import 'package:cached_network_image/cached_network_image.dart';
import 'package:flutter/material.dart';
import 'package:flutter_markdown/flutter_markdown.dart';
import '../theme.dart';

class MarkdownMessage extends StatelessWidget {
  final String data;
  final MarkdownStyleSheet styleSheet;
  final Map<String, MarkdownElementBuilder> builders;

  const MarkdownMessage({
    super.key,
    required this.data,
    required this.styleSheet,
    this.builders = const {},
  });

  @override
  Widget build(BuildContext context) {
    final segments = _split(data);
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      mainAxisSize: MainAxisSize.min,
      children: [
        for (final seg in segments)
          if (seg.isTable)
            _ScrollableTable(rows: seg.rows!, styleSheet: styleSheet)
          else
            MarkdownBody(
              data: seg.text,
              styleSheet: styleSheet,
              builders: builders,
              imageBuilder: (uri, title, alt) =>
                  _MarkdownImage(uri: uri, alt: alt ?? title),
              shrinkWrap: true,
            ),
      ],
    );
  }

  static final _tableSep = RegExp(r'^\s*\|?\s*:?-+:?\s*(\|\s*:?-+:?\s*)+\|?\s*$');
  static final _tableRow = RegExp(r'^\s*\|.*\|\s*$');

  List<_Segment> _split(String src) {
    final lines = src.split('\n');
    final result = <_Segment>[];
    final buffer = <String>[];

    void flushText() {
      if (buffer.isEmpty) return;
      final text = buffer.join('\n').trim();
      if (text.isNotEmpty) result.add(_Segment.text(text));
      buffer.clear();
    }

    for (var i = 0; i < lines.length; i++) {
      final line = lines[i];
      final isHeader = _tableRow.hasMatch(line);
      final next = i + 1 < lines.length ? lines[i + 1] : '';
      if (isHeader && _tableSep.hasMatch(next)) {
        flushText();
        final rows = <List<String>>[];
        rows.add(_cells(line));
        i += 2;
        while (i < lines.length && _tableRow.hasMatch(lines[i])) {
          rows.add(_cells(lines[i]));
          i++;
        }
        i--;
        result.add(_Segment.table(rows));
      } else {
        buffer.add(line);
      }
    }
    flushText();
    return result;
  }

  List<String> _cells(String line) {
    var trimmed = line.trim();
    if (trimmed.startsWith('|')) trimmed = trimmed.substring(1);
    if (trimmed.endsWith('|')) trimmed = trimmed.substring(0, trimmed.length - 1);
    return trimmed.split('|').map((c) => c.trim()).toList();
  }
}

class _Segment {
  final String text;
  final List<List<String>>? rows;
  bool get isTable => rows != null;

  _Segment.text(this.text) : rows = null;
  _Segment.table(this.rows) : text = '';
}

class _MarkdownImage extends StatelessWidget {
  final Uri uri;
  final String? alt;

  const _MarkdownImage({required this.uri, this.alt});

  @override
  Widget build(BuildContext context) {
    final url = uri.toString();
    final tag = 'md-img:$url';
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 6),
      child: GestureDetector(
        behavior: HitTestBehavior.opaque,
        onTap: () {
          FocusManager.instance.primaryFocus?.unfocus();
          Navigator.of(context, rootNavigator: true).push(
            PageRouteBuilder(
              opaque: false,
              barrierColor: Colors.black,
              transitionDuration: const Duration(milliseconds: 240),
              pageBuilder: (_, __, ___) =>
                  _ImageViewer(url: url, heroTag: tag, alt: alt),
            ),
          );
        },
        child: Hero(
          tag: tag,
          child: ClipRRect(
            borderRadius: BorderRadius.circular(10),
            child: CachedNetworkImage(
              imageUrl: url,
              fit: BoxFit.cover,
              width: double.infinity,
              placeholder: (context, _) => AspectRatio(
                aspectRatio: 16 / 9,
                child: Container(
                  color: AppColors.divider.withOpacity(0.3),
                  alignment: Alignment.center,
                  child: const SizedBox(
                    width: 22,
                    height: 22,
                    child: CircularProgressIndicator(strokeWidth: 2),
                  ),
                ),
              ),
              errorWidget: (context, _, __) => AspectRatio(
                aspectRatio: 16 / 9,
                child: Container(
                  color: AppColors.divider.withOpacity(0.3),
                  alignment: Alignment.center,
                  child: Icon(
                    Icons.broken_image_outlined,
                    color: AppColors.textTertiary,
                    size: 32,
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

