gl-sdk 0.4.0

# gl-sdk

Rust SDK for Greenlight with UniFFI bindings support.

## Building

Build the library using Task:

```bash
task sdk:build
```

Or directly with cargo from the workspace root:

```bash
cd /home/cdecker/dev/greenlight/202509-sdk/public
cargo build -p gl-sdk
```

## Generating Language Bindings

### Using Task (Recommended)

The easiest way to generate bindings is using the Task commands:

```bash
# Generate Python bindings
task sdk:bindings-python

# Generate Kotlin bindings
task sdk:bindings-kotlin

# Generate Swift bindings
task sdk:bindings-swift

# Generate Ruby bindings
task sdk:bindings-ruby

# Generate C++ bindings (requires uniffi-bindgen-cpp)
task sdk:bindings-cpp

# Generate all language bindings
task sdk:bindings-all
```

These commands work from any directory in the workspace.

### Using uniffi-bindgen Directly

The project uses [UniFFI](https://mozilla.github.io/uniffi-rs/) to generate bindings for multiple languages from the UDL definition in `src/sdk.udl`.

The `uniffi-bindgen` tool is included in the workspace at `libs/uniffi-bindgen`.

**Note:** When using uniffi-bindgen directly, all commands must be run from the workspace root.

#### Generate Python Bindings

```bash
cd /home/cdecker/dev/greenlight/202509-sdk/public
cargo run --bin uniffi-bindgen -- generate \
  --library $CARGO_TARGET_DIR/debug/libglsdk.so \
  --language python \
  --out-dir ./libs/gl-sdk/bindings
```

#### Generate Bindings for Other Languages

Replace `--language python` with:
- `kotlin` for Kotlin
- `swift` for Swift
- `ruby` for Ruby

Example for Kotlin:

```bash
cargo run --bin uniffi-bindgen -- generate \
  --library $CARGO_TARGET_DIR/debug/libglsdk.so \
  --language kotlin \
  --out-dir ./libs/gl-sdk/bindings
```

### Generate C++ Bindings

C++ bindings use [uniffi-bindgen-cpp](https://github.com/NordSecurity/uniffi-bindgen-cpp) instead of the built-in `uniffi-bindgen`. Install it first:

```bash
cargo install uniffi-bindgen-cpp --git https://github.com/NordSecurity/uniffi-bindgen-cpp --tag v0.8.1+v0.29.4
```

Then build and generate bindings:

```bash
cargo build --release -p gl-sdk
uniffi-bindgen-cpp --library target/release/libglsdk.dylib --out-dir libs/gl-sdk/bindings
```

> On Linux, replace `libglsdk.dylib` with `libglsdk.so`.

The generated files require patching to avoid conflicts with the C++ reserved keyword `register`:

```bash
perl -pi -e 's/std::shared_ptr<Node> register\(/std::shared_ptr<Node> register_node\(/g; s/std::shared_ptr<Credentials> register\(/std::shared_ptr<Credentials> register_node\(/g' libs/gl-sdk/bindings/glsdk.hpp
perl -pi -e 's/NodeBuilder::register\(/NodeBuilder::register_node\(/g; s/Scheduler::register\(/Scheduler::register_node\(/g' libs/gl-sdk/bindings/glsdk.cpp
```

The `task sdk:bindings-cpp` command handles all of the above automatically, including platform detection.

## Synchronous API Design

The entire public API exposed by the SDK through UniFFI is
**synchronous**. Functions that need to perform async work (network
I/O, gRPC calls) block the calling thread while an internal Tokio
runtime executes the underlying async operations.

This is a deliberate design choice:

- **Uniform bindings** -- every target language (Python, Kotlin,
  Swift, Ruby, C++) gets the same blocking API. No language needs
  an async runtime, coroutine support, or special feature flags on
  the caller side.
- **Simpler integration** -- callers that need concurrency can use
  their language's native threading primitives (e.g. `threading` in
  Python, `std::thread` in C++, coroutines in Kotlin) to call SDK
  methods off the main thread.
- **No conditional compilation** -- a single build of the shared
  library works for all bindings, avoiding feature-flag divergence
  between languages.

The internal Tokio runtime is created lazily on the first call and
lives for the lifetime of the process (see `src/util.rs`).

## Files

- `src/sdk.udl` - UniFFI interface definition
- `build.rs` - Build script that generates Rust scaffolding
- `bindings/` - Generated language bindings (created by uniffi-bindgen)