Refactor the code into separate files

Separate repository/odb functions into their own file. Add odb_exists
to go through the repository's odb. Adjust the test script.

c_src/repository.c

@@ -0,0 +1,91 @@
+#include "repository.h"
+#include "geef.h"
+#include <git2.h>
+
+void geef_repository_free(ErlNifEnv *env, void *cd)
+{
+    geef_repository *grepo = (geef_repository *) cd;
+    git_repository_free(grepo->repo);
+}
+
+void geef_odb_free(ErlNifEnv *env, void *cd)
+{
+    geef_odb *odb = (geef_odb *) cd;
+    git_odb_free(odb->odb);
+}
+
+ERL_NIF_TERM
+geef_repository_open(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
+{
+  char path[MAXBUFLEN];
+  git_repository *repo;
+  geef_repository *res_repo;
+  ERL_NIF_TERM term_repo;
+
+  if (enif_get_string(env, argv[0], path, sizeof(path), ERL_NIF_LATIN1) < 1)
+      return enif_make_badarg(env);
+
+  if (git_repository_open(&repo, path) < 0)
+      return geef_error(env);
+
+  res_repo = enif_alloc_resource(geef_repository_type, sizeof(geef_repository));
+  res_repo->repo = repo;
+  term_repo = enif_make_resource(env, res_repo);
+  enif_release_resource(res_repo);
+
+  return enif_make_tuple2(env, geef_atoms.ok, term_repo);
+}
+
+ERL_NIF_TERM
+geef_repository_path(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
+{
+    geef_repository *repo;
+
+    if (!enif_get_resource(env, argv[0], geef_repository_type, (void **) &repo))
+        return enif_make_badarg(env);
+
+    return enif_make_string(env, git_repository_path(repo->repo), ERL_NIF_LATIN1);
+}
+
+ERL_NIF_TERM
+geef_repository_odb(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
+{
+    geef_repository *repo;
+    geef_odb *odb;
+    ERL_NIF_TERM term_odb;
+
+    if (!enif_get_resource(env, argv[0], geef_repository_type, (void **) &repo))
+        return enif_make_badarg(env);
+
+    odb = enif_alloc_resource(geef_odb_type, sizeof(geef_odb));
+    if (git_repository_odb(&odb->odb, repo->repo) < 0)
+	return geef_error(env);
+
+    term_odb = enif_make_resource(env, odb);
+    enif_release_resource(odb);
+
+    return enif_make_tuple2(env, geef_atoms.ok, term_odb);
+}
+
+ERL_NIF_TERM
+geef_odb_exists(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
+{
+    char sha[MAXBUFLEN] = {0};
+    geef_odb *odb;
+    git_oid oid;
+    int exists;
+
+    if (!enif_get_resource(env, argv[0], geef_odb_type, (void **) &odb))
+        return enif_make_badarg(env);
+
+    if (enif_get_string(env, argv[1], sha, sizeof(sha), ERL_NIF_LATIN1) < 1)
+	return enif_make_badarg(env);
+
+    git_oid_fromstr(&oid, sha);
+    exists = git_odb_exists(odb->odb, &oid);
+
+    if (exists)
+	return geef_atoms.true;
+
+    return geef_atoms.false;
+}