From 6bf58adf0de9d1e4550f0ee9b998ed5e7d9b239b Mon Sep 17 00:00:00 2001
From: womax <antonin.ruan@student-cs.fr>
Date: Mon, 3 Jun 2024 15:16:48 +0200
Subject: [PATCH] Branch checkout

---
 src/commit.c |  4 ++--
 src/fs.c     | 39 ++++++++++++++++++++++++++++++++++++++-
 src/fs.h     |  3 ++-
 3 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/src/commit.c b/src/commit.c
index 8f02a78..cf73740 100644
--- a/src/commit.c
+++ b/src/commit.c
@@ -137,7 +137,7 @@ int commit()
     char commit_checksum[DIGEST_LENGTH * 2 + 1];
     hash_object(&commit_obj, commit_checksum);
 
-    update_head(commit_checksum);
+    update_current_branch_head(commit_checksum);
 
     free_commit(&commit);
     free_object(&commit_obj);
@@ -196,7 +196,7 @@ void diff_commit(struct commit *commit_a, struct commit *commit_b)
     dump_tree(TMP"/a", &tree_a);
     dump_tree(TMP"/b", &tree_b);
 
-    FILE *f = popen("diff -ruN "TMP"/a "TMP"/b | less", "w");
+    FILE *f = popen("diff -ruN "TMP"/a "TMP"/b > "LOCAL_REPO"/last.diff", "w");
     pclose(f);
 
     free_tree(&tree_a);
diff --git a/src/fs.c b/src/fs.c
index 6309705..b8f2285 100644
--- a/src/fs.c
+++ b/src/fs.c
@@ -393,7 +393,7 @@ int get_last_commit(struct object *commit)
     return FS_OK;
 }
 
-int update_head(char *new_head)
+int update_current_branch_head(char *new_head)
 {
     size_t head_size = 0;
     if(!local_repo_exist() || !head_file_exist(&head_size) || !heads_dir_exist)
@@ -465,6 +465,43 @@ int new_branch(char* branch_name)
     return FS_OK;
 }
 
+int checkout_branch(char *branch)
+{
+    if(!branch_exist(branch))
+    {
+        return BRANCH_DOES_NOT_EXIST;
+    }
+
+    char branch_path[strlen(HEADS_DIR) + strlen(branch) + 2];
+    sprintf(branch_path, "%s/%s", HEADS_DIR, branch);
+
+    char commit_checksum[DIGEST_LENGTH * 2 + 1];
+    FILE *branch_head = fopen(branch_path, "r");
+    fread(commit_checksum, DIGEST_LENGTH * 2 + 1, 1, branch_head);
+    fclose(branch_head);
+
+    struct object obj = {0};
+    read_object(commit_checksum, &obj);
+
+    struct commit commit = {0};
+    commit_from_object(&commit, &obj);
+
+    revert_to(&commit);
+
+    free_commit(&commit);
+    free_object(&obj);
+
+    FILE *head_file = fopen(HEAD_FILE, "w");
+    fwrite(branch_path, DIGEST_LENGTH * 2 + 1, 1, head_file);
+    fclose(head_file);
+}
+
+void print_diff()
+{
+    FILE *p = popen("cat "LOCAL_REPO"/last.diff | less", "w");
+    pclose(p);
+}
+
 int revert(char* commit_checksum)
 {
     struct object obj = {0};
diff --git a/src/fs.h b/src/fs.h
index efa65cb..ceaf3eb 100644
--- a/src/fs.h
+++ b/src/fs.h
@@ -23,6 +23,7 @@
 #define OBJECT_DOES_NOT_EXIST (-21)
 #define WRONG_OBJECT_TYPE (-22)
 #define BRANCH_ALREADY_EXIST (-23)
+#define BRANCH_DOES_NOT_EXIST (-24)
 #define FILE_NOT_FOUND (-30)
 #define ENTRY_NOT_FOUND (-31)
 
@@ -36,7 +37,7 @@ int read_object(char *checksum, struct object *obj);
 int save_index(struct tree *tree);
 int load_index(struct tree *index);
 int load_tree(char* checksum, struct tree *tree);
-int update_head(char *new_head);
+int update_current_branch_head(char *new_head);
 int get_last_commit(struct object *commit);
 int tmp_dump(struct object *obj, char* filename);
 int init_tmp_diff_dir(char* dir);