Merge conflict (#60)

Merge conflicts

Author: SandrineP

src/subcommand/merge_subcommand.cpp

@@ -1,18 +1,24 @@
 #include <cassert>
+#include <git2/reset.h>
 #include <git2/types.h>
+#include <iostream>
+#include <termcolor/termcolor.hpp>
 
 #include "merge_subcommand.hpp"
-#include <iostream>
+#include "../wrapper/status_wrapper.hpp"
 
 
 merge_subcommand::merge_subcommand(const libgit2_object&, CLI::App& app)
 {
     auto *sub = app.add_subcommand("merge", "Join two or more development histories together");
 
     sub->add_option("<branch>", m_branches_to_merge, "Branch(es) to merge");
-    // sub->add_flag("--no-ff", m_no_ff, "");
+    // sub->add_flag("--no-ff", m_no_ff, "Create a merge commit in all cases, even when the merge could instead be resolved as a fast-forward.");
     // sub->add_flag("--commit", m_commit, "Perform the merge and commit the result. This option can be used to override --no-commit.");
     sub->add_flag("--no-commit", m_no_commit, "With --no-commit perform the merge and stop just before creating a merge commit, to give the user a chance to inspect and further tweak the merge result before committing. \nNote that fast-forward updates do not create a merge commit and therefore there is no way to stop those merges with --no-commit. Thus, if you want to ensure your branch is not changed or updated by the merge command, use --no-ff with --no-commit.");
+    sub->add_flag("--abort", m_abort, "Abort the current conflict resolution process, and try to reconstruct the pre-merge state. If an autostash entry is present, apply it to the worktree.\nIf there were uncommitted worktree changes present when the merge started, git merge --abort will in some cases be unable to reconstruct these changes. It is therefore recommended to always commit or stash your changes before running git merge.\ngit merge --abort is equivalent to git reset --merge when MERGE_HEAD is present unless MERGE_AUTOSTASH is also present in which case git merge --abort applies the stash entry to the worktree whereas git reset --merge will save the stashed changes in the stash list.");
+    sub->add_flag("--quit", m_quit, "Forget about the current merge in progress. Leave the index and the working tree as-is. If MERGE_AUTOSTASH is present, the stash entry will be saved to the stash list.");
+    sub->add_flag("--continue", m_continue, "After a git merge stops due to conflicts you can conclude the merge by running git merge --continue");   //  (see "HOW TO RESOLVE CONFLICTS" section below).
 
     sub->callback([this]() { this->run(); });
 }
@@ -33,7 +39,23 @@ annotated_commit_list_wrapper merge_subcommand::resolve_heads(const repository_w
     return annotated_commit_list_wrapper(std::move(commits_to_merge));
 }
 
-void perform_fastforward(repository_wrapper& repo, const git_oid target_oid, int is_unborn)
+annotated_commit_list_wrapper resolve_mergeheads(const repository_wrapper& repo, const std::vector<git_oid>& oid_list)
+{
+    std::vector<annotated_commit_wrapper> commits_to_merge;
+    commits_to_merge.reserve(oid_list.size());
+
+    for (const auto& id:oid_list)
+    {
+        std::optional<annotated_commit_wrapper> commit = repo.find_annotated_commit(id);
+        if (commit.has_value())
+        {
+            commits_to_merge.push_back(std::move(commit).value());
+        }
+    }
+    return annotated_commit_list_wrapper(std::move(commits_to_merge));
+}
+
+void perform_fastforward(repository_wrapper& repo, const git_oid& target_oid, int is_unborn)
 {
     const git_checkout_options ff_checkout_options = GIT_CHECKOUT_OPTIONS_INIT;
 
@@ -60,12 +82,13 @@ void perform_fastforward(repository_wrapper& repo, const git_oid target_oid, int
 void merge_subcommand::create_merge_commit(
     repository_wrapper& repo,
     const index_wrapper& index,
+    const std::vector<std::string>& branches_to_merge,
     const annotated_commit_list_wrapper& commits_to_merge,
     size_t num_commits_to_merge)
 {
     auto head_ref = repo.head();
-    auto merge_ref = repo.find_reference_dwim(m_branches_to_merge.front());
-    auto merge_commit = repo.resolve_local_ref(m_branches_to_merge.front()).value();
+    auto merge_ref = repo.find_reference_dwim(branches_to_merge.front());
+    auto merge_commit = repo.resolve_local_ref(branches_to_merge.front()).value();
 
     std::vector<commit_wrapper> parents_list;
     parents_list.reserve(num_commits_to_merge + 1);
@@ -85,6 +108,7 @@ void merge_subcommand::create_merge_commit(
 
