diff --git a/CalculatorCInterface/git_library.cpp b/CalculatorCInterface/git_library.cpp
index eb71961..cb8e3f8 100644
--- a/CalculatorCInterface/git_library.cpp
+++ b/CalculatorCInterface/git_library.cpp
@@ -340,7 +340,8 @@ on_error:
 //
 // git merge
 //
-struct merge_options { const char **heads;
+struct merge_options { 
+    const char **heads;
     size_t heads_count;
 
     git_annotated_commit **annotated;
@@ -376,6 +377,208 @@ static void parse_options(const char **repo_path, struct merge_options *opts) {
 #endif
 }
 
+static void opts_add_refish(struct merge_options *opts, const char *refish) {
+  size_t sz;
+
+  assert(opts != NULL);
+
+  sz = ++opts->heads_count * sizeof(opts->heads[0]);
+  opts->heads = xrealloc((void *) opts->heads, sz);
+  opts->heads[opts->heads_count - 1] = refish;
+}
+
+static int resolve_heads(git_repository *repo, struct merge_options *opts)
+{
+  git_annotated_commit **annotated = calloc(opts->heads_count, sizeof(git_annotated_commit *));
+  size_t annotated_count = 0, i;
+  int err = 0;
+
+  for (i = 0; i < opts->heads_count; i++) {
+    err = resolve_refish(&annotated[annotated_count++], repo, opts->heads[i]);
+    if (err != 0) {
+      fprintf(stderr, "failed to resolve refish %s: %s\n", opts->heads[i], git_error_last()->message);
+      annotated_count--;
+      continue;
+    }
+  }
+
+  if (annotated_count != opts->heads_count) {
+    fprintf(stderr, "unable to parse some refish\n");
+    free(annotated);
+    return -1;
+  }
+
+  opts->annotated = annotated;
+  opts->annotated_count = annotated_count;
+  return 0;
+}
+
+static int perform_fastforward(git_repository *repo, const git_oid *target_oid, int is_unborn)
+{
+  git_checkout_options ff_checkout_options = GIT_CHECKOUT_OPTIONS_INIT;
+  git_reference *target_ref;
+  git_reference *new_target_ref;
+  git_object *target = NULL;
+  int err = 0;
+
+  if (is_unborn) {
+    const char *symbolic_ref;
+    git_reference *head_ref;
+
+    /* HEAD reference is unborn, lookup manually so we don't try to resolve it */
+    err = git_reference_lookup(&head_ref, repo, "HEAD");
+    if (err != 0) {
+      fprintf(stderr, "failed to lookup HEAD ref\n");
+      return -1;
+    }
+
+    /* Grab the reference HEAD should be pointing to */
+    symbolic_ref = git_reference_symbolic_target(head_ref);
+
+    /* Create our master reference on the target OID */
+    err = git_reference_create(&target_ref, repo, symbolic_ref, target_oid, 0, NULL);
+    if (err != 0) {
+      fprintf(stderr, "failed to create master reference\n");
+      return -1;
+    }
+
+    git_reference_free(head_ref);
+  } else {
+    /* HEAD exists, just lookup and resolve */
+    err = git_repository_head(&target_ref, repo);
+    if (err != 0) {
+      fprintf(stderr, "failed to get HEAD reference\n");
+      return -1;
+    }
+  }
+
+  /* Lookup the target object */
+  err = git_object_lookup(&target, repo, target_oid, GIT_OBJECT_COMMIT);
+  if (err != 0) {
+    fprintf(stderr, "failed to lookup OID %s\n", git_oid_tostr_s(target_oid));
+    return -1;
+  }
+
+  /* Checkout the result so the workdir is in the expected state */
+  ff_checkout_options.checkout_strategy = GIT_CHECKOUT_SAFE;
+  err = git_checkout_tree(repo, target, &ff_checkout_options);
+  if (err != 0) {
+    fprintf(stderr, "failed to checkout HEAD reference\n");
+    return -1;
+  }
+
+  /* Move the target reference to the target OID */
+  err = git_reference_set_target(&new_target_ref, target_ref, target_oid, NULL);
+  if (err != 0) {
+    fprintf(stderr, "failed to move HEAD reference\n");
+    return -1;
+  }
+
+  git_reference_free(target_ref);
+  git_reference_free(new_target_ref);
+  git_object_free(target);
+
+  return 0;
+}
+
+static void output_conflicts(git_index *index)
+{
+  git_index_conflict_iterator *conflicts;
+  const git_index_entry *ancestor;
+  const git_index_entry *our;
+  const git_index_entry *their;
+  int err = 0;
+
+  check(git_index_conflict_iterator_new(&conflicts, index), "failed to create conflict iterator", NULL);
+
+  while ((err = git_index_conflict_next(&ancestor, &our, &their, conflicts)) == 0) {
+    fprintf(stderr, "conflict: a:%s o:%s t:%s\n",
+            ancestor ? ancestor->path : "NULL",
+            our->path ? our->path : "NULL",
+            their->path ? their->path : "NULL");
+  }
+
+  if (err != GIT_ITEROVER) {
+    fprintf(stderr, "error iterating conflicts\n");
+  }
+
+  git_index_conflict_iterator_free(conflicts);
+}
+
+static int create_merge_commit(git_repository *repo, git_index *index, struct merge_options *opts)
+{
+  git_oid tree_oid, commit_oid;
+  git_tree *tree;
+  git_signature *sign;
+  git_reference *merge_ref = NULL;
+  git_annotated_commit *merge_commit;
+  git_reference *head_ref;
+  git_commit **parents = calloc(opts->annotated_count + 1, sizeof(git_commit *));
+  const char *msg_target = NULL;
+  size_t msglen = 0;
+  char *msg;
+  size_t i;
+  int err;
+
+  /* Grab our needed references */
+  check(git_repository_head(&head_ref, repo), "failed to get repo HEAD", NULL);
+  if (resolve_refish(&merge_commit, repo, opts->heads[0])) {
+    fprintf(stderr, "failed to resolve refish %s", opts->heads[0]);
+    free(parents);
+    return -1;
+  }
+
+  /* Maybe that's a ref, so DWIM it */
+  err = git_reference_dwim(&merge_ref, repo, opts->heads[0]);
+  check(err, "failed to DWIM reference", git_error_last()->message);
+
+  /* Grab a signature */
+  check(git_signature_now(&sign, "Me", "me@example.com"), "failed to create signature", NULL);
+
+#define MERGE_COMMIT_MSG "Merge %s '%s'"
+  /* Prepare a standard merge commit message */
+  if (merge_ref != NULL) {
+    check(git_branch_name(&msg_target, merge_ref), "failed to get branch name of merged ref", NULL);
+  } else {
+    msg_target = git_oid_tostr_s(git_annotated_commit_id(merge_commit));
+  }
+
+  msglen = snprintf(NULL, 0, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);
+  if (msglen > 0) msglen++;
+  msg = malloc(msglen);
+  err = snprintf(msg, msglen, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);
+
+  /* This is only to silence the compiler */
+  if (err < 0) goto cleanup;
+
+  /* Setup our parent commits */
+  err = git_reference_peel((git_object **)&parents[0], head_ref, GIT_OBJECT_COMMIT);
+  check(err, "failed to peel head reference", NULL);
+  for (i = 0; i < opts->annotated_count; i++) {
+    git_commit_lookup(&parents[i + 1], repo, git_annotated_commit_id(opts->annotated[i]));
+  }
+
+  /* Prepare our commit tree */
+  check(git_index_write_tree(&tree_oid, index), "failed to write merged tree", NULL);
+  check(git_tree_lookup(&tree, repo, &tree_oid), "failed to lookup tree", NULL);
+
+  /* Commit time ! */
+  err = git_commit_create(&commit_oid,
+                          repo, git_reference_name(head_ref),
+                          sign, sign,
+                          NULL, msg,
+                          tree,
+                          opts->annotated_count + 1, parents);
+  check(err, "failed to create commit", NULL);
+
+  /* We're done merging, cleanup the repository state */
+  git_repository_state_cleanup(repo);
+
+cleanup:
+  free(parents);
+  return err;
+}
+
 static int merge(git_repository *repo) {
     struct merge_options opts;
     git_index *index;
@@ -388,6 +591,72 @@ static int merge(git_repository *repo) {
     merge_options_init(&opts);
     parse_options(&path, &opts);
 
