backend/src/git.cpp

/*  This file is part of FediBlock-backend.
 *  Copyright © 2020 tastytea <tastytea@tastytea.de>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, version 3.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "git.hpp"
#include "files.hpp"

#include <cstdint>
#include <git2/branch.h>
#include <git2/buffer.h>
#include <git2/clone.h>
#include <git2/commit.h>
#include <git2/errors.h>
#include <git2/global.h>
#include <git2/types.h>

#include <stdexcept>
#include <string>
#include <string_view>

namespace FediBlock
{

using std::runtime_error;
using std::stoull;
using std::string;
using std::string_view;
using std::uint64_t;

git_repository *_repo = nullptr;

void check_git_error(int error)
{
    if (error != 0)
    {
        const git_error *e = git_error_last();
        throw runtime_error{e->message};
    }
}

void clone_repo()
{
    int error = git_clone(&_repo, "https://schlomp.space/FediBlock/data.git",
                          (get_tmpdir() / "repo").c_str(), nullptr);
    check_git_error(error);
}

uint64_t get_last_id()
{
    constexpr string_view branch_prefix{"from-web-"};
    uint64_t id{0};

    git_branch_iterator *it;
    if (git_branch_iterator_new(&it, _repo, GIT_BRANCH_ALL) == 0)
    {
        git_reference *ref;
        git_branch_t type;
        while (git_branch_next(&ref, &type, it) == 0)
        {
            const char *out{nullptr};
            git_branch_name(&out, ref);
            if (type == GIT_BRANCH_REMOTE)
            {
                const string branch_name{out};
                size_t pos{branch_name.find(branch_prefix)};
                if (pos != string::npos)
                {
                    pos += branch_prefix.size();
                    uint64_t newid{stoull(branch_name.substr(pos))};
                    if (newid > id)
                    {
                        id = newid;
                    }
                }
            }
            git_reference_free(ref);
        }
        git_branch_iterator_free(it);
    }

    return id;
}

void make_new_branch()
{
    git_oid oid_parent;
    git_commit *commit;

    // Get SHA1 of HEAD.
    int error{git_reference_name_to_id(&oid_parent, _repo, "HEAD")};
    check_git_error(error);

    // Translate SHA-1 to git_commit.
    error = git_commit_lookup(&commit, _repo, &oid_parent);
    check_git_error(error);

    git_reference *branch;
    // Create new branch.
    error = git_branch_create(&branch, _repo, "test", commit, 0);
    check_git_error(error);
}

} // namespace FediBlock