alef 0.79.4

//! Elixir NIF precompiled binary packaging.
//!
//! Produces one tarball per (target × nif_version) combination in the format
//! expected by `RustlerPrecompiled`:
//!
//! `{lib}-v{version}-nif-{nif_version}-{target}.{ext}.tar.gz`
//!
//! where `{ext}` is `dll` (Windows) or `so` (everything else, including macOS).
//! Darwin uses `so` — not `dylib` — to match `rustler_precompiled 0.9.0`'s
//! `lib_name_with_ext/2` consumer-side URL construction, which hardcodes `so`
//! for every non-Windows target and cannot be overridden. No newer
//! `rustler_precompiled` version exists on Hex with `.dylib` support.
//!
//! Also provides `write_elixir_checksums()` to generate the
//! `checksum-Elixir.{App}.exs` file that RustlerPrecompiled validates.

use super::PackageArtifact;
use crate::core::config::ResolvedCrateConfig;
use crate::publish::platform::RustTarget;
use anyhow::{Context, Result};
use std::collections::BTreeMap;
use std::fs;
use std::path::{Path, PathBuf};

/// Package NIF binaries for a single target × all configured NIF versions.
///
/// Returns one `PackageArtifact` per NIF version.
pub fn package_elixir(
    config: &ResolvedCrateConfig,
    target: &RustTarget,
    workspace_root: &Path,
    output_dir: &Path,
    version: &str,
) -> Result<Vec<PackageArtifact>> {
    let nif_versions = resolve_nif_versions(config);
    let rustler_crate = crate::publish::crate_name_from_output(config, crate::core::config::extras::Language::Elixir)
        .unwrap_or_else(|| config.elixir_app_name().to_lowercase().replace('-', "_") + "_rustler");
    let lib_name = rustler_crate.replace('-', "_");
    let shared_lib = target.shared_lib_name(&lib_name);

    let lib_src = super::find_built_artifact(workspace_root, target, &shared_lib, super::BuildProfile::Release)?;

    let ext = nif_extension(target);

    let mut artifacts = Vec::new();
    for nif_version in &nif_versions {
        let tarball_name = format!(
            "lib{lib_name}-v{version}-nif-{nif_version}-{triple}.{ext}.tar.gz",
            triple = target.triple,
        );
        let tarball_path = output_dir.join(&tarball_name);

        let stage_dir = output_dir.join(format!("_stage_{lib_name}_{nif_version}"));
        if stage_dir.exists() {
            fs::remove_dir_all(&stage_dir)?;
        }
        fs::create_dir_all(&stage_dir)?;

        let staged_name = format!("lib{lib_name}.{ext}");
        fs::copy(&lib_src, stage_dir.join(&staged_name))?;

        super::create_tar_gz(&stage_dir, &tarball_path)
            .with_context(|| format!("creating tarball {}", tarball_path.display()))?;

        let _ = fs::remove_dir_all(&stage_dir);

        artifacts.push(PackageArtifact {
            path: tarball_path,
            name: tarball_name,
            checksum: None,
        });
    }

    Ok(artifacts)
}

/// Generate a `checksum-Elixir.{App}.exs` file from all `.tar.gz` files in `output_dir`.
///
/// Walks `output_dir` for files matching `lib{app}*nif*.tar.gz`, computes SHA256 for each,
/// and writes an Elixir map literal compatible with RustlerPrecompiled.
pub fn write_elixir_checksums(config: &ResolvedCrateConfig, output_dir: &Path) -> Result<PathBuf> {
    let app_name = config.elixir_app_name();
    let module_name = {
        let mut chars = app_name.chars();
        chars.next().map(|c| c.to_uppercase().to_string()).unwrap_or_default() + chars.as_str()
    };

    let mut checksums: BTreeMap<String, String> = BTreeMap::new();
    for entry in fs::read_dir(output_dir)? {
        let entry = entry?;
        let path = entry.path();
        if !path.is_file() {
            continue;
        }
        let name = path.file_name().unwrap_or_default().to_string_lossy();
        if !name.ends_with(".tar.gz") || !name.contains("-nif-") {
            continue;
        }
        let digest = sha256_file(&path)?;
        checksums.insert(name.to_string(), format!("sha256:{digest}"));
    }

    let pkg_dir = config.package_dir(crate::core::config::extras::Language::Elixir);
    let pkg_dir = Path::new(&pkg_dir);
    let checksum_path = pkg_dir.join(format!("checksum-Elixir.{module_name}.Native.exs"));
    let content = render_checksum_map(&checksums, formatter_line_length(pkg_dir));
    fs::create_dir_all(checksum_path.parent().unwrap_or(Path::new(".")))?;
    fs::write(&checksum_path, content)?;

