const Shader = {}

Shader.load = async (vertexPath, fragmentPath) => {
    let vertexCode = await File.read(vertexPath)
    if(!vertexCode) {
        console.log("Invalid shader path:", vertexPath)
        return
    }

    let fragmentCode = await File.read(fragmentPath)
    if(!fragmentCode) {
        console.log("Invalid shader path:", fragmentPath)
        return
    }

    var vertexShader = gl.createShader(gl.VERTEX_SHADER)
    var fragmentShader = gl.createShader(gl.FRAGMENT_SHADER)

    gl.shaderSource(vertexShader, vertexCode)
    gl.shaderSource(fragmentShader, fragmentCode)

    gl.compileShader(vertexShader)
    if (!gl.getShaderParameter(vertexShader, gl.COMPILE_STATUS)) {
        console.error('Failed to compile ' + vertexPath + '!', gl.getShaderInfoLog(vertexShader))
        return
    }

    gl.compileShader(fragmentShader)
    if (!gl.getShaderParameter(fragmentShader, gl.COMPILE_STATUS)) {
        console.error('Failed to compile ' + fragmentPath + '!', gl.getShaderInfoLog(fragmentShader))
        return
    }

    var program = gl.createProgram()
    gl.attachShader(program, vertexShader)
    gl.attachShader(program, fragmentShader)
    gl.linkProgram(program)
    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
        console.error("Failed to link shader program!", gl.getProgramInfoLog(program));
        return
    }

    gl.validateProgram(program);
    if (!gl.getProgramParameter(program, gl.VALIDATE_STATUS)) {
        console.error("Failed to validate shader program!", gl.getProgramInfoLog(program));
        return
    }

    return program
}