<?php
/**
 * Term Meta Class
 *
 * Provides per-term Open Graph fields (title, image, description) on the
 * category and tag edit pages (term.php), and exposes the stored image to the
 * taxonomy archive image resolution via the `robotstxt_og_taxonomy_image`
 * filter.
 *
 * @package ROBOTSTXT_OG
 * @since 1.2.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly.
}

/**
 * Class Robotstxt_OG_Term_Meta
 *
 * @since 1.2.0
 */
class Robotstxt_OG_Term_Meta {

	/**
	 * Term meta key for the custom OG title.
	 *
	 * @since 1.2.0
	 * @var string
	 */
	public const META_TITLE = '_og_title';

	/**
	 * Term meta key for the custom OG image URL.
	 *
	 * @since 1.2.0
	 * @var string
	 */
	public const META_IMAGE = '_og_image';

	/**
	 * Term meta key for the custom OG description.
	 *
	 * @since 1.2.0
	 * @var string
	 */
	public const META_DESCRIPTION = '_og_description';

	/**
	 * Term meta key for the custom OG image alt text.
	 *
	 * @since 1.2.0
	 * @var string
	 */
	public const META_IMAGE_ALT = '_og_image_alt';

	/**
	 * Nonce action for the term edit form.
	 *
	 * @since 1.2.0
	 * @var string
	 */
	public const NONCE_ACTION = 'robotstxt_og_term_meta';

	/**
	 * Nonce field name for the term edit form.
	 *
	 * @since 1.2.0
	 * @var string
	 */
	public const NONCE_NAME = 'robotstxt_og_term_meta_nonce';

	/**
	 * Initialize hooks.
	 *
	 * @since 1.2.0
	 *
	 * @return void
	 */
	public function init(): void {
		add_action( 'init', array( $this, 'register_term_meta' ) );
		add_filter( 'robotstxt_og_taxonomy_image', array( $this, 'filter_taxonomy_image' ), 10, 2 );

		if ( ! is_admin() ) {
			return;
		}

		foreach ( $this->get_supported_taxonomies() as $taxonomy ) {
			add_action( "{$taxonomy}_edit_form_fields", array( $this, 'render_term_fields' ) );
			add_action(
				"edited_{$taxonomy}",
				function ( $term_id ) use ( $taxonomy ): void {
					$this->save_term_meta( (int) $term_id, $taxonomy );
				}
			);
		}
	}

	/**
	 * Get the list of taxonomies the OG fields are exposed on.
	 *
	 * @since 1.2.0
	 *
	 * @return string[] Taxonomy slugs.
	 */
	protected function get_supported_taxonomies(): array {
		$taxonomies = array( 'category', 'post_tag' );

		/**
		 * Filter the taxonomies that expose per-term Open Graph fields.
		 *
		 * @since 1.2.0
		 *
		 * @param string[] $taxonomies Taxonomy slugs.
		 */
		return apply_filters( 'robotstxt_og_term_meta_taxonomies', $taxonomies );
	}

	/**
	 * Register term meta for REST API / block editor access.
	 *
	 * @since 1.2.0
	 *
	 * @return void
	 */
	public function register_term_meta(): void {
		$fields = array(
			self::META_TITLE       => 'sanitize_text_field',
			self::META_IMAGE       => 'sanitize_url',
			self::META_IMAGE_ALT   => 'sanitize_text_field',
			self::META_DESCRIPTION => 'sanitize_textarea_field',
		);

		foreach ( $this->get_supported_taxonomies() as $taxonomy ) {
			$cap = $this->get_edit_cap( $taxonomy );

			foreach ( $fields as $key => $sanitize ) {
				register_term_meta(
					$taxonomy,
					$key,
					array(
						'type'              => 'string',
						'single'            => true,
						'sanitize_callback' => $sanitize,
						'auth_callback'     => static function () use ( $cap ) {
							return current_user_can( $cap );
						},
						'show_in_rest'      => true,
					)
				);
			}
		}
	}

