# Utility class to choose an EGLConfig
class EGLConfigChooser
	var array = new Array[Int]
	var closed = false
	protected var inserted_attribs = new Array[Int]

	protected fun insert_attrib_key(key: Int)
	do
		assert not inserted_attribs.has(key) else
			print "Duplicate attrib passed to EGLConfigChooser"
		end
		array.add key
	end

	protected fun insert_attrib_with_val(key, val: Int)
	do
		insert_attrib_key key
		array.add val
	end

	fun close do
		insert_attrib_key 0x3038
		closed = true
	end

	fun surface_type=(flag: Int) do insert_attrib_with_val(0x3033, flag)
	fun surface_type_egl do surface_type = 4

	# Set which client rendering APIs are supported
	fun renderable_type=(flag: Int) do insert_attrib_with_val(0x3040, flag)

	# Set EGL as the only supported rendering API
	fun renderable_type_egl do renderable_type = 4

	fun blue_size=(size: Int) do insert_attrib_with_val(0x3022, size)
	fun green_size=(size: Int) do insert_attrib_with_val(0x3023, size)
	fun red_size=(size: Int) do insert_attrib_with_val(0x3024, size)

	fun buffer_size=(size: Int) do insert_attrib_with_val(0x3020, size)
	fun alpha_size=(size: Int) do insert_attrib_with_val(0x3021, size)
	fun depth_size=(size: Int) do insert_attrib_with_val(0x3025, size)
	fun stencil_size=(size: Int) do insert_attrib_with_val(0x3026, size)
	fun samples=(count: Int) do insert_attrib_with_val(0x3031, count)
	fun sample_buffers=(size: Int) do insert_attrib_with_val(0x3032, size)

	fun caveat=(caveat: EGLConfigCaveat) do insert_attrib_with_val(0x3050, caveat.to_i)

	fun conformant=(conformant: EGLConformant) do insert_attrib_with_val(0x3042, conformant.to_i)

	fun choose(display: EGLDisplay): nullable Array[EGLConfig]
	do
		assert closed else print "EGLConfigChooser not closed."
		return display.choose_configs(array)
	end
end