// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use git2::Oid;
use jj_lib::commit::Commit;
use jj_lib::git;
use jj_lib::git::GitPushError;
use jj_lib::repo::ReadonlyRepo;
use jj_lib::settings::UserSettings;
use jj_lib::store::CommitId;
use jj_lib::testutils;
use std::path::{Path, PathBuf};
use std::sync::Arc;
use tempfile::TempDir;

/// Create a Git repo with a single commit in the "main" branch.
fn create_source_repo(dir: &Path) -> CommitId {
    let git_repo = git2::Repository::init_bare(dir).unwrap();
    let signature = git2::Signature::now("Someone", "someone@example.com").unwrap();
    let empty_tree_id = Oid::from_str("4b825dc642cb6eb9a060e54bf8d69288fbee4904").unwrap();
    let empty_tree = git_repo.find_tree(empty_tree_id).unwrap();
    let oid = git_repo
        .commit(
            Some("refs/heads/main"),
            &signature,
            &signature,
            "message",
            &empty_tree,
            &[],
        )
        .unwrap();
    CommitId(oid.as_bytes().to_vec())
}

fn create_repo_clone(source: &Path, destination: &Path) {
    git2::Repository::clone(&source.to_str().unwrap(), destination).unwrap();
}

struct PushTestSetup {
    source_repo_dir: PathBuf,
    clone_repo_dir: PathBuf,
    jj_repo: Arc<ReadonlyRepo>,
    new_commit: Commit,
}

fn set_up_push_repos(settings: &UserSettings, temp_dir: &TempDir) -> PushTestSetup {
    let source_repo_dir = temp_dir.path().join("source");
    let clone_repo_dir = temp_dir.path().join("clone");
    let jj_repo_dir = temp_dir.path().join("jj");
    let initial_commit_id = create_source_repo(&source_repo_dir);
    create_repo_clone(&source_repo_dir, &clone_repo_dir);
    std::fs::create_dir(&jj_repo_dir).unwrap();
    let mut jj_repo =
        ReadonlyRepo::init_external_git(&settings, jj_repo_dir.clone(), clone_repo_dir.clone());
    let new_commit = testutils::create_random_commit(&settings, &jj_repo)
        .set_parents(vec![initial_commit_id.clone()])
        .write_to_new_transaction(&jj_repo, "test");
    Arc::get_mut(&mut jj_repo).unwrap().reload();
    PushTestSetup {
        source_repo_dir,
        clone_repo_dir,
        jj_repo,
        new_commit,
    }
}

#[test]
fn test_push_commit_success() {
    let settings = testutils::user_settings();
    let temp_dir = tempfile::tempdir().unwrap();
    let setup = set_up_push_repos(&settings, &temp_dir);
    let result = git::push_commit(&setup.new_commit, "origin", "main");
    assert_eq!(result, Ok(()));

    // Check that the ref got updated in the source repo
    let source_repo = git2::Repository::open(&setup.source_repo_dir).unwrap();
    let new_target = source_repo
        .find_reference("refs/heads/main")
        .unwrap()
        .target();
    let new_oid = Oid::from_bytes(&setup.new_commit.id().0).unwrap();
    assert_eq!(new_target, Some(new_oid));

    // Check that the ref got updated in the cloned repo. This just tests our
    // assumptions about libgit2 because we want the refs/remotes/origin/main
    // branch to be updated.
    let clone_repo = git2::Repository::open(&setup.clone_repo_dir).unwrap();
    let new_target = clone_repo
        .find_reference("refs/remotes/origin/main")
        .unwrap()
        .target();
    assert_eq!(new_target, Some(new_oid));
}

#[test]
fn test_push_commit_not_fast_forward() {
    let settings = testutils::user_settings();
    let temp_dir = tempfile::tempdir().unwrap();
    let mut jj_repo = set_up_push_repos(&settings, &temp_dir).jj_repo;
    let new_commit = testutils::create_random_commit(&settings, &jj_repo)
        .write_to_new_transaction(&jj_repo, "test");
    Arc::get_mut(&mut jj_repo).unwrap().reload();
    let result = git::push_commit(&new_commit, "origin", "main");
    assert_eq!(result, Err(GitPushError::NotFastForward));
}

#[test]
fn test_push_commit_no_such_remote() {
    let settings = testutils::user_settings();
    let temp_dir = tempfile::tempdir().unwrap();
    let setup = set_up_push_repos(&settings, &temp_dir);
    let result = git::push_commit(&setup.new_commit, "invalid-remote", "main");
    assert_eq!(result, Err(GitPushError::NoSuchRemote));
}

#[test]
fn test_push_commit_invalid_remote() {
    let settings = testutils::user_settings();
    let temp_dir = tempfile::tempdir().unwrap();
    let setup = set_up_push_repos(&settings, &temp_dir);
    let result = git::push_commit(&setup.new_commit, "http://invalid-remote", "main");
    assert_eq!(result, Err(GitPushError::NoSuchRemote));
}

#[test]
fn test_push_commit_non_git() {
    let settings = testutils::user_settings();
    let (_temp_dir, repo) = testutils::init_repo(&settings, false);
    let commit =
        testutils::create_random_commit(&settings, &repo).write_to_new_transaction(&repo, "test");
    let result = git::push_commit(&commit, "origin", "main");
    assert_eq!(result, Err(GitPushError::NotAGitRepo));
}