<?php
/**
 * Asset handling.
 *
 * @package MM_Post_Grid
 */

namespace MM_Post_Grid;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Registers the front end assets and enqueues them only where a grid renders.
 *
 * Handles are registered on `wp_enqueue_scripts`. When the shortcode can be
 * found in the main content the style goes out in the head, otherwise it is
 * enqueued while the shortcode renders and WordPress prints it in the footer.
 *
 * @since 0.1
 */
final class Assets {

	/**
	 * Style handle.
	 *
	 * @since 0.1
	 * @var string
	 */
	const STYLE = 'mm-post-grid';

	/**
	 * Load more script handle.
	 *
	 * @since 0.1
	 * @var string
	 */
	const SCRIPT = 'mm-post-grid-load-more';

	/**
	 * Whether the stylesheet was already enqueued in this request.
	 *
	 * @since 0.1
	 * @var bool
	 */
	private static $enqueued = false;

	/**
	 * Hooks the asset callbacks.
	 *
	 * @since 0.1
	 * @return void
	 */
	public function register() {
		add_action( 'wp_enqueue_scripts', array( $this, 'on_enqueue_scripts' ) );
	}

	/**
	 * Registers the handles and enqueues early when possible.
	 *
	 * @since 0.1
	 * @return void
	 */
	public function on_enqueue_scripts() {
		self::register_handles();

		if ( self::content_has_shortcode() ) {
			self::enqueue();
		}
	}

	/**
	 * Registers the style and script handles.
	 *
	 * @since 0.1
	 * @return void
	 */
	public static function register_handles() {
		if ( wp_style_is( self::STYLE, 'registered' ) ) {
			return;
		}

		wp_register_style(
			self::STYLE,
			MM_POST_GRID_URL . 'assets/css/mmpg-frontend.css',
			array(),
			MM_POST_GRID_VERSION
		);

		wp_register_script(
			self::SCRIPT,
			MM_POST_GRID_URL . 'assets/js/mmpg-load-more.js',
			array(),
			MM_POST_GRID_VERSION,
			true
		);

		wp_localize_script(
			self::SCRIPT,
			'mmpgLoadMore',
			array(
				'endpoint' => esc_url_raw( rest_url( REST_Controller::REST_NAMESPACE . '/grid' ) ),
				// The route only returns published content, the nonce is sent so
				// that logged in visitors keep their own REST context.
				'nonce'    => is_user_logged_in() ? wp_create_nonce( 'wp_rest' ) : '',
				'i18n'     => array(
					'loading' => __( 'Loading', 'mm-post-grid' ),
					/* translators: %d: Number of posts that were added to the grid. */
					'added'   => __( 'Posts added: %d', 'mm-post-grid' ),
					'done'    => __( 'All posts are loaded.', 'mm-post-grid' ),
					'error'   => __( 'The posts could not be loaded. Please try again.', 'mm-post-grid' ),
				),
			)
		);
	}

	/**
	 * Enqueues the grid stylesheet and the settings driven custom properties.
	 *
	 * @since 0.1
	 * @return void
	 */
	public static function enqueue() {
		if ( self::$enqueued ) {
			return;
		}

		self::$enqueued = true;

		if ( Settings::get( 'disable_css' ) ) {
			return;
		}

		self::register_handles();
		wp_enqueue_style( self::STYLE );

		$css = self::inline_css();

		// The values are sanitized when built, but mmpg_inline_css may return
		// anything. Stripping tags means a filter can never close the style
		// element and inject markup.
		$css = wp_strip_all_tags( $css );

		if ( '' !== $css ) {
			wp_add_inline_style( self::STYLE, $css );
		}
	}

	/**
	 * Enqueues the load more script.
	 *
	 * @since 0.1
	 * @return void
	 */
	public static function enqueue_load_more() {
		self::register_handles();
		wp_enqueue_script( self::SCRIPT );
	}

	/**
	 * Whether the shortcode is present in the content of the requested post.
	 *
	 * @since 0.1
	 * @return bool
	 */
	private static function content_has_shortcode() {
		if ( ! is_singular() ) {
			return false;
		}

		$post = get_queried_object();

