From 2aac7043cd7f9778cc46eade1126af3177954456 Mon Sep 17 00:00:00 2001
From: Ivan Kuchin <i.kuchin@openproject.com>
Date: Thu, 2 May 2024 20:05:26 +0200
Subject: [PATCH] add only_changed input to run rubocop only against changed
 files
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Switch to bash for process substitution and working with arrays.

Ignore if there are more than 100. Protecting from possibly hitting the
command line length limit, it can be much higher and can be calculated
or also extracted as one more input if needed. The effect from limiting
number of files processed by rubocop is also smaller.

Fix ci workflow to fetch all commits for pr branch plus head commit of
base branch to be able to find changed files.

Co-authored-by: Oliver Günther <mail@oliverguenther.de>
---
 .github/workflows/ci.yml |  8 ++++++++
 README.md                |  5 +++++
 action.yml               |  6 ++++++
 script.sh                | 21 +++++++++++++++++++--
 4 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 61280dd..79f81c3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,6 +11,14 @@ jobs:
       BUNDLE_GEMFILE: ${{ github.workspace }}/test/using_bundler/Gemfile
     steps:
       - uses: actions/checkout@v4
+      - name: Fetch all commits for PR branch plus head commit of base branch
+        run: |
+          # fetch all commits of the PR branch
+          git fetch --shallow-exclude "${{ github.base_ref }}" origin "${{ github.ref }}"
+          # fix for "fatal: error in object: unshallow"
+          git repack -d
+          # fetch head commit of base branch
+          git fetch --deepen 1 origin "${{ github.ref }}"
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: 2.6
diff --git a/README.md b/README.md
index 1ae8817..07caf3d 100644
--- a/README.md
+++ b/README.md
@@ -98,6 +98,11 @@ Optional. Do not install Rubocop or its extensions. Default: `false`.
 
 Optional. Run Rubocop with bundle exec. Default: `false`.
 
+### `only_changed`
+
+Optional. Run Rubocop only on changed (and added) files, for speedup [`true`, `false`].
+Default: `false`.
+
 ## Example usage
 
 This action will use your [RuboCop Configuration](https://docs.rubocop.org/rubocop/configuration.html) automatically.
diff --git a/action.yml b/action.yml
index 7cd76cc..d7e8b2f 100644
--- a/action.yml
+++ b/action.yml
@@ -46,6 +46,9 @@ inputs:
   use_bundler:
     description: "Run Rubocop with bundle exec. Default: `false`"
     default: 'false'
+  only_changed:
+    description: "Run Rubocop only on changed (and added) files, for speedup [`true`, `false`]"
+    default: 'false'
 runs:
   using: 'composite'
   steps:
@@ -68,6 +71,9 @@ runs:
         INPUT_WORKDIR: ${{ inputs.workdir }}
         INPUT_SKIP_INSTALL: ${{ inputs.skip_install }}
         INPUT_USE_BUNDLER: ${{ inputs.use_bundler }}
+        INPUT_ONLY_CHANGED: ${{ inputs.only_changed }}
+        BASE_REF: ${{ github.event.pull_request.base.sha }}
+        HEAD_REF: ${{ github.sha }}
 branding:
   icon: 'check-circle'
   color: 'red'
diff --git a/script.sh b/script.sh
index 81a06bc..f247c82 100755
--- a/script.sh
+++ b/script.sh
@@ -1,4 +1,6 @@
-#!/bin/sh -e
+#!/usr/bin/env bash
+
+set -e
 
 cd "${GITHUB_WORKSPACE}/${INPUT_WORKDIR}" || exit
 export REVIEWDOG_GITHUB_API_TOKEN="${INPUT_GITHUB_TOKEN}"
@@ -85,9 +87,24 @@ else
   BUNDLE_EXEC="bundle exec "
 fi
 
+if [ "${INPUT_ONLY_CHANGED}" = "true" ]; then
+  echo '::group:: Getting changed files list'
+  readarray -t CHANGED_FILES < <(
+    comm -12 \
+      <(git diff --diff-filter=d --name-only "${BASE_REF}..${HEAD_REF}" | sort) \
+      <(${BUNDLE_EXEC}rubocop --list-target-files | sort)
+  )
+  echo "${CHANGED_FILES[@]}"
+  if (( ${#CHANGED_FILES[@]} > 100 )); then
+    echo "More than 100 changed files (${#CHANGED_FILES[@]}), running rubocop on all files"
+    unset CHANGED_FILES
+  fi
+  echo '::endgroup::'
+fi
+
 echo '::group:: Running rubocop with reviewdog 🐶 ...'
 # shellcheck disable=SC2086
-${BUNDLE_EXEC}rubocop ${INPUT_RUBOCOP_FLAGS} --require ${GITHUB_ACTION_PATH}/rdjson_formatter/rdjson_formatter.rb --format RdjsonFormatter \
+${BUNDLE_EXEC}rubocop ${INPUT_RUBOCOP_FLAGS} --require ${GITHUB_ACTION_PATH}/rdjson_formatter/rdjson_formatter.rb --format RdjsonFormatter "${CHANGED_FILES[@]}" \
   | reviewdog -f=rdjson \
       -name="${INPUT_TOOL_NAME}" \
       -reporter="${INPUT_REPORTER}" \