comment.rs

use alloy_primitives::map::HashMap;
use derive_more::{Deref, DerefMut, derive::Display};

/// The natspec comment tag explaining the purpose of the comment.
/// See: <https://docs.soliditylang.org/en/v0.8.17/natspec-format.html#tags>.
#[derive(Clone, Debug, Display, PartialEq, Eq)]
pub enum CommentTag {
    /// A title that should describe the contract/interface
    Title,
    /// The name of the author
    Author,
    /// Explain to an end user what this does
    Notice,
    /// Explain to a developer any extra details
    Dev,
    /// Documents a parameter just like in Doxygen (must be followed by parameter name)
    Param,
    /// Documents the return variables of a contract’s function
    Return,
    /// Copies all missing tags from the base function (must be followed by the contract name)
    Inheritdoc,
    /// Custom tag, semantics is application-defined
    Custom(String),
}

impl CommentTag {
    fn from_str(s: &str) -> Option<Self> {
        let trimmed = s.trim();
        let tag = match trimmed {
            "title" => Self::Title,
            "author" => Self::Author,
            "notice" => Self::Notice,
            "dev" => Self::Dev,
            "param" => Self::Param,
            "return" => Self::Return,
            "inheritdoc" => Self::Inheritdoc,
            _ if trimmed.starts_with("custom:") => {
                // `@custom:param` tag will be parsed as `CommentTag::Param` due to a limitation
                // on specifying parameter docs for unnamed function arguments.
                let custom_tag = trimmed.trim_start_matches("custom:").trim();
                match custom_tag {
                    "param" => Self::Param,
                    _ => Self::Custom(custom_tag.to_owned()),
                }
            }
            _ => {
                warn!(target: "forge::doc", tag=trimmed, "unknown comment tag. custom tags must be preceded by `custom:`");
                return None;
            }
        };
        Some(tag)
    }
}

/// The natspec documentation comment.
///
/// Ref: <https://docs.soliditylang.org/en/v0.8.17/natspec-format.html>
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Comment {
    /// The doc comment tag.
    pub tag: CommentTag,
    /// The doc comment value.
    pub value: String,
}

impl Comment {
    /// Create new instance of [Comment].
    pub const fn new(tag: CommentTag, value: String) -> Self {
        Self { tag, value }
    }

    /// Create new instance of [Comment] from a tag string and value,
    /// if it has a valid natspec tag.
    pub fn from_tag_and_value(tag: &str, value: String) -> Option<Self> {
        CommentTag::from_str(tag).map(|tag| Self { tag, value })
    }

    /// Split the comment at first word.
    /// Useful for [CommentTag::Param] and [CommentTag::Return] comments.
    pub fn split_first_word(&self) -> Option<(&str, &str)> {
        self.value.trim_start().split_once(' ')
    }

    /// Match the first word of the comment with the expected.
    /// Returns [None] if the word doesn't match.
    /// Useful for [CommentTag::Param] and [CommentTag::Return] comments.
    pub fn match_first_word(&self, expected: &str) -> Option<&str> {
        self.split_first_word().and_then(|(word, rest)| (word == expected).then_some(rest))
    }

    /// Check if this comment is a custom tag.
    pub const fn is_custom(&self) -> bool {
        matches!(self.tag, CommentTag::Custom(_))
    }
}

/// The collection of natspec [Comment] items.
#[derive(Clone, Debug, Default, PartialEq, Eq, Deref, DerefMut)]
pub struct Comments(Vec<Comment>);

