feat: add git apply features (#174)

Author: seokju-na

index.d.ts

@@ -2640,6 +2640,43 @@ export declare class Repository {
    * @returns An Annotated Commit created from `FETCH_HEAD`.
    */
   getAnnotatedCommitFromFetchHead(branchName: string, remoteUrl: string, id: string): AnnotatedCommit
+  /**
+   * Apply a Diff to the given repo, making changes directly in the working directory, the index, or both.
+   *
+   * @category Repository/Methods
+   * ```ts
+   * class Repository {
+   *   apply(diff: Diff, location: ApplyLocation, options?: ApplyOptions | null | undefined): void;
+   * }
+   * ```
+   *
+   * @param {Diff} diff - The diff to apply
+   * @param {ApplyLocation} location - The location to apply
+   * @param {ApplyOptions} [options] - The options for the apply
+   */
+  apply(diff: Diff, location: ApplyLocation, options?: ApplyOptions | undefined | null): void
+  /**
+   * Apply a Diff to the provided tree, and return the resulting Index.
+   *
+   * @category Repository/Methods
+   * @signature
+   * ```ts
+   * class Repository {
+   *   applyToTree(
+   *     tree: Tree,
+   *     diff: Diff,
+   *     options?: ApplyOptions | null | undefined
+   *   ): Index;
+   * }
+   * ```
+   *
+   * @param {Tree} tree - The tree to apply the diff to
+   * @param {Diff} diff - The diff to apply
+   * @param {ApplyOptions} [options] - The options for the apply
+   *
+   * @returns The postimage of the application
+   */
+  applyToTree(tree: Tree, diff: Diff, options?: ApplyOptions | undefined | null): Index
   /**
    * Creates a blame object for the file at the given path
    *
@@ -5673,6 +5710,23 @@ export interface AmendOptions {
   messageEncoding?: string
 }
 
+/**
+ * Possible application locations for git_apply
+ * see <https://libgit2.org/libgit2/#HEAD/type/git_apply_options>
+ */
+export type ApplyLocation = /** Apply the patch to the workdir */
+'WorkDir'|
+/** Apply the patch to the index */
+'Index'|
+/** Apply the patch to both the working directory and the index */
+'Both';
+
+/** Options to specify when applying a diff */
+export interface ApplyOptions {
+  /** Don't actually make changes, just test that the patch applies. */
+  check?: boolean
+}
+
 /**
  * - `Unspecified` : Use the setting from the remote's configuration
  * - `Auto` : Ask the server for tags pointing to objects we're already downloading