     // TODO: add a prompt to edit the merge message
     std::string msg_target = merge_ref ? merge_ref->short_name() : git_oid_tostr_s(&(merge_commit.oid()));
+    msg_target = "\'" + msg_target + "\'";
 	std::string msg = merge_ref ? "Merge branch " : "Merge commit ";
 	msg.append(msg_target);
 
@@ -93,15 +117,159 @@ void merge_subcommand::create_merge_commit(
 	repo.state_cleanup();
 }
 
+// This function is used as a callback in git_repository_mergehead_foreach and therefore its type must be git_repository_mergehead_foreach_cb.
+int populate_list(const git_oid* oid, void* payload)
+{
+    auto* l = reinterpret_cast<std::vector<git_oid>*>(payload);
+    l->push_back(*oid);
+    return 0;
+}
+
 void merge_subcommand::run()
 {
     auto directory = get_current_git_path();
     auto bare = false;
     auto repo = repository_wrapper::open(directory);
-
     auto state = repo.state();
-    if (state != GIT_REPOSITORY_STATE_NONE)
+    index_wrapper index = repo.make_index();
+    stream_colour_fn yellow = termcolor::yellow;
+
+    if (state == GIT_REPOSITORY_STATE_MERGE)
     {
+        if (m_abort)
+        {
+            // git merge --abort is equivalent to git reset --merge when MERGE_HEAD is present
+            // unless MERGE_AUTOSTASH is also present in which case git merge --abort applies
+            // the stash entry to the worktree whereas git reset --merge will save the stashed
+            // changes in the stash list.
+
+            if (m_quit | m_continue)
+            {
+                std::cout << "fatal: --abort expects no arguments" << std::endl;   // TODO: add the help info
+                return;
+            }
+
+            std::cout << "Warning: 'merge --abort' is not implemented yet. A 'reset --hard HEAD' will be executed." << std::endl;
+            std::cout << "Do you want to continue [y/N] ?" << std::endl;
+            std::string answer;
+            std::cin >> answer;
+            if (answer == "y")
+            {
+                repo.state_cleanup();
+                index.conflict_cleanup();
+
+                git_checkout_options options;
+                git_checkout_options_init(&options, GIT_CHECKOUT_OPTIONS_VERSION);
+                auto head_ref = repo.head();
+                repo.reset(head_ref.peel<object_wrapper>(), GIT_RESET_HARD, options);
+            }
+            else
+            {
+                std::cout << "Abort." << std::endl;   // maybe another message would be more clear?
+            }
+            return;
+        }
+        else if (m_quit)
+        {
+            // Forget about the current merge in progress. Leave the index and the working tree as-is.
+            // If MERGE_AUTOSTASH is present, the stash entry will be saved to the stash list.
+            //
+
+            // if (m_continue)
+            // {
+            //     std::cout << "fatal: --abort expects no arguments" << std::endl;   // TODO: add the help info
+            //     return;
+            // }
+
+            // problem: can't do a reset if the state is not cleaned up, but it shouldn't be.
+            // Idem for the index and the conflicts.
+
+            // repo.state_cleanup();
+            // index.conflict_cleanup();
+
+            // git_checkout_options options;
+            // git_checkout_options_init(&options, GIT_CHECKOUT_OPTIONS_VERSION);
+            // auto head_ref = repo.head();
+            // repo.reset(head_ref.peel<object_wrapper>(), GIT_RESET_SOFT, options);
+
+            std::cout << "merge --quit is not implemented yet." << std::endl;
+            return;
+        }
+        else if (m_continue)
+		{
+		    auto sl = status_list_wrapper::status_list(repo);
+		    if (!sl.has_unmerged_header())
+			{
+			    // std::string commit_message = "Merge branch ";    // how to get the name of the branch the merge was started on ?
+ 			    // auto author_committer_signatures = signature_wrapper::get_default_signature_from_env(repo);
+                // repo.create_commit(author_committer_signatures, commit_message, std::nullopt);
+
+                std::vector<git_oid> oid_list;
+                git_repository_mergehead_foreach(repo, populate_list, &oid_list);
+
+                annotated_commit_list_wrapper commits_to_merge = resolve_mergeheads(repo, oid_list);
+                size_t num_commits_to_merge = commits_to_merge.size();
+
+                std::vector<std::string> branches_to_merge_names;
+                for (const auto& id:oid_list)
+				{
+				    git_reference_iterator* iter;
+					git_reference_iterator_new(&iter, repo);
+					git_reference* ref;
+					git_reference_next(&ref, iter);
+					if (git_oid_equal(git_reference_target(ref), &id))
+					{
+	                    auto name = git_reference_name(ref);
+						branches_to_merge_names.push_back(name);
+					}
+					git_reference_free(ref);
+				}
+
+                create_merge_commit(repo, index, branches_to_merge_names, commits_to_merge, num_commits_to_merge);
+                std::cout << "Merge made" << std::endl;     // TODO: change the outpout to something like this: 3c22161 (HEAD -> master) Merge branch 'foregone'
+
+                repo.state_cleanup();
+                index.conflict_cleanup();
+			    return;
+			}
+			else
+			{
+			    auto entry_status = get_status_msg(GIT_STATUS_CONFLICTED).short_mod;
+                const auto& entry_list = sl.get_entry_list(GIT_STATUS_CONFLICTED);
+                for (auto* entry : entry_list)
+			    {
+					git_diff_delta* diff_delta = entry->head_to_index; //ou entry->index_to_workdir ???
+                    const char* old_path = diff_delta->old_file.path;
+                    std::cout << entry_status << "\t" << old_path << std::endl;
+				}
+			    std::cout << "error: Committing is not possible because you have unmerged files." << std::endl;
+			}
+		}
+        else
+        {
+            std::cout << "error: Merging is not possible because you have unmerged files." << std::endl;
+        }
+        std::cout << yellow << "hint: Fix them up in the work tree, and then use 'git add/rm <file>'" << std::endl;
+        std::cout << "hint: as appropriate to mark resolution and make a commit." << termcolor::reset << std::endl;
+        std::cout << "fatal: Exiting because of an unresolved conflict." << std::endl;
+        return;
+    }
+    else
+    {
+        if (m_abort)
+        {
+            std::cout << "fatal: There is no merge to abort (MERGE_HEAD missing)." << std::endl;
+            return;
+        }
+        if (m_continue)
+        {
+            std::cout << "fatal: There is no merge in progress (MERGE_HEAD missing)." << std::endl;
+            return;
+        }
+    }
+
+    if (state != GIT_REPOSITORY_STATE_NONE)  // Could this be a "else if before the "else" above ?
+     {
         std::cout << "repository is in unexpected state " << state <<std::endl;
     }
 