	/**
	 * Resolve the edit capability for a taxonomy.
	 *
	 * @since 1.2.0
	 *
	 * @param string $taxonomy Taxonomy slug.
	 * @return string Capability name.
	 */
	protected function get_edit_cap( string $taxonomy ): string {
		$tax_obj = get_taxonomy( $taxonomy );

		if ( $tax_obj && isset( $tax_obj->cap->edit_terms ) && '' !== $tax_obj->cap->edit_terms ) {
			return $tax_obj->cap->edit_terms;
		}

		return 'manage_categories';
	}

	/**
	 * Supply the stored term image URL during taxonomy archive resolution.
	 *
	 * Hooked to `robotstxt_og_taxonomy_image`. The resolver still validates the
	 * URL and resolves a compatible format, so a raw stored value is fine.
	 *
	 * @since 1.2.0
	 *
	 * @param string $url     Default URL (empty string).
	 * @param int    $term_id Term ID.
	 * @return string
	 */
	public function filter_taxonomy_image( string $url, $term_id ): string {
		$term_id = (int) $term_id;

		if ( $term_id <= 0 ) {
			return $url;
		}

		$stored = get_term_meta( $term_id, self::META_IMAGE, true );
		$stored = is_string( $stored ) ? $stored : '';

		return '' !== $stored ? $stored : $url;
	}

	/**
	 * Render the OG fields on the term edit page.
	 *
	 * Fires inside the existing term-edit form-table, so rows are emitted
	 * directly (no wrapping table).
	 *
	 * @since 1.2.0
	 *
	 * @param WP_Term $term The term being edited.
	 * @return void
	 */
	public function render_term_fields( WP_Term $term ): void {
		wp_nonce_field( self::NONCE_ACTION, self::NONCE_NAME );

		$title = $this->get_meta_string( (int) $term->term_id, self::META_TITLE );
		$image = $this->get_meta_string( (int) $term->term_id, self::META_IMAGE );
		$alt   = $this->get_meta_string( (int) $term->term_id, self::META_IMAGE_ALT );
		$desc  = $this->get_meta_string( (int) $term->term_id, self::META_DESCRIPTION );
		?>
		<tr class="form-field robotstxt-og-term-row">
			<th scope="row">
				<label for="robotstxt_og_term_title"><?php esc_html_e( 'Custom OG Title', 'robotstxt-og' ); ?></label>
			</th>
			<td>
				<input
					type="text"
					id="robotstxt_og_term_title"
					name="robotstxt_og_term_title"
					value="<?php echo esc_attr( $title ); ?>"
					class="large-text"
				/>
				<p class="description">
					<?php esc_html_e( 'Overrides og:title for this term archive. Leave blank to use the term name.', 'robotstxt-og' ); ?>
				</p>
			</td>
		</tr>
		<tr class="form-field robotstxt-og-term-row">
			<th scope="row">
				<label for="robotstxt_og_term_image"><?php esc_html_e( 'OG Image URL', 'robotstxt-og' ); ?></label>
			</th>
			<td>
				<input
					type="url"
					id="robotstxt_og_term_image"
					name="robotstxt_og_term_image"
					value="<?php echo esc_attr( $image ); ?>"
					class="large-text"
				/>
				<p class="description">
					<?php esc_html_e( 'Absolute HTTPS URL for og:image on this term archive. JPEG or PNG recommended.', 'robotstxt-og' ); ?>
				</p>
			</td>
		</tr>
		<tr class="form-field robotstxt-og-term-row">
			<th scope="row">
				<label for="robotstxt_og_term_image_alt"><?php esc_html_e( 'OG Image Alt', 'robotstxt-og' ); ?></label>
			</th>
			<td>
				<input
					type="text"
					id="robotstxt_og_term_image_alt"
					name="robotstxt_og_term_image_alt"
					value="<?php echo esc_attr( $alt ); ?>"
					class="large-text"
				/>
				<p class="description">
					<?php esc_html_e( 'Alt text for the term archive og:image. Leave blank to use the media library alt text.', 'robotstxt-og' ); ?>
				</p>
			</td>
		</tr>
		<tr class="form-field robotstxt-og-term-row">
			<th scope="row">
				<label for="robotstxt_og_term_description"><?php esc_html_e( 'Custom OG Description', 'robotstxt-og' ); ?></label>
			</th>
			<td>
				<textarea
					id="robotstxt_og_term_description"
					name="robotstxt_og_term_description"
					class="large-text"
					rows="3"
				><?php echo esc_textarea( $desc ); ?></textarea>
				<p class="description">
					<?php esc_html_e( 'Overrides og:description for this term archive. Leave blank to use the term description.', 'robotstxt-og' ); ?>
				</p>
			</td>
		</tr>
		<?php
	}