/// Forward the [Comments] function implementation to the [CommentsRef]
/// reference type.
macro_rules! ref_fn {
    ($vis:vis fn $name:ident(&self$(, )?$($arg_name:ident: $arg:ty),*) -> $ret:ty) => {
        /// Forward the function implementation to [CommentsRef] reference type.
        $vis fn $name(&self, $($arg_name: $arg),*) -> $ret {
            CommentsRef::from(self).$name($($arg_name),*)
        }
    };
}

impl Comments {
    ref_fn!(pub fn include_tag(&self, tag: CommentTag) -> CommentsRef<'_>);
    ref_fn!(pub fn include_tags(&self, tags: &[CommentTag]) -> CommentsRef<'_>);
    ref_fn!(pub fn exclude_tags(&self, tags: &[CommentTag]) -> CommentsRef<'_>);
    ref_fn!(pub fn contains_tag(&self, tag: &Comment) -> bool);
    ref_fn!(pub fn find_inheritdoc_base(&self) -> Option<&'_ str>);

    /// Attempts to lookup inherited comments and merge them with the current collection.
    ///
    /// Looks up comments in `inheritdocs` using the key `{base}.{ident}` where `base` is
    /// extracted from an `@inheritdoc` tag. Merges the found comments by inserting
    /// [CommentTag] from the inherited collection into the current one unless they are
    /// already present.
    pub fn merge_inheritdoc(
        &self,
        ident: &str,
        inheritdocs: Option<HashMap<String, Self>>,
    ) -> Self {
        let mut result = self.clone();

        if let (Some(inheritdocs), Some(base)) = (inheritdocs, self.find_inheritdoc_base()) {
            let key = format!("{base}.{ident}");
            if let Some(other) = inheritdocs.get(&key) {
                for comment in other.iter() {
                    if !result.contains_tag(comment) {
                        result.push(comment.clone());
                    }
                }
            }
        }

        result
    }
}

impl Comments {
    /// Parse natspec comments from raw doc comment lines.
    ///
    /// Each line should be the raw text content of a `///` or `/** */` doc comment
    /// with the comment delimiters already stripped (as provided by solar's `DocComment::symbol`).
    ///
    /// Natspec tags start with `@` (e.g. `@notice`, `@dev`, `@param`).
    /// Lines without a tag at the start are treated as continuations of the previous tag,
    /// or as `@notice` if no previous tag exists.
    pub fn from_doc_lines(lines: impl IntoIterator<Item = impl AsRef<str>>) -> Self {
        let mut comments = Vec::new();
        let mut current_tag: Option<String> = None;
        let mut current_value = String::new();

        let flush = |tag: &Option<String>, value: &str, out: &mut Vec<Comment>| {
            let value = value.trim();
            if value.is_empty() && tag.is_none() {
                return;
            }
            let tag_str = tag.as_deref().unwrap_or("notice");
            // Filter out `@solidity` tags and empty tags
            if tag_str.trim() == "solidity" || tag_str.trim().is_empty() {
                return;
            }
            if let Some(c) = Comment::from_tag_and_value(tag_str, value.to_string()) {
                out.push(c);
            }
        };

        for raw_line in lines {
            let raw = raw_line.as_ref();
            // For block comments, process each line individually
            for line in raw.lines() {
                let trimmed = line.trim().trim_start_matches('*').trim();

                if let Some(rest) = trimmed.strip_prefix('@') {
                    // Flush previous
                    flush(&current_tag, &current_value, &mut comments);
                    // Parse new tag
                    let (tag, value) = rest.split_once(char::is_whitespace).unwrap_or((rest, ""));
                    current_tag = Some(tag.to_string());
                    current_value = value.trim().to_string();
                } else if !trimmed.is_empty() {
                    // Continuation of current tag
                    if current_value.is_empty() {
                        current_value = trimmed.to_string();
                    } else {
                        current_value.push('\n');
                        current_value.push_str(trimmed);
                    }
                }
            }
        }

        // Flush last
        flush(&current_tag, &current_value, &mut comments);

        Self(comments)
    }
}

/// The collection of references to natspec [Comment] items.
#[derive(Debug, Default, PartialEq, Eq, Deref)]
pub struct CommentsRef<'a>(Vec<&'a Comment>);

impl<'a> CommentsRef<'a> {
    /// Filter a collection of comments and return only those that match a provided tag.
    pub fn include_tag(&self, tag: CommentTag) -> Self {
        self.include_tags(&[tag])
    }