    Ok(checksum_path)
}

/// Line width `mix format` assumes when `.formatter.exs` declares none.
const ELIXIR_DEFAULT_LINE_LENGTH: usize = 98;

/// Indent Elixir's formatter gives a map entry inside a multi-line `%{}`.
const MAP_ENTRY_INDENT: &str = "  ";

/// Separator between a map key and its value.
const MAP_ARROW: &str = " => ";

/// Resolve the line width `mix format` will apply inside `package_dir`.
///
/// Alef scaffolds `line_length: 140`, but `.formatter.exs` is user-owned once
/// written, so the declared value — not alef's preference — decides where the
/// formatter wraps. Falling back to Elixir's own default keeps the emitted file
/// stable even where no `.formatter.exs` exists. ~keep
fn formatter_line_length(package_dir: &Path) -> usize {
    let Ok(source) = fs::read_to_string(package_dir.join(".formatter.exs")) else {
        return ELIXIR_DEFAULT_LINE_LENGTH;
    };
    source
        .lines()
        .find_map(|line| {
            let value = line.trim().strip_prefix("line_length:")?;
            value.trim().trim_end_matches(',').parse::<usize>().ok()
        })
        .unwrap_or(ELIXIR_DEFAULT_LINE_LENGTH)
}

/// Render the checksum map exactly as `mix format` would, so the written file is
/// already a fixed point of the formatter.
///
/// `alef fmt` runs `mix format` over `packages/elixir` as the sole authority for
/// `.ex`/`.exs`. Emitting each entry on one long line left every regeneration
/// producing a pure-reformat diff — identical digests, rewrapped lines — that
/// masked real changes. Elixir's formatter keeps an entry on one line only while
/// the rendered line (trailing comma included) fits the configured width, and it
/// drops the comma after the final entry; past the width the value moves to its
/// own continuation line. ~keep
fn render_checksum_map(checksums: &BTreeMap<String, String>, line_length: usize) -> String {
    #[derive(serde::Serialize)]
    struct ChecksumEntry {
        key: String,
        value: String,
        wrap: bool,
    }

    let last_index = checksums.len().saturating_sub(1);
    let entries: Vec<ChecksumEntry> = checksums
        .iter()
        .enumerate()
        .map(|(index, (file, digest))| {
            let key = format!("\"{file}\"");
            let value = format!("\"{digest}\"");
            let trailing_comma = usize::from(index != last_index);
            let one_line_width =
                MAP_ENTRY_INDENT.len() + key.chars().count() + MAP_ARROW.len() + value.chars().count() + trailing_comma;
            ChecksumEntry {
                wrap: one_line_width > line_length,
                key,
                value,
            }
        })
        .collect();

    super::template_env::render("elixir_checksums.jinja", minijinja::context! { entries => entries })
}

/// Return the native extension suffix for RustlerPrecompiled filenames.
///
/// Returns `dll` for Windows and `so` for every other OS (including macOS).
/// `rustler_precompiled 0.9.0`'s `lib_name_with_ext/2` hardcodes `so` for
/// every non-Windows target when constructing the consumer download URL and
/// cannot be overridden. Publishing `.dylib.tar.gz` for darwin would 404
/// every `mix deps.get` on macOS.
fn nif_extension(target: &RustTarget) -> &'static str {
    match target.os {
        crate::publish::platform::Os::Windows => "dll",
        _ => "so",
    }
}

fn resolve_nif_versions(config: &ResolvedCrateConfig) -> Vec<String> {
    if let Some(publish) = &config.publish
        && let Some(lang_cfg) = publish.languages.get("elixir")
        && let Some(versions) = &lang_cfg.nif_versions
        && !versions.is_empty()
    {
        return versions.clone();
    }
    vec!["2.16".to_string(), "2.17".to_string()]
}

/// Compute SHA-256 hex digest of a file.
fn sha256_file(path: &Path) -> Result<String> {
    use sha2::{Digest, Sha256};
    use std::io::Read;
    let mut file = fs::File::open(path).with_context(|| format!("opening {}", path.display()))?;
    let mut hasher = Sha256::new();
    let mut buf = [0u8; 65536];
    loop {
        let n = file.read(&mut buf)?;
        if n == 0 {
            break;
        }
        hasher.update(&buf[..n]);
    }
    let digest = hasher.finalize();
    let mut hex = String::with_capacity(digest.len() * 2);
    for byte in digest.iter() {
        use std::fmt::Write as _;
        write!(&mut hex, "{byte:02x}").expect("writing to String never fails");
    }
    Ok(hex)
}

