<?php
/**
 * Settings: defaults, access and sanitising.
 *
 * @package AriAccess
 */

defined( 'ABSPATH' ) || exit;

/**
 * Settings store (one option, grouped by area).
 */
class AriAccess_Settings {

	const OPTION = 'ariaccess_settings';

	/**
	 * Cached settings for this request.
	 *
	 * @var array|null
	 */
	private static $cache = null;

	/**
	 * Toolbar modules that exist, in display order, grouped.
	 *
	 * @return array group => [ module keys ]
	 */
	public static function module_groups() {
		return array(
			'text'   => array( 'text_size', 'line_height', 'letter_spacing', 'readable_font', 'dyslexia_font', 'align_left' ),
			'colour' => array( 'contrast_dark', 'contrast_light', 'monochrome', 'low_saturation', 'highlight_links', 'highlight_headings' ),
			'focus'  => array( 'stop_motion', 'hide_images', 'big_cursor', 'reading_guide', 'reading_mask', 'focus_ring', 'read_aloud' ),
		);
	}

	/**
	 * Flat list of all module keys.
	 *
	 * @return string[]
	 */
	public static function all_modules() {
		return array_merge( ...array_values( self::module_groups() ) );
	}

	/**
	 * Default settings.
	 *
	 * @return array
	 */
	public static function defaults() {
		return array(
			'toolbar' => array(
				'enabled'       => true,
				'position'      => 'bottom-right',
				'color'         => '#1d4ed8',
				'icon'          => 'person',
				'size'          => 'm',
				'hide_mobile'   => false,
				'modules'       => self::all_modules(),
				'profiles'      => true,
				'shortcut'      => true,
				'statement_url' => '',
				'offset_x'      => 20,
				'offset_y'      => 20,
			),
			'fixes'   => array(
				'skip_link'       => true,
				'skip_target'     => '',
				'focus_outline'   => true,
				'focus_color'     => '#1d4ed8',
				'form_labels'     => true,
				'zoom'            => true,
				'new_window'      => 'warn',
				'strip_titles'    => true,
				'tabindex'        => true,
				'read_more'       => true,
				'media_alt'       => true,
				'lang_dir'        => true,
				'empty_search'    => true,
				'underline_links' => false,
				'reduced_motion'  => false,
			),
			'checker' => array(
				'post_types'      => array( 'post', 'page' ),
				'scan_on_save'    => true,
				'standard'        => 'no-private',
				'ambiguous_extra' => '',
			),
			'general' => array(
				'delete_on_uninstall' => false,
			),
		);
	}

	/**
	 * All settings merged over the defaults.
	 *
	 * @return array
	 */
	public static function all() {
		if ( null === self::$cache ) {
			$saved       = get_option( self::OPTION, array() );
			self::$cache = self::merge( self::defaults(), is_array( $saved ) ? $saved : array() );
		}
		return self::$cache;
	}

	/**
	 * One area or one value.
	 *
	 * @param string      $area Area key.
	 * @param string|null $key  Optional key inside the area.
	 * @return mixed
	 */
	public static function get( $area, $key = null ) {
		$all = self::all();
		if ( ! isset( $all[ $area ] ) ) {
			return null;
		}
		if ( null === $key ) {
			return $all[ $area ];
		}
		return isset( $all[ $area ][ $key ] ) ? $all[ $area ][ $key ] : null;
	}

	/**
	 * Save one area after sanitising it.
	 *
	 * @param string $area  Area key.
	 * @param array  $input Raw input.
	 */
	public static function save_area( $area, $input ) {
		$all          = self::all();
		$all[ $area ] = self::sanitize_area( $area, is_array( $input ) ? $input : array() );
		update_option( self::OPTION, $all );
		self::$cache = null;
	}

	/**
	 * Replace everything (used by import) after sanitising.
	 *
	 * @param array $input Raw settings.
	 */
	public static function save_all( $input ) {
		$clean = array();
		foreach ( array_keys( self::defaults() ) as $area ) {
			$clean[ $area ] = self::sanitize_area( $area, isset( $input[ $area ] ) && is_array( $input[ $area ] ) ? $input[ $area ] : array() );
		}
		update_option( self::OPTION, $clean );
		self::$cache = null;
	}

