From e53f331f484fec65d41030a92cf3b868d7bc63ec Mon Sep 17 00:00:00 2001
From: John Jetmore <jj33@pobox.com>
Date: Thu, 8 May 2025 04:18:46 -0400
Subject: [PATCH] Add only_changed_pr (#135)
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* allow `only_changed` and `dry` to work together

Before this change, if you tried to use `dry` and `only_changed together, it acted as if `only_changed` was ignored.  There was no code specific to `only_changed` down the `dry` code path.

This commit’s solution is to run prettier on the entire code base (as was already being done) and then, before doing any comparisons, reset changes to files that were not modified in the last commit.

* add `only_changed_pr` option

This behaves similarly to only_changed, except instead of only considering files which were modified in the last commit, this option only considers files which were modified in any commit included in the current PR.
---
 action.yml    |  7 ++++++-
 entrypoint.sh | 40 +++++++++++++++++++++++++++-------------
 2 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/action.yml b/action.yml
index de7f649..a48ceb3 100644
--- a/action.yml
+++ b/action.yml
@@ -23,7 +23,7 @@ inputs:
     description: Git push options
     required: false
   file_pattern:
-    description: File pattern used for `git add`, can't be used with only_changed!
+    description: File pattern used for `git add`, can't be used with only_changed or only_changed_pr!
     required: false
     default: "*"
   prettier_options:
@@ -50,6 +50,10 @@ inputs:
     description: Only prettify files changed in the last commit, can't be used with file_pattern!
     required: false
     default: false
+  only_changed_pr:
+    description: Only prettify files changed in the current PR.  If specified with only_changed, only_changed will take precedent. Can't be used with file_pattern!
+    required: false
+    default: false
   prettier_plugins:
     description: Install Prettier plugins, i.e. `@prettier/plugin-php @prettier/plugin-other`
     required: false
@@ -87,6 +91,7 @@ runs:
         INPUT_NO_COMMIT: ${{ inputs.no_commit }}
         INPUT_PRETTIER_VERSION: ${{ inputs.prettier_version }}
         INPUT_ONLY_CHANGED: ${{ inputs.only_changed }}
+        INPUT_ONLY_CHANGED_PR: ${{ inputs.only_changed_pr }}
         INPUT_PRETTIER_PLUGINS: ${{ inputs.prettier_plugins }}
         INPUT_WORKING_DIRECTORY: ${{ inputs.working_directory }}
         INPUT_GITHUB_TOKEN: ${{ inputs.github_token }}
diff --git a/entrypoint.sh b/entrypoint.sh
index b59ef7b..619b1d9 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -85,6 +85,31 @@ else
   echo "No package-lock.json file."
 fi
 
+# If running under only_changed, reset every modified file that wasn't also modified in the last commit
+# This allows only_changed and dry to work together, and simplified the non-dry logic below
+if [ $INPUT_ONLY_CHANGED = true -o $INPUT_ONLY_CHANGED_PR = true ] ; then
+  BASE_BRANCH=origin/$GITHUB_BASE_REF
+  if $INPUT_ONLY_CHANGED; then
+    BASE_BRANCH=HEAD~1
+  fi
+
+  echo "Resetting changes, removing changes to files not changed since $BASE_BRANCH"
+  # list of all files changed in the previous commit
+  git diff --name-only HEAD $BASE_BRANCH > /tmp/prev.txt
+  # list of all files with outstanding changes
+  git diff --name-only HEAD > /tmp/cur.txt
+
+  OLDIFS="$IFS"
+  IFS=$'\n'
+  # get all files that are in prev.txt that aren't also in cur.txt
+  for file in $(comm -1 -3 /tmp/prev.txt /tmp/cur.txt)
+  do
+    echo "resetting: $file"
+    git restore -- "$file"
+  done
+  IFS="$OLDIFS"
+fi
+
 # To keep runtime good, just continue if something was changed
 if _git_changed; then
   # case when --write is used with dry-run so if something is unpretty there will always have _git_changed
@@ -101,19 +126,8 @@ if _git_changed; then
     # Calling method to configure the git environemnt
     _git_setup
 
-    if $INPUT_ONLY_CHANGED; then
-      # --diff-filter=d excludes deleted files
-      OLDIFS="$IFS"
-      IFS=$'\n'
-      for file in $(git diff --name-only --diff-filter=d HEAD^..HEAD)
-      do
-        git add "$file"
-      done
-      IFS="$OLDIFS"
-    else
-      # Add changes to git
-      git add "${INPUT_FILE_PATTERN}" || echo "Problem adding your files with pattern ${INPUT_FILE_PATTERN}"
-    fi
+    # Add changes to git
+    git add "${INPUT_FILE_PATTERN}" || echo "Problem adding your files with pattern ${INPUT_FILE_PATTERN}"
 
     if $INPUT_NO_COMMIT; then
       echo "There are changes that won't be commited, you can use an external job to do so."