<?php
/**
 * Normalized submission context for generic checks.
 *
 * @package ZeroSpamForms
 */

namespace TwoOTwoCode\ZeroSpamForms\Engine;

defined( 'ABSPATH' ) || exit;

/**
 * Immutable, in-memory context for a single submission.
 */
final class SubmissionContext {
	/**
	 * Generic form identifier.
	 *
	 * @var string
	 */
	private $form_id;

	/**
	 * Sanitized honeypot value.
	 *
	 * @var string
	 */
	private $honeypot_value;

	/**
	 * Completion time in seconds.
	 *
	 * @var int|null
	 */
	private $completion_time_seconds;

	/**
	 * Submitted token.
	 *
	 * @var string
	 */
	private $token;

	/**
	 * Privacy-sensitive identifier used only for immediate hashing.
	 *
	 * @var string
	 */
	private $rate_limit_identifier;

	/**
	 * In-memory scalar field values for local checks only.
	 *
	 * @var array<int, string>
	 */
	private $field_values;

	/**
	 * Current timestamp.
	 *
	 * @var int
	 */
	private $timestamp;

	/**
	 * Constructor.
	 *
	 * @param string             $form_id                 Generic form identifier.
	 * @param string             $honeypot_value          Honeypot value.
	 * @param int|null           $completion_time_seconds Completion time.
	 * @param string             $token                   Submitted token.
	 * @param string             $rate_limit_identifier   Identifier used only for hashing.
	 * @param array<int, string> $field_values            In-memory field values.
	 * @param int                $timestamp               Current timestamp.
	 */
	private function __construct(
		string $form_id,
		string $honeypot_value,
		?int $completion_time_seconds,
		string $token,
		string $rate_limit_identifier,
		array $field_values,
		int $timestamp
	) {
		$this->form_id                 = $this->sanitize_key_like_value( $form_id );
		$this->honeypot_value          = $this->limit_string( $honeypot_value, 1000 );
		$this->completion_time_seconds = null === $completion_time_seconds ? null : max( 0, $completion_time_seconds );
		$this->token                   = $this->limit_string( $token, 2048 );
		$this->rate_limit_identifier   = $this->limit_string( $rate_limit_identifier, 512 );
		$this->field_values            = $field_values;
		$this->timestamp               = max( 1, $timestamp );
	}

	/**
	 * Create a context from raw data.
	 *
	 * @param array<string, mixed> $data Raw data.
	 */
	public static function from_array( array $data ): self {
		$field_values = array();

		if ( isset( $data['field_values'] ) && is_array( $data['field_values'] ) ) {
			foreach ( $data['field_values'] as $value ) {
				if ( is_scalar( $value ) ) {
					$field_values[] = self::static_limit_string( (string) $value, 5000 );
				}
			}
		}

		return new self(
			isset( $data['form_id'] ) && is_scalar( $data['form_id'] ) ? (string) $data['form_id'] : 'generic',
			isset( $data['honeypot_value'] ) && is_scalar( $data['honeypot_value'] ) ? (string) $data['honeypot_value'] : '',
			isset( $data['completion_time_seconds'] ) && is_scalar( $data['completion_time_seconds'] ) ? (int) $data['completion_time_seconds'] : null,
			isset( $data['token'] ) && is_scalar( $data['token'] ) ? (string) $data['token'] : '',
			isset( $data['rate_limit_identifier'] ) && is_scalar( $data['rate_limit_identifier'] ) ? (string) $data['rate_limit_identifier'] : '',
			$field_values,
			isset( $data['timestamp'] ) && is_scalar( $data['timestamp'] ) ? (int) $data['timestamp'] : time()
		);
	}

	/**
	 * Get form ID.
	 */
	public function get_form_id(): string {
		return $this->form_id;
	}

	/**
	 * Get honeypot value.
	 */
	public function get_honeypot_value(): string {
		return $this->honeypot_value;
	}

	/**
	 * Get completion time.
	 */
	public function get_completion_time_seconds(): ?int {
		return $this->completion_time_seconds;
	}

	/**
	 * Get submitted token.
	 */
	public function get_token(): string {
		return $this->token;
	}

	/**
	 * Get rate-limit identifier for immediate hashing only.
	 */
	public function get_rate_limit_identifier(): string {
		return $this->rate_limit_identifier;
	}

	/**
	 * Get in-memory field values.
	 *
	 * @return array<int, string>
	 */
	public function get_field_values(): array {
		return $this->field_values;
	}

	/**
	 * Get timestamp.
	 */
	public function get_timestamp(): int {
		return $this->timestamp;
	}

	/**
	 * Sanitize a key-like value without relying on WordPress runtime.
	 *
	 * @param string $value Raw value.
	 */
	private function sanitize_key_like_value( string $value ): string {
		$sanitized = strtolower( preg_replace( '/[^a-zA-Z0-9_.:-]/', '', $value ) ?? '' );

		if ( '' === $sanitized ) {
			return 'generic';
		}

		return $this->limit_string( $sanitized, 128 );
	}

	/**
	 * Limit string length.
	 *
	 * @param string $value  Raw value.
	 * @param int    $length Maximum length.
	 */
	private function limit_string( string $value, int $length ): string {
		return self::static_limit_string( $value, $length );
	}

	/**
	 * Limit string length without needing an instance.
	 *
	 * @param string $value  Raw value.
	 * @param int    $length Maximum length.
	 */
	private static function static_limit_string( string $value, int $length ): string {
		$value = trim( str_replace( "\0", '', $value ) );

		if ( function_exists( 'mb_substr' ) ) {
			return mb_substr( $value, 0, $length );
		}

		return substr( $value, 0, $length );
	}
}