step seventeen: implement log

src/base.rs

@@ -5,6 +5,12 @@ use std::path::Path;
 #[path = "data.rs"]
 mod data;
 
+pub struct Commit {
+    pub tree: String,
+    pub parent: String,
+    pub message: String,
+}
+
 pub fn write_tree(directory: String) -> String {
     let mut entries: Vec<(String, String, String)> = vec![];
     let mut name;
@@ -77,6 +83,32 @@ pub fn commit(message: &str) -> String {
     return oid;
 }
 
+pub fn get_commit(oid: String) -> Commit {
+    let commit = data::get_object(oid, "commit".to_owned());
+    let tree: String;
+    let mut parent: String = "".to_owned();
+    let message: String;
+    let mut message_start = 2;
+
+    let lines: Vec<&str> = commit.lines().collect();
+    let mut line_items: Vec<&str> = lines[0].splitn(2, " ").collect();
+    tree = line_items[1].to_owned();
+
+    line_items = lines[1].splitn(2, " ").collect();
+    if line_items[0] == "parent" {
+        parent = line_items[1].to_owned();
+        message_start = 3;
+    }
+
+    message = lines[message_start..].join("\n");
+
+    return Commit {
+        tree,
+        parent,
+        message,
+    };
+}
+
 fn is_ignored(path: &String) -> bool {
     if path.contains(".rgit") {
         true

src/main.rs

@@ -38,6 +38,7 @@ fn main() {
                         .takes_value(true),
                 ),
         )
+        .subcommand(SubCommand::with_name("log").about("List all commits"))
         .get_matches();
 
     match matches.subcommand_name() {
@@ -47,6 +48,7 @@ fn main() {
         Some("write-tree") => write_tree(),
         Some("read-tree") => read_tree(matches),
         Some("commit") => commit(matches),
+        Some("log") => log_commits(),
         _ => println!("unknown sub command"),
     }
 }
@@ -94,3 +96,20 @@ fn commit(matches: ArgMatches) {
         println!("{}", base::commit(message));
     }
 }
+
+fn log_commits() {
+    let mut oid = data::get_head().expect("Cannot read HEAD file");
+    loop {
+        let commit = base::get_commit(oid.clone());
+
+        println!("commit {}", oid);
+        println!("{}", commit.message);
+        println!("");
+
+        if commit.parent == "" {
+            break;
+        }
+
+        oid = commit.parent;
+    }
+}