// Copyright 2021 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 jujutsu_lib::op_store::RefTarget;
use jujutsu_lib::refs::merge_ref_targets;
use testutils::{CommitGraphBuilder, TestWorkspace};

#[test]
fn test_merge_ref_targets() {
    let settings = testutils::user_settings();
    let test_workspace = TestWorkspace::init(&settings, false);
    let repo = &test_workspace.repo;

    // 6 7
    // |/
    // 5
    // | 3 4
    // | |/
    // | 2
    // |/
    // 1
    let mut tx = repo.start_transaction("test");
    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
    let commit1 = graph_builder.initial_commit();
    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
    let commit3 = graph_builder.commit_with_parents(&[&commit2]);
    let commit4 = graph_builder.commit_with_parents(&[&commit2]);
    let commit5 = graph_builder.commit_with_parents(&[&commit1]);
    let commit6 = graph_builder.commit_with_parents(&[&commit5]);
    let commit7 = graph_builder.commit_with_parents(&[&commit5]);
    let repo = tx.commit();

    let target1 = RefTarget::Normal(commit1.id().clone());
    let target2 = RefTarget::Normal(commit2.id().clone());
    let target3 = RefTarget::Normal(commit3.id().clone());
    let target4 = RefTarget::Normal(commit4.id().clone());
    let target5 = RefTarget::Normal(commit5.id().clone());
    let target6 = RefTarget::Normal(commit6.id().clone());
    let _target7 = RefTarget::Normal(commit7.id().clone());

    let index = repo.index();
    let index_ref = index.as_index_ref();

    // Left moved forward
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target1), Some(&target1)),
        Some(target3.clone())
    );

    // Right moved forward
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target1), Some(&target1), Some(&target3)),
        Some(target3.clone())
    );

    // Left moved backward
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target1), Some(&target3), Some(&target3)),
        Some(target1.clone())
    );

    // Right moved backward
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target3), Some(&target1)),
        Some(target1.clone())
    );

    // Left moved sideways
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target4), Some(&target3), Some(&target3)),
        Some(target4.clone())
    );

    // Right moved sideways
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target3), Some(&target4)),
        Some(target4.clone())
    );

    // Both added same target
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), None, Some(&target3)),
        Some(target3.clone())
    );

    // Left added target, right added descendant target
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target2), None, Some(&target3)),
        Some(target3.clone())
    );

    // Right added target, left added descendant target
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), None, Some(&target2)),
        Some(target3.clone())
    );

    // Both moved forward to same target
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target1), Some(&target3)),
        Some(target3.clone())
    );

    // Both moved forward, left moved further
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target1), Some(&target2)),
        Some(target3.clone())
    );

    // Both moved forward, right moved further
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target2), Some(&target1), Some(&target3)),
        Some(target3.clone())
    );

    // Left and right moved forward to divergent targets
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target1), Some(&target4)),
        Some(RefTarget::Conflict {
            removes: vec![commit1.id().clone()],
            adds: vec![commit3.id().clone(), commit4.id().clone()]
        })
    );

    // Left moved back, right moved forward
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target1), Some(&target2), Some(&target3)),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone()],
            adds: vec![commit1.id().clone(), commit3.id().clone()]
        })
    );

    // Right moved back, left moved forward
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target2), Some(&target1)),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone()],
            adds: vec![commit3.id().clone(), commit1.id().clone()]
        })
    );

    // Left removed
    assert_eq!(
        merge_ref_targets(index_ref, None, Some(&target3), Some(&target3)),
        None
    );

    // Right removed
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target3), None),
        None
    );

    // Left removed, right moved forward
    assert_eq!(
        merge_ref_targets(index_ref, None, Some(&target1), Some(&target3)),
        Some(RefTarget::Conflict {
            removes: vec![commit1.id().clone()],
            adds: vec![commit3.id().clone()]
        })
    );

    // Right removed, left moved forward
    assert_eq!(
        merge_ref_targets(index_ref, Some(&target3), Some(&target1), None),
        Some(RefTarget::Conflict {
            removes: vec![commit1.id().clone()],
            adds: vec![commit3.id().clone()]
        })
    );

    // Left became conflicted, right moved forward
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            }),
            Some(&target1),
            Some(&target3)
        ),
        // TODO: "removes" should have commit 2, just like it does in the next test case
        Some(RefTarget::Conflict {
            removes: vec![commit1.id().clone()],
            adds: vec![commit4.id().clone(), commit3.id().clone()]
        })
    );

    // Right became conflicted, left moved forward
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&target3),
            Some(&target1),
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            })
        ),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone()],
            adds: vec![commit3.id().clone(), commit4.id().clone()]
        })
    );

    // Existing conflict on left, right moves an "add" sideways
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            }),
            Some(&target3),
            Some(&target5)
        ),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone()],
            adds: vec![commit4.id().clone(), commit5.id().clone()]
        })
    );

    // Existing conflict on right, left moves an "add" sideways
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&target5),
            Some(&target3),
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            })
        ),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone()],
            adds: vec![commit5.id().clone(), commit4.id().clone()]
        })
    );

    // Existing conflict on left, right moves an "add" backwards, past point of
    // divergence
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            }),
            Some(&target3),
            Some(&target1)
        ),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone()],
            adds: vec![commit4.id().clone(), commit1.id().clone()]
        })
    );

    // Existing conflict on right, left moves an "add" backwards, past point of
    // divergence
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&target1),
            Some(&target3),
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            })
        ),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone()],
            adds: vec![commit1.id().clone(), commit4.id().clone()]
        })
    );

    // Existing conflict on left, right undoes one side of conflict
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            }),
            Some(&target3),
            Some(&target2)
        ),
        Some(target4.clone())
    );

    // Existing conflict on right, left undoes one side of conflict
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&target2),
            Some(&target3),
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            })
        ),
        Some(target4)
    );

    // Existing conflict on left, right makes unrelated update
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            }),
            Some(&target5),
            Some(&target6)
        ),
        Some(RefTarget::Conflict {
            removes: vec![commit2.id().clone(), commit5.id().clone()],
            adds: vec![
                commit3.id().clone(),
                commit4.id().clone(),
                commit6.id().clone()
            ]
        })
    );

    // Existing conflict on right, left makes unrelated update
    assert_eq!(
        merge_ref_targets(
            index_ref,
            Some(&target6),
            Some(&target5),
            Some(&RefTarget::Conflict {
                removes: vec![commit2.id().clone()],
                adds: vec![commit3.id().clone(), commit4.id().clone()]
            })
        ),
        Some(RefTarget::Conflict {
            removes: vec![commit5.id().clone(), commit2.id().clone()],
            adds: vec![
                commit6.id().clone(),
                commit3.id().clone(),
                commit4.id().clone()
            ]
        })
    );
}