# PR Commenter Diff-Aware Action

A GitHub Action to automatically post comments to pull requests on **GitHub** or **Gitea**, based on a `git diff`. Supports:

- Inline comments per changed line
- Multiline comment templates
- Cross-platform support (GitHub and Gitea)
- Diff-aware commenting, automatically detecting added lines
- Default comment template with optional overrides

---

## Features

- **GitHub & Gitea support**: Works seamlessly on both platforms.
- **Diff-aware**: Parses a `git diff` to determine which lines were added.
- **Inline comments**: Comments appear directly on changed lines in PRs.
- **Multiline templates**: Supports `{line}` for single line and `{lines}` for all added lines in a file.
- **Reusable**: Works as a composite action and can be called from any workflow.

---

## Inputs

| Input | Description | Required | Default |
|-------|-------------|----------|---------|
| `platform` | Target platform: `github` or `gitea` | yes | `github` |
| `token` | API token for authentication | yes | - |
| `api_url` | Gitea API URL (only required for Gitea, e.g., `https://gitea.example.com/api/v1`) | no | - |
| `repo_owner` | Repository owner (user/org) | yes | - |
| `repo_name` | Repository name | yes | - |
| `pr_index` | PR number (GitHub) or index (Gitea) | yes | - |
| `diff` | Git diff to parse (generated via `git diff`) | yes | - |
| `comment_template` | Multiline template for comment body. Use `{line}` for a single line and `{lines}` for all added lines in the file | yes | `Auto-comment: changed line -> {line}` |

---

## Example Usage

```yaml
jobs:
  comment-pr-diff:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Set up Python
        uses: actions/setup-python@v4
        with:
          python-version: "3.11"

      - name: Generate git diff
        id: gitdiff
        run: |
          git fetch origin main
          git diff origin/main > diff.txt

      - name: Post diff-aware comments to GitHub PR
        uses: ./  # path to this action
        with:
          platform: github
          token: ${{ secrets.GITHUB_TOKEN }}
          repo_owner: ${{ github.repository_owner }}
          repo_name: ${{ github.event.repository.name }}
          pr_index: ${{ github.event.pull_request.number }}
          diff: ${{ steps.gitdiff.outputs.diff }}
          comment_template: |
            Auto-comment on file:
            ---
            Changed line: {line}
            Full added lines in this file:
            {lines}