import 'dart:convert';
import 'dart:io';
import 'dart:math';
import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_markdown/flutter_markdown.dart';
import 'package:path_provider/path_provider.dart';
import 'package:share_plus/share_plus.dart';
import 'package:url_launcher/url_launcher.dart';
import 'package:intl/intl.dart';

import '../models/message.dart';
import '../theme/app_theme.dart';
import 'image_viewer.dart';
import 'pdf_viewer.dart';

// Cache decoded image bytes to prevent flicker on widget rebuild
final Map<String, Uint8List> _imageCache = {};

/// Chat message bubble with support for text, voice, and image types.
class MessageBubble extends StatelessWidget {
  final Message message;
  final VoidCallback? onPlay;
  final VoidCallback? onChainPlay;
  final VoidCallback? onDelete;
  final bool isPlaying;

  const MessageBubble({
    super.key,
    required this.message,
    this.onPlay,
    this.onChainPlay,
    this.onDelete,
    this.isPlaying = false,
  });

  bool get _isUser => message.role == MessageRole.user;
  bool get _isSystem => message.role == MessageRole.system;

  @override
  Widget build(BuildContext context) {
    if (_isSystem) return _buildSystem(context);

    final isDark = Theme.of(context).brightness == Brightness.dark;

    return Align(
      alignment: _isUser ? Alignment.centerRight : Alignment.centerLeft,
      child: GestureDetector(
        onLongPress: () => _showContextMenu(context),
        child: Container(
          constraints: BoxConstraints(
            maxWidth: MediaQuery.of(context).size.width * 0.78,
          ),
          margin: EdgeInsets.only(
            left: _isUser ? 48 : 16,
            right: _isUser ? 16 : 48,
            bottom: 6,
          ),
          padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
          decoration: BoxDecoration(
            color: _isUser
                ? (isDark ? AppColors.userBubble : AppColors.lightUserBubble)
                : (isDark
                    ? AppColors.assistantBubble
                    : AppColors.lightAssistantBubble),
            borderRadius: BorderRadius.only(
              topLeft: const Radius.circular(16),
              topRight: const Radius.circular(16),
              bottomLeft: Radius.circular(_isUser ? 16 : 4),
              bottomRight: Radius.circular(_isUser ? 4 : 16),
            ),
          ),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              _buildContent(context),
              const SizedBox(height: 4),
              _buildFooter(context),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildSystem(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;
    return Center(
      child: Container(
        margin: const EdgeInsets.symmetric(vertical: 4, horizontal: 32),
        padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
        decoration: BoxDecoration(
          color: isDark ? AppColors.systemBubble : Colors.grey.shade200,
          borderRadius: BorderRadius.circular(12),
        ),
        child: Text(
          message.content,
          style: TextStyle(
            fontSize: 12,
            color: isDark ? AppColors.darkTextTertiary : Colors.grey.shade600,
            fontStyle: FontStyle.italic,
          ),
          textAlign: TextAlign.center,
        ),
      ),
    );
  }

  Widget _buildContent(BuildContext context) {
    switch (message.type) {
      case MessageType.text:
        if (_isUser) {
          return SelectableText(
            message.content,
            style: const TextStyle(
              fontSize: 15,
              color: Colors.white,
              height: 1.4,
            ),
          );
        }
        return _buildMarkdown(context);

      case MessageType.voice:
        return _buildVoiceContent(context);

      case MessageType.image:
        return _buildImageContent(context);
    }
  }

  Widget _buildMarkdown(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;
    final textColor = isDark ? Colors.white : Colors.black87;
    final codeBackground = isDark
        ? Colors.white.withAlpha(20)
        : Colors.black.withAlpha(15);

    return MarkdownBody(
      data: message.content,
      selectable: true,
      softLineBreak: true,
      styleSheet: MarkdownStyleSheet(
        p: TextStyle(fontSize: 15, height: 1.4, color: textColor),
        h1: TextStyle(fontSize: 20, fontWeight: FontWeight.bold, color: textColor),
        h2: TextStyle(fontSize: 18, fontWeight: FontWeight.bold, color: textColor),
        h3: TextStyle(fontSize: 16, fontWeight: FontWeight.bold, color: textColor),
        strong: TextStyle(fontWeight: FontWeight.bold, color: textColor),
        em: TextStyle(fontStyle: FontStyle.italic, color: textColor),
        code: TextStyle(
          fontSize: 13,
          fontFamily: 'monospace',
          color: textColor,
          backgroundColor: codeBackground,
        ),
        codeblockDecoration: BoxDecoration(
          color: codeBackground,
          borderRadius: BorderRadius.circular(8),
        ),
        codeblockPadding: const EdgeInsets.all(10),
        listBullet: TextStyle(fontSize: 15, color: textColor),
        blockquoteDecoration: BoxDecoration(
          border: Border(
            left: BorderSide(color: AppColors.accent, width: 3),
          ),
        ),
        blockquotePadding: const EdgeInsets.only(left: 12, top: 4, bottom: 4),
      ),
      onTapLink: (text, href, title) {
        if (href != null) {
          final uri = Uri.tryParse(href);
          if (uri != null) {
            launchUrl(uri, mode: LaunchMode.externalApplication);
          }
        }
      },
    );
  }

