babyrite/
expand.rs

1//! Link expansion module.
2//!
3//! This module provides common types for expanding various types of links
4//! (Discord message links, GitHub permalinks, etc.) into rich preview content.
5
6pub mod discord;
7pub mod github;
8
9use crate::config::BabyriteConfig;
10use regex::Regex;
11use serenity::all::{Context, GuildId, Message};
12use serenity_builder::model::embed::SerenityEmbed;
13use std::collections::HashSet;
14
15/// Shared inputs for expanding the links of one message.
16pub struct ExpandContext<'a> {
17    /// The serenity context.
18    pub ctx: &'a Context,
19    /// The message whose links are being expanded.
20    pub message: &'a Message,
21    /// The guild the message was sent in.
22    pub guild_id: GuildId,
23}
24
25/// A link expander: parses its own link type out of a message and expands
26/// each link into [`ExpandedContent`].
27///
28/// Adding a new link type means implementing this trait and registering the
29/// expander in [`EXPANDERS`]; the event handler needs no changes.
30#[serenity::async_trait]
31pub trait LinkExpander: Send + Sync {
32    /// Whether this expander is enabled under `config`.
33    fn enabled(&self, config: &BabyriteConfig) -> bool;
34
35    /// Parses and expands all links of this expander's type in the message.
36    ///
37    /// Failures are logged per link and never abort the other links or
38    /// expanders, so this returns only the successful expansions.
39    async fn expand_all(&self, cx: &ExpandContext<'_>) -> Vec<ExpandedContent>;
40}
41
42/// All registered link expanders, in the order their results appear in a reply.
43pub static EXPANDERS: &[&dyn LinkExpander] = &[&discord::DiscordExpander, &github::GitHubExpander];
44
45/// Maximum number of links expanded per message.
46const MAX_LINKS_PER_MESSAGE: usize = 3;
47
48/// Extracts links matching `regex` from `text`, applying the shared link policy:
49/// URLs wrapped in angle brackets (e.g. `<https://...>`) are skipped, duplicate
50/// URLs are ignored, and at most [`MAX_LINKS_PER_MESSAGE`] links are returned.
51///
52/// `parse` converts a regex match into the expander-specific link type;
53/// returning `None` drops that match.
54pub(crate) fn parse_links<T>(
55    text: &str,
56    regex: &Regex,
57    parse: impl Fn(&regex::Captures) -> Option<T>,
58) -> Vec<T> {
59    let mut seen_urls = HashSet::new();
60    regex
61        .captures_iter(text)
62        .filter_map(|captures| {
63            let m = captures.get(0)?;
64            if m.start() > 0 && text.as_bytes()[m.start() - 1] == b'<' {
65                return None;
66            }
67            if !seen_urls.insert(m.as_str()) {
68                return None;
69            }
70            parse(&captures)
71        })
72        .take(MAX_LINKS_PER_MESSAGE)
73        .collect()
74}
75
76/// Expanded content produced by a link expander.
77///
78/// Represents the different kinds of content that can result from
79/// expanding a link.
80pub enum ExpandedContent {
81    /// A Discord message preview displayed as an embed.
82    Embed(Box<SerenityEmbed>),
83    /// A code block with syntax highlighting (e.g. GitHub permalink).
84    CodeBlock {
85        /// The programming language for syntax highlighting.
86        language: String,
87        /// The code content.
88        code: String,
89        /// Metadata line displayed above the code block (e.g. file path, line range).
90        metadata: String,
91    },
92}
93
94/// Errors that can occur during link expansion.
95#[derive(thiserror::Error, Debug)]
96pub enum ExpandError {
97    /// An error from the Discord message link expander.
98    #[error(transparent)]
99    Discord(#[from] discord::PreviewError),
100    /// An error from the GitHub permalink expander.
101    #[error(transparent)]
102    GitHub(#[from] github::GitHubExpandError),
103}
babyrite/expand.rs

babyrite/
expand.rs
