// Copyright 2022 The Ebitengine Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package gl

import (
	"fmt"
	"strings"

	"github.com/ebitengine/purego"
)

var (
	opengl uintptr
)

func (c *defaultContext) init() error {
	opengl = purego.Dlopen("OpenGLES.framework/OpenGLES", purego.RTLD_LAZY|purego.RTLD_GLOBAL)
	if opengl != 0 {
		c.isES = true
		return nil
	}
	opengl = purego.Dlopen("OpenGL.framework/OpenGL", purego.RTLD_LAZY|purego.RTLD_GLOBAL)
	if opengl != 0 {
		return nil
	}
	return fmt.Errorf("gl: failed to load OpenGL.framework and OpenGLES.framework")
}

func (c *defaultContext) getProcAddress(name string) uintptr {
	if c.isES {
		const ext = "EXT"
		if strings.HasSuffix(name, ext) {
			name = name[:len(name)-len(ext)]
		}
	}
	return purego.Dlsym(opengl, name)
}