94 lines
3.5 KiB
C#
94 lines
3.5 KiB
C#
#nullable enable
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using System.Text.RegularExpressions;
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using PluralKit.Core;
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namespace PluralKit.Bot;
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public class ProxyTagParser
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{
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private readonly Regex prefixPattern = new(@"^<(?:@!?|#|@&|a?:[\d\w_]+?:)\d+>");
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private readonly Regex suffixPattern = new(@"<(?:@!?|#|@&|a?:[\d\w_]+?:)\d+>$");
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public bool TryMatch(IEnumerable<ProxyMember> members, string? input, out ProxyMatch result)
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{
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result = default;
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// Null input is valid and is equivalent to empty string
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if (input == null) return false;
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// If the message starts with a @mention, and then proceeds to have proxy tags,
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// extract the mention and place it inside the inner message
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// eg. @Ske [text] => [@Ske text]
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var leadingMention = ExtractLeadingMention(ref input);
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// "Flatten" list of members to a list of tag-member pairs
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// Then order them by "tag specificity"
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// (prefix+suffix length desc = inner message asc = more specific proxy first)
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var tags = members
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.SelectMany(member => member.ProxyTags.Select(tag => (tag, member)))
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.OrderByDescending(p => p.tag.ProxyString.Length);
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// Iterate now-ordered list of tags and try matching each one
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foreach (var (tag, member) in tags)
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{
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result.ProxyTags = tag;
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result.Member = member;
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// Skip blank tags (shouldn't ever happen in practice)
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if (tag.Prefix == null && tag.Suffix == null) continue;
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if (tag.Prefix == "<" && prefixPattern.IsMatch(input)) continue;
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if (tag.Suffix == ">" && suffixPattern.IsMatch(input)) continue;
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// Can we match with these tags?
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if (TryMatchTagsInner(input, tag, out result.Content))
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{
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// If we extracted a leading mention before, add that back now
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if (leadingMention != null) result.Content = $"{leadingMention} {result.Content}";
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return true;
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}
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// (if not, keep going)
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}
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// We couldn't match anything :(
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return false;
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}
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private bool TryMatchTagsInner(string input, ProxyTag tag, out string inner)
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{
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inner = "";
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// Normalize null tags to empty strings
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var prefix = tag.Prefix ?? "";
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var suffix = tag.Suffix ?? "";
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// Check if our input starts/ends with the tags
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var isMatch = input.Length >= prefix.Length + suffix.Length
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&& input.StartsWith(prefix) && input.EndsWith(suffix);
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// Special case: image-only proxies + proxy tags with spaces
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// Trim everything, then see if we have a "contentless tag pair" (normally disallowed, but OK if we have an attachment)
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// Note `input` is still "", even if there are spaces between
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if (!isMatch && input.Trim() == prefix.TrimEnd() + suffix.TrimStart())
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return true;
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if (!isMatch) return false;
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// We got a match, extract inner text
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inner = input.Substring(prefix.Length, input.Length - prefix.Length - suffix.Length);
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// (see https://github.com/PluralKit/PluralKit/pull/181)
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return inner.Trim() != "\U0000fe0f";
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}
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private string? ExtractLeadingMention(ref string input)
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{
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var mentionPos = 0;
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if (!DiscordUtils.HasMentionPrefix(input, ref mentionPos, out _)) return null;
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var leadingMention = input.Substring(0, mentionPos);
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input = input.Substring(mentionPos);
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return leadingMention;
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}
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} |