import 'package:flutter/material.dart';
import 'package:iconsax/iconsax.dart';
import 'package:animate_do/animate_do.dart';
import '../api/api.dart';
import 'message_bubble.dart';

/// A chat window component for interacting with a single AI agent
class AgentChatWindow extends StatefulWidget {
  final String title;
  final List<AgentDto> availableAgents;

  const AgentChatWindow({
    super.key,
    required this.title,
    required this.availableAgents,
  });

  @override
  State<AgentChatWindow> createState() => _AgentChatWindowState();
}

class _AgentChatWindowState extends State<AgentChatWindow> {
  AgentDto? _selectedAgent;
  final TextEditingController _messageController = TextEditingController();
  final ScrollController _scrollController = ScrollController();
  final List<_ChatMessage> _messages = [];
  bool _isSending = false;
  String? _conversationId; // Track current conversation
  final CqrsApiClient _apiClient = CqrsApiClient(
    config: ApiClientConfig.development,
  );

  @override
  void initState() {
    super.initState();
    if (widget.availableAgents.isNotEmpty) {
      _selectedAgent = widget.availableAgents.first;
    }
  }

  @override
  void dispose() {
    _messageController.dispose();
    _scrollController.dispose();
    _apiClient.dispose();
    super.dispose();
  }

  Future<void> _sendMessage() async {
    if (_messageController.text.trim().isEmpty || _selectedAgent == null) {
      return;
    }

    final String messageText = _messageController.text.trim();

    setState(() {
      _messages.add(_ChatMessage(
        message: messageText,
        isUser: true,
        senderName: 'You',
        timestamp: DateTime.now(),
      ));
      _isSending = true;
    });

    _messageController.clear();
    _scrollToBottom();

    // Send message to agent via API
    final Result<SendMessageResult> result = await _apiClient.sendMessage(
      SendMessageCommand(
        agentId: _selectedAgent!.id,
        conversationId: _conversationId, // null for first message
        message: messageText,
      ),
    );

    if (!mounted) return;

    result.when(
      success: (SendMessageResult response) {
        setState(() {
          // Store conversation ID for subsequent messages
          _conversationId = response.conversationId;

          // Add agent's response to chat
          _messages.add(_ChatMessage(
            message: response.agentResponse.content,
            isUser: false,
            senderName: _selectedAgent!.name,
            timestamp: response.agentResponse.timestamp,
            inputTokens: response.agentResponse.inputTokens,
            outputTokens: response.agentResponse.outputTokens,
            estimatedCost: response.agentResponse.estimatedCost,
          ));
          _isSending = false;
        });
        _scrollToBottom();
      },
      error: (ApiErrorInfo error) {
        setState(() {
          _isSending = false;
        });

        // Show error message to user
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              content: Row(
                children: [
                  const Icon(Iconsax.danger, color: Colors.white, size: 18),
                  const SizedBox(width: 8),
                  Expanded(
                    child: Text(
                      error.type == ApiErrorType.timeout
                          ? 'Request timed out. Agent may be processing...'
                          : 'Failed to send message: ${error.message}',
                    ),
                  ),
                ],
              ),
              backgroundColor: Theme.of(context).colorScheme.error,
              duration: const Duration(seconds: 4),
              behavior: SnackBarBehavior.floating,
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(8),
              ),
            ),
          );
        }
      },
    );
  }

  void _scrollToBottom() {
    Future.delayed(const Duration(milliseconds: 100), () {
      if (_scrollController.hasClients) {
        _scrollController.animateTo(
          _scrollController.position.maxScrollExtent,
          duration: const Duration(milliseconds: 300),
          curve: Curves.easeOut,
        );
      }
    });
  }

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

    return FadeInUp(
      duration: const Duration(milliseconds: 400),
      child: Container(
        decoration: BoxDecoration(
          color: colorScheme.surfaceContainerLow,
          borderRadius: BorderRadius.circular(16),
          border: Border.all(
            color: colorScheme.outline.withValues(alpha: 0.2),
            width: 1,
          ),
        ),
        child: Column(
          children: [
            // Header with agent selector
            _buildHeader(colorScheme),

            // Divider
            Divider(
              height: 1,
              color: colorScheme.outline.withValues(alpha: 0.2),
            ),

            // Messages area
            Expanded(
              child: _buildMessagesArea(colorScheme),
            ),

            // Divider
            Divider(
              height: 1,
              color: colorScheme.outline.withValues(alpha: 0.2),
            ),

            // Input area
            _buildInputArea(colorScheme),
          ],
        ),
      ),
    );
  }

  Widget _buildHeader(ColorScheme colorScheme) {
    return Container(
      padding: const EdgeInsets.all(16),
      child: Row(
        children: [
          // Title
          Icon(
            Iconsax.messages_3,
            color: colorScheme.primary,
            size: 20,
          ),
          const SizedBox(width: 8),
          Text(
            widget.title,
            style: TextStyle(
              fontSize: 14,
              fontWeight: FontWeight.bold,
              color: colorScheme.onSurface,
            ),
          ),
          const SizedBox(width: 16),

