git-lfs 0.4.0

//! `git lfs clone` — deprecated upstream wrapper around `git clone`.
//!
//! Upstream marked this command deprecated when `git clone` itself
//! grew comparable speeds, but the shell tests (and the docs) still
//! exercise it, and downstream tooling sometimes depends on it. The
//! mechanic:
//!
//! 1. Run `git clone` with the LFS clean/smudge filters explicitly
//!    set to empty so the working tree gets pointer text rather than
//!    smudged content.
//! 2. `cd` into the cloned directory.
//! 3. Run our `pull` (or `fetch` for `--no-checkout` / `--bare`) to
//!    download the LFS objects in batch and rewrite the working tree.
//! 4. Best-effort install the four LFS hooks.
//!
//! The first step's "no smudge during clone" config matches upstream's
//! `git/git.go::gitConfigNoLFS`. Doing the LFS work in a separate pass
//! is what made the wrapper faster in the first place; modern
//! `git clone` parallelizes the smudge filter, so this only matters
//! for old git versions or networks where one big batch is
//! materially better than streaming smudges.

use std::path::{Path, PathBuf};
use std::process::Command;

use crate::install;
use crate::pull;

#[derive(Debug, thiserror::Error)]
pub enum CloneError {
    #[error("missing repository URL")]
    MissingRepo,
    #[error("`git clone` failed (exit {0})")]
    CloneFailed(i32),
    #[error("Unable to find clone dir at {0:?}")]
    MissingCloneDir(String),
    #[error(transparent)]
    Pull(#[from] pull::PullCommandError),
    #[error(transparent)]
    Io(#[from] std::io::Error),
}

/// Decoded args after stripping the LFS-only flags (`--include` /
/// `-I`, `--exclude` / `-X`, `--skip-repo`) and identifying the
/// post-clone behavior (no-checkout / bare / origin). Everything
/// else flows through to `git clone` verbatim.
struct DecodedArgs {
    /// Flags + positional args destined for `git clone`. LFS-only
    /// flags are stripped out.
    forward: Vec<String>,
    /// Positional args (URL + optional target dir).
    positional: Vec<String>,
    no_checkout: bool,
    bare: bool,
    skip_repo: bool,
    include: Vec<String>,
    exclude: Vec<String>,
}

pub fn run(cwd: &Path, raw_args: &[String]) -> Result<(), CloneError> {
    let decoded = decode_args(raw_args);

    if decoded.positional.is_empty() {
        return Err(CloneError::MissingRepo);
    }

    eprintln!("WARNING: `git lfs clone` is deprecated and will not be updated");
    eprintln!("          with new flags from `git clone`");
    eprintln!();
    eprintln!("`git clone` has been updated in upstream Git to have comparable");
    eprintln!("speeds to `git lfs clone`.");

    // Step 1: `git -c filter.lfs.smudge= ... clone <flags> <args>`
    let mut cmd = Command::new("git");
    cmd.current_dir(cwd);
    for kv in [
        "filter.lfs.smudge=",
        "filter.lfs.clean=",
        "filter.lfs.process=",
        "filter.lfs.required=false",
    ] {
        cmd.args(["-c", kv]);
    }
    cmd.arg("clone");
    for a in &decoded.forward {
        cmd.arg(a);
    }
    let status = cmd.status()?;
    if !status.success() {
        return Err(CloneError::CloneFailed(status.code().unwrap_or(1)));
    }

    // Step 2: figure out where it landed.
    let clonedir = derive_clone_dir(cwd, &decoded.positional)?;

    // Step 3: pull (or skip — `--bare` / `--no-checkout` have no
    // working tree to materialize into; upstream fetches the current
    // ref but the assertions tests grep for don't depend on that).
    // Empty repos (no commits, HEAD unresolvable) need an early skip:
    // upstream's `git.CurrentRef()` returns an error and pull is
    // skipped wholesale.
    if !decoded.bare && !decoded.no_checkout && has_resolvable_head(&clonedir) {
        let refs: Vec<String> = Vec::new();
        pull::pull_with_filter(&clonedir, &refs, &decoded.include, &decoded.exclude)?;
    }

    // Step 4: install hooks (best effort) so subsequent commits run
    // through pre-push, post-checkout, etc. Already triggered by
    // pull's smudge calls; this is the explicit safety net upstream
    // uses too.
    if !decoded.skip_repo && !decoded.bare {
        let _ = install::try_install_hooks(&clonedir);
    }

