# YAMLMerger

Swift utility for assembling folder-organized YAML fragments into one OpenAPI
specification.

YAMLMerger is useful when a large OpenAPI document is easier to maintain as
small files grouped by section, but the build or generator still needs one
combined `openapi.yaml`.

## Directory Model

Files are merged in a predictable order:

1. Subfolders are processed alphabetically. Prefix folders with numbers when
   order matters.
2. YAML files inside each folder are processed alphabetically.
3. Header files such as `__paths.yaml` sort before ordinary files and can define
   the parent key for the section.

Example:

```text
Schema/
├── 01_Info/
│   ├── __info.yaml
│   └── api-info.yaml
├── 02_Servers/
│   ├── __servers.yaml
│   └── production.yaml
├── 04_Paths/
│   ├── __paths.yaml
│   ├── users.yaml
│   └── products.yaml
└── 06_Components/
    ├── __components.yaml
    ├── User.yaml
    └── Product.yaml
```

## Usage

```swift
import YAMLMerger

let merger = YAMLMerger(
    rootDirectory: URL(fileURLWithPath: "Schema"),
    outputFileName: "openapi.yaml"
)

merger.merge()
```

The merged file is written inside `rootDirectory`.

## Why This Exists

OpenAPI specs tend to outgrow a single file. Splitting by paths, schemas, and
metadata makes review and collaboration easier, while merging keeps the output
compatible with tools that expect one document.

YAMLMerger is intentionally simple: it concatenates already-shaped YAML
fragments in deterministic order. It does not validate OpenAPI semantics and it
does not try to be a general YAML parser.

## Testing

The test fixture under `Tests/YAMLMergerTests/Schema/` demonstrates the folder
layout and merge order.

```bash
swift test
```