Reimplement insert blank commit

Author: Caleb-T-Owens

crates/but-rebase/src/graph_rebase/commit.rs

@@ -1,6 +1,6 @@
 //! Provides some slightly higher level tools to help with manipulating commits, in preparation for use in the editor.
 
-use anyhow::Result;
+use anyhow::{Context as _, Result};
 use gix::prelude::ObjectIdExt;
 
 use crate::{
@@ -22,4 +22,35 @@ impl Editor {
     ) -> Result<gix::ObjectId> {
         create(&self.repo, commit.inner, date_mode)
     }
+
+    /// Creates a commit with only the signature and author set correctly.
+    ///
+    /// The ID of the commit is all zeros & the commit hasn't been written into any ODB
+    pub fn empty_commit(&self) -> Result<but_core::Commit<'_>> {
+        let kind = gix::hash::Kind::Sha1;
+        let committer = dbg!(self.repo.committer())
+            .transpose()?
+            .context("Need committer to be configured when creating a new commit")?
+            .into();
+        let author = self
+            .repo
+            .committer()
+            .transpose()?
+            .context("Need author to be configured when creating a new commit")?
+            .into();
+        let obj = gix::objs::Commit {
+            tree: gix::ObjectId::empty_tree(kind),
+            parents: vec![].into(),
+            committer,
+            author,
+            encoding: None,
+            message: b"".into(),
+            extra_headers: vec![],
+        };
+
+        Ok(but_core::Commit::<'_> {
+            id: gix::ObjectId::null(kind).attach(&self.repo),
+            inner: obj,
+        })
+    }
 }

crates/but-workspace/src/commit/insert_blank_commit.rs

@@ -0,0 +1,58 @@
+//! Insertion of a blank commit
+
+use std::collections::HashMap;
+
+/// Describes where the blank commit should be inserted relative to.
+#[derive(Debug, Clone)]
+pub enum RelativeTo<'a> {
+    /// Relative to a commit
+    Commit(gix::ObjectId),
+    /// Relative to a reference
+    Reference(&'a gix::refs::FullNameRef),
+}
+
+/// Describes the outcome of the rebase
+#[derive(Debug, Clone)]
+pub struct InsertCommitOutcome {
+    /// The blank commit that was creatd
+    pub blank_commit_id: gix::ObjectId,
+    /// Any commits that were mapped.
+    pub commit_mapping: HashMap<gix::ObjectId, gix::ObjectId>,
+}
+
+pub(crate) mod function {
+    use anyhow::Result;
+    use but_rebase::{
+        commit::DateMode,
+        graph_rebase::{GraphExt, Step, mutate::InsertSide},
+    };
+
+    use crate::commit::insert_blank_commit::{InsertCommitOutcome, RelativeTo};
+
+    /// Inserts a blank commit relative to either a reference or a commit
+    pub fn insert_blank_commit(
+        graph: &but_graph::Graph,
+        repo: &gix::Repository,
+        side: InsertSide,
+        relative_to: RelativeTo,
+    ) -> Result<InsertCommitOutcome> {
+        let mut editor = graph.to_editor(repo)?;
+        let target_selector = match relative_to {
+            RelativeTo::Commit(id) => editor.select_commit(id)?,
+            RelativeTo::Reference(r) => editor.select_reference(r)?,
+        };
+
+        let commit = editor.empty_commit()?;
+        let new_id = editor.write_commit(commit, DateMode::CommitterUpdateAuthorUpdate)?;
+
+        editor.insert(&target_selector, Step::new_pick(new_id), side);
+
+        let outcome = editor.rebase()?;
+        let mat_output = outcome.materialize()?;
+
+        Ok(InsertCommitOutcome {
+            blank_commit_id: new_id,
+            commit_mapping: mat_output.commit_mapping,
+        })
+    }
+}

crates/but-workspace/src/commit/mod.rs

@@ -6,6 +6,8 @@ use crate::WorkspaceCommit;
 
 pub mod reword;
 pub use reword::function::reword;
+pub mod insert_blank_commit;
+pub use insert_blank_commit::function::insert_blank_commit;
 
