// Copyright 2021 The Jujutsu Authors
//
// 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 jj_lib::backend::FileId;
use jj_lib::conflicts::{
    extract_as_single_hunk, materialize_merge_result, parse_conflict, update_from_content,
};
use jj_lib::merge::Merge;
use jj_lib::repo::Repo;
use jj_lib::repo_path::RepoPath;
use jj_lib::store::Store;
use pollster::FutureExt;
use testutils::TestRepo;

#[test]
fn test_materialize_conflict_basic() {
    let test_repo = TestRepo::init();
    let store = test_repo.repo.store();

    let path = RepoPath::from_internal_string("file");
    let base_id = testutils::write_file(
        store,
        path,
        "line 1
line 2
line 3
line 4
line 5
",
    );
    let left_id = testutils::write_file(
        store,
        path,
        "line 1
line 2
left 3.1
left 3.2
left 3.3
line 4
line 5
",
    );
    let right_id = testutils::write_file(
        store,
        path,
        "line 1
line 2
right 3.1
line 4
line 5
",
    );

    // The left side should come first. The diff should be use the smaller (right)
    // side, and the left side should be a snapshot.
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone())],
        vec![Some(left_id.clone()), Some(right_id.clone())],
    );
    insta::assert_snapshot!(
        &materialize_conflict_string(store, path, &conflict),
        @r###"
    line 1
    line 2
    <<<<<<<
    +++++++
    left 3.1
    left 3.2
    left 3.3
    %%%%%%%
    -line 3
    +right 3.1
    >>>>>>>
    line 4
    line 5
    "###
    );
    // Swap the positive terms in the conflict. The diff should still use the right
    // side, but now the right side should come first.
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone())],
        vec![Some(right_id.clone()), Some(left_id.clone())],
    );
    insta::assert_snapshot!(
        &materialize_conflict_string(store, path, &conflict),
        @r###"
    line 1
    line 2
    <<<<<<<
    %%%%%%%
    -line 3
    +right 3.1
    +++++++
    left 3.1
    left 3.2
    left 3.3
    >>>>>>>
    line 4
    line 5
    "###
    );
}

#[test]
fn test_materialize_conflict_multi_rebase_conflicts() {
    let test_repo = TestRepo::init();
    let store = test_repo.repo.store();

    // Create changes (a, b, c) on top of the base, and linearize them.
    let path = RepoPath::from_internal_string("file");
    let base_id = testutils::write_file(
        store,
        path,
        "line 1
line 2 base
line 3
",
    );
    let a_id = testutils::write_file(
        store,
        path,
        "line 1
line 2 a.1
line 2 a.2
line 2 a.3
line 3
",
    );
    let b_id = testutils::write_file(
        store,
        path,
        "line 1
line 2 b.1
line 2 b.2
line 3
",
    );
    let c_id = testutils::write_file(
        store,
        path,
        "line 1
line 2 c.1
line 3
",
    );

    // The order of (a, b, c) should be preserved. For all cases, the "a" side
    // should be a snapshot.
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone()), Some(base_id.clone())],
        vec![Some(a_id.clone()), Some(b_id.clone()), Some(c_id.clone())],
    );
    insta::assert_snapshot!(
        &materialize_conflict_string(store, path, &conflict),
        @r###"
    line 1
    <<<<<<<
    +++++++
    line 2 a.1
    line 2 a.2
    line 2 a.3
    %%%%%%%
    -line 2 base
    +line 2 b.1
    +line 2 b.2
    %%%%%%%
    -line 2 base
    +line 2 c.1
    >>>>>>>
    line 3
    "###
    );
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone()), Some(base_id.clone())],
        vec![Some(c_id.clone()), Some(b_id.clone()), Some(a_id.clone())],
    );
    insta::assert_snapshot!(
        &materialize_conflict_string(store, path, &conflict),
        @r###"
    line 1
    <<<<<<<
    %%%%%%%
    -line 2 base
    +line 2 c.1
    %%%%%%%
    -line 2 base
    +line 2 b.1
    +line 2 b.2
    +++++++
    line 2 a.1
    line 2 a.2
    line 2 a.3
    >>>>>>>
    line 3
    "###
    );
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone()), Some(base_id.clone())],
        vec![Some(c_id.clone()), Some(a_id.clone()), Some(b_id.clone())],
    );
    insta::assert_snapshot!(
        &materialize_conflict_string(store, path, &conflict),
        @r###"
    line 1
    <<<<<<<
    %%%%%%%
    -line 2 base
    +line 2 c.1
    +++++++
    line 2 a.1
    line 2 a.2
    line 2 a.3
    %%%%%%%
    -line 2 base
    +line 2 b.1
    +line 2 b.2
    >>>>>>>
    line 3
    "###
    );
}

#[test]
fn test_materialize_parse_roundtrip() {
    let test_repo = TestRepo::init();
    let store = test_repo.repo.store();

    let path = RepoPath::from_internal_string("file");
    let base_id = testutils::write_file(
        store,
        path,
        "line 1
line 2
line 3
line 4
line 5
",
    );
    let left_id = testutils::write_file(
        store,
        path,
        "line 1 left
line 2 left
line 3
line 4
line 5 left
",
    );
    let right_id = testutils::write_file(
        store,
        path,
        "line 1 right
line 2
line 3
line 4 right
line 5 right
",
    );