+    state = git_repository_state(repo);
+    if (state != GIT_REPOSITORY_STATE_NONE) {
+        fprintf(stderr, "repository is in unexpected state %d\n", state);
+        goto cleanup;
+    }
+
+    err = resolve_heads(repo, &opts);
+    if (err != 0)
+        goto cleanup;
+
+    err = git_merge_analysis(&analysis, &preference,
+                               repo,
+                               (const git_annotated_commit **)opts.annotated,
+                               opts.annotated_count);
+    check(err, "merge analysis failed", NULL);
+
+    if (analysis & GIT_MERGE_ANALYSIS_UP_TO_DATE) {
+        printf("Already up-to-date\n");
+        return 0;
+    } else if (analysis & GIT_MERGE_ANALYSIS_UNBORN ||
+                (analysis & GIT_MERGE_ANALYSIS_FASTFORWARD &&
+                !(preference & GIT_MERGE_PREFERENCE_NO_FASTFORWARD))) {
+        const git_oid *target_oid;
+        if (analysis & GIT_MERGE_ANALYSIS_UNBORN) {
+            printf("Unborn\n");
+        } else {
+            printf("Fast-forward\n");
+        }
+
+        /* Since this is a fast-forward, there can be only one merge head */
+        target_oid = git_annotated_commit_id(opts.annotated[0]);
+        assert(opts.annotated_count == 1);
+
+        return perform_fastforward(repo, target_oid, (analysis & GIT_MERGE_ANALYSIS_UNBORN));
+    } else if (analysis & GIT_MERGE_ANALYSIS_NORMAL) {
+        git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
+        git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
+
+        merge_opts.flags = 0;
+        merge_opts.file_flags = GIT_MERGE_FILE_STYLE_DIFF3;
+
+        checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE|GIT_CHECKOUT_ALLOW_CONFLICTS;
+
+        if (preference & GIT_MERGE_PREFERENCE_FASTFORWARD_ONLY) {
+            printf("Fast-forward is preferred, but only a merge is possible\n");
+            return -1;
+        }
+
+        err = git_merge(repo,
+                        (const git_annotated_commit **)opts.annotated, opts.annotated_count,
+                        &merge_opts, &checkout_opts);
+        check(err, "merge failed", NULL);
+    }
+
+    /* If we get here, we actually performed the merge above */
+
+    check(git_repository_index(&index, repo), "failed to get repository index", NULL);
+
+    if (git_index_has_conflicts(index)) {
+        /* Handle conflicts */
+        output_conflicts(index);
+    } else if (!opts.no_commit) {
+        create_merge_commit(repo, index, &opts);
+        printf("Merge made\n");
+    }
+
 cleanup:
     free((char **)opts.heads);
     free(opts.annotated);