    /// Filter a collection of comments and return only those that match provided tags.
    pub fn include_tags(&self, tags: &[CommentTag]) -> Self {
        // Cloning only references here
        CommentsRef(self.iter().copied().filter(|c| tags.contains(&c.tag)).collect())
    }

    /// Filter a collection of comments and return only those that do not match provided tags.
    pub fn exclude_tags(&self, tags: &[CommentTag]) -> Self {
        // Cloning only references here
        CommentsRef(self.iter().copied().filter(|c| !tags.contains(&c.tag)).collect())
    }

    /// Check if the collection contains a target comment.
    pub fn contains_tag(&self, target: &Comment) -> bool {
        self.iter().any(|c| match (&c.tag, &target.tag) {
            (CommentTag::Inheritdoc, CommentTag::Inheritdoc) => c.value == target.value,
            (CommentTag::Param, CommentTag::Param) | (CommentTag::Return, CommentTag::Return) => {
                c.split_first_word().map(|(name, _)| name)
                    == target.split_first_word().map(|(name, _)| name)
            }
            (tag1, tag2) => tag1 == tag2,
        })
    }

    /// Find an [CommentTag::Inheritdoc] comment and extract the base.
    fn find_inheritdoc_base(&self) -> Option<&'a str> {
        self.iter()
            .find(|c| matches!(c.tag, CommentTag::Inheritdoc))
            .and_then(|c| c.value.split_whitespace().next())
    }

    /// Filter a collection of comments and only return the custom tags.
    pub fn get_custom_tags(&self) -> Self {
        CommentsRef(self.iter().copied().filter(|c| c.is_custom()).collect())
    }
}

impl<'a> From<&'a Comments> for CommentsRef<'a> {
    fn from(value: &'a Comments) -> Self {
        Self(value.iter().collect())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn parse_comment_tag() {
        assert_eq!(CommentTag::from_str("title"), Some(CommentTag::Title));
        assert_eq!(CommentTag::from_str(" title  "), Some(CommentTag::Title));
        assert_eq!(CommentTag::from_str("author"), Some(CommentTag::Author));
        assert_eq!(CommentTag::from_str("notice"), Some(CommentTag::Notice));
        assert_eq!(CommentTag::from_str("dev"), Some(CommentTag::Dev));
        assert_eq!(CommentTag::from_str("param"), Some(CommentTag::Param));
        assert_eq!(CommentTag::from_str("return"), Some(CommentTag::Return));
        assert_eq!(CommentTag::from_str("inheritdoc"), Some(CommentTag::Inheritdoc));
        assert_eq!(CommentTag::from_str("custom:"), Some(CommentTag::Custom(String::new())));
        assert_eq!(
            CommentTag::from_str("custom:some"),
            Some(CommentTag::Custom("some".to_owned()))
        );
        assert_eq!(
            CommentTag::from_str("  custom:   some   "),
            Some(CommentTag::Custom("some".to_owned()))
        );

        assert_eq!(CommentTag::from_str(""), None);
        assert_eq!(CommentTag::from_str("custom"), None);
        assert_eq!(CommentTag::from_str("sometag"), None);
    }

    #[test]
    fn test_is_custom() {
        // Test custom tag.
        let custom_comment = Comment::new(
            CommentTag::from_str("custom:test").unwrap(),
            "dummy custom tag".to_owned(),
        );
        assert!(custom_comment.is_custom(), "Custom tag should return true for is_custom");

        // Test non-custom tags.
        let non_custom_tags = [
            CommentTag::Title,
            CommentTag::Author,
            CommentTag::Notice,
            CommentTag::Dev,
            CommentTag::Param,
            CommentTag::Return,
            CommentTag::Inheritdoc,
        ];
        for tag in non_custom_tags {
            let comment = Comment::new(tag.clone(), "Non-custom comment".to_string());
            assert!(
                !comment.is_custom(),
                "Non-custom tag {tag:?} should return false for is_custom"
            );
        }
    }
}