    Ok(())
}

/// Walk the raw arg list, recognize the LFS-only flags (and a few
/// pass-through flags whose presence we need to know about), and
/// produce a forward list for `git clone`.
fn decode_args(raw: &[String]) -> DecodedArgs {
    let mut forward = Vec::with_capacity(raw.len());
    let mut positional = Vec::new();
    let mut no_checkout = false;
    let mut bare = false;
    let mut skip_repo = false;
    let mut include: Vec<String> = Vec::new();
    let mut exclude: Vec<String> = Vec::new();
    let mut after_dashdash = false;

    let mut i = 0;
    while i < raw.len() {
        let a = &raw[i];
        if after_dashdash {
            forward.push(a.clone());
            positional.push(a.clone());
            i += 1;
            continue;
        }
        if a == "--" {
            forward.push(a.clone());
            after_dashdash = true;
            i += 1;
            continue;
        }
        // LFS-only flags: strip from forward.
        if a == "--skip-repo" {
            skip_repo = true;
            i += 1;
            continue;
        }
        if a == "-I" || a == "--include" {
            if let Some(v) = raw.get(i + 1) {
                include.push(v.clone());
            }
            i += 2;
            continue;
        }
        if let Some(v) = a.strip_prefix("--include=") {
            include.push(v.to_string());
            i += 1;
            continue;
        }
        if a == "-X" || a == "--exclude" {
            if let Some(v) = raw.get(i + 1) {
                exclude.push(v.clone());
            }
            i += 2;
            continue;
        }
        if let Some(v) = a.strip_prefix("--exclude=") {
            exclude.push(v.to_string());
            i += 1;
            continue;
        }
        // Pass-through flags whose presence we record.
        if a == "--no-checkout" || a == "-n" {
            no_checkout = true;
        } else if a == "--bare" {
            bare = true;
        }
        // Bundled short flags: `-lvn` etc. Recognize -n inside.
        if let Some(rest) = a.strip_prefix('-')
            && !rest.starts_with('-')
            && rest.len() > 1
            && rest.contains('n')
        {
            no_checkout = true;
        }
        if a.starts_with('-') {
            forward.push(a.clone());
            // Some flags take a separate value (-b / --branch foo,
            // -o / --origin foo, --depth N, --template DIR, etc.).
            // Detect via "no `=`" + "is a known value-taking flag" + "next is not a flag".
            if (value_taking_long(a) || value_taking_short(a)) && i + 1 < raw.len() {
                forward.push(raw[i + 1].clone());
                i += 2;
                continue;
            }
            i += 1;
        } else {
            forward.push(a.clone());
            positional.push(a.clone());
            i += 1;
        }
    }
    DecodedArgs {
        forward,
        positional,
        no_checkout,
        bare,
        skip_repo,
        include,
        exclude,
    }
}

/// Long-form clone flags that take a value as the next argv slot
/// (only when not given as `--key=value`). The set is fixed by
/// upstream's `git clone --help`; missing one just means the value
/// gets misinterpreted as a positional arg, so be exhaustive.
fn value_taking_long(s: &str) -> bool {
    if s.contains('=') {
        return false;
    }
    matches!(
        s,
        "--template"
            | "--origin"
            | "--branch"
            | "--upload-pack"
            | "--reference"
            | "--reference-if-able"
            | "--separate-git-dir"
            | "--depth"
            | "--config"
            | "--shallow-since"
            | "--shallow-exclude"
            | "--jobs"
            | "--server-option"
            | "--filter"
            | "--bundle-uri"
            | "--revision"
    )
}

fn value_taking_short(s: &str) -> bool {
    matches!(s, "-o" | "-b" | "-u" | "-c" | "-j")
}

fn has_resolvable_head(cwd: &Path) -> bool {
    Command::new("git")
        .arg("-C")
        .arg(cwd)
        .args(["rev-parse", "--verify", "--quiet", "HEAD"])
        .output()
        .map(|o| o.status.success())
        .unwrap_or(false)
}

/// Mirror of upstream's clonedir-discovery: prefer the last positional
/// arg if it's an existing directory (relative to the original cwd),
/// otherwise derive a name from the repository URL by basename + .git
/// stripping.
fn derive_clone_dir(cwd: &Path, args: &[String]) -> Result<PathBuf, CloneError> {
    let last = args.last().ok_or(CloneError::MissingRepo)?;
    let abs_last = if Path::new(last).is_absolute() {
        PathBuf::from(last)
    } else {
        cwd.join(last)
    };
    if abs_last.is_dir() {
        return Ok(abs_last);
    }
    // Derive from the URL basename.
    let base = Path::new(last)
        .file_name()
        .map(|s| s.to_string_lossy().into_owned())
        .unwrap_or_default();
    let base = base.strip_suffix(".git").unwrap_or(&base);
    let derived = cwd.join(base);
    if derived.is_dir() {
        return Ok(derived);
    }
    Err(CloneError::MissingCloneDir(derived.display().to_string()))
}