import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'dart:cli';

// +---------+------------------+------+-----+---------+----------------+
// | Field   | Type             | Null | Key | Default | Extra          |
// +---------+------------------+------+-----+---------+----------------+
// | postID  | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
// | title   | text             | NO   |     | NULL    |                |
// | content | text             | NO   |     | NULL    |                |
// | stamp   | int(10) unsigned | NO   |     | 0       |                |
// +---------+------------------+------+-----+---------+----------------+

const Map<String, String> titles = <String, String>{
  'https://plus.google.com/+IanHickson/posts/2S1ETVb5SKL': 'Improving on HTML',
  'https://plus.google.com/+IanHickson/posts/NZBJe6Jjt1f': 'Living Standards',
  'https://plus.google.com/+IanHickson/posts/SiLdNL9MsFw': 'Replacing HTML',
  'https://plus.google.com/+IanHickson/posts/4MrPNJzE8vV': 'Consensus',
  'https://plus.google.com/+IanHickson/posts/iPmatxBYuj2': 'DRM',
  'https://plus.google.com/+IanHickson/posts/aXEBL5BwXYw': 'HTML 8000',
  'https://plus.google.com/+IanHickson/posts/iAozXGH7Eck': 'Looping constructs',
  'https://plus.google.com/+IanHickson/posts/RaHnqNJYGoB': 'Flutter: Accessibility',
  'https://plus.google.com/+IanHickson/posts/fJBZkA5Tu4V': 'Flutter: Developer experience',
  'https://plus.google.com/+IanHickson/posts/GJBrEN9ukRo': 'Flutter: Performance and testing',
  'https://plus.google.com/+IanHickson/posts/KyDSnQXomUH': 'Flutter\'s mahogany staircase',
  'https://plus.google.com/+IanHickson/posts/2ZMcXwkKLDG': 'Flutter at Google I/O',
  'https://plus.google.com/+IanHickson/posts/hmUd1Q7FSD2': 'Flutter: Embrace the yak shave',
  'https://plus.google.com/+IanHickson/posts/K8HVNrLCFvc': 'Flutter: Hot reload',
  'https://plus.google.com/+IanHickson/posts/a1bdr27bDK8': 'Tolerance',
  'https://plus.google.com/+IanHickson/posts/ihQjXCRvmEK': 'Flutter: So what\'d I miss?',
  'https://plus.google.com/+IanHickson/posts/P3SnMrKCpoq': 'Flutter: Negative margins',
  'https://plus.google.com/+IanHickson/posts/DQ114jUKaXo': 'Indexing into a string',
};

class FailedMigration implements Exception {
  FailedMigration(this.message);
  final String message;
  String toString() => message;
}

String escapeSql(String raw) {
  if (raw == null)
    return '';
  return raw
    .replaceAll(r"\", r"\\")
    .replaceAll("\b", r"\b")
    .replaceAll("\n", r"\n")
    .replaceAll("\r", r"\r")
    .replaceAll("\t", r"\t")
    .replaceAll(r"%", r"\%")
    .replaceAll(r"'", r"\'")
    .replaceAll(r"_", r"\_");
}

String escapeHtml(String raw) {
  if (raw == null)
    return '';
  return raw
    .replaceAll('&', '&amp;')
    .replaceAll('<', '&lt;')
    .replaceAll('>', '&gt;')
    .replaceAll('"', '&quot;');
}

class Post {
  Post(this.id, this.title, this.content, this.stamp);

  final String id;
  final String title;
  final String content;
  final DateTime stamp;

  String toSql() => "INSERT INTO posts (title, content, stamp) VALUES ('${escapeSql(title)}', '${escapeSql(content)}', ${stamp.millisecondsSinceEpoch ~/ 1000});";
  String toHtml() => "<article class=\"google-plus-migration\"><h3><a href=\"\" rel=\"bookmark\">${escapeHtml(stamp.toIso8601String())}</a>$title</h3>\n$content\n<p><label><input type=\"checkbox\" onclick=\"toggle('$id', checked)\"> INCLUDE</label></article>\n";
}

