//! Thin shell wrappers around `git`. We avoid pulling in libgit2 — the daemon
//! shells out for `cargo build` and friends anyway, and `git` is always on the
//! MakeMachine.

use anyhow::{Context, Result};
use std::path::Path;
use tokio::process::Command;

const POST_RECEIVE: &str = include_str!("../../hooks/post-receive");

pub async fn ensure_bare_repo(path: &Path) -> Result<()> {
    if !path.join("HEAD").exists() {
        tokio::fs::create_dir_all(path).await?;
        let out = Command::new("git")
            .args(["init", "--bare", "--initial-branch=main"])
            .arg(path)
            .output()
            .await
            .context("spawning git init")?;
        anyhow::ensure!(
            out.status.success(),
            "git init --bare failed: {}",
            String::from_utf8_lossy(&out.stderr),
        );
    }
    install_hook(path).await?;
    Ok(())
}

async fn install_hook(bare: &Path) -> Result<()> {
    let hook = bare.join("hooks").join("post-receive");
    tokio::fs::create_dir_all(bare.join("hooks")).await?;
    tokio::fs::write(&hook, POST_RECEIVE).await?;
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        let mut perm = tokio::fs::metadata(&hook).await?.permissions();
        perm.set_mode(0o755);
        tokio::fs::set_permissions(&hook, perm).await?;
    }
    Ok(())
}

pub async fn resolve_ref(bare: &Path, refname: &str) -> Result<String> {
    let out = Command::new("git")
        .arg("--git-dir")
        .arg(bare)
        .args(["rev-parse", refname])
        .output()
        .await?;
    anyhow::ensure!(
        out.status.success(),
        "git rev-parse {refname} failed: {}",
        String::from_utf8_lossy(&out.stderr),
    );
    Ok(String::from_utf8(out.stdout)?.trim().to_string())
}

pub async fn checkout_worktree(bare: &Path, sha: &str, dest: &Path) -> Result<()> {
    if dest.exists() {
        // Pre-existing worktree (re-trigger of same sha). Idempotent — nothing to do.
        return Ok(());
    }
    tokio::fs::create_dir_all(dest.parent().unwrap()).await?;
    let out = Command::new("git")
        .arg("--git-dir")
        .arg(bare)
        .args(["worktree", "add", "--detach"])
        .arg(dest)
        .arg(sha)
        .output()
        .await?;
    anyhow::ensure!(
        out.status.success(),
        "git worktree add failed: {}",
        String::from_utf8_lossy(&out.stderr),
    );
    Ok(())
}