<?php
/**
 * @package    Customizer_Library
 * @author        The Theme Foundry
 */

if (!class_exists('Customizer_Library_Styles')) :
    /**
     * Singleton to collect and print CSS based on user input.
     *
     * This class provides a mechanism to gather all of the CSS needed to implement theme options. It allows for handling
     * of conflicting rules and sorts out what the final CSS should be. The primary function is `add()`. It allows the
     * caller to add a new rule to be generated in the CSS.
     */
    class Customizer_Library_Styles
    {

        /**
         * The one instance of Customizer_Library_Styles.
         *
         * @since 1.0.0.
         *
         * @var   Customizer_Library_Styles    The one instance for the singleton.
         */
        private static $instance;

        /**
         * The array for storing added CSS rule data.
         *
         * @since 1.0.0.
         *
         * @var   array    Holds the data to be printed out.
         */

        public $data = array();

        /**
         * Optional line ending character for debug mode.
         *
         * @since 1.0.0.
         *
         * @var   string    Line ending character used to better style the CSS.
         */
        private $line_ending = '';

        /**
         * Optional tab character for debug mode.
         *
         * @since 1.0.0.
         *
         * @var   string    Line ending character used to better style the CSS.
         */
        private $tab = '';

        /**
         * Instantiate or return the one Customizer_Library_Styles instance.
         *
         * @since  1.0.0.
         *
         * @return Customizer_Library_Styles
         */
        public static function instance()
        {
            if (is_null(self::$instance)) {
                self::$instance = new self();
            }

            return self::$instance;
        }

        /**
         * Initialize the object.
         *
         * @since  1.0.0.
         *
         * @return Customizer_Library_Styles
         */
        function __construct()
        {
            // Set line ending and tab
            if (defined('SCRIPT_DEBUG') && true === SCRIPT_DEBUG) {
                $this->line_ending = "\n";
                $this->tab = "\t";
            }
        }

        /**
         * Add a new CSS rule to the array.
         *
         * Accepts data to eventually be turned into CSS. Usage:
         *
         * Customizer_Library_Styles()->add( array(
         *     'selectors'    => array( '.site-header-main' ),
         *     'declarations' => array(
         *         'background-color' => $header_background_color
         *     ),
         *     'media' => 'print',
         * ) );
         *
         * Selectors represent the CSS selectors; declarations are the CSS properties and values with keys being properties
         * and values being values. 'media' can also be declared to specify the media query.
         *
         * Note that data *must* be sanitized when adding to the data array. Because every piece of CSS data has special
         * sanitization concerns, it must be handled at the time of addition, not at the time of output. The theme handles
         * this in the the other helper files, i.e., the data is already sanitized when `add()` is called.
         *
         * @since  1.0.0.
         *
         * @param  array $data The selectors and properties to add to the CSS.
         * @return void
         */
        public function add($data)
        {
            if (!isset($data['selectors']) || !isset($data['declarations'])) {
                return;
            }

            $entry = array();

            // Sanitize selectors
            $entry['selectors'] = array_map('trim', (array)$data['selectors']);
            $entry['selectors'] = array_unique($entry['selectors']);

            // Sanitize declarations
            $entry['declarations'] = array_map('trim', (array)$data['declarations']);

            // Check for media query
            if (isset($data['media'])) {
                $media = $data['media'];
            } else {
                $media = 'all';
            }

            // Create new media query if it doesn't exist yet
            if (!isset($this->data[$media]) || !is_array($this->data[$media])) {
                $this->data[$media] = array();
            }

            // Look for matching selector sets
            $match = false;
            foreach ($this->data[$media] as $key => $rule) {
                $diff1 = array_diff($rule['selectors'], $entry['selectors']);
                $diff2 = array_diff($entry['selectors'], $rule['selectors']);
                if (empty($diff1) && empty($diff2)) {
                    $match = $key;
                    break;
                }
            }

            // No matching selector set, add a new entry
            if (false === $match) {
                $this->data[$media][] = $entry;
            } // Yes, matching selector set, merge declarations
            else {
                $this->data[$media][$match]['declarations'] = array_merge($this->data[$media][$match]['declarations'], $entry['declarations']);
            }
        }

        /**
         * Compile the data array into CSS syntax
         *
         * @since  1.0.0.
         *
         * @return string    The CSS that is built from the data.
         */
        public function build()
        {
            if (empty($this->data)) {
                return '';
            }

            $n = $this->line_ending;

            // Make sure the 'all' array is first
            if (isset($this->data['all']) && count($this->data) > 1) {
                $all = array('all' => $this->data['all']);
                unset($this->data['all']);
                $this->data = array_merge($all, $this->data);
            }

            $output = '';

            foreach ($this->data as $query => $ruleset) {
                $t = '';

                if ('all' !== $query) {
                    $output .= "\n@media " . $query . '{' . $n;
                    $t = $this->tab;
                }

                // Build each rule
                foreach ($ruleset as $rule) {
                    $output .= $this->parse_selectors($rule['selectors'], $t) . '{' . $n;
                    $output .= $this->parse_declarations($rule['declarations'], $t);
                    $output .= $t . '}' . $n;
                }

                if ('all' !== $query) {
                    $output .= '}' . $n;
                }
            }

            return $output;
        }

        /**
         * Compile the selectors in a rule into a string.
         *
         * @since  1.0.0.
         *
         * @param  array $selectors Selectors to combine into single selector.
         * @param  string $tab Tab character.
         * @return string                  Results of the selector combination.
         */
        private function parse_selectors($selectors, $tab = '')
        {
            /**
             * Note that these selectors are hardcoded in the code base. They are never the result of user input and can
             * thus be trusted to be sane.
             */
            $n = $this->line_ending;
            $output = $tab . implode(",{$n}{$tab}", $selectors);
            return $output;
        }

        /**
         * Compile the declarations in a rule into a string.
         *
         * @since  1.0.0.
         *
         * @param  array $declarations Declarations for a selector.
         * @param  string $tab Tab character.
         * @return string                     The combines declarations.
         */
        private function parse_declarations($declarations, $tab = '')
        {
            $n = $this->line_ending;
            $t = $this->tab . $tab;

            $output = '';

            /**
             * Note that when this output is prepared, it is not escaped, sanitized or otherwise altered. The sanitization
             * routines are implemented when the developer calls `Customizer_Library_Styles()->add`. Because every property value has
             * special sanitization needs, it is handled at that point.
             */
            foreach ($declarations as $property => $value) {
                // Exception for px/rem font size
                if ('font-size-px' === $property || 'font-size-rem' === $property) {
                    $property = 'font-size';
                }
                $output .= "{$t}{$property}:{$value};$n";
            }

            return $output;
        }
    }
endif;

if (!function_exists('customizer_library_styles')) :
    /**
     * Return the one Customizer_Library_Styles object.
     *
     * @since  1.0.0.
     *
     * @return Customizer_Library_Styles    The Customizer_Library_Styles object.
     */
    function customizer_library_styles()
    {
        return Customizer_Library_Styles::instance();
    }
endif;

add_action('init', 'customizer_library_styles', 1);