	/**
	 * Save the term OG fields.
	 *
	 * @since 1.2.0
	 *
	 * @param int    $term_id  Term ID.
	 * @param string $taxonomy Taxonomy slug.
	 * @return void
	 */
	public function save_term_meta( int $term_id, string $taxonomy ): void {
		$nonce_raw = filter_input( INPUT_POST, self::NONCE_NAME, FILTER_SANITIZE_FULL_SPECIAL_CHARS );
		$nonce     = $nonce_raw ? sanitize_text_field( wp_unslash( $nonce_raw ) ) : '';

		if ( ! wp_verify_nonce( $nonce, self::NONCE_ACTION ) ) {
			return;
		}

		if ( ! current_user_can( $this->get_edit_cap( $taxonomy ) ) ) {
			return;
		}

		$title_raw = filter_input( INPUT_POST, 'robotstxt_og_term_title', FILTER_SANITIZE_FULL_SPECIAL_CHARS );
		$title     = $title_raw ? sanitize_text_field( wp_unslash( $title_raw ) ) : '';

		$image_raw = filter_input( INPUT_POST, 'robotstxt_og_term_image', FILTER_UNSAFE_RAW );
		$image     = $image_raw ? sanitize_url( wp_unslash( $image_raw ) ) : '';

		$alt_raw = filter_input( INPUT_POST, 'robotstxt_og_term_image_alt', FILTER_SANITIZE_FULL_SPECIAL_CHARS );
		$alt     = $alt_raw ? sanitize_text_field( wp_unslash( $alt_raw ) ) : '';

		$desc_raw = filter_input( INPUT_POST, 'robotstxt_og_term_description', FILTER_UNSAFE_RAW );
		$desc     = $desc_raw ? sanitize_textarea_field( wp_unslash( $desc_raw ) ) : '';

		$this->store_meta( $term_id, self::META_TITLE, $title );
		$this->store_meta( $term_id, self::META_IMAGE, $image );
		$this->store_meta( $term_id, self::META_IMAGE_ALT, $alt );
		$this->store_meta( $term_id, self::META_DESCRIPTION, $desc );
	}

	/**
	 * Store (or delete) a single term meta value.
	 *
	 * @since 1.2.0
	 *
	 * @param int    $term_id Term ID.
	 * @param string $key     Meta key.
	 * @param string $value   Sanitized value.
	 * @return void
	 */
	protected function store_meta( int $term_id, string $key, string $value ): void {
		if ( '' === trim( $value ) ) {
			delete_term_meta( $term_id, $key );
			return;
		}

		update_term_meta( $term_id, $key, $value );
	}

	/**
	 * Read a term meta value as a string.
	 *
	 * @since 1.2.0
	 *
	 * @param int    $term_id Term ID.
	 * @param string $key     Meta key.
	 * @return string
	 */
	private function get_meta_string( int $term_id, string $key ): string {
		$raw = get_term_meta( $term_id, $key, true );

		return is_string( $raw ) ? $raw : '';
	}
}