feat: prepare tree objects

src/main.rs

@@ -8,9 +8,10 @@ use clap::Subcommand;
 mod error;
 mod kind;
 mod object;
+mod tree;
 
-use crate::object::read_object;
-use crate::object::write_object;
+use crate::object::{read_object, write_object};
+use crate::tree::write_tree;
 
 #[derive(Parser)]
 #[command(name = "mg", about = "A simple git clone")]
@@ -37,6 +38,11 @@ enum Command {
         /// The file to write
         file: PathBuf,
     },
+    /// Write a tree object
+    WriteTree {
+        /// The path to write
+        path: PathBuf,
+    },
 }
 
 fn default_init_path() -> PathBuf {
@@ -59,21 +65,25 @@ fn init_repository(path: PathBuf) -> Result<PathBuf> {
 
 fn main() -> Result<(), Error> {
     let cli = Cli::parse();
-    let path = default_init_path();
+    let repo_path = default_init_path();
 
     match cli.command {
         Command::Init { path } => match init_repository(path) {
             Ok(path) => println!("Initialized empty Git repository in {:?}", path),
             Err(e) => eprintln!("Failed to initialize repository: {}", e),
         },
-        Command::CatFile { hash } => match read_object(&path, &hash) {
+        Command::CatFile { hash } => match read_object(&repo_path, &hash) {
             Ok(mut obj) => print!("{}", obj.string()?),
             Err(e) => eprintln!("Failed to read object: {}", e),
         },
-        Command::WriteBlob { file } => match write_object(&path, &file) {
-            Ok(hash) => println!("{}", hash),
+        Command::WriteBlob { file } => match write_object(&repo_path, &file) {
+            Ok(hash) => println!("{}", hex::encode(hash)),
             Err(e) => eprintln!("Failed to write object: {}", e),
         },
+        Command::WriteTree { path } => match write_tree(&repo_path, &path) {
+            Ok(hash) => println!("{}", hex::encode(hash)),
+            Err(e) => eprintln!("Failed to write tree: {}", e),
+        },
     }
 
     Ok(())

src/object.rs

@@ -18,11 +18,11 @@ pub struct Object<Reader> {
 }
 
 #[derive(Debug)]
-struct TreeObject {
-    mode: String,
-    kind: Kind,
-    name: String,
-    hash: [u8; 20],
+pub struct TreeObject {
+    pub mode: String,
+    pub kind: Kind,
+    pub name: String,
+    pub hash: [u8; 20],
 }
 
 pub fn read_object(path: &Path, object: &str) -> Result<Object<impl BufRead>> {
@@ -80,7 +80,7 @@ fn is_path_in_repo(repo_path: &Path, file_path: &Path) -> Result<bool> {
     Ok(file_canonical.starts_with(repo_canonical))
 }
 
-pub fn hash_file(file: &Path) -> Result<String> {
+pub fn hash_file(file: &Path) -> Result<[u8; 20]> {
     let fd = File::open(file).context("opening file for sha1")?;
     let mut buf_reader = std::io::BufReader::new(fd);
 
@@ -91,27 +91,27 @@ pub fn hash_file(file: &Path) -> Result<String> {
     let mut hasher = Sha1::new();
     hasher.update(header.as_bytes());
     copy(&mut buf_reader, &mut hasher)?;
-    let hash_bytes = hasher.finalize();
 
-    Ok(hex::encode(hash_bytes))
+    Ok(hasher.finalize().into())
 }
 
-pub fn write_object(repo_path: &Path, file: &Path) -> Result<String> {
+pub fn write_object(repo_path: &Path, file: &Path) -> Result<[u8; 20]> {
     if !file.exists() || !is_path_in_repo(repo_path, file)? {
         return Err(anyhow!("path does not exist"));
     }
 
     let hash = hash_file(file)?;
+    let hash_str = hex::encode(hash);
     let bytes_num = file.metadata()?.len();
     let mut buf_reader = std::io::BufReader::new(File::open(file)?);
 
-    let target_dir = repo_path.join(".git").join("objects").join(&hash[..2]);
+    let target_dir = repo_path.join(".git").join("objects").join(&hash_str[..2]);
 
     if !target_dir.exists() {
         create_dir(&target_dir).context("could not create directory in .git/objects")?;
     }
 
-    let target_file = target_dir.join(&hash[2..]);
+    let target_file = target_dir.join(&hash_str[2..]);
     let file_out_fd = File::create(target_file).context("could not open target file")?;
 
     let mut zlib_out = ZlibEncoder::new(file_out_fd, Compression::default());

src/tree.rs

@@ -0,0 +1,55 @@
+use anyhow::{Context, Result};
+use sha1::{Digest, Sha1};
+use std::path::PathBuf;
+
+use crate::kind::Kind;
+use crate::object::{hash_file, TreeObject};
+
+pub fn write_tree(_repo_path: &PathBuf, path: &PathBuf) -> Result<[u8; 20]> {
+    let mut entries = Vec::new();
+
+    let files = std::fs::read_dir(path)?;
+    for file in files {
+        let file = file?;
+        let file_type = file.file_type()?;
+        let file_name = file.file_name();
+        let file_path = file.path();
+
+        let hash: [u8; 20];
+        let kind;
+
+        if file_type.is_dir() {
+            hash = write_tree(_repo_path, &file_path).context("could not write_tree of subtree")?;
+            kind = Kind::Tree;
+        } else {
+            hash = hash_file(&file_path)?;
+            kind = Kind::Blob;
+        }
+
+        entries.push(TreeObject {
+            mode: "100644".to_string(),
+            kind,
+            name: file_name.into_string().unwrap(),
+            hash,
+        })
+    }
+
+    entries.sort_by(|a, b| a.name.cmp(&b.name));
+
+    let mut out: Vec<u8> = Vec::new();
+    for entry in &entries {
+        out.extend_from_slice(entry.mode.as_bytes());
+        out.push(b' ');
+        out.extend_from_slice(entry.name.as_bytes());
+        out.push(0);
+        out.extend_from_slice(&entry.hash);
+    }
+
+    let header = format!("tree {}\0", out.len());
+
+    let mut hasher = Sha1::new();
+    hasher.update(header);
+    hasher.update(out);
+
+    Ok(hasher.finalize().into())
+}