From b54604ac72ee90fe917b4733f93576030bbb3e0a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gon=C3=A7alo=20Val=C3=A9rio?= <gon@ovalerio.net>
Date: Fri, 13 Nov 2020 20:17:20 +0000
Subject: [PATCH] step thirty six: switch branches

---
 src/base.rs | 28 ++++++++++++++++++++--------
 src/main.rs |  6 +++---
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/src/base.rs b/src/base.rs
index 901a3ff..b23b9f5 100644
--- a/src/base.rs
+++ b/src/base.rs
@@ -137,17 +137,25 @@ pub fn iter_commits_and_parents(mut oids: VecDeque<String>) -> Vec<String> {
     return oid_sequence;
 }
 
-pub fn checkout(oid: String) {
+pub fn checkout(name: String) {
+    let oid = get_oid(name.clone());
     let commit = get_commit(oid.clone());
+    let head;
     read_tree(commit.tree);
-    data::update_ref(
-        "HEAD".to_owned(),
-        data::RefValue {
-            value: oid,
+
+    if is_branch(name.clone()) {
+        head = data::RefValue {
+            symbolic: true,
+            value: format!("refs/heads/{}", name),
+        };
+    } else {
+        head = data::RefValue {
             symbolic: false,
-        },
-        true,
-    );
+            value: oid,
+        };
+    }
+
+    data::update_ref("HEAD".to_owned(), head, false);
 }
 
 pub fn create_tag(name: String, oid: String) {
@@ -269,3 +277,7 @@ fn empty_current_directory(dir: &str) -> io::Result<()> {
     }
     Ok(())
 }
+
+fn is_branch(name: String) -> bool {
+    return data::get_ref(name, true).value != "";
+}
diff --git a/src/main.rs b/src/main.rs
index 9dd46e0..5c00368 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -49,7 +49,7 @@ fn main() {
         .subcommand(
             SubCommand::with_name("checkout")
                 .about("Move the current content and HEAD to given commit")
-                .arg(Arg::with_name("oid").index(1).required(true)),
+                .arg(Arg::with_name("commit").index(1).required(true)),
         )
         .subcommand(
             SubCommand::with_name("tag")
@@ -147,8 +147,8 @@ fn log_commits(matches: ArgMatches) {
 
 fn checkout(matches: ArgMatches) {
     if let Some(cmd_matches) = matches.subcommand_matches("checkout") {
-        let oid = base::get_oid(cmd_matches.value_of("oid").unwrap().to_owned());
-        base::checkout(oid);
+        let name = cmd_matches.value_of("commit").unwrap().to_owned();
+        base::checkout(name);
     }
 }