package pixelgl

import (
	"github.com/go-gl/gl/v3.3-core/gl"
	"github.com/pkg/errors"
)

// getLastError returns (and consumes) the last error generated by OpenGL inside the current Do, DoErr or DoVal.
// If no error has been generated, this function returns nil.
//
// Call this function only inside the OpenGL thread (Do, DoErr or DoVal function). It's not guaranteed
// to work correctly outside of it, because the thread swallows extra unchecked errors.
func getLastError() error {
	err := uint32(gl.NO_ERROR)
	for e := gl.GetError(); e != gl.NO_ERROR; e = gl.GetError() {
		err = e
	}
	if err == gl.NO_ERROR {
		return nil
	}
	switch err {
	case gl.INVALID_ENUM:
		return errors.New("invalid enum")
	case gl.INVALID_VALUE:
		return errors.New("invalid value")
	case gl.INVALID_OPERATION:
		return errors.New("invalid operation")
	case gl.STACK_OVERFLOW:
		return errors.New("stack overflow")
	case gl.STACK_UNDERFLOW:
		return errors.New("stack underflow")
	case gl.OUT_OF_MEMORY:
		return errors.New("out of memory")
	case gl.INVALID_FRAMEBUFFER_OPERATION:
		return errors.New("invalid framebuffer operation")
	case gl.CONTEXT_LOST:
		return errors.New("context lost")
	default:
		return errors.New("unknown error")
	}
}