import 'package:flutter/material.dart';

import '../api/oa_client.dart';
import '../theme.dart';
import 'auth_image.dart';

/// 公告 HTML：按块渲染标题、段落、列表、加粗，不依赖 flutter_html。
class HtmlBody extends StatelessWidget {
  const HtmlBody({super.key, required this.html, this.api});
  final String html;
  final OaClient? api;

  @override
  Widget build(BuildContext context) {
    final blocks = parseHtmlBlocks(html);
    if (blocks.isEmpty) {
      return const Text('暂无正文', style: TextStyle(color: kMute, fontSize: 15));
    }
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        for (final b in blocks) ...[
          if (b.kind == 'img' && b.src != null)
            Padding(
              padding: const EdgeInsets.only(bottom: 12),
              child: _img(b.src!),
            )
          else
            Padding(
              padding: EdgeInsets.only(bottom: b.kind.startsWith('h') ? 10 : 12, left: b.kind == 'li' ? 12 : 0),
              child: Text.rich(
                TextSpan(children: b.spans),
                style: _style(b.kind),
              ),
            ),
        ],
      ],
    );
  }

  TextStyle _style(String kind) {
    switch (kind) {
      case 'h1':
        return const TextStyle(fontSize: 22, fontWeight: FontWeight.w700, color: kInk, height: 1.4);
      case 'h2':
        return const TextStyle(fontSize: 18, fontWeight: FontWeight.w700, color: kInk, height: 1.4);
      case 'h3':
        return const TextStyle(fontSize: 16, fontWeight: FontWeight.w700, color: kInk, height: 1.45);
      case 'li':
        return const TextStyle(fontSize: 16, color: kInk, height: 1.7);
      default:
        return const TextStyle(fontSize: 16, color: kInk, height: 1.7);
    }
  }

  Widget _img(String src) {
    final m = RegExp(r'/files/([0-9a-f-]{36})', caseSensitive: false).firstMatch(src);
    if (m != null && api != null) {
      return ClipRRect(
        borderRadius: BorderRadius.circular(6),
        child: AuthImage(api: api!, fileId: m.group(1)!, fit: BoxFit.contain),
      );
    }
    return const SizedBox.shrink();
  }
}

class HtmlBlock {
  HtmlBlock(this.kind, this.spans, {this.src});
  final String kind;
  final List<InlineSpan> spans;
  final String? src;
}

List<HtmlBlock> parseHtmlBlocks(String raw) {
  var s = raw.trim();
  if (s.isEmpty) return [];
  s = s.replaceAll(RegExp(r'<(script|style)[^>]*>[\s\S]*?</\1>', caseSensitive: false), '');
  if (!RegExp(r'<[a-z][\s\S]*>', caseSensitive: false).hasMatch(s)) {
    return s
        .split(RegExp(r'\n+'))
        .where((e) => e.trim().isNotEmpty)
        .map((e) => HtmlBlock('p', _inline(e.trim())))
        .toList();
  }
  s = s
      .replaceAll(RegExp(r'<br\s*/?>', caseSensitive: false), '\n')
      .replaceAll(RegExp(r'</(p|div|h1|h2|h3|li|tr|blockquote)>', caseSensitive: false), '\n')
      .replaceAll(RegExp(r'<(p|div|blockquote)[^>]*>', caseSensitive: false), '\n')
      .replaceAll(RegExp(r'<h1[^>]*>', caseSensitive: false), '\n#h1#')
      .replaceAll(RegExp(r'<h2[^>]*>', caseSensitive: false), '\n#h2#')
      .replaceAll(RegExp(r'<h3[^>]*>', caseSensitive: false), '\n#h3#')
      .replaceAll(RegExp(r'<li[^>]*>', caseSensitive: false), '\n#li#')
      .replaceAll(RegExp(r'</?(ul|ol)[^>]*>', caseSensitive: false), '\n')
      .replaceAll(RegExp(r'<(strong|b)[^>]*>', caseSensitive: false), '«b»')
      .replaceAll(RegExp(r'</(strong|b)>', caseSensitive: false), '«/b»');
  final imgRe = RegExp(r'<img[^>]*src=["'']([^"'']+)["''][^>]*>', caseSensitive: false);
  s = s.replaceAllMapped(imgRe, (m) => '\n#img#${m.group(1)}#\n');
  s = s.replaceAll(RegExp(r'<[^>]+>'), '');
  s = decodeEntities(s);
  final out = <HtmlBlock>[];
  for (final line in s.split('\n')) {
    final t = line.trim();
    if (t.isEmpty) continue;
    if (t.startsWith('#img#') && t.endsWith('#')) {
      out.add(HtmlBlock('img', const [], src: t.substring(5, t.length - 1)));
      continue;
    }
    var kind = 'p';
    var text = t;
    if (t.startsWith('#h1#')) {
      kind = 'h1';
      text = t.substring(4);
    } else if (t.startsWith('#h2#')) {
      kind = 'h2';
      text = t.substring(4);
    } else if (t.startsWith('#h3#')) {
      kind = 'h3';
      text = t.substring(4);
    } else if (t.startsWith('#li#')) {
      kind = 'li';
      text = '• ${t.substring(4)}';
    }
    text = text.trim();
    if (text.isEmpty) continue;
    out.add(HtmlBlock(kind, _inline(text)));
  }
  return out;
}

List<InlineSpan> _inline(String text) {
  final out = <InlineSpan>[];
  final re = RegExp(r'«b»(.*?)«/b»');
  var i = 0;
  for (final m in re.allMatches(text)) {
    if (m.start > i) out.add(TextSpan(text: text.substring(i, m.start)));
    out.add(TextSpan(text: m.group(1), style: const TextStyle(fontWeight: FontWeight.w700)));
    i = m.end;
  }
  if (i < text.length) out.add(TextSpan(text: text.substring(i)));
  if (out.isEmpty) out.add(TextSpan(text: text));
  return out;
}

String decodeEntities(String s) {
  return s
      .replaceAll('&nbsp;', ' ')
      .replaceAll('&amp;', '&')
      .replaceAll('&lt;', '<')
      .replaceAll('&gt;', '>')
      .replaceAll('&quot;', '"')
      .replaceAll('&#39;', "'")
      .replaceAllMapped(RegExp(r'&#(\d+);'), (m) {
        final n = int.tryParse(m.group(1)!);
        return n == null ? m.group(0)! : String.fromCharCode(n);
      });
}