    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone())],
        vec![Some(left_id.clone()), Some(right_id.clone())],
    );
    let materialized = materialize_conflict_string(store, path, &conflict);
    insta::assert_snapshot!(
        materialized,
        @r###"
    <<<<<<<
    +++++++
    line 1 left
    line 2 left
    %%%%%%%
    -line 1
    +line 1 right
     line 2
    >>>>>>>
    line 3
    <<<<<<<
    %%%%%%%
     line 4
    -line 5
    +line 5 left
    +++++++
    line 4 right
    line 5 right
    >>>>>>>
    "###
    );

    // The first add should always be from the left side
    insta::assert_debug_snapshot!(
        parse_conflict(materialized.as_bytes(), conflict.num_sides()),
        @r###"
    Some(
        [
            Conflicted(
                [
                    "line 1 left\nline 2 left\n",
                    "line 1\nline 2\n",
                    "line 1 right\nline 2\n",
                ],
            ),
            Resolved(
                "line 3\n",
            ),
            Conflicted(
                [
                    "line 4\nline 5 left\n",
                    "line 4\nline 5\n",
                    "line 4 right\nline 5 right\n",
                ],
            ),
        ],
    )
    "###);
}

#[test]
fn test_materialize_conflict_modify_delete() {
    let test_repo = TestRepo::init();
    let store = test_repo.repo.store();

    let path = RepoPath::from_internal_string("file");
    let base_id = testutils::write_file(
        store,
        path,
        "line 1
line 2
line 3
line 4
line 5
",
    );
    let modified_id = testutils::write_file(
        store,
        path,
        "line 1
line 2
modified
line 4
line 5
",
    );
    let deleted_id = testutils::write_file(
        store,
        path,
        "line 1
line 2
line 4
line 5
",
    );

    // left modifies a line, right deletes the same line.
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone())],
        vec![Some(modified_id.clone()), Some(deleted_id.clone())],
    );
    insta::assert_snapshot!(&materialize_conflict_string(store, path, &conflict), @r###"
    line 1
    line 2
    <<<<<<<
    +++++++
    modified
    %%%%%%%
    -line 3
    >>>>>>>
    line 4
    line 5
    "###
    );

    // right modifies a line, left deletes the same line.
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone())],
        vec![Some(deleted_id.clone()), Some(modified_id.clone())],
    );
    insta::assert_snapshot!(&materialize_conflict_string(store, path, &conflict), @r###"
    line 1
    line 2
    <<<<<<<
    %%%%%%%
    -line 3
    +++++++
    modified
    >>>>>>>
    line 4
    line 5
    "###
    );

    // modify/delete conflict at the file level
    let conflict = Merge::from_removes_adds(
        vec![Some(base_id.clone())],
        vec![Some(modified_id.clone()), None],
    );
    insta::assert_snapshot!(&materialize_conflict_string(store, path, &conflict), @r###"
    <<<<<<<
    %%%%%%%
     line 1
     line 2
    -line 3
    +modified
     line 4
     line 5
    +++++++
    >>>>>>>
    "###
    );
}

#[test]
fn test_parse_conflict_resolved() {
    assert_eq!(
        parse_conflict(
            b"line 1
line 2
line 3
line 4
line 5
",
            2
        ),
        None
    )
}

#[test]
fn test_parse_conflict_simple() {
    insta::assert_debug_snapshot!(
        parse_conflict(
            b"line 1
<<<<<<<
%%%%%%%
 line 2
-line 3
+left
 line 4
+++++++
right
>>>>>>>
line 5
",
            2
        ),
        @r###"
    Some(
        [
            Resolved(
                "line 1\n",
            ),
            Conflicted(
                [
                    "line 2\nleft\nline 4\n",
                    "line 2\nline 3\nline 4\n",
                    "right\n",
                ],
            ),
            Resolved(
                "line 5\n",
            ),
        ],
    )
    "###
    )
}

#[test]
fn test_parse_conflict_multi_way() {
    insta::assert_debug_snapshot!(
        parse_conflict(
            b"line 1
<<<<<<<
%%%%%%%
 line 2
-line 3
+left
 line 4
+++++++
right
%%%%%%%
 line 2
+forward
 line 3
 line 4
>>>>>>>
line 5
",
            3
        ),
        @r###"
    Some(
        [
            Resolved(
                "line 1\n",
            ),
            Conflicted(
                [
                    "line 2\nleft\nline 4\n",
                    "line 2\nline 3\nline 4\n",
                    "right\n",
                    "line 2\nline 3\nline 4\n",
                    "line 2\nforward\nline 3\nline 4\n",
                ],
            ),
            Resolved(
                "line 5\n",
            ),
        ],
    )
    "###
    )
}

#[test]
fn test_parse_conflict_different_wrong_arity() {
    assert_eq!(
        parse_conflict(
            b"line 1
<<<<<<<
%%%%%%%
 line 2
-line 3
+left
 line 4
+++++++
right
>>>>>>>
line 5
",
            3
        ),
        None
    )
}

