par date de dernier message
    final sorted = List.of(conversations)
      ..sort((a, b) {
        if (a.hasUnread && !b.hasUnread) return -1;
        if (!a.hasUnread && b.hasUnread) return 1;
        final aDate = a.dernierMessageAt;
        final bDate = b.dernierMessageAt;
        if (aDate == null && bDate == null) return 0;
        if (aDate == null) return 1;
        if (bDate == null) return -1;
        return bDate.compareTo(aDate);
      });

    return RefreshIndicator(
      color: ModuleColors.communication,
      onRefresh: () async {
        context.read<MessagingBloc>().add(const LoadMesConversations());
      },
      child: ListView.separated(
        padding: const EdgeInsets.all(SpacingTokens.md),
        itemCount: sorted.length,
        separatorBuilder: (_, __) => const SizedBox(height: SpacingTokens.sm),
        itemBuilder: (context, index) {
          final conv = sorted[index];
          return ConversationTile(
            conversation: conv,
            onTap: () => _openDetail(context, conv.id),
          );
        },
      ),
    );
  }

  Widget _buildEmpty(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    return RefreshIndicator(
      color: ModuleColors.communication,
      onRefresh: () async {
        context.read<MessagingBloc>().add(const LoadMesConversations());
      },
      child: SingleChildScrollView(
        physics: const AlwaysScrollableScrollPhysics(),
        child: SizedBox(
          height: MediaQuery.of(context).size.height * 0.6,
          child: Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                Icon(
                  Icons.chat_bubble_outline,
                  size: 64,
                  color: scheme.onSurfaceVariant.withOpacity(0.4),
                ),
                const SizedBox(height: SpacingTokens.md),
                Text('Aucune conversation', style: AppTypography.headerSmall),
                const SizedBox(height: SpacingTokens.sm),
                Text(
                  'Contactez un membre ou le bureau\nde votre organisation',
                  style: AppTypography.bodyTextSmall,
                  textAlign: TextAlign.center,
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }

  void _openDetail(BuildContext context, String conversationId) {
    Navigator.of(context).push(
      MaterialPageRoute(
        builder: (_) => BlocProvider.value(
          value: context.read<MessagingBloc>(),
          child: ConversationDetailPage(conversationId: conversationId),
        ),
      ),
    );
  }
}