chore(build): Replace vergen with git-based build scriptHEADmain

1 files changed, 49 insertions, 3 deletions

diff --git a/build.rs b/build.rs
index 2b8c3be..349f946 100644
--- a/build.rs
+++ b/build.rs
@@ -1,5 +1,51 @@
-fn main() -> Result<(), Box<dyn std::error::Error>> {
-  vergen::EmitBuilder::builder().git_sha(true).emit()?;
+use std::{fs, path::Path, process::Command};
 
-  Ok(())
+fn git_directory() -> Option<std::path::PathBuf> {
+  let directory = Path::new(".git");
+
+  if directory.is_dir() {
+    return Some(directory.to_path_buf());
+  }
+
+  let content = fs::read_to_string(directory).ok()?;
+  let path = Path::new(content.trim().strip_prefix("gitdir: ")?);
+
+  if path.is_absolute() {
+    Some(path.to_path_buf())
+  } else {
+    Some(directory.parent()?.join(path))
+  }
+}
+
+fn git_sha() -> Option<String> {
+  let output = Command::new("git").args(["rev-parse", "HEAD"]).output().ok()?;
+
+  if !output.status.success() {
+    return None;
+  }
+
+  let sha = String::from_utf8(output.stdout).ok()?.trim().to_string();
+
+  if sha.is_empty() { None } else { Some(sha) }
+}
+
+fn main() {
+  if let Some(git_dir) = git_directory() {
+    let head_path = git_dir.join("HEAD");
+
+    println!("cargo:rerun-if-changed={}", head_path.display());
+
+    if let Ok(head_contents) = fs::read_to_string(&head_path) {
+      if let Some(reference) = head_contents.trim().strip_prefix("ref: ") {
+        println!(
+          "cargo:rerun-if-changed={}",
+          git_dir.join(reference).display()
+        );
+      }
+    }
+  }
+
+  let sha = git_sha().unwrap_or_else(|| "UNKNOWN".to_string());
+
+  println!("cargo:rustc-env=VERGEN_GIT_SHA={sha}");
 }