  Widget _buildVoiceContent(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            // Play button
            GestureDetector(
              onTap: onPlay,
              onDoubleTap: onChainPlay,
              child: Container(
                width: 36,
                height: 36,
                decoration: BoxDecoration(
                  color: _isUser
                      ? Colors.white.withAlpha(50)
                      : AppColors.accent.withAlpha(50),
                  shape: BoxShape.circle,
                ),
                child: Icon(
                  isPlaying ? Icons.pause : Icons.play_arrow,
                  color: _isUser ? Colors.white : AppColors.accent,
                  size: 20,
                ),
              ),
            ),
            const SizedBox(width: 8),
            // Waveform bars
            SizedBox(
              width: 120,
              height: 24,
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: List.generate(20, (i) {
                  final height = 4.0 + 16.0 * sin(i * 0.5).abs();
                  return Container(
                    width: 3,
                    height: height,
                    decoration: BoxDecoration(
                      color: _isUser
                          ? Colors.white.withAlpha(180)
                          : (isDark
                              ? AppColors.darkTextSecondary
                              : AppColors.lightTextSecondary),
                      borderRadius: BorderRadius.circular(2),
                    ),
                  );
                }),
              ),
            ),
            const SizedBox(width: 8),
            // Duration
            if (message.duration != null)
              Text(
                _formatDuration(message.duration!),
                style: TextStyle(
                  fontSize: 12,
                  color: _isUser
                      ? Colors.white70
                      : (isDark
                          ? AppColors.darkTextTertiary
                          : AppColors.lightTextSecondary),
                ),
              ),
          ],
        ),
        // Transcript
        if (message.content.isNotEmpty) ...[
          const SizedBox(height: 8),
          if (_isUser)
            SelectableText(
              message.content,
              style: TextStyle(
                fontSize: 14,
                color: Colors.white.withAlpha(220),
                height: 1.3,
              ),
            )
          else
            _buildMarkdown(context),
        ],
      ],
    );
  }

  /// True if the mimeType is a renderable image format.
  bool get _isImageMime {
    final mime = message.mimeType?.toLowerCase() ?? 'image/jpeg';
    return mime.startsWith('image/');
  }

  Widget _buildImageContent(BuildContext context) {
    if (message.imageBase64 == null || message.imageBase64!.isEmpty) {
      return const Text('Image unavailable');
    }

    // Non-image files (PDF, CSV, etc.) — show file card instead of Image.memory
    if (!_isImageMime) {
      return _buildFileCard(context);
    }

    // Cache decoded bytes to prevent flicker on rebuild; evict oldest if over 50 entries
    if (!_imageCache.containsKey(message.id)) {
      if (_imageCache.length >= 50) {
        _imageCache.remove(_imageCache.keys.first);
      }
      final raw = message.imageBase64!;
      _imageCache[message.id] = Uint8List.fromList(base64Decode(
        raw.contains(',') ? raw.split(',').last : raw,
      ));
    }
    final bytes = _imageCache[message.id]!;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        GestureDetector(
          onTap: () {
            Navigator.of(context).push(
              MaterialPageRoute(
                builder: (_) => ImageViewer(imageBytes: bytes),
              ),
            );
          },
          child: ClipRRect(
            borderRadius: BorderRadius.circular(8),
            child: Image.memory(
              bytes,
              width: 260,
              height: 180,
              fit: BoxFit.cover,
              gaplessPlayback: true,
              errorBuilder: (_, e, st) => const SizedBox(
                width: 260,
                height: 60,
                child: Center(child: Text('Image decode error')),
              ),
            ),
          ),
        ),
        if (message.content.isNotEmpty) ...[
          const SizedBox(height: 6),
          Text(
            message.content,
            style: TextStyle(
              fontSize: 14,
              color: _isUser ? Colors.white.withAlpha(220) : null,
              height: 1.3,
            ),
          ),
        ],
      ],
    );
  }

  Widget _buildFileCard(BuildContext context) {
    final mime = message.mimeType ?? 'application/octet-stream';
    final caption = message.content.isNotEmpty ? message.content : 'File';
    final isPdf = mime == 'application/pdf';

    // File type icon
    IconData icon;
    Color iconColor;
    if (isPdf) {
      icon = Icons.picture_as_pdf;
      iconColor = Colors.red;
    } else if (mime.contains('spreadsheet') || mime.contains('excel') || mime == 'text/csv') {
      icon = Icons.table_chart;
      iconColor = Colors.green;
    } else if (mime.contains('word') || mime.contains('document')) {
      icon = Icons.description;
      iconColor = Colors.blue;
    } else if (mime == 'text/plain' || mime == 'application/json') {
      icon = Icons.text_snippet;
      iconColor = Colors.grey;
    } else {
      icon = Icons.insert_drive_file;
      iconColor = Colors.blueGrey;
    }

    final sizeKB = ((message.imageBase64?.length ?? 0) * 3 / 4 / 1024).round();

