Add use_repo_config parameter to automatically detect prettier configuration

This addresses GitHub issue #41 by adding an optional `use_repo_config` parameter
that allows the action to automatically detect and use the repository's prettier
configuration files and .prettierignore.

Changes:
- Added `use_repo_config` input parameter (default: false for backward compatibility)
- Implemented config file detection in entrypoint.sh for all prettier config formats
- Automatically changes file pattern to current directory when using repo config
- Provides helpful messages about found config files and warnings when none exist
- Updated README with new parameter documentation and Example 5

Benefits:
- Users no longer need to manually specify --config or --ignore-path
- Eliminates confusion about whether config files are being used
- Maintains backward compatibility (opt-in via parameter)
- Supports all prettier configuration file formats

Related: #41

README.md

@@ -33,6 +33,7 @@ A GitHub action for styling files with [prettier](https://prettier.io).
 | github_token        |   :x:    |    `${{ github.token }}`    | The default [GITHUB_TOKEN](https://docs.github.com/en/actions/reference/authentication-in-a-workflow#about-the-github_token-secret) or a [Personal Access Token](https://docs.github.com/en/github/authenticating-to-github/keeping-your-account-and-data-secure/creating-a-personal-access-token) |
 | git_identity        |   :x:    |          `actions`          | Set to `author` to use author's user as committer. This allows triggering [further workflow runs](https://github.com/peter-evans/create-pull-request/blob/main/docs/concepts-guidelines.md#triggering-further-workflow-runs)                                                                       |
 | allow_other_plugins |   :x:    |           `false`           | Allow other plugins to be installed (prevents the @prettier-XYZ regex check)                                                                                                                                                                                                                       |
+| use_repo_config     |   :x:    |           `false`           | Automatically use the repository's prettier configuration files (.prettierrc, prettier.config.js, etc.) and .prettierignore. When enabled, prettier will search for and use config files in your repository, eliminating the need to specify `--config` or `--ignore-path` manually.                |
 
 > Note: using the same_commit option may lead to problems if other actions are relying on the commit being the same before and after the prettier action has ran. Keep this in mind.
 
@@ -157,6 +158,49 @@ jobs:
           github_token: ${{ secrets.PERSONAL_GITHUB_TOKEN }}
 ```
 
+#### Example 5 (using repository prettier configuration)
+
+This example demonstrates the `use_repo_config` option, which automatically detects and uses your repository's prettier configuration files (`.prettierrc`, `prettier.config.js`, etc.) and `.prettierignore` file.
+
+```yaml
+name: Continuous Integration
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  prettier:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Prettify code
+        uses: creyD/prettier_action@v4.6
+        with:
+          # Automatically use repository's prettier config and .prettierignore
+          use_repo_config: true
+```
+
+With `use_repo_config: true`, the action will:
+- Search for prettier configuration files in your repository (.prettierrc, prettier.config.js, package.json, etc.)
+- Automatically use your .prettierignore file if present
+- Apply prettier to all supported files in your repository
+- Warn you if no configuration file is found (prettier will use defaults)
+
+You can still customize the file pattern if needed:
+
+```yaml
+- name: Prettify code
+  uses: creyD/prettier_action@v4.6
+  with:
+    use_repo_config: true
+    prettier_options: --write "src/**/*.{js,ts,jsx,tsx}"
+```
+
 More documentation for writing a workflow can be found [here](https://help.github.com/en/actions/automating-your-workflow-with-github-actions/workflow-syntax-for-github-actions).
 
 ## Issues

action.yml

@@ -77,6 +77,10 @@ inputs:
     description: Allow other plugins to be installed. By default, we are checking if the plugins are actually prettier plugins.
     required: false
     default: false
+  use_repo_config:
+    description: Use the repository's prettier configuration files (.prettierrc, prettier.config.js, etc.) and .prettierignore automatically. When enabled, prettier will search for config files in the repository.
+    required: false
+    default: false
 
 runs:
   using: "composite"
@@ -106,6 +110,7 @@ runs:
         INPUT_CLEAN_NODE_FOLDER: ${{ inputs.clean_node_folder }}
         INPUT_GIT_IDENTITY: ${{ inputs.git_identity }}
         INPUT_ALLOW_OTHER_PLUGINS: ${{ inputs.allow_other_plugins }}
+        INPUT_USE_REPO_CONFIG: ${{ inputs.use_repo_config }}
 
 branding:
   icon: "award"

entrypoint.sh

@@ -63,6 +63,46 @@ if [ -n "$INPUT_PRETTIER_PLUGINS" ]; then
 fi
 )
 
+# Handle repository configuration files
+if [ "$INPUT_USE_REPO_CONFIG" = "true" ]; then
+  echo "Using repository prettier configuration..."
+
+  # Check for prettier config files
+  CONFIG_FOUND=false
+  for config_file in .prettierrc .prettierrc.json .prettierrc.yml .prettierrc.yaml .prettierrc.js .prettierrc.cjs .prettierrc.mjs prettier.config.js prettier.config.cjs prettier.config.mjs .prettierrc.toml; do
+    if [ -f "$config_file" ]; then
+      echo "  Found prettier config: $config_file"
+      CONFIG_FOUND=true
+      break
+    fi
+  done
+
+  # Check package.json for prettier config
+  if [ -f "package.json" ] && grep -q '"prettier"' package.json; then
+    echo "  Found prettier config in package.json"
+    CONFIG_FOUND=true
+  fi
+
+  if [ "$CONFIG_FOUND" = "false" ]; then
+    echo "  Warning: No prettier config file found. Prettier will use its default configuration."
+  fi
+
+  # Check for .prettierignore
+  if [ -f ".prettierignore" ]; then
+    echo "  Found .prettierignore file"
+  else
+    echo "  Note: No .prettierignore file found. All files will be processed."
+  fi
+
+  # When using repo config, if prettier_options is still the default, use a more sensible pattern
+  if [ "$INPUT_PRETTIER_OPTIONS" = "--write **/*.js" ]; then
+    echo "  Using default file pattern: . (current directory)"
+    INPUT_PRETTIER_OPTIONS="--write ."
+  else
+    echo "  Using custom prettier_options: $INPUT_PRETTIER_OPTIONS"
+  fi
+fi
+
 PRETTIER_RESULT=0
 echo "Prettifying files..."
 echo "Files:"