HttpClient client = new HttpClient()
  ..userAgent = 'Google+ to ln.hixie.ch migration agent, contact ian@hixie.ch';

Map<String, HttpClientResponse> attempts = <String, HttpClientResponse>{};

String substituteLinks(String oldUrl) {
  assert(oldUrl != null);
  if (oldUrl == 'http://www.koncision.com/using-reasonable-and-reasonably-in-contracts/')
    return 'https://web.archive.org/web/20130211130051/$oldUrl';
  try {
    if (!attempts.containsKey(oldUrl)) {
      attempts[oldUrl] = waitFor(client.getUrl(Uri.parse(oldUrl)).then((request) => request.close()), timeout: const Duration(seconds: 5))
        ..drain();
    }
    HttpClientResponse response = attempts[oldUrl];
    if (response.statusCode != 200)
      throw FailedMigration('${response.statusCode} when fetching $oldUrl');
  } on TimeoutException {
    throw FailedMigration('Timeout when fetching $oldUrl');
  }
  return oldUrl;
}

final RegExp _htmlBrRegexp = RegExp(r'(<br>)+');
final RegExp _htmlTrailingSpaceInTag = RegExp(' +>');
final RegExp _htmlMultispace = RegExp(' +');
final RegExp _htmlLinebreaks = RegExp('\n+');

String processHtml(String html) {
  return '<p>' + html
    .replaceAll(_htmlBrRegexp, '\n<p>')
    .replaceAll('class="ot-anchor bidi_isolate"', '')
    .replaceAll('dir="ltr"', '')
    .replaceAll('jslog="10929; track:click"', '')
    .replaceAll('rel="nofollow"', '')
    .replaceAll('target="_blank"', '')
    .replaceAll(_htmlTrailingSpaceInTag, '>')
    .replaceAll(_htmlMultispace, ' ')
    .replaceAll(_htmlLinebreaks, '\n');
}

String processMedia(var media) {
  switch (media['contentType']) {
    case 'image/*':
    case 'image/png':
    case 'image/jpeg':
      return '\n<p><figure><img src="${escapeHtml(substituteLinks(media['url']))}"><figcaption>${escapeHtml(media['description'])}</figcaption></figure>';
    case 'video/*':
      String url = media['url'];
      const String kYouTube = '//www.youtube.com/';
      if (url.contains(kYouTube)) {
        url = url.replaceAll('http://', 'https://');
        String videoId;
        const String kYouTubeWatch = 'https://www.youtube.com/watch?v=';
        if (url.startsWith(kYouTubeWatch))
          videoId = url.substring(kYouTubeWatch.length);
        const String kYouTubeAttribution = 'https://www.youtube.com/attribution_link?a=';
        if (url.startsWith(kYouTubeAttribution))
          videoId = url.substring(kYouTubeAttribution.length, url.indexOf('&'));
        return '\n<p><figure><iframe width="560" height="315" src="https://www.youtube.com/embed/$videoId" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><figcaption>${escapeHtml(media['description'])}</figcaption></figure>';
      }
      return '\n<p><figure><video src="${escapeHtml(substituteLinks(url))}"></video><figcaption>${escapeHtml(media['description'])}</figcaption></figure>';
    default: throw 'no code to handle ${media['contentType']}';
  }
}

String processLink(var link) {
  if (link['imageUrl'] != null) {
    try {
      return '\n<p><figure><a href="${escapeHtml(substituteLinks(link['url']))}"><img src="${escapeHtml(substituteLinks(link['imageUrl']))}"></a><figcaption><a href="${escapeHtml(substituteLinks(link['url']))}">${escapeHtml(link['title'])}</a></figcaption></figure>';
    } on FailedMigration {
      // try again below
    }
  }
  return '\n<p><a href="${escapeHtml(substituteLinks(link['url']))}">${escapeHtml(link['title'])}</a>';
}

