use std::sync::Once;

static INIT: Once = Once::new();
static mut CONTEXT: Option<Result<Context, String>> = None;

mod sdl;
use sdl::Context;
pub use sdl::Window;
pub use sdl::WindowInner;

mod event_handler;
pub use event_handler::EventHandler;
pub use event_handler::EventHandlerContext;

/// Get the global context.
///
/// If the global context was not yet initialized, this function will initialize it.
fn context() -> Result<&'static Context, &'static str> {
	unsafe {
		INIT.call_once(|| {
			let context = Context::new()
				.map_err(|e| format!("failed to initialize global context: {}", e));
			CONTEXT = Some(context);
		});
		match CONTEXT.as_ref().expect("global context not initialized") {
			Ok(ref x) => Ok(x),
			Err(ref e) => Err(e),
		}
	}
}

/// Make a window with default options using the global context.
///
/// See [`Context::make_window`] for more details.
///
/// If the global context was not yet initialized, this function will initialize it.
pub fn make_window(name: impl Into<String>) -> Result<Window, String> {
	context()?.make_window(name)
}

/// Make a window with the given options using the global context.
///
/// See [`Context::make_window_full`] for more details.
///
/// If the global context was not yet initialized, this function will initialize it.
pub fn make_window_full(options: crate::WindowOptions) -> Result<Window, String> {
	context()?.make_window_full(options)
}

/// Close all windows, stop the global context and join the background thread.
///
/// If you don't call this function, images being saved in the background thread may be corrupted when the thread is killed.
/// Note that this function will also block until any file dialogs for saving images have been closed.
///
/// Once this function has been called, no new window handles can be created and none of the existing window handles can be used anymore,
pub fn stop() -> Result<(), String> {
	let context = context()?;
	context.stop()?;
	context.join()
}