#[test]
fn test_parse_conflict_malformed_marker() {
    // The conflict marker is missing `%%%%%%%`
    assert_eq!(
        parse_conflict(
            b"line 1
<<<<<<<
 line 2
-line 3
+left
 line 4
+++++++
right
>>>>>>>
line 5
",
            2
        ),
        None
    )
}

#[test]
fn test_parse_conflict_malformed_diff() {
    // The diff part is invalid (missing space before "line 4")
    assert_eq!(
        parse_conflict(
            b"line 1
<<<<<<<
%%%%%%%
 line 2
-line 3
+left
line 4
+++++++
right
>>>>>>>
line 5
",
            2
        ),
        None
    )
}

#[test]
fn test_update_conflict_from_content() {
    let test_repo = TestRepo::init();
    let store = test_repo.repo.store();

    let path = RepoPath::from_internal_string("dir/file");
    let base_file_id = testutils::write_file(store, path, "line 1\nline 2\nline 3\n");
    let left_file_id = testutils::write_file(store, path, "left 1\nline 2\nleft 3\n");
    let right_file_id = testutils::write_file(store, path, "right 1\nline 2\nright 3\n");
    let conflict = Merge::from_removes_adds(
        vec![Some(base_file_id.clone())],
        vec![Some(left_file_id.clone()), Some(right_file_id.clone())],
    );

    // If the content is unchanged compared to the materialized value, we get the
    // old conflict id back.
    let materialized = materialize_conflict_string(store, path, &conflict);
    let parse = |content| {
        update_from_content(&conflict, store, path, content)
            .block_on()
            .unwrap()
    };
    assert_eq!(parse(materialized.as_bytes()), conflict);

    // If the conflict is resolved, we get None back to indicate that.
    let expected_file_id = testutils::write_file(store, path, "resolved 1\nline 2\nresolved 3\n");
    assert_eq!(
        parse(b"resolved 1\nline 2\nresolved 3\n"),
        Merge::normal(expected_file_id)
    );

    // If the conflict is partially resolved, we get a new conflict back.
    let new_conflict = parse(
        b"resolved 1\nline 2\n<<<<<<<\n%%%%%%%\n-line 3\n+left 3\n+++++++\nright 3\n>>>>>>>\n",
    );
    assert_ne!(new_conflict, conflict);
    // Calculate expected new FileIds
    let new_base_file_id = testutils::write_file(store, path, "resolved 1\nline 2\nline 3\n");
    let new_left_file_id = testutils::write_file(store, path, "resolved 1\nline 2\nleft 3\n");
    let new_right_file_id = testutils::write_file(store, path, "resolved 1\nline 2\nright 3\n");
    assert_eq!(
        new_conflict,
        Merge::from_removes_adds(
            vec![Some(new_base_file_id.clone())],
            vec![
                Some(new_left_file_id.clone()),
                Some(new_right_file_id.clone())
            ]
        )
    );
}

#[test]
fn test_update_conflict_from_content_modify_delete() {
    let test_repo = TestRepo::init();
    let store = test_repo.repo.store();

    let path = RepoPath::from_internal_string("dir/file");
    let before_file_id = testutils::write_file(store, path, "line 1\nline 2 before\nline 3\n");
    let after_file_id = testutils::write_file(store, path, "line 1\nline 2 after\nline 3\n");
    let conflict =
        Merge::from_removes_adds(vec![Some(before_file_id)], vec![Some(after_file_id), None]);

    // If the content is unchanged compared to the materialized value, we get the
    // old conflict id back.
    let materialized = materialize_conflict_string(store, path, &conflict);
    let parse = |content| {
        update_from_content(&conflict, store, path, content)
            .block_on()
            .unwrap()
    };
    assert_eq!(parse(materialized.as_bytes()), conflict);

    // If the conflict is resolved, we get None back to indicate that.
    let expected_file_id = testutils::write_file(store, path, "resolved\n");
    assert_eq!(parse(b"resolved\n"), Merge::normal(expected_file_id));

    // If the conflict is modified, we get a new conflict back.
    let new_conflict = parse(
        b"<<<<<<<\n%%%%%%%\n line 1\n-line 2 before\n+line 2 modified after\n line 3\n+++++++\n>>>>>>>\n",
    );
    // Calculate expected new FileIds
    let new_base_file_id = testutils::write_file(store, path, "line 1\nline 2 before\nline 3\n");
    let new_left_file_id =
        testutils::write_file(store, path, "line 1\nline 2 modified after\nline 3\n");

    assert_eq!(
        new_conflict,
        Merge::from_removes_adds(
            vec![Some(new_base_file_id.clone())],
            vec![Some(new_left_file_id.clone()), None]
        )
    );
}

fn materialize_conflict_string(
    store: &Store,
    path: &RepoPath,
    conflict: &Merge<Option<FileId>>,
) -> String {
    let mut result: Vec<u8> = vec![];
    let contents = extract_as_single_hunk(conflict, store, path).block_on();
    materialize_merge_result(&contents, &mut result).unwrap();
    String::from_utf8(result).unwrap()
}