		if ( ! $post instanceof \WP_Post ) {
			return false;
		}

		return has_shortcode( (string) $post->post_content, Plugin::SHORTCODE );
	}

	/**
	 * Maps settings to the CSS custom properties they drive.
	 *
	 * Each entry holds the property name, a unit suffix, an optional divisor
	 * (percent settings such as line height are stored as integers), and the
	 * value to print when an optional colour is left empty. An empty value
	 * without a replacement prints nothing, so the stylesheet default applies.
	 *
	 * @since 0.1
	 * @return array<string, array<string, mixed>>
	 */
	public static function properties() {
		return array(
			'columns'             => array( 'var' => '--mmpg-columns' ),
			'columns_tablet'      => array( 'var' => '--mmpg-columns-tablet' ),
			'columns_mobile'      => array( 'var' => '--mmpg-columns-mobile' ),
			'gap'                 => array(
				'var'  => '--mmpg-gap',
				'unit' => 'px',
			),
			'card_bg'             => array(
				'var'   => '--mmpg-card-bg',
				'empty' => 'transparent',
			),
			'card_border_color'   => array( 'var' => '--mmpg-card-border-color' ),
			'card_border_width'   => array(
				'var'  => '--mmpg-card-border-width',
				'unit' => 'px',
			),
			'card_border_hover'   => array( 'var' => '--mmpg-card-border-hover' ),
			'card_radius'         => array(
				'var'  => '--mmpg-card-radius',
				'unit' => 'px',
			),
			'card_padding'        => array(
				'var'  => '--mmpg-card-padding',
				'unit' => 'px',
			),
			'content_gap'         => array(
				'var'  => '--mmpg-content-gap',
				'unit' => 'px',
			),
			'image_radius'        => array(
				'var'  => '--mmpg-image-radius',
				'unit' => 'px',
			),
			'media_width'         => array(
				'var'  => '--mmpg-media-width',
				'unit' => '%',
			),
			'overlay_opacity'     => array(
				'var'    => '--mmpg-overlay-opacity',
				'divide' => 100,
			),
			'title_color'         => array( 'var' => '--mmpg-title-color' ),
			'title_hover_color'   => array( 'var' => '--mmpg-title-hover-color' ),
			'title_size'          => array(
				'var'  => '--mmpg-title-size',
				'unit' => 'px',
			),
			'title_weight'        => array( 'var' => '--mmpg-title-weight' ),
			'title_line_height'   => array(
				'var'    => '--mmpg-title-line-height',
				'divide' => 100,
			),
			'title_lines'         => array( 'var' => '--mmpg-title-lines' ),
			'meta_color'          => array( 'var' => '--mmpg-meta-color' ),
			'meta_size'           => array(
				'var'  => '--mmpg-meta-size',
				'unit' => 'px',
			),
			'excerpt_color'       => array( 'var' => '--mmpg-excerpt-color' ),
			'excerpt_size'        => array(
				'var'  => '--mmpg-excerpt-size',
				'unit' => 'px',
			),
			'excerpt_line_height' => array(
				'var'    => '--mmpg-excerpt-line-height',
				'divide' => 100,
			),
			'excerpt_lines'       => array( 'var' => '--mmpg-excerpt-lines' ),
			'term_color'          => array( 'var' => '--mmpg-term-color' ),
			'accent_color'        => array( 'var' => '--mmpg-accent-color' ),
			'button_bg'           => array( 'var' => '--mmpg-button-bg' ),
			'button_bg_hover'     => array( 'var' => '--mmpg-button-bg-hover' ),
			'button_color'        => array( 'var' => '--mmpg-button-color' ),
			'button_radius'       => array(
				'var'  => '--mmpg-button-radius',
				'unit' => 'px',
			),
		);
	}

	/**
	 * Builds the custom property declarations for one setting.
	 *
	 * Returns an empty array when the setting has no property, or when an
	 * optional colour is empty and the stylesheet default should apply.
	 * Presets that expand into several properties are handled here too.
	 *
	 * @since 0.1
	 *
	 * @param string $key   Setting key.
	 * @param mixed  $value Sanitized value.
	 * @return string[] Declarations such as "--mmpg-gap:28px".
	 */
	public static function declarations( $key, $value ) {
		if ( 'card_shadow' === $key ) {
			$shadow = Helpers::shadow( (string) $value );

			return array(
				'--mmpg-card-shadow:' . Helpers::css_value( $shadow['shadow'] ),
				'--mmpg-card-shadow-hover:' . Helpers::css_value( $shadow['hover'] ),
			);
		}

		if ( 'image_ratio' === $key ) {
			return array( '--mmpg-image-ratio:' . Helpers::css_value( Helpers::ratio( (string) $value ) ) );
		}

		$properties = self::properties();

		if ( ! isset( $properties[ $key ] ) ) {
			return array();
		}

		$property = $properties[ $key ];
		$value    = (string) $value;

		if ( '' === $value ) {
			if ( ! isset( $property['empty'] ) ) {
				return array();
			}

			$value = $property['empty'];
		} elseif ( isset( $property['divide'] ) ) {
			$value = (string) round( (float) $value / (float) $property['divide'], 2 );
		} elseif ( isset( $property['unit'] ) ) {
			$value .= $property['unit'];
		}

		$value = Helpers::css_value( $value );

		return '' === $value ? array() : array( $property['var'] . ':' . $value );
	}

	/**
	 * Builds the inline custom properties for the saved settings.
	 *
	 * Only settings that differ from the shipped defaults are printed, since
	 * the stylesheet already holds every default value.
	 *
	 * @since 0.1
	 * @return string
	 */
	private static function inline_css() {
		$settings     = Settings::all();
		$defaults     = Settings::defaults();
		$keys         = array_merge( array_keys( self::properties() ), array( 'card_shadow', 'image_ratio' ) );
		$declarations = array();

		foreach ( $keys as $key ) {
			if ( ! array_key_exists( $key, $settings ) || ! array_key_exists( $key, $defaults ) ) {
				continue;
			}

			if ( (string) $defaults[ $key ] === (string) $settings[ $key ] ) {
				continue;
			}

			$declarations = array_merge( $declarations, self::declarations( $key, $settings[ $key ] ) );
		}

		$css = empty( $declarations ) ? '' : '.mmpg{' . implode( ';', $declarations ) . '}';

		/**
		 * Filters the inline custom properties printed after the stylesheet.
		 *
		 * @since 0.1
		 *
		 * @param string               $css      Inline CSS.
		 * @param array<string, mixed> $settings Current settings.
		 */
		return (string) apply_filters( 'mmpg_inline_css', $css, $settings );
	}
}