feat: reuse a git repository when it was previously cloned (#158)

* feat: reuse a git repository when it was previously cloned

* fix: avoid pulling the repository twice when fetching remote branches

crates/project/src/lib.rs

@@ -37,7 +37,7 @@ pub enum ProjectType {
 pub async fn prepare_project(
     location: &Path,
     force_type: Option<ProjectType>,
-    options: Option<Options>,
+    options: Options,
 ) -> Result<PathBuf> {
     let project_type = if force_type.is_some() {
         force_type.unwrap()

crates/project/src/types/git.rs

@@ -3,11 +3,10 @@
 
 use crate::options::{GitReference, Options};
 use anyhow::{anyhow, bail, Result};
-use git2::{Oid, Repository};
+use git2::{build::CheckoutBuilder, FetchOptions, Oid, Repository};
 use sha256::digest as sha256_digest;
 use std::{
     env::temp_dir,
-    fs::remove_dir_all,
     path::{Path, PathBuf},
 };
 
@@ -16,58 +15,136 @@ static DEFAULT_REMOTE: &str = "origin";
 
 /// Prepare a project based on a git repository. This method
 /// clones the repo locally and returns the path in which it's located.
-pub fn prepare_git_project(location: &Path, options: Option<Options>) -> Result<PathBuf> {
+pub fn prepare_git_project(location: &Path, options: Options) -> Result<PathBuf> {
     let project_url = location
         .to_str()
         .ok_or(anyhow!("The project URL cannot be retrieved"))?;
+    let (folder, git_ref) = parse_options(options);
     // By default, we use temporary dirs
     let mut dir = temp_dir().join(sha256_digest(project_url));
 
-    if dir.exists() {
-        // Clean up a previous download
-        remove_dir_all(&dir)?;
-    }
-
-    let repo = match Repository::clone(project_url, &dir) {
-        Ok(repo) => repo,
-        Err(e) => bail!("There was an error cloning the repository: {e}"),
+    let repo = if dir.exists() {
+        // Reuse the same repository.
+        Repository::open(&dir)
+            .map_err(|e| anyhow!("There was an error opening the repository: {e}"))?
+    } else {
+        // clone it
+        Repository::clone(project_url, &dir)
+            .map_err(|e| anyhow!("There was an error cloning the repository: {e}"))?
     };
 
-    if let Some(options) = options {
-        if let Some(git) = options.git {
-            if let Some(git_ref) = git.git_ref {
-                match git_ref {
-                    GitReference::Commit(commit) => {
-                        let oid = Oid::from_str(&commit)?;
-                        let commit = repo.find_commit(oid)?;
-                        repo.checkout_tree(commit.as_object(), None)?;
-                    }
-                    GitReference::Tag(tag) => {
-                        let mut remote = repo.find_remote(DEFAULT_REMOTE)?;
-                        let tag_remote = format!("refs/tags/{tag}:refs/tags/{tag}");
-                        remote.fetch(&[&tag_remote], None, None)?;
-
-                        let oid = Oid::from_str(&tag)?;
-                        let tag = repo.find_tag(oid)?;
-                        repo.checkout_tree(tag.as_object(), None)?;
-                    }
-                    GitReference::Branch(branch) => {
-                        let mut remote = repo.find_remote(DEFAULT_REMOTE)?;
-                        let head_remote = format!("refs/heads/{branch}:refs/heads/{branch}");
-                        remote.fetch(&[&head_remote], None, None)?;
-
-                        let branch = repo.find_branch(&branch, git2::BranchType::Local)?;
-                        let reference = branch.into_reference();
-                        repo.checkout_tree(&reference.peel(git2::ObjectType::Tree)?, None)?;
-                    }
-                }
+    if let Some(git_ref) = git_ref.as_ref() {
+        match git_ref {
+            GitReference::Commit(commit) => {
+                pull_default_branch(&repo)?;
+
+                let oid = Oid::from_str(commit)?;
+                repo.set_head_detached(oid)?;
+                repo.checkout_head(Some(&mut default_checkout()))?;
+            }
+            GitReference::Tag(tag) => {
+                let mut remote = repo.find_remote(DEFAULT_REMOTE)?;
+                let tag_remote = format!("refs/tags/{tag}:refs/tags/{tag}");
+                remote.fetch(&[&tag_remote], None, None)?;
+
+                repo.set_head(&format!("refs/tags/{tag}"))?;
+                repo.checkout_head(Some(&mut default_checkout()))?;
             }
+            GitReference::Branch(branch) => {
+                let mut remote = repo.find_remote(DEFAULT_REMOTE)?;
+                let head_remote = format!("refs/heads/{branch}:refs/heads/{branch}");
+                remote.fetch(&[&head_remote], None, None)?;
 