@@ -159,17 +327,13 @@ void merge_subcommand::run()
 								 &checkout_opts));
     }
 
-    index_wrapper index = repo.make_index();
-
-    if (git_index_has_conflicts(index))
+    if (index.has_conflict())
     {
-        std::cout << "Conflict. To be implemented" << std::endl;
-        /* Handle conflicts */
-		// output_conflicts(index);
+		index.output_conflicts();
 	}
 	else if (!m_no_commit)
 	{
-		create_merge_commit(repo, index, commits_to_merge, num_commits_to_merge);
-		printf("Merge made\n");
+	    create_merge_commit(repo, index, m_branches_to_merge, commits_to_merge, num_commits_to_merge);
+		std::cout << "Merge made" << std::endl;
 	}
 }

src/subcommand/merge_subcommand.hpp

@@ -18,11 +18,15 @@ class merge_subcommand
     void create_merge_commit(
         repository_wrapper& repo,
         const index_wrapper& index,
+        const std::vector<std::string>& branches_to_merge,
         const annotated_commit_list_wrapper& commits_to_merge,
         size_t num_commits_to_merge);
 
     std::vector<std::string> m_branches_to_merge;
     // bool m_no_ff = false;
     // bool m_commit = false;
     bool m_no_commit = false;
+    bool m_abort = false;
+    bool m_quit = false;
+    bool m_continue = false;
 };