rtango 0.3.1

Package manager for AI agent skills, agents, and system instruction files
Documentation 
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use std::collections::BTreeMap;

use super::permission::Permission;

#[derive(Debug, Clone, Default)]
pub struct FrontMatter {
    pub name: Option<String>,
    pub description: Option<String>,
    pub allowed_tools: Vec<Permission>,
    pub extra: BTreeMap<String, serde_yml::Value>,
}

pub trait FrontMatterMapper {
    fn parse_frontmatter(&self, yaml: &str) -> anyhow::Result<FrontMatter>;
    fn parse_permission(&self, token: &str) -> Permission;
}

pub fn split_frontmatter(content: &str) -> (Option<&str>, &str) {
    let trimmed = content.trim_start();
    if !trimmed.starts_with("---") {
        return (None, content);
    }
    let after_open = &trimmed[3..];
    let after_open = match after_open.find('\n') {
        Some(i) => &after_open[i + 1..],
        None => return (None, content),
    };
    match after_open.find("\n---") {
        Some(i) => {
            let yaml = &after_open[..i];
            let rest = &after_open[i + 4..];
            let body = match rest.find('\n') {
                Some(j) => &rest[j + 1..],
                None => "",
            };
            (Some(yaml), body)
        }
        None => (None, content),
    }
}

pub fn join_frontmatter(yaml: &str, body: &str) -> String {
    let mut out = String::with_capacity(yaml.len() + body.len() + 10);
    out.push_str("---\n");
    out.push_str(yaml);
    if !yaml.ends_with('\n') {
        out.push('\n');
    }
    out.push_str("---\n");
    out.push_str(body);
    out
}

pub fn extract_string(map: &BTreeMap<String, serde_yml::Value>, key: &str) -> Option<String> {
    map.get(key).and_then(|v| v.as_str()).map(|s| s.to_string())
}

/// Standard frontmatter parsing shared by agents that use YAML with
/// `name`, `description`, and `allowed-tools` keys.
pub fn parse_standard_frontmatter(
    yaml: &str,
    mapper: &dyn FrontMatterMapper,
) -> anyhow::Result<FrontMatter> {
    let raw: BTreeMap<String, serde_yml::Value> = serde_yml::from_str(yaml)?;
    let mut fm = FrontMatter::default();

    fm.name = extract_string(&raw, "name");
    fm.description = extract_string(&raw, "description");

    if let Some(tools_str) = extract_string(&raw, "allowed-tools") {
        fm.allowed_tools = tokenize_tools(&tools_str)
            .into_iter()
            .map(|t| mapper.parse_permission(&t))
            .collect();
    }

    fm.extra = raw
        .into_iter()
        .filter(|(k, _)| !matches!(k.as_str(), "name" | "description" | "allowed-tools"))
        .collect();

    Ok(fm)
}

pub fn tokenize_tools(s: &str) -> Vec<String> {
    let mut tokens = Vec::new();
    let mut current = String::new();
    let mut depth = 0u32;
    for ch in s.chars() {
        match ch {
            '(' => {
                depth += 1;
                current.push(ch);
            }
            ')' => {
                depth = depth.saturating_sub(1);
                current.push(ch);
            }
            ' ' | '\t' if depth == 0 => {
                let t = current.trim().to_string();
                if !t.is_empty() {
                    tokens.push(t);
                }
                current.clear();
            }
            _ => current.push(ch),
        }
    }
    let t = current.trim().to_string();
    if !t.is_empty() {
        tokens.push(t);
    }
    tokens
}