String replaceBareLinks(String html, String url, String replacement) {
  String pattern = '\n<p><a href="${escapeHtml(url)}">${escapeHtml(url)}</a>';
  if (html.contains(pattern))
    return html.replaceAll(pattern, replacement);
  return html += replacement;
}

void main() {
  List<Post> posts = <Post>[];
  for (File file in Directory('Posts').listSync().whereType<File>()) {
    try {
      String rawData = file.readAsStringSync();
      var data = json.decode(rawData);

      if (data['postAcl']['isPublic'] != true) {
        throw FailedMigration('not public');
      }

      if (!titles.containsKey(data['url'])) {
        throw FailedMigration('excluded');
      }

      if (data.containsKey('resharedPost')) {
        throw FailedMigration('reshared post');
      }

      if (data.containsKey('poll')) {
        throw FailedMigration('poll');
      }

      String html = '';
      bool hasContent;
      if (data.containsKey('content')) {
        //if (data['content'].contains('comments'))
        //  throw FailedMigration('contains mention of comments');
        html += processHtml(data['content']);
        hasContent = true;
      } else {
        hasContent = false;
      }
      if (data.containsKey('media')) {
        assert(!data.containsKey('album'));
        assert(!data.containsKey('link'));
        if (!hasContent || !data['content'].contains(data['media']['url']))
          html = replaceBareLinks(html, data['media']['url'], processMedia(data['media']));
      }
      if (data.containsKey('album')) {
        assert(!data.containsKey('media'));
        assert(!data.containsKey('link'));
        for (var media in data['album']['media']) {
          html = replaceBareLinks(html, media['url'], processMedia(media));
        }
      }
      if (data.containsKey('link')) {
        assert(!data.containsKey('media'));
        assert(!data.containsKey('album'));
        if (!hasContent || !data['content'].contains(data['link']['url']))
          html = replaceBareLinks(html, data['link']['url'], processLink(data['link']));
      }

      if (!hasContent)
        throw FailedMigration('no content except for $html');

      String title = '';
      if (titles.containsKey(data['url'])) {
        title = titles[data['url']];
      } else if (data['postAcl'].containsKey('collectionAcl')) {
        title = data['postAcl']['collectionAcl']['collection']['displayName'] + ': ';
      } else {
        title = 'TODO(ianh): Add title to migrated blog post';
      }

      stderr.writeln('+ migrated ${file.path} ("$title")');
      posts.add(Post(data['url'], title, html, DateTime.parse(data['creationTime'])));
    } on FailedMigration catch (error) {
      stderr.writeln('- not migrating because $error: ${file.path}');
    }
  }
  
  print('''
<!DOCTYPE HTML>
<html lang="en-GB-x-Hixie">
 <head>
  <base href="http://ln.hixie.ch/">
  <link rel="stylesheet" href="/resources/style/2010/">
  <link rel="alternate" type="application/rss+xml" title="RSS Feed" href="/rss/html">
  <link rel="pingback" href="http://ln.hixie.ch/">
  <link rel="icon" href="/resources/images/astrophy/16-a">
  <link rel="author" href="https://plus.google.com/107429617152575897589">
  <link rel="author" href="http://ian.hixie.ch/">
  <title>Hixie's Natural Log</title>
 </head>
 <body class="index">
  <header>
   <hgroup>
    <h1><span class="domain"><!--
    --><span class="subdomain"><span class="site-label-ln">log<sub>e</sub></span></span><!--
    --><span class="dot">.</span><!--
    --><span class="hixie">hixie</span><!--
    --><span class="dot">.</span><!--
    --><span class="ch"><span class="c">c</span>h</span><!--
    --></span></h1>
    <h2>Hixie's Natural Log</h2>
   </hgroup>
  </header>
  <div id="yes"></div>
  <script>
    function toggle(id, on) {
      if (on) {
        var node = document.createElement('p');
        node.appendChild(document.createTextNode(id));
        node.id = id;
        document.getElementById('yes').appendChild(node);
      } else {
        var node = document.getElementById(id);
        node.parentNode.removeChild(node);
      }
    }
  </script>
''');

  print(posts.map((Post post) => post.toHtml()).join('\n'));

  print('<!-- ${posts.length} posts; SQL:');
  posts.sort((Post a, Post b) => a.stamp.compareTo(b.stamp));
  print(posts.map((Post post) => post.toSql()).join('\n'));
  print('-->');
}