-            if let Some(folder) = git.folder {
-                dir = dir.join(folder);
+                repo.set_head(&format!("refs/heads/{branch}"))?;
+                repo.checkout_head(Some(&mut default_checkout()))?;
             }
         }
+    } else {
+        pull_default_branch(&repo)?;
+    }
+
+    if let Some(folder) = folder {
+        dir = dir.join(folder);
     }
 
     Ok(dir)
 }
+
+/// Generates a default configuration to checkout the git repository
+fn default_checkout<'cb>() -> CheckoutBuilder<'cb> {
+    let mut checkout_builder = CheckoutBuilder::default();
+
+    checkout_builder
+        .allow_conflicts(true)
+        .conflict_style_merge(true)
+        .force();
+
+    checkout_builder
+}
+
+/// Parse the different configuration parameters from the given Options
+fn parse_options(options: Options) -> (Option<String>, Option<GitReference>) {
+    if let Some(git) = options.git {
+        (git.folder, git.git_ref)
+    } else {
+        (None, None)
+    }
+}
+
+/// Pull the changes from the default branch
+fn pull_default_branch(repo: &Repository) -> Result<()> {
+    let branch = detect_main_branch(repo)?;
+    pull_repository(repo, branch)
+}
+
+/// Detech the main branch of this repository
+fn detect_main_branch(repo: &Repository) -> Result<&str> {
+    // For now, we only distinguish between the two most common branch names.
+    // Ask the user to set the branch in any other case.
+    if repo.find_branch("main", git2::BranchType::Local).is_ok() {
+        Ok("main")
+    } else if repo.find_branch("master", git2::BranchType::Local).is_ok() {
+        Ok("master")
+    } else {
+        bail!("Couldn't find the default main branch. Please, set the Git branch you want to use.")
+    }
+}
+
+/// Fetch the latest references from a repository and pull all mising
+/// objects. This method ensures an existing repo is not stale
+fn pull_repository(repo: &Repository, branch: &str) -> Result<()> {
+    let mut remote = repo.find_remote(DEFAULT_REMOTE)?;
+    let mut fo = FetchOptions::new();
+
+    remote.fetch(&[branch], Some(&mut fo), None)?;
+
+    let fetch_head = repo.find_reference("FETCH_HEAD")?;
+    let fetch_commit = fetch_head.peel_to_commit()?;
+
+    // Follow a fast-forward merge by default. These repositories shouldn't be
+    // modified. In any other case, it will fail.
+    let refname = format!("refs/heads/{}", branch);
+
+    match repo.find_reference(&refname) {
+        Ok(mut reference) => {
+            // Get the reference name
+            let name = match reference.name() {
+                Some(s) => s.to_string(),
+                None => String::from_utf8_lossy(reference.name_bytes()).to_string(),
+            };
+
+            // Perform the pull
+            reference.set_target(fetch_commit.id(), "")?;
+            repo.set_head(&name)?;
+            repo.checkout_head(Some(&mut default_checkout()))?;
+        }
+        Err(_) => {
+            // The branch doesn't exist
+            repo.reference(&refname, fetch_commit.id(), true, "")?;
+            repo.set_head(&refname)?;
+            repo.checkout_head(Some(&mut default_checkout()))?;
+        }
+    };
+
+    Ok(())
+}

src/main.rs

@@ -135,7 +135,7 @@ async fn main() -> std::io::Result<()> {
         let project_opts = options::build_project_options(&args);
 
         println!("⚙️  Preparing the project from: {}", &args.path.display());
-        let project_path = match prepare_project(&args.path, None, Some(project_opts)).await {
+        let project_path = match prepare_project(&args.path, None, project_opts).await {
             Ok(p) => p,
             Err(err) => {
                 eprintln!("❌ There was an error preparing the project: {err}");