# Generate Changelog

Generate a changelog from git history between two tags, grouped by [conventional commit](https://www.conventionalcommits.org/) types. Designed for use in Forgejo Actions release workflows.

## Features

- **Automatic tag detection**: Finds the previous tag automatically, or accepts a manual override
- **Conventional commit grouping**: Categorizes commits by type (`feat`, `fix`, `chore`, `refactor`, etc.)
- **Customizable categories**: Define your own commit type to section header mapping via JSON
- **Compare link**: Automatically adds a full changelog link when running on Forgejo

## Usage

```yaml
steps:
  - uses: actions/checkout@v4
    with:
      fetch-depth: 0  # Required: full history needed for tag detection

  - name: Generate changelog
    id: changelog
    uses: your-org/generate-changelog@v1
    with:
      tag: ${{ github.ref_name }}

  - name: Create release
    uses: actions/forgejo-release@v2
    with:
      body: ${{ steps.changelog.outputs.changelog }}
```

## Inputs

| Input | Description | Required | Default |
|-------|-------------|----------|---------|
| `tag` | The current release tag | Yes | `${{ github.ref_name }}` |
| `previous-tag` | Override for the previous tag. Auto-detected if omitted | No | |
| `categories` | JSON mapping of commit prefixes to section headers | No | See below |

### Default categories

```json
{
  "feat": "✨ Features",
  "fix": "🐛 Bug Fixes",
  "refactor": "♻️ Refactoring",
  "chore": "🔧 Chores"
}
```

Commits that don't match any category are listed under **📝 Other Changes**.

## Outputs

| Output | Description |
|--------|-------------|
| `changelog` | The generated changelog as a markdown string |

## Examples

### Custom categories

```yaml
- name: Generate changelog
  id: changelog
  uses: your-org/generate-changelog@v1
  with:
    tag: ${{ github.ref_name }}
    categories: '{"feat": "New Features", "fix": "Bug Fixes", "docs": "Documentation", "perf": "Performance"}'
```

### Manual tag override

```yaml
- name: Generate changelog
  id: changelog
  uses: your-org/generate-changelog@v1
  with:
    tag: v2.0.0
    previous-tag: v1.0.0
```

### Sample output

```markdown
# Release v1.2.0

## ✨ Features

- add user authentication (a1b2c3d)
- add rate limiting to API (e4f5g6h)

## 🐛 Bug Fixes

- handle empty input gracefully (i7j8k9l)

---
**Full Changelog**: https://forgejo.example.com/org/repo/compare/v1.1.0...v1.2.0
```

## Requirements

- The checkout step **must** use `fetch-depth: 0` so that the full git history and tags are available.
- `jq` is recommended on the runner for category parsing. A pure bash fallback is included.

## License

MIT