/**
 * Implement the Sass compiler in PHP
 * https://github.com/leafo/scssphp
 * This requires PHP 5.3 or higher because it uses namespacing.
 */
require get_template_directory() . '/inc/scssphp/scss.inc.php';
use Leafo\ScssPhp\Compiler;

/* First, add the controls to the Customizer itself. */
function sass_customizer( $wp_customize ) {
    $wp_customize->add_setting( 'color_scheme', array(
        'default'   => '#16dff9',
        'transport' => 'postMessage'
    ) );

    $wp_customize->add_control( new WP_Customize_Color_Control( $wp_customize, 'color_scheme', array(
        'label'       => 'Sass color picker',
        'section'     => 'colors'
    ) ) );
}
add_action( 'customize_register', 'sass_customizer' );

/* This function runs after the customizer options are saved, generating the appropriate stylesheet. */
function compile_sass() {
    $scss = new Compiler();
    $base_color = get_theme_mod( 'color_scheme' );

    $compiler_string = '$base-color: %1$s; a { color: $base-color; &:hover { color: darken( $base-color, 15 ); } };';
    $compiler_string = sprintf( $compiler_string, $base_color );

    $compiled = $scss->compile( $compiler_string );

    $file = fopen( get_template_directory() . '/css/customizer.css', 'a+' );
    if ( $file ) {
        fwrite( $file, $compiled );
        fclose( $file );
    }
}
add_action( 'customize_save_after', 'compile_sass' );

/* Then, load the newly-created stylesheet. */
function load_customizer_css() {
    wp_enqueue_style( 'customizer-css', get_template_directory_uri() . '/css/customizer.css' );
}
add_action( 'wp_enqueue_scripts', 'load_customizer_css' );

/* Alternatively, write the CSS directly to the header. */
function write_css_to_head() {
    $scss = new Compiler();
    $base_color = get_theme_mod( 'color_scheme' );

    $compiler_string = '$base-color: %1$s; a { color: $base-color; &:hover { color: darken( $base-color, 15 ); } };';
    $compiler_string = sprintf( $compiler_string, $base_color );

    $compiled = $scss->compile( $compiler_string );

    echo '<style type="text/css">' . $compiled . '</style>';
}
add_action( 'wp_head', 'write_css_to_head' );
/* End implementation of the Sass compiler in PHP. This is only a test. */