    return GestureDetector(
      onTap: () => _openFile(context),
      child: Container(
        width: 260,
        padding: const EdgeInsets.all(12),
        decoration: BoxDecoration(
          color: (_isUser ? Colors.white : Theme.of(context).colorScheme.primary).withAlpha(25),
          borderRadius: BorderRadius.circular(8),
          border: Border.all(
            color: (_isUser ? Colors.white : Colors.grey).withAlpha(50),
          ),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Row(
              children: [
                Icon(icon, size: 32, color: iconColor),
                const SizedBox(width: 10),
                Expanded(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        caption,
                        style: TextStyle(
                          fontSize: 14,
                          fontWeight: FontWeight.w600,
                          color: _isUser ? Colors.white : null,
                        ),
                        maxLines: 2,
                        overflow: TextOverflow.ellipsis,
                      ),
                      const SizedBox(height: 2),
                      Text(
                        '${mime.split('/').last.toUpperCase()} - ${sizeKB} KB',
                        style: TextStyle(
                          fontSize: 11,
                          color: (_isUser ? Colors.white : Colors.grey).withAlpha(180),
                        ),
                      ),
                    ],
                  ),
                ),
                Icon(
                  Icons.open_in_new,
                  size: 20,
                  color: (_isUser ? Colors.white : Colors.grey).withAlpha(150),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Future<void> _openFile(BuildContext context) async {
    final data = message.imageBase64;
    if (data == null || data.isEmpty) return;

    try {
      final bytes = Uint8List.fromList(
        base64Decode(data.contains(',') ? data.split(',').last : data),
      );
      final mime = message.mimeType ?? 'application/octet-stream';

      // PDFs: open inline viewer
      if (mime == 'application/pdf') {
        if (context.mounted) {
          Navigator.of(context).push(
            MaterialPageRoute(
              builder: (_) => PdfViewerScreen(
                pdfBytes: bytes,
                title: message.content.isNotEmpty ? message.content : 'PDF',
              ),
            ),
          );
        }
        return;
      }

      // Other files: save to temp and share
      final ext = _mimeToExt(mime);
      final dir = await getTemporaryDirectory();
      final fileName = '${message.content.isNotEmpty ? message.content.replaceAll(RegExp(r'[^\w\s.-]'), '').trim() : 'file'}.$ext';
      final file = File('${dir.path}/$fileName');
      await file.writeAsBytes(bytes);

      await SharePlus.instance.share(
        ShareParams(files: [XFile(file.path, mimeType: mime)]),
      );
    } catch (e) {
      if (context.mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Could not open file: $e')),
        );
      }
    }
  }

  String _mimeToExt(String mime) {
    const map = {
      'application/pdf': 'pdf',
      'application/msword': 'doc',
      'application/vnd.openxmlformats-officedocument.wordprocessingml.document': 'docx',
      'application/vnd.ms-excel': 'xls',
      'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet': 'xlsx',
      'text/plain': 'txt',
      'text/csv': 'csv',
      'application/json': 'json',
    };
    return map[mime] ?? 'bin';
  }

  Widget _buildFooter(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;
    final dt = DateTime.fromMillisecondsSinceEpoch(message.timestamp);
    final time = DateFormat('dd.MM. HH:mm').format(dt);

    return Row(
      mainAxisSize: MainAxisSize.min,
      children: [
        Text(
          time,
          style: TextStyle(
            fontSize: 11,
            color: _isUser
                ? Colors.white60
                : (isDark
                    ? AppColors.darkTextTertiary
                    : Colors.grey.shade500),
          ),
        ),
        if (message.status == MessageStatus.sending) ...[
          const SizedBox(width: 4),
          SizedBox(
            width: 10,
            height: 10,
            child: CircularProgressIndicator(
              strokeWidth: 1.5,
              color: _isUser ? Colors.white60 : AppColors.accent,
            ),
          ),
        ],
        if (message.status == MessageStatus.error) ...[
          const SizedBox(width: 4),
          const Icon(Icons.error_outline, size: 14, color: AppColors.error),
        ],
      ],
    );
  }

  void _showContextMenu(BuildContext context) {
    showModalBottomSheet(
      context: context,
      builder: (ctx) => SafeArea(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            ListTile(
              leading: const Icon(Icons.copy),
              title: const Text('Copy'),
              onTap: () {
                Clipboard.setData(ClipboardData(text: message.content));
                Navigator.pop(ctx);
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(
                    content: Text('Copied to clipboard'),
                    duration: Duration(seconds: 1),
                  ),
                );
              },
            ),
            if (onDelete != null)
              ListTile(
                leading: const Icon(Icons.delete_outline, color: AppColors.error),
                title: const Text('Delete', style: TextStyle(color: AppColors.error)),
                onTap: () {
                  Navigator.pop(ctx);
                  onDelete?.call();
                },
              ),
          ],
        ),
      ),
    );
  }

  String _formatDuration(int ms) {
    final seconds = (ms / 1000).ceil();
    final m = seconds ~/ 60;
    final s = seconds % 60;
    return '$m:${s.toString().padLeft(2, '0')}';
  }
}