1 files changed, 56 insertions, 0 deletions
diff --git a/crates/shirabe/src/util/tar.rs b/crates/shirabe/src/util/tar.rs
index 4dc91ca..253f142 100644
--- a/crates/shirabe/src/util/tar.rs
+++ b/crates/shirabe/src/util/tar.rs
@@ -1 +1,57 @@
 //! ref: composer/src/Composer/Util/Tar.php
+
+use anyhow::Result;
+use indexmap::IndexMap;
+use shirabe_php_shim::{PharData, RuntimeException};
+
+pub struct Tar;
+
+impl Tar {
+    pub fn get_composer_json(path_to_archive: &str) -> Result<Option<String>> {
+        let phar = PharData::new(path_to_archive.to_string());
+
+        if !phar.valid() {
+            return Ok(None);
+        }
+
+        Ok(Some(Self::extract_composer_json_from_folder(&phar)?))
+    }
+
+    fn extract_composer_json_from_folder(phar: &PharData) -> Result<String> {
+        if let Some(file) = phar.get("composer.json") {
+            return Ok(file.get_content());
+        }
+
+        let mut top_level_paths: IndexMap<String, bool> = IndexMap::new();
+        for folder_file in phar.iter() {
+            let name = folder_file.get_basename();
+            if folder_file.is_dir() {
+                top_level_paths.insert(name, true);
+                if top_level_paths.len() > 1 {
+                    return Err(anyhow::anyhow!(RuntimeException {
+                        message: format!(
+                            "Archive has more than one top level directories, and no composer.json was found on the top level, so it's an invalid archive. Top level paths found were: {}",
+                            top_level_paths.keys().cloned().collect::<Vec<_>>().join(",")
+                        ),
+                        code: 0,
+                    }));
+                }
+            }
+        }
+
+        let composer_json_path = format!(
+            "{}/composer.json",
+            top_level_paths.keys().next().cloned().unwrap_or_default()
+        );
+        if !top_level_paths.is_empty() {
+            if let Some(file) = phar.get(&composer_json_path) {
+                return Ok(file.get_content());
+            }
+        }
+
+        Err(anyhow::anyhow!(RuntimeException {
+            message: "No composer.json found either at the top level or within the topmost directory".to_string(),
+            code: 0,
+        }))
+    }
+}