          // Agent Selector Dropdown
          Expanded(
            child: Container(
              padding: const EdgeInsets.symmetric(horizontal: 12),
              decoration: BoxDecoration(
                color: colorScheme.surfaceContainerHighest,
                borderRadius: BorderRadius.circular(8),
                border: Border.all(
                  color: colorScheme.outline.withValues(alpha: 0.3),
                  width: 1,
                ),
              ),
              child: DropdownButton<AgentDto>(
                value: _selectedAgent,
                isExpanded: true,
                underline: const SizedBox(),
                icon: Icon(
                  Iconsax.arrow_down_1,
                  size: 16,
                  color: colorScheme.onSurface,
                ),
                style: TextStyle(
                  fontSize: 13,
                  color: colorScheme.onSurface,
                  fontWeight: FontWeight.w500,
                ),
                dropdownColor: colorScheme.surfaceContainerHigh,
                items: widget.availableAgents.isEmpty
                    ? [
                        DropdownMenuItem<AgentDto>(
                          value: null,
                          child: Text(
                            'No agents available',
                            style: TextStyle(
                              color: colorScheme.onSurfaceVariant,
                              fontSize: 13,
                            ),
                          ),
                        ),
                      ]
                    : widget.availableAgents.map((AgentDto agent) {
                        return DropdownMenuItem<AgentDto>(
                          value: agent,
                          child: Row(
                            children: [
                              Icon(
                                Iconsax.cpu,
                                size: 14,
                                color: colorScheme.primary,
                              ),
                              const SizedBox(width: 8),
                              Expanded(
                                child: Text(
                                  agent.name,
                                  overflow: TextOverflow.ellipsis,
                                ),
                              ),
                            ],
                          ),
                        );
                      }).toList(),
                onChanged: widget.availableAgents.isEmpty
                    ? null
                    : (AgentDto? newAgent) {
                        setState(() {
                          _selectedAgent = newAgent;
                        });
                      },
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildMessagesArea(ColorScheme colorScheme) {
    if (_messages.isEmpty) {
      return Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(
              Iconsax.message_text,
              size: 48,
              color: colorScheme.onSurfaceVariant.withValues(alpha: 0.3),
            ),
            const SizedBox(height: 16),
            Text(
              'No messages yet',
              style: TextStyle(
                fontSize: 14,
                color: colorScheme.onSurfaceVariant,
              ),
            ),
            const SizedBox(height: 8),
            Text(
              _selectedAgent != null
                  ? 'Start chatting with ${_selectedAgent!.name}'
                  : 'Select an agent to begin',
              style: TextStyle(
                fontSize: 12,
                color: colorScheme.onSurfaceVariant.withValues(alpha: 0.7),
              ),
            ),
          ],
        ),
      );
    }

    return ListView.builder(
      controller: _scrollController,
      padding: const EdgeInsets.all(16),
      itemCount: _messages.length,
      itemBuilder: (BuildContext context, int index) {
        final _ChatMessage msg = _messages[index];
        return MessageBubble(
          message: msg.message,
          isUser: msg.isUser,
          senderName: msg.senderName,
          timestamp: msg.timestamp,
          inputTokens: msg.inputTokens,
          outputTokens: msg.outputTokens,
          estimatedCost: msg.estimatedCost,
        );
      },
    );
  }

  Widget _buildInputArea(ColorScheme colorScheme) {
    final bool canSend =
        _selectedAgent != null && !_isSending && _messageController.text.isNotEmpty;

    return Container(
      padding: const EdgeInsets.all(16),
      child: Row(
        children: [
          // Text input
          Expanded(
            child: TextField(
              controller: _messageController,
              enabled: _selectedAgent != null && !_isSending,
              maxLines: null,
              textCapitalization: TextCapitalization.sentences,
              decoration: InputDecoration(
                hintText: _selectedAgent != null
                    ? 'Type your message...'
                    : 'Select an agent first',
                hintStyle: TextStyle(
                  color: colorScheme.onSurfaceVariant.withValues(alpha: 0.6),
                  fontSize: 13,
                ),
                filled: true,
                fillColor: colorScheme.surfaceContainerHighest,
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(12),
                  borderSide: BorderSide.none,
                ),
                contentPadding: const EdgeInsets.symmetric(
                  horizontal: 16,
                  vertical: 12,
                ),
              ),
              style: TextStyle(
                fontSize: 14,
                color: colorScheme.onSurface,
              ),
              onChanged: (_) => setState(() {}),
              onSubmitted: (_) => canSend ? _sendMessage() : null,
            ),
          ),
          const SizedBox(width: 12),

          // Send button
          Material(
            color: canSend
                ? colorScheme.primary
                : colorScheme.surfaceContainerHighest,
            borderRadius: BorderRadius.circular(12),
            child: InkWell(
              onTap: canSend ? _sendMessage : null,
              borderRadius: BorderRadius.circular(12),
              child: Container(
                padding: const EdgeInsets.all(12),
                child: _isSending
                    ? SizedBox(
                        width: 20,
                        height: 20,
                        child: CircularProgressIndicator(
                          strokeWidth: 2,
                          valueColor: AlwaysStoppedAnimation<Color>(
                            Colors.white,
                          ),
                        ),
                      )
                    : Icon(
                        Iconsax.send_1,
                        color: canSend
                            ? Colors.white
                            : colorScheme.onSurfaceVariant.withValues(alpha: 0.5),
                        size: 20,
                      ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

/// Internal message model for chat display
class _ChatMessage {
  final String message;
  final bool isUser;
  final String senderName;
  final DateTime timestamp;
  final int? inputTokens;
  final int? outputTokens;
  final double? estimatedCost;

  _ChatMessage({
    required this.message,
    required this.isUser,
    required this.senderName,
    required this.timestamp,
    this.inputTokens,
    this.outputTokens,
    this.estimatedCost,
  });
}