Add build file to handle wasmstan feature

crates/augurs-prophet/build.rs

@@ -107,7 +107,32 @@ fn handle_cmdstan() -> Result<(), Box<dyn std::error::Error>> {
     Ok(())
 }
 
+#[cfg(feature = "wasmstan")]
+fn copy_wasmstan() -> Result<(), Box<dyn std::error::Error>> {
+    let out_dir = std::path::PathBuf::from(std::env::var("OUT_DIR")?);
+    let prophet_path = std::path::PathBuf::from(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/prophet-wasmstan.wasm"
+    ))
+    .canonicalize()?;
+    let wasmstan_path = out_dir.join("prophet-wasmstan.wasm");
+    std::fs::copy(&prophet_path, &wasmstan_path)?;
+    eprintln!(
+        "Copied prophet-wasmstan.wasm from {} to {}",
+        prophet_path.display(),
+        wasmstan_path.display(),
+    );
+    Ok(())
+}
+
+fn handle_wasmstan() -> Result<(), Box<dyn std::error::Error>> {
+    #[cfg(feature = "wasmstan")]
+    copy_wasmstan()?;
+    Ok(())
+}
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     handle_cmdstan()?;
+    handle_wasmstan()?;
     Ok(())
 }