function compileShader(gl, kind, source) {
    let shader = gl.createShader(kind);

    gl.shaderSource(shader, source);
    gl.compileShader(shader);

    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
        let error = new Error(`failed to compile shader: ${gl.getShaderInfoLog(shader)}`);
        gl.deleteShader(shader);
        throw error;
    } else {
        return shader;
    }
}

export function compileProgram(gl, vertexSource, fragmentSource) {
    let vertexShader = compileShader(gl, gl.VERTEX_SHADER, vertexSource);
    let fragmentShader = compileShader(gl, gl.FRAGMENT_SHADER, fragmentSource);

    let program = gl.createProgram();
    gl.attachShader(program, vertexShader);
    gl.attachShader(program, fragmentShader);
    gl.linkProgram(program);

    gl.deleteShader(vertexShader);
    gl.deleteShader(fragmentShader);

    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
        let error = new Error(`failed to link program: ${gl.getProgramInfoLog(program)}`);
        gl.deleteProgram(program);
        throw error;
    } else {
        return program;
    }
}

export function orthographicProjection(left, right, top, bottom, near, far) {
    // prettier-ignore
    return [
        2 / (right - left), 0, 0, -((right + left) / (right - left)),
        0, 2 / (top - bottom), 0, -((top + bottom) / (top - bottom)),
        0, 0, -2 / (far - near), -((far + near) / (far - near)),
        0, 0, 0, 1,
    ];
}