82 lines
3.1 KiB
C#
82 lines
3.1 KiB
C#
using System.Net;
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using System.Text.RegularExpressions;
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namespace Journal.Core.Services.Entries;
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public static partial class HtmlSanitizer
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{
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[GeneratedRegex("<(script|style)\\b[^>]*>.*?</\\1>", RegexOptions.IgnoreCase | RegexOptions.Singleline)]
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private static partial Regex ScriptStyleRegex();
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[GeneratedRegex("<br\\s*/?>", RegexOptions.IgnoreCase)]
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private static partial Regex BrTagRegex();
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[GeneratedRegex("</(p|div|h[1-6]|tr|table|ul|ol|blockquote)>", RegexOptions.IgnoreCase)]
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private static partial Regex BlockEndTagRegex();
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[GeneratedRegex("<li\\b[^>]*>", RegexOptions.IgnoreCase)]
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private static partial Regex LiStartTagRegex();
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[GeneratedRegex("</li>", RegexOptions.IgnoreCase)]
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private static partial Regex LiEndTagRegex();
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[GeneratedRegex("<(td|th)\\b[^>]*>", RegexOptions.IgnoreCase)]
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private static partial Regex CellStartTagRegex();
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[GeneratedRegex("</(td|th)>", RegexOptions.IgnoreCase)]
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private static partial Regex CellEndTagRegex();
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[GeneratedRegex("<hr\\b[^>]*>", RegexOptions.IgnoreCase)]
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private static partial Regex HrTagRegex();
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[GeneratedRegex("<[^>]+>", RegexOptions.Singleline)]
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private static partial Regex AllTagsRegex();
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[GeneratedRegex("[ \\t]{2,}")]
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private static partial Regex MultipleSpacesRegex();
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[GeneratedRegex("\n{3,}")]
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private static partial Regex MultipleNewlinesRegex();
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[GeneratedRegex("</?[a-z][^>]*>")]
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private static partial Regex HtmlTagCountRegex();
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public static string StripRichHtml(string content)
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{
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if (string.IsNullOrWhiteSpace(content))
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return content;
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if (!LooksLikeRichHtml(content))
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return content;
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var text = content.Replace("\r\n", "\n").Replace("\r", "\n");
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text = ScriptStyleRegex().Replace(text, "");
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text = BrTagRegex().Replace(text, "\n");
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text = BlockEndTagRegex().Replace(text, "\n");
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text = LiStartTagRegex().Replace(text, "\n- ");
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text = LiEndTagRegex().Replace(text, "\n");
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text = CellStartTagRegex().Replace(text, " | ");
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text = CellEndTagRegex().Replace(text, " ");
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text = HrTagRegex().Replace(text, "\n---\n");
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text = AllTagsRegex().Replace(text, "");
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text = WebUtility.HtmlDecode(text)
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.Replace('\u00a0', ' ')
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.Replace("\u200b", "", StringComparison.Ordinal);
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text = string.Join("\n", text.Split('\n').Select(line => line.TrimEnd()));
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text = MultipleSpacesRegex().Replace(text, " ");
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text = MultipleNewlinesRegex().Replace(text, "\n\n").Trim();
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return string.IsNullOrEmpty(text) ? content : text;
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}
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public static bool LooksLikeRichHtml(string content)
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{
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var lowered = content.ToLowerInvariant();
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string[] markers =
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[
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"<p", "</p>", "<div", "<span", "<table", "<tr", "<td", "<li", "<ul", "<ol",
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"style=", "font-family:", "-webkit-text-stroke"
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];
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if (markers.Any(marker => lowered.Contains(marker, StringComparison.Ordinal)))
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return true;
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return HtmlTagCountRegex().Matches(lowered).Count >= 8;
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}
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}
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