	/**
	 * Forget the per-request cache (tests, imports).
	 */
	public static function flush() {
		self::$cache = null;
	}

	/**
	 * Sanitise one area. Checkboxes missing from the input are false.
	 *
	 * @param string $area  Area key.
	 * @param array  $input Raw input.
	 * @return array
	 */
	public static function sanitize_area( $area, $input ) {
		$defaults = self::defaults();
		$out      = array();
		if ( ! isset( $defaults[ $area ] ) ) {
			return $out;
		}
		foreach ( $defaults[ $area ] as $key => $default ) {
			$value = isset( $input[ $key ] ) ? $input[ $key ] : null;
			if ( is_bool( $default ) ) {
				$out[ $key ] = ! empty( $value );
			} elseif ( is_int( $default ) ) {
				$out[ $key ] = null === $value ? $default : max( 0, min( 200, (int) $value ) );
			} elseif ( is_array( $default ) ) {
				$out[ $key ] = is_array( $value ) ? array_values( array_map( 'sanitize_key', $value ) ) : array();
			} else {
				$out[ $key ] = null === $value ? $default : self::sanitize_string( $area, $key, (string) $value, $default );
			}
		}
		if ( 'toolbar' === $area ) {
			$out['modules'] = array_values( array_intersect( $out['modules'], self::all_modules() ) );
		}
		if ( 'checker' === $area ) {
			$types              = get_post_types( array( 'public' => true ) );
			$out['post_types']  = array_values( array_intersect( $out['post_types'], array_keys( $types ) ) );
		}
		return $out;
	}

	/**
	 * Sanitise a string setting against its allowed values.
	 *
	 * @param string $area    Area.
	 * @param string $key     Key.
	 * @param string $value   Raw value.
	 * @param string $default Default.
	 * @return string
	 */
	private static function sanitize_string( $area, $key, $value, $default ) {
		$choices = array(
			'toolbar.position' => array( 'bottom-right', 'bottom-left', 'top-right', 'top-left', 'middle-right', 'middle-left' ),
			'toolbar.icon'     => array( 'person', 'eye', 'sliders' ),
			'toolbar.size'     => array( 's', 'm', 'l' ),
			'fixes.new_window' => array( 'warn', 'remove', 'off' ),
			'checker.standard' => array( 'no-private', 'no-public', 'wcag21aa', 'wcag22aa' ),
		);
		$id = $area . '.' . $key;
		if ( isset( $choices[ $id ] ) ) {
			return in_array( $value, $choices[ $id ], true ) ? $value : $default;
		}
		if ( in_array( $id, array( 'toolbar.color', 'fixes.focus_color' ), true ) ) {
			$color = sanitize_hex_color( $value );
			return $color ? $color : $default;
		}
		if ( 'toolbar.statement_url' === $id ) {
			return esc_url_raw( $value );
		}
		if ( 'fixes.skip_target' === $id ) {
			// A simple CSS selector: #id, .class, tag, [role=main].
			$value = trim( $value );
			return preg_match( '/^[#.\w\-\[\]=" \']{0,80}$/', $value ) ? $value : '';
		}
		if ( 'checker.ambiguous_extra' === $id ) {
			return sanitize_textarea_field( $value );
		}
		return sanitize_text_field( $value );
	}

	/**
	 * Recursive merge where saved values win and lists are replaced, not merged.
	 *
	 * @param array $defaults Defaults.
	 * @param array $saved    Saved.
	 * @return array
	 */
	private static function merge( $defaults, $saved ) {
		foreach ( $defaults as $key => $value ) {
			if ( ! array_key_exists( $key, $saved ) ) {
				continue;
			}
			if ( is_array( $value ) && self::is_assoc( $value ) && is_array( $saved[ $key ] ) ) {
				$defaults[ $key ] = self::merge( $value, $saved[ $key ] );
			} else {
				$defaults[ $key ] = $saved[ $key ];
			}
		}
		return $defaults;
	}

	/**
	 * Whether an array has string keys.
	 *
	 * @param array $arr Array.
	 * @return bool
	 */
	private static function is_assoc( $arr ) {
		return array() !== $arr && array_keys( $arr ) !== range( 0, count( $arr ) - 1 );
	}
}