<?php
/**
 * Rule registry.
 *
 * @package A11yMate
 */

namespace A11yMate\Rules;

use A11yMate\Settings;

defined( 'ABSPATH' ) || exit;

/**
 * Loads rule metadata from data/rules.json and passes it through the a11ymate_rules filter.
 */
class Registry {

	/**
	 * Cached rules keyed by id.
	 *
	 * @var array|null
	 */
	private static $rules = null;

	/**
	 * Cached categories.
	 *
	 * @var array|null
	 */
	private static $categories = null;

	/**
	 * Cached phrases.
	 *
	 * @var array|null
	 */
	private static $phrases = null;

	/**
	 * Read a JSON data file.
	 *
	 * @param string $name File name inside data/.
	 * @return array
	 */
	private static function read( $name ) {
		$file = A11YMATE_DIR . 'data/' . $name;
		if ( ! is_readable( $file ) ) {
			return array();
		}
		$json = file_get_contents( $file ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
		$data = json_decode( (string) $json, true );
		return is_array( $data ) ? $data : array();
	}

	/**
	 * All rules keyed by id.
	 *
	 * @return array
	 */
	public static function all() {
		if ( null === self::$rules ) {
			$data  = self::read( 'rules.json' );
			$rules = array();
			foreach ( isset( $data['rules'] ) ? $data['rules'] : array() as $rule ) {
				// The copy lives in rules.json (one file for the plugin, editor and website); bin/rules-strings.php
				// lists the same strings so translators see them in a11ymate.pot.
				foreach ( array( 'title', 'why', 'fix' ) as $field ) {
					if ( isset( $rule[ $field ] ) ) {
						$rule[ $field ] = translate( $rule[ $field ], 'a11ymate' ); // phpcs:ignore WordPress.WP.I18n.LowLevelTranslationFunction,WordPress.WP.I18n.NonSingularStringLiteralText,WordPress.WP.I18n.NonSingularStringLiteralDomain
					}
				}
				$rules[ $rule['id'] ] = $rule;
			}
			self::$categories = isset( $data['categories'] ) ? $data['categories'] : array();
			foreach ( self::$categories as $i => $cat ) {
				self::$categories[ $i ]['title'] = translate( $cat['title'], 'a11ymate' ); // phpcs:ignore WordPress.WP.I18n.LowLevelTranslationFunction,WordPress.WP.I18n.NonSingularStringLiteralText,WordPress.WP.I18n.NonSingularStringLiteralDomain
			}
			/**
			 * Filter the rule metadata. Add your own rules or tweak the plain-English copy.
			 *
			 * @param array $rules Rules keyed by id.
			 */
			$filtered = apply_filters( 'a11ymate_rules', $rules );
			$rules    = array();
			foreach ( (array) $filtered as $id => $rule ) {
				if ( ! is_array( $rule ) || empty( $rule['id'] ) ) {
					continue;
				}
				$rules[ $rule['id'] ] = self::normalise( $rule );
			}
			self::$rules = $rules;
		}
		return self::$rules;
	}

	/**
	 * Fill in defaults for third-party rules.
	 *
	 * @param array $rule Rule.
	 * @return array
	 */
	private static function normalise( array $rule ) {
		$defaults = array(
			'title'    => $rule['id'],
			'wcag'     => array(
				'sc'    => '',
				'name'  => '',
				'level' => 'A',
			),
			'severity' => 'moderate',
			'category' => 'content',
			'pass'     => 'server',
			'mode'     => 'automated',
			'why'      => '',
			'fix'      => '',
			'example'  => '',
			'helpUrl'  => '',
		);
		return array_merge( $defaults, $rule );
	}

	/**
	 * One rule.
	 *
	 * @param string $id Rule id.
	 * @return array|null
	 */
	public static function get( $id ) {
		$all = self::all();
		return isset( $all[ $id ] ) ? $all[ $id ] : null;
	}

	/**
	 * Categories list.
	 *
	 * @return array
	 */
	public static function categories() {
		self::all();
		return (array) self::$categories;
	}

	/**
	 * Category titles keyed by id.
	 *
	 * @return array
	 */
	public static function category_titles() {
		$out = array();
		foreach ( self::categories() as $c ) {
			$out[ $c['id'] ] = $c['title'];
		}
		return $out;
	}

	/**
	 * Shared phrase lists.
	 *
	 * @return array
	 */
	public static function phrases() {
		if ( null === self::$phrases ) {
			self::$phrases = self::read( 'phrases.json' );
		}
		return self::$phrases;
	}

	/**
	 * Level rank so AAA > AA > A.
	 *
	 * @param string $level Level.
	 * @return int
	 */
	public static function level_rank( $level ) {
		$map = array(
			'A'   => 1,
			'AA'  => 2,
			'AAA' => 3,
		);
		return isset( $map[ $level ] ) ? $map[ $level ] : 1;
	}

	/**
	 * Ids of rules enabled by the current settings (categories and WCAG target).
	 *
	 * @param string|null $pass Limit to server|rendered|editor, or null for all.
	 * @return string[]
	 */
	public static function enabled_ids( $pass = null ) {
		$settings = Settings::all();
		$target   = self::level_rank( $settings['wcag_target'] );
		$cats     = (array) $settings['categories'];
		$ids      = array();
		foreach ( self::all() as $id => $rule ) {
			if ( null !== $pass && $rule['pass'] !== $pass ) {
				continue;
			}
			if ( ! in_array( $rule['category'], $cats, true ) ) {
				continue;
			}
			if ( 'needs-review' === $rule['mode'] ) {
				// Advisory checks ignore the level target; they have their own switch.
				if ( empty( $settings['show_needs_review'] ) ) {
					continue;
				}
			} elseif ( self::level_rank( $rule['wcag']['level'] ) > $target ) {
				continue;
			}
			$ids[] = $id;
		}
		return $ids;
	}

	/**
	 * Rules as a list for the REST API and the editor.
	 *
	 * @return array
	 */
	public static function listing() {
		return array_values( self::all() );
	}

	/**
	 * Reset the cache (tests).
	 *
	 * @return void
	 */
	public static function flush() {
		self::$rules      = null;
		self::$categories = null;
		self::$phrases    = null;
	}
}