 /// A minimal stack for use by [WorkspaceCommit::new_from_stacks()].
 #[derive(Clone)]

crates/but-workspace/tests/fixtures/scenario/insert-blank-commit-three-commits copy.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+
+set -eu -o pipefail
+
+echo "/remote/" > .gitignore
+mkdir remote
+pushd remote
+git init
+popd
+
+git init
+
+git remote add origin ./remote
+
+git checkout -b one
+echo "foo" > one.txt
+git add .
+git commit -m "commit one"
+
+git checkout -b two
+echo "foo" > two.txt
+git add .
+git commit -m "commit two"
+
+git push -u origin two
+
+git checkout -b three
+echo "foo" > three.txt
+git add .
+git commit -m "commit three"

crates/but-workspace/tests/workspace/commit/insert_blank_commit.rs

@@ -0,0 +1,141 @@
+use anyhow::Result;
+use but_rebase::graph_rebase::mutate::InsertSide;
+use but_testsupport::{assure_stable_env, visualize_commit_graph_all};
+use but_workspace::commit::insert_blank_commit;
+use but_workspace::commit::insert_blank_commit::RelativeTo;
+
+use crate::ref_info::with_workspace_commit::utils::named_writable_scenario_with_description_and_graph as writable_scenario;
+
+#[test]
+fn insert_below_commit() -> Result<()> {
+    assure_stable_env();
+    let (_tmp, graph, repo, mut _meta, _description) =
+        writable_scenario("reword-three-commits", |_| {})?;
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * c9f444c (HEAD -> three) commit three
+    * 16fd221 (origin/two, two) commit two
+    * 8b426d0 (one) commit one
+    ");
+
+    let head_tree = repo.head_tree_id()?;
+    let id = repo.rev_parse_single("two")?;
+
+    insert_blank_commit(
+        &graph,
+        &repo,
+        InsertSide::Below,
+        RelativeTo::Commit(id.detach()),
+    )?;
+
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * 31dbfdc (HEAD -> three) commit three
+    * b65c813 (two) commit two
+    * d2b480d 
+    | * 16fd221 (origin/two) commit two
+    |/  
+    * 8b426d0 (one) commit one
+    ");
+
+    assert_eq!(head_tree, repo.head_tree_id()?);
+
+    Ok(())
+}
+
+#[test]
+fn insert_above_commit() -> Result<()> {
+    assure_stable_env();
+    let (_tmp, graph, repo, mut _meta, _description) =
+        writable_scenario("reword-three-commits", |_| {})?;
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * c9f444c (HEAD -> three) commit three
+    * 16fd221 (origin/two, two) commit two
+    * 8b426d0 (one) commit one
+    ");
+
+    let head_tree = repo.head_tree_id()?;
+    let id = repo.rev_parse_single("two")?;
+
+    insert_blank_commit(
+        &graph,
+        &repo,
+        InsertSide::Above,
+        RelativeTo::Commit(id.detach()),
+    )?;
+
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * 923c9cd (HEAD -> three) commit three
+    * 8bf04f0 (two) 
+    * 16fd221 (origin/two) commit two
+    * 8b426d0 (one) commit one
+    ");
+
+    assert_eq!(head_tree, repo.head_tree_id()?);
+
+    Ok(())
+}
+
+#[test]
+fn insert_below_reference() -> Result<()> {
+    assure_stable_env();
+    let (_tmp, graph, repo, mut _meta, _description) =
+        writable_scenario("reword-three-commits", |_| {})?;
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * c9f444c (HEAD -> three) commit three
+    * 16fd221 (origin/two, two) commit two
+    * 8b426d0 (one) commit one
+    ");
+
+    let head_tree = repo.head_tree_id()?;
+    let reference = repo.find_reference("two")?;
+
+    insert_blank_commit(
+        &graph,
+        &repo,
+        InsertSide::Below,
+        RelativeTo::Reference(reference.name()),
+    )?;
+
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * 923c9cd (HEAD -> three) commit three
+    * 8bf04f0 (two) 
+    * 16fd221 (origin/two) commit two
+    * 8b426d0 (one) commit one
+    ");
+
+    assert_eq!(head_tree, repo.head_tree_id()?);
+
+    Ok(())
+}
+
+#[test]
+fn insert_above_reference() -> Result<()> {
+    assure_stable_env();
+    let (_tmp, graph, repo, mut _meta, _description) =
+        writable_scenario("reword-three-commits", |_| {})?;
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * c9f444c (HEAD -> three) commit three
+    * 16fd221 (origin/two, two) commit two
+    * 8b426d0 (one) commit one
+    ");
+
+    let head_tree = repo.head_tree_id()?;
+    let reference = repo.find_reference("two")?;
+
+    insert_blank_commit(
+        &graph,
+        &repo,
+        InsertSide::Above,
+        RelativeTo::Reference(reference.name()),
+    )?;
+
+    insta::assert_snapshot!(visualize_commit_graph_all(&repo)?, @r"
+    * 923c9cd (HEAD -> three) commit three
+    * 8bf04f0 
+    * 16fd221 (origin/two, two) commit two
+    * 8b426d0 (one) commit one
+    ");
+
+    assert_eq!(head_tree, repo.head_tree_id()?);
+
+    Ok(())
+}

crates/but-workspace/tests/workspace/commit/mod.rs

@@ -1,3 +1,4 @@
+mod insert_blank_commit;
 mod reword;
 
 mod from_new_merge_with_metadata {