<?php
/**
 * Final anti-spam engine decision.
 *
 * @package ZeroSpamForms
 */

namespace TwoOTwoCode\ZeroSpamForms\Engine;

defined( 'ABSPATH' ) || exit;

/**
 * Immutable decision returned by the spam engine.
 */
final class SpamDecision {
	public const VERDICT_ALLOW      = 'allow';
	public const VERDICT_SUSPICIOUS = 'suspicious';
	public const VERDICT_BLOCK      = 'block';

	/**
	 * Frontend-safe generic block message.
	 */
	private const GENERIC_BLOCK_MESSAGE = 'Your submission could not be accepted. Please try again.';

	/**
	 * Decision verdict.
	 *
	 * @var string
	 */
	private $verdict;

	/**
	 * Safe internal reason codes.
	 *
	 * @var array<int, string>
	 */
	private $reason_codes;

	/**
	 * Constructor.
	 *
	 * @param string             $verdict      Decision verdict.
	 * @param array<int, string> $reason_codes Safe internal reason codes.
	 */
	private function __construct( string $verdict, array $reason_codes = array() ) {
		$this->verdict      = $verdict;
		$this->reason_codes = array_values( array_unique( $reason_codes ) );
	}

	/**
	 * Create an allow decision.
	 */
	public static function allow(): self {
		return new self( self::VERDICT_ALLOW );
	}

	/**
	 * Create a suspicious decision.
	 *
	 * @param array<int, string> $reason_codes Safe internal reason codes.
	 */
	public static function suspicious( array $reason_codes ): self {
		return new self( self::VERDICT_SUSPICIOUS, $reason_codes );
	}

	/**
	 * Create a block decision.
	 *
	 * @param array<int, string> $reason_codes Safe internal reason codes.
	 */
	public static function block( array $reason_codes ): self {
		return new self( self::VERDICT_BLOCK, $reason_codes );
	}

	/**
	 * Get decision verdict.
	 */
	public function get_verdict(): string {
		return $this->verdict;
	}

	/**
	 * Whether the submission should be blocked.
	 */
	public function should_block(): bool {
		return self::VERDICT_BLOCK === $this->verdict;
	}

	/**
	 * Whether the submission should be treated as suspicious.
	 */
	public function is_suspicious(): bool {
		return self::VERDICT_SUSPICIOUS === $this->verdict;
	}

	/**
	 * Get safe internal reason codes.
	 *
	 * @return array<int, string>
	 */
	public function get_reason_codes(): array {
		return $this->reason_codes;
	}

	/**
	 * Get a generic frontend-facing message.
	 */
	public function get_frontend_message(): string {
		return self::GENERIC_BLOCK_MESSAGE;
	}
}