<?php
/**
 * Error Protection API: WP_Recovery_Mode_Key_Service class
 *
 * @package WordPress
 * @since 5.2.0
 */

/**
 * Core class used to generate and validate keys used to enter Recovery Mode.
 *
 * @since 5.2.0
 */
#[AllowDynamicProperties]
final class WP_Recovery_Mode_Key_Service {

    /**
     * The option name used to store the keys.
     *
     * @since 5.2.0
     * @var string
     */
    private $option_name = 'recovery_keys';

    /**
     * Creates a recovery mode token.
     *
     * @since 5.2.0
     *
     * @return string A random string to identify its associated key in storage.
     */
    public function generate_recovery_mode_token() {
        return wp_generate_password( 22, false );
    }

    /**
     * Creates a recovery mode key.
     *
     * @since 5.2.0
     * @since 6.8.0 The stored key is now hashed using wp_fast_hash() instead of phpass.
     *
     * @param string $token A token generated by {@see WP_Recovery_Mode_Key_Service::generate_recovery_mode_token()}.
     * @return string Recovery mode key.
     */
    public function generate_and_store_recovery_mode_key( $token ) {
        $key = wp_generate_password( 22, false );

        $records = $this->get_keys();

        $records[ $token ] = array(
            'hashed_key' => wp_fast_hash( $key ),
            'created_at' => time(),
        );

        $this->update_keys( $records );

        /**
         * Fires when a recovery mode key is generated.
         *
         * @since 5.2.0
         *
         * @param string $token The recovery data token.
         * @param string $key   The recovery mode key.
         */
        do_action( 'generate_recovery_mode_key', $token, $key );

        return $key;
    }

    /**
     * Verifies if the recovery mode key is correct.
     *
     * Recovery mode keys can only be used once; the key will be consumed in the process.
     *
     * @since 5.2.0
     *
     * @param string $token The token used when generating the given key.
     * @param string $key   The plain text key.
     * @param int    $ttl   Time in seconds for the key to be valid for.
     * @return true|WP_Error True on success, error object on failure.
     */
    public function validate_recovery_mode_key( $token, $key, $ttl ) {
        $records = $this->get_keys();

        if ( ! isset( $records[ $token ] ) ) {
            return new WP_Error( 'token_not_found', __( 'Recovery Mode not initialized.' ) );
        }

        $record = $records[ $token ];

        $this->remove_key( $token );

        if ( ! is_array( $record ) || ! isset( $record['hashed_key'], $record['created_at'] ) ) {
            return new WP_Error( 'invalid_recovery_key_format', __( 'Invalid recovery key format.' ) );
        }

        if ( ! wp_verify_fast_hash( $key, $record['hashed_key'] ) ) {
            return new WP_Error( 'hash_mismatch', __( 'Invalid recovery key.' ) );
        }

        if ( time() > $record['created_at'] + $ttl ) {
            return new WP_Error( 'key_expired', __( 'Recovery key expired.' ) );
        }

        return true;
    }

    /**
     * Removes expired recovery mode keys.
     *
     * @since 5.2.0
     *
     * @param int $ttl Time in seconds for the keys to be valid for.
     */
    public function clean_expired_keys( $ttl ) {

        $records = $this->get_keys();

        foreach ( $records as $key => $record ) {
            if ( ! isset( $record['created_at'] ) || time() > $record['created_at'] + $ttl ) {
                unset( $records[ $key ] );
            }
        }

        $this->update_keys( $records );
    }

    /**
     * Removes a used recovery key.
     *
     * @since 5.2.0
     *
     * @param string $token The token used when generating a recovery mode key.
     */
    private function remove_key( $token ) {

        $records = $this->get_keys();

        if ( ! isset( $records[ $token ] ) ) {
            return;
        }

        unset( $records[ $token ] );

        $this->update_keys( $records );
    }

    /**
     * Gets the recovery key records.
     *
     * @since 5.2.0
     * @since 6.8.0 Each key is now hashed using wp_fast_hash() instead of phpass.
     *              Existing keys may still be hashed using phpass.
     *
     * @return array {
     *     Associative array of token => data pairs, where the data is an associative
     *     array of information about the key.
     *
     *     @type array ...$0 {
     *         Information about the key.
     *
     *         @type string $hashed_key The hashed value of the key.
     *         @type int    $created_at The timestamp when the key was created.
     *     }
     * }
     */
    private function get_keys() {
        return (array) get_option( $this->option_name, array() );
    }

    /**
     * Updates the recovery key records.
     *
     * @since 5.2.0
     * @since 6.8.0 Each key should now be hashed using wp_fast_hash() instead of phpass.
     *
     * @param array $keys {
     *     Associative array of token => data pairs, where the data is an associative
     *     array of information about the key.
     *
     *     @type array ...$0 {
     *         Information about the key.
     *
     *         @type string $hashed_key The hashed value of the key.
     *         @type int    $created_at The timestamp when the key was created.
     *     }
     * }
     * @return bool True on success, false on failure.
     */
    private function update_keys( array $keys ) {
        return update_option( $this->option_name, $keys, false );
    }
}