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

    /// Hash `contents` through the real file path `sha256_file` takes.
    fn sha256_of(contents: &[u8]) -> String {
        let tmp = TempDir::new().unwrap();
        let path = tmp.path().join("payload.bin");
        fs::write(&path, contents).unwrap();
        sha256_file(&path).unwrap()
    }

    #[test]
    fn sha256_known_vector() {
        assert_eq!(
            sha256_of(b""),
            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
        );
    }

    #[test]
    fn sha256_hello() {
        assert_eq!(
            sha256_of(b"hello"),
            "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824"
        );
    }

    /// Guards the streaming read loop: a payload larger than the 64 KiB buffer
    /// exercises multiple `update` calls, where an off-by-one in chunking would
    /// silently produce a wrong digest.
    #[test]
    fn sha256_spans_multiple_read_chunks() {
        // 1_000_000 repetitions of "a" — the standard SHA-256 long-message vector.
        let payload: Vec<u8> = std::iter::repeat_n(b'a', 1_000_000).collect();
        assert_eq!(
            sha256_of(&payload),
            "cdc76e5c9914fb9281a1c7e284d73e67f1809a48a497200e046d39ccc7112cd0"
        );
    }

    #[test]
    fn nif_extension_linux() {
        let t = RustTarget::parse("x86_64-unknown-linux-gnu").unwrap();
        assert_eq!(nif_extension(&t), "so");
    }

    #[test]
    fn nif_extension_macos() {
        let t = RustTarget::parse("x86_64-apple-darwin").unwrap();
        assert_eq!(nif_extension(&t), "so");
    }

    #[test]
    fn nif_extension_windows() {
        let t = RustTarget::parse("x86_64-pc-windows-msvc").unwrap();
        assert_eq!(nif_extension(&t), "dll");
    }

    #[test]
    fn resolve_nif_versions_defaults() {
        let cfg: crate::core::config::NewAlefConfig = toml::from_str(
            r#"
[workspace]
languages = ["elixir"]
[[crates]]
name = "my-lib"
sources = ["src/lib.rs"]
"#,
        )
        .unwrap();
        let config = cfg.resolve().unwrap().remove(0);
        let versions = resolve_nif_versions(&config);
        assert!(!versions.is_empty());
    }

    #[test]
    fn write_checksums_produces_exs_file() {
        let tmp = TempDir::new().unwrap();
        let cfg: crate::core::config::NewAlefConfig = toml::from_str(
            r#"
[workspace]
languages = ["elixir"]
[[crates]]
name = "mylib"
sources = ["src/lib.rs"]
"#,
        )
        .unwrap();
        let mut config = cfg.resolve().unwrap().remove(0);
        // `elixir.scaffold_output` is set directly on the resolved config rather than through
        // `[crates.elixir] scaffold_output` TOML: path-safety validation now rejects an
        // absolute `scaffold_output` value at `resolve()` time (it would let a hostile config
        // value write generated files outside the project root), but this test needs
        // `package_dir()` to resolve to a real absolute tempdir so the checksum file it writes
        // lands there instead of inside the real repo checkout (`package_dir_raw` reads
        // `elixir.scaffold_output` directly for `Language::Elixir`; it does not consult
        // `output_paths`). ~keep
        config
            .elixir
            .get_or_insert_with(|| toml::from_str("").expect("an empty table deserializes to all-default ElixirConfig"))
            .scaffold_output = Some(tmp.path().to_path_buf());

        let tarball = tmp
            .path()
            .join("libmylib-v1.0.0-nif-2.16-x86_64-unknown-linux-gnu.so.tar.gz");
        fs::write(&tarball, b"fake tarball content").unwrap();

        let result = write_elixir_checksums(&config, tmp.path());
        assert!(result.is_ok(), "{result:?}");
        let checksum_file = result.unwrap();
        assert!(checksum_file.exists());
        let content = fs::read_to_string(&checksum_file).unwrap();
        assert!(content.contains("sha256:"));
        assert!(content.contains("nif-2.16"));
    }

    /// A 64-hex digest behind the `sha256:` tag, quoted: a fixed 73 columns.
    fn digest(fill: char) -> String {
        format!("sha256:{}", std::iter::repeat_n(fill, 64).collect::<String>())
    }

    fn map_of(entries: &[(&str, String)]) -> BTreeMap<String, String> {
        entries
            .iter()
            .map(|(file, digest)| ((*file).to_owned(), digest.clone()))
            .collect()
    }

