// Copyright (c) 2017 Philip M. Hubbard
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
// associated documentation files (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge, publish, distribute,
// sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
// NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// http://opensource.org/licenses/MIT

import OpenGLES

// A component that factors out the core OpenGL calls for compling a shader, and reporting any
// errors that occurred.

public class ShadingCore {
    public private(set) var id: GLuint = 0
    
    public init?(shaderType: GLenum, shaderStr: String) {
        id = glCreateShader(shaderType)
        
        let shaderStrNS = shaderStr as NSString
        glShaderSource(id, 1, [shaderStrNS.utf8String], nil)
        
        glCompileShader(id)
        var compileStatus: GLint = GL_NO_ERROR
        glGetShaderiv(id, GLenum(GL_COMPILE_STATUS), &compileStatus);
        guard compileStatus == GL_TRUE else {
            let MaxErrorSize: GLsizei = 1024
            var errorBuffer = [CChar](repeating: 0, count: Int(MaxErrorSize))
            var errorSize: GLsizei = 1
            glGetShaderInfoLog(id, MaxErrorSize, &errorSize, &errorBuffer);
            let errorString = String(utf8String: errorBuffer)!
            print("glCompileShader() failed: \(errorString)")
            id = 0
            return nil
        }
    }
}