class _ImageViewer extends StatelessWidget {
  final String url;
  final String heroTag;
  final String? alt;

  const _ImageViewer({required this.url, required this.heroTag, this.alt});

  void _close(BuildContext context) {
    FocusManager.instance.primaryFocus?.unfocus();
    Navigator.of(context).maybePop();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      body: GestureDetector(
        onTap: () => _close(context),
        behavior: HitTestBehavior.opaque,
        child: SafeArea(
          child: Stack(
            children: [
              Center(
                child: Hero(
                  tag: heroTag,
                  child: InteractiveViewer(
                    minScale: 1,
                    maxScale: 4,
                    child: CachedNetworkImage(
                      imageUrl: url,
                      fit: BoxFit.contain,
                      placeholder: (context, _) => const Center(
                        child: CircularProgressIndicator(
                          strokeWidth: 2,
                          valueColor:
                              AlwaysStoppedAnimation<Color>(Colors.white),
                        ),
                      ),
                      errorWidget: (context, _, __) => const Icon(
                        Icons.broken_image_outlined,
                        color: Colors.white54,
                        size: 64,
                      ),
                    ),
                  ),
                ),
              ),
              Positioned(
                top: 8,
                right: 8,
                child: IconButton(
                  icon: const Icon(Icons.close, color: Colors.white),
                  onPressed: () => _close(context),
                ),
              ),
              if (alt != null && alt!.isNotEmpty)
                Positioned(
                  left: 16,
                  right: 16,
                  bottom: 16,
                  child: Text(
                    alt!,
                    textAlign: TextAlign.center,
                    style: const TextStyle(
                      color: Colors.white70,
                      fontSize: 13,
                    ),
                  ),
                ),
            ],
          ),
        ),
      ),
    );
  }
}

class _ScrollableTable extends StatelessWidget {
  final List<List<String>> rows;
  final MarkdownStyleSheet styleSheet;

  const _ScrollableTable({required this.rows, required this.styleSheet});

  @override
  Widget build(BuildContext context) {
    if (rows.isEmpty) return const SizedBox.shrink();
    final header = rows.first;
    final body = rows.skip(1).toList();
    final cols = header.length;

    final padding = styleSheet.tableCellsPadding ?? const EdgeInsets.all(8);
    final headStyle = styleSheet.tableHead ??
        const TextStyle(fontWeight: FontWeight.w600);
    final bodyStyle = styleSheet.tableBody ?? const TextStyle();
    final border = styleSheet.tableBorder ??
        TableBorder.all(color: AppColors.divider, width: 1);

    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 8),
      child: LayoutBuilder(
        builder: (context, constraints) {
          return SingleChildScrollView(
            scrollDirection: Axis.horizontal,
            physics: const BouncingScrollPhysics(),
            child: ConstrainedBox(
              constraints: BoxConstraints(minWidth: constraints.maxWidth),
              child: Table(
                defaultColumnWidth: const IntrinsicColumnWidth(),
                border: border,
                children: [
                  TableRow(
                    decoration: BoxDecoration(
                      color: AppColors.primary.withOpacity(0.06),
                    ),
                    children: [
                      for (var c = 0; c < cols; c++)
                        Padding(
                          padding: padding,
                          child: Text(
                            c < header.length ? header[c] : '',
                            style: headStyle,
                          ),
                        ),
                    ],
                  ),
                  for (final row in body)
                    TableRow(
                      children: [
                        for (var c = 0; c < cols; c++)
                          Padding(
                            padding: padding,
                            child: Text(
                              c < row.length ? row[c] : '',
                              style: bodyStyle,
                            ),
                          ),
                      ],
                    ),
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}