    /// Format `source` the way `mix format` does, or `None` when Elixir is absent.
    ///
    /// `mix format` is `Code.format_string!` plus a trailing newline, so driving
    /// the compiler directly needs no mix project on disk. ~keep
    fn mix_format(source: &str, line_length: usize) -> Option<String> {
        let script = format!(
            "IO.write(IO.iodata_to_binary(Code.format_string!(IO.read(:stdio, :eof), line_length: {line_length})) <> \"\\n\")"
        );
        let mut child = std::process::Command::new("elixir")
            .args(["-e", &script])
            .stdin(std::process::Stdio::piped())
            .stdout(std::process::Stdio::piped())
            .stderr(std::process::Stdio::piped())
            .spawn()
            .ok()?;
        use std::io::Write as _;
        child
            .stdin
            .take()
            .expect("stdin was piped")
            .write_all(source.as_bytes())
            .expect("write source to elixir");
        let out = child.wait_with_output().expect("wait for elixir");
        assert!(
            out.status.success(),
            "elixir formatter failed: {}",
            String::from_utf8_lossy(&out.stderr)
        );
        Some(String::from_utf8(out.stdout).expect("formatter output is UTF-8"))
    }

    /// The property that actually matters: what alef writes must already be what
    /// `mix format` would produce, so regeneration stops churning the file.
    #[test]
    fn rendered_checksum_map_is_already_mix_format_stable() {
        let checksums = map_of(&[
            (
                "libsample_rustler-v1.0.0-nif-2.16-aarch64-apple-darwin.so.tar.gz",
                digest('a'),
            ),
            (
                "libsample_rustler-v1.0.0-nif-2.16-x86_64-unknown-linux-gnu.so.tar.gz",
                digest('b'),
            ),
            (
                "libsample_rustler-v1.0.0-nif-2.17-x86_64-pc-windows-msvc.dll.tar.gz",
                digest('c'),
            ),
            ("libs-v1.0.0-nif-2.16-x86_64-apple-darwin.so.tar.gz", digest('d')),
        ]);

        for line_length in [98, 140] {
            let rendered = render_checksum_map(&checksums, line_length);
            let Some(formatted) = mix_format(&rendered, line_length) else {
                tracing::warn!("elixir not on PATH, skipping formatter-stability check");
                return;
            };
            assert_eq!(
                rendered, formatted,
                "emitted checksum map must be a fixed point of mix format at line_length {line_length}"
            );
        }
    }

    /// The wrap decision is per entry and counts the trailing comma, which the
    /// final entry does not carry — so an entry exactly at the limit stays inline
    /// only when it is last.
    #[test]
    fn entry_wraps_only_when_rendered_line_exceeds_line_length() {
        let line_length = 98;
        // 2 indent + 4 arrow + 73 digest = 79 columns before the quoted key.
        let at_limit = "f".repeat(line_length - 79 - 2);
        let over_limit = "f".repeat(line_length - 79 - 1);

        let last_at_limit = render_checksum_map(&map_of(&[(&at_limit, digest('a'))]), line_length);
        assert!(
            !last_at_limit.contains("=>\n"),
            "final entry at exactly the limit stays inline: {last_at_limit}"
        );

        let last_over_limit = render_checksum_map(&map_of(&[(&over_limit, digest('a'))]), line_length);
        assert!(
            last_over_limit.contains("=>\n"),
            "final entry one column over the limit wraps: {last_over_limit}"
        );

        // Same key, now non-final: the comma pushes it one column over.
        let with_comma = render_checksum_map(
            &map_of(&[(&at_limit, digest('a')), ("z.tar.gz", digest('b'))]),
            line_length,
        );
        assert!(
            with_comma.starts_with(&format!("%{{\n  \"{at_limit}\" =>\n")),
            "trailing comma counts toward the width: {with_comma}"
        );
    }

    #[test]
    fn empty_checksum_map_renders_as_collapsed_literal() {
        assert_eq!(render_checksum_map(&BTreeMap::new(), 98), "%{}\n");
    }

    #[test]
    fn formatter_line_length_reads_scaffolded_formatter_exs() {
        let tmp = TempDir::new().unwrap();
        assert_eq!(formatter_line_length(tmp.path()), ELIXIR_DEFAULT_LINE_LENGTH);

        fs::write(
            tmp.path().join(".formatter.exs"),
            "[\n  import_deps: [:rustler],\n  inputs: [\"{mix,.formatter}.exs\"],\n  line_length: 140\n]\n",
        )
        .unwrap();
        assert_eq!(formatter_line_length(tmp.path()), 140);
    }
}