vanta-migrate 0.0.2

//! `vanta-migrate` — import foreign version files into a Vanta `[tools]` set.
//!
//! Reads the common version files (`.tool-versions`, `.nvmrc`, `.python-version`,
//! `rust-toolchain.toml`, …) and produces tool→version pairs plus the source they
//! came from, which the CLI renders into a `vanta.toml`. See `docs/30-migration.md`.
//! Pure-std parsing; no foreign tool is invoked.
#![forbid(unsafe_code)]

use std::path::Path;

/// One imported tool pin and the file it came from.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Imported {
    pub tool: String,
    pub version: String,
    pub source: String,
}

/// Translate a foreign tool name to Vanta's canonical name.
fn canonical_name(name: &str) -> String {
    match name {
        "nodejs" => "node",
        "golang" => "go",
        other => other,
    }
    .to_string()
}

fn clean_version(v: &str) -> String {
    v.trim().trim_start_matches('v').to_string()
}

/// Parse an asdf/mise `.tool-versions` body ("name version" per line).
pub fn parse_tool_versions(body: &str, source: &str) -> Vec<Imported> {
    let mut out = Vec::new();
    for line in body.lines() {
        let line = line.trim();
        if line.is_empty() || line.starts_with('#') {
            continue;
        }
        let mut parts = line.split_whitespace();
        if let (Some(name), Some(version)) = (parts.next(), parts.next()) {
            out.push(Imported {
                tool: canonical_name(name),
                version: clean_version(version),
                source: source.to_string(),
            });
        }
    }
    out
}

fn single(tool: &str, body: &str, source: &str) -> Option<Imported> {
    let version = clean_version(body);
    let version = version.lines().next().unwrap_or("").trim().to_string();
    if version.is_empty() {
        None
    } else {
        Some(Imported {
            tool: tool.to_string(),
            version,
            source: source.to_string(),
        })
    }
}

fn parse_rust_toolchain(body: &str, source: &str) -> Option<Imported> {
    // Minimal: find `channel = "<x>"`; default to "stable".
    let channel = body
        .lines()
        .find_map(|l| {
            let l = l.trim();
            l.strip_prefix("channel")
                .and_then(|r| r.split('=').nth(1))
                .map(|v| v.trim().trim_matches('"').to_string())
        })
        .unwrap_or_else(|| "stable".to_string());
    Some(Imported {
        tool: "rust".to_string(),
        version: channel,
        source: source.to_string(),
    })
}

/// Scan a directory for known version files and import them. The first file to
/// mention a tool wins (specific files are scanned before broad ones).
pub fn import_dir(dir: &Path) -> Vec<Imported> {
    let mut found: Vec<Imported> = Vec::new();
    let mut seen = std::collections::BTreeSet::new();

    let read = |name: &str| std::fs::read_to_string(dir.join(name)).ok();

    let push =
        |imp: Imported, acc: &mut Vec<Imported>, seen: &mut std::collections::BTreeSet<String>| {
            if seen.insert(imp.tool.clone()) {
                acc.push(imp);
            }
        };

    // Specific single-tool files first (they express intent most precisely).
    if let Some(b) = read(".nvmrc").or_else(|| read(".node-version")) {
        if let Some(i) = single("node", &b, ".nvmrc") {
            push(i, &mut found, &mut seen);
        }
    }
    if let Some(b) = read(".python-version") {
        if let Some(i) = single("python", &b, ".python-version") {
            push(i, &mut found, &mut seen);
        }
    }
    if let Some(b) = read(".ruby-version") {
        if let Some(i) = single("ruby", &b, ".ruby-version") {
            push(i, &mut found, &mut seen);
        }
    }
    if let Some(b) = read(".go-version") {
        if let Some(i) = single("go", &b, ".go-version") {
            push(i, &mut found, &mut seen);
        }
    }
    if let Some(b) = read("rust-toolchain.toml") {
        if let Some(i) = parse_rust_toolchain(&b, "rust-toolchain.toml") {
            push(i, &mut found, &mut seen);
        }
    }
    // Broad multi-tool files last.
    if let Some(b) = read(".tool-versions") {
        for i in parse_tool_versions(&b, ".tool-versions") {
            push(i, &mut found, &mut seen);
        }
    }

    found
}

/// Render imported tools into a `vanta.toml` `[tools]` table.
pub fn to_manifest_toml(tools: &[Imported]) -> String {
    let mut s = String::from("[tools]\n");
    for t in tools {
        s.push_str(&format!("{} = \"{}\"\n", t.tool, t.version));
    }
    s
}

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

    #[test]
    fn tool_versions_parsing_and_aliases() {
        let body = "# comment\nnodejs 20.11.0\npython 3.12.2\n\ngolang 1.23.0\n";
        let imported = parse_tool_versions(body, ".tool-versions");
        assert_eq!(imported.len(), 3);
        assert_eq!(imported[0].tool, "node"); // nodejs → node
        assert_eq!(imported[0].version, "20.11.0");
        assert_eq!(imported[2].tool, "go"); // golang → go
    }

    #[test]
    fn single_file_strips_v_prefix() {
        let i = single("node", "v20.11.0\n", ".nvmrc").unwrap();
        assert_eq!(i.version, "20.11.0");
    }

    #[test]
    fn rust_toolchain_channel() {
        let i = parse_rust_toolchain("[toolchain]\nchannel = \"1.79.0\"\n", "rust-toolchain.toml")
            .unwrap();
        assert_eq!(i.tool, "rust");
        assert_eq!(i.version, "1.79.0");
    }

    #[test]
    fn renders_manifest() {
        let tools = vec![Imported {
            tool: "node".into(),
            version: "24".into(),
            source: "x".into(),
        }];
        assert_eq!(to_manifest_toml(&tools), "[tools]\nnode = \"24\"\n");
    }
}