index.js

@@ -0,0 +1,102 @@
+use crate::diff::Diff;
+use crate::index::Index;
+use crate::repository::Repository;
+use crate::tree::Tree;
+use napi_derive::napi;
+
+#[derive(Debug, Copy, Clone)]
+#[napi(string_enum)]
+/// Possible application locations for git_apply
+/// see <https://libgit2.org/libgit2/#HEAD/type/git_apply_options>
+pub enum ApplyLocation {
+  /// Apply the patch to the workdir
+  WorkDir,
+  /// Apply the patch to the index
+  Index,
+  /// Apply the patch to both the working directory and the index
+  Both,
+}
+
+impl From<ApplyLocation> for git2::ApplyLocation {
+  fn from(value: ApplyLocation) -> Self {
+    match value {
+      ApplyLocation::Both => Self::Both,
+      ApplyLocation::Index => Self::Index,
+      ApplyLocation::WorkDir => Self::WorkDir,
+    }
+  }
+}
+
+#[napi(object, object_to_js = false)]
+/// Options to specify when applying a diff
+pub struct ApplyOptions {
+  /// Don't actually make changes, just test that the patch applies.
+  pub check: Option<bool>,
+  // TODO(@seokju-na): Consider node.js is single-thread so the calling callback from Rust side
+  // will make dead-lock. May be we should make `apply` function as async?
+  //
+  // #[napi(ts_type = "(data: DiffHunkData | null | undefined) => boolean")]
+  // pub hunk_callback: Option<HunkCallback>,
+  // #[napi(ts_type = "(data: DeltaData | null | undefined) => boolean")]
+  // pub delta_callback: Option<DeltaCallback>,
+}
+
+impl From<ApplyOptions> for git2::ApplyOptions<'_> {
+  fn from(value: ApplyOptions) -> Self {
+    let mut options = git2::ApplyOptions::new();
+    if let Some(check) = value.check {
+      options.check(check);
+    }
+    options
+  }
+}
+
+#[napi]
+impl Repository {
+  #[napi]
+  /// Apply a Diff to the given repo, making changes directly in the working directory, the index, or both.
+  ///
+  /// @category Repository/Methods
+  /// ```ts
+  /// class Repository {
+  ///   apply(diff: Diff, location: ApplyLocation, options?: ApplyOptions | null | undefined): void;
+  /// }
+  /// ```
+  ///
+  /// @param {Diff} diff - The diff to apply
+  /// @param {ApplyLocation} location - The location to apply
+  /// @param {ApplyOptions} [options] - The options for the apply
+  pub fn apply(&self, diff: &Diff, location: ApplyLocation, options: Option<ApplyOptions>) -> crate::Result<()> {
+    self
+      .inner
+      .apply(&diff.inner, location.into(), options.map(|x| x.into()).as_mut())?;
+    Ok(())
+  }
+
+  #[napi]
+  /// Apply a Diff to the provided tree, and return the resulting Index.
+  ///
+  /// @category Repository/Methods
+  /// @signature
+  /// ```ts
+  /// class Repository {
+  ///   applyToTree(
+  ///     tree: Tree,
+  ///     diff: Diff,
+  ///     options?: ApplyOptions | null | undefined
+  ///   ): Index;
+  /// }
+  /// ```
+  ///
+  /// @param {Tree} tree - The tree to apply the diff to
+  /// @param {Diff} diff - The diff to apply
+  /// @param {ApplyOptions} [options] - The options for the apply
+  ///
+  /// @returns The postimage of the application
+  pub fn apply_to_tree(&self, tree: &Tree, diff: &Diff, options: Option<ApplyOptions>) -> crate::Result<Index> {
+    let inner = self
+      .inner
+      .apply_to_tree(&tree.inner, &diff.inner, options.map(|x| x.into()).as_mut())?;
+    Ok(Index { inner })
+  }
+}

src/apply.rs

@@ -1,6 +1,7 @@
 #![deny(clippy::all)]
 #![allow(clippy::len_without_is_empty)]
 pub mod annotated_commit;
+pub mod apply;
 pub mod blame;
 pub mod blob;
 pub mod branch;

src/lib.rs

@@ -0,0 +1,47 @@
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import { describe, expect, it } from 'vitest';
+import { openRepository } from '../index';
+import { useFixture } from './fixtures';
+
+describe('apply', () => {
+  it('apply at working directory', async () => {
+    const p = await useFixture('diff');
+    const repo = await openRepository(p);
+
+    const headTree = repo.head().peelToTree();
+    await fs.writeFile(path.join(p, 'A'), 'A modified');
+
+    const index = repo.index();
+    index.addPath('A');
+    index.write();
+    const treeId = repo.getTree(index.writeTree());
+
+    const diff = repo.diffTreeToTree(headTree, treeId);
+    repo.checkoutHead({ force: true });
+    repo.apply(diff, 'WorkDir');
+
+    const content = await fs.readFile(path.join(p, 'A'), 'utf-8');
+    expect(content).toEqual('A modified');
+  });
+
+  it('will not actually apply if check option is enabled', async () => {
+    const p = await useFixture('diff');
+    const repo = await openRepository(p);
+
+    const headTree = repo.head().peelToTree();
+    await fs.writeFile(path.join(p, 'A'), 'A modified');
+
+    const index = repo.index();
+    index.addPath('A');
+    index.write();
+    const treeId = repo.getTree(index.writeTree());
+
+    const diff = repo.diffTreeToTree(headTree, treeId);
+    repo.checkoutHead({ force: true });
+    repo.apply(diff, 'WorkDir', { check: true });
+
+    const content = await fs.readFile(path.join(p, 'A'), 'utf-8');
+    expect(content).not.toEqual('A modified');
+  });
+});