Add log command

Add "tog log" command to view the last n commit hashes. Also
refactor tog.cpp into main.cpp, cli.cpp

CMakeLists.txt

@@ -11,7 +11,7 @@ find_package(CryptoPP REQUIRED)
 # TODO there's probably a better way to do this with CMake
 include_directories("libs/")
 add_executable(
-    ${PROJECT_NAME} src/tog.cpp src/repository.cpp src/blob.cpp src/crypto.cpp
-     src/tree.cpp src/commit.cpp
+    ${PROJECT_NAME} src/main.cpp src/repository.cpp src/blob.cpp src/crypto.cpp
+     src/tree.cpp src/commit.cpp src/cli.cpp
 )
 target_link_libraries(tog PRIVATE CryptoPP::CryptoPP) 

src/cli.cpp

@@ -0,0 +1,96 @@
+#include "cli.h"
+
+#include <filesystem>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include "repository.h"
+
+namespace fs = std::filesystem;
+
+namespace tog::cli {
+
+using namespace tog;
+
+tog::Repository load_repository() {
+    const auto path = fs::current_path() / ".tog";
+
+    if (!fs::exists(path)) {
+        throw TogException("Not a tog repository");
+    }
+
+    return Repository{path};
+}
+
+void init() {
+    try {
+        Repository::init(fs::current_path());
+    } catch (const TogException &err) {
+        std::cerr << "Error " << err.what() << std::endl;
+    }
+
+    std::cout << "Initialized tog repository" << std::endl;
+}
+
+void commit(const std::string &message) {
+    try {
+        auto repo = load_repository();
+        auto hash = repo.commit(message);
+
+        std::cout << "Created commit " << hash << std::endl;
+
+    } catch (const std::exception &e) {
+        std::cout << "Error: " << e.what() << std::endl;
+    }
+}
+
+void checkout(const std::string &hash) {
+    try {
+        auto repo = load_repository();
+        repo.checkout(hash);
+
+        std::cout << "Checked out commit " << hash << std::endl;
+
+    } catch (const std::exception &e) {
+        std::cout << "Error: " << e.what() << std::endl;
+    }
+}
+
+void status() {
+    try {
+        auto repo = load_repository();
+
+        auto head = repo.head();
+        auto main = repo.main();
+
+        std::cout << "On branch main" << std::endl;
+
+        if (main) {
+            std::cout << "Current commit: " << *head << std::endl;
+            std::cout << "Latest commit: " << *main << std::endl;
+        } else {
+            std::cout << "No commits yet" << std::endl;
+        }
+    } catch (const std::exception &e) {
+        std::cout << "Error: " << e.what() << std::endl;
+    }
+}
+
+void log(int history_length) {
+    try {
+        auto repo = load_repository();
+        auto history = repo.history(history_length);
+
+        if (history.empty()) {
+            std::cout << "No commits yet" << std::endl;
+        }
+
+        for (const auto &hash : history) {
+            std::cout << hash << std::endl;
+        }
+    } catch (const std::exception &e) {
+        std::cout << "Error: " << e.what() << std::endl;
+    }
+}
+}  // namespace tog::cli

src/cli.h

@@ -0,0 +1,31 @@
+#ifndef TOG_CLI_H
+#define TOG_CLI_H
+
+#include <filesystem>
+#include <string>
+
+#include "repository.h"
+
+namespace tog::cli {
+
+// helper function to load reposiotries
+tog::Repository load_repository();
+
+// initializes a new tog repository
+void init();
+
+// commits the current workdir contents with the given commit message
+void commit(const std::string &message);
+
+// restores workdir contents to the commti with the given hash
+void checkout(const std::string &hash);
+
+// prints out status information about the current branch/commit
+void status();
+
+// prints the hashes of the last n commits
+void log(int n);
+
+}  // namespace tog::cli
+
+#endif  // TOG_TOG_H

src/commit.h

@@ -23,6 +23,14 @@ class Commit : public TogObject {
         return _tree;
     }
 
+    const std::string& message() const {
+        return _message;
+    }
+
+    const std::optional<Handle<Commit>>& parent() {
+        return _parent;
+    }
+
 private:
     // the top-level tree of the commit (i.e. the worktree)
     Handle<Tree> _tree;

src/main.cpp

@@ -0,0 +1,58 @@
+#include <CLI11/CLI11.h>
+#include <tomlplusplus/toml.h>
+
+#include <filesystem>
+#include <iostream>
+
+#include "cli.h"
+
+int main(int argc, char **argv) {
+    CLI::App app{"The simple version control system", "tog"};
+
+    // Require exactly one argument (such as "init", "commit", ...)
+    app.require_subcommand(1);
+
+    // tog init
+    auto init_cmd = app.add_subcommand(
+        "init", "Creates a new repository in the current directory");
+    init_cmd->callback(tog::cli::init);
+
+    // tog commit [-m <message>]
+    auto commit_cmd = app.add_subcommand("commit", "Creates a new commit");
+    std::string commit_message;
+    commit_cmd->add_option("-m,--message", commit_message, "Commit message");
+    commit_cmd->callback(
+        [&commit_message]() { tog::cli::commit(commit_message); });
+
+    // tog checkout <commit>
+    auto checkout_cmd = app.add_subcommand("checkout", "Checkout a commit");
+    std::string checkout_hash;
+
+    // TODO fix formatting in .clang-format
+    checkout_cmd->add_option("commit", checkout_hash, "Commit hash")
+        ->required();
+    checkout_cmd->callback(
+        [&checkout_hash]() { tog::cli::checkout(checkout_hash); });
+
+    // tog status command
+    auto status_cmd =
+        app.add_subcommand("status", "Display the current branch/commit");
+    status_cmd->callback(tog::cli::status);
+
+    // tog log command
+    auto log_cmd = app.add_subcommand("log", "Display the commit history");
+    int history_length;
+    log_cmd
+        ->add_option("-n,--number", history_length,
+                     "Number of commits to display")
+        ->default_val<int>(10);
+    log_cmd->callback([&history_length]() { tog::cli::log(history_length); });
+
+    try {
+        CLI11_PARSE(app, argc, argv);
+    } catch (const CLI::ParseError &e) {
+        return app.exit(e);
+    }
+
+    return 0;
+}

src/repository.cpp

@@ -138,6 +138,24 @@ void Repository::checkout(const std::string& hash) {
     persist_ref(_togdir_path / "refs" / "head", _head);
 }
 
+std::vector<std::string> Repository::history(int n) {
+    std::vector<std::string> commits;
+
+    std::optional<Handle<Commit>> current = _head;
+
+    for (int i = 0; i < n; ++i) {
+        if (!current) {
+            return commits;
+        }
+
+        commits.push_back(current->hash());
+        resolve(*current);
+        current = (current->object()->parent());
+    }
+
+    return commits;
+}
+
 void Repository::resolve(Handle<Blob>& blob) {
     if (blob.resolved()) {
         return;

src/repository.h

@@ -35,6 +35,10 @@ class Repository {
     // restores the worktree to the state captured by the given commit
     void checkout(const std::string& hash);
 
+    // returns the current branch's last n commit hashes in
+    // reverse-chronological order (newest first).
+    std::vector<std::string> history(int n);
+
     // Initialized a new repository in the given directory.
     static void init(const std::filesystem::path& path);