<?php
/**
 * Visitor context captured earlier and replayed later.
 *
 * @package AdPix\Analytics
 */

declare( strict_types = 1 );

namespace AdPix\Analytics\Model;

use AdPix\Analytics\Contracts\VisitorContextInterface;

defined( 'ABSPATH' ) || exit;

/**
 * The visitor's cookies, frozen at the moment they mattered.
 *
 * An order is created while the customer is on the site, with their cookies on the request — and then
 * reported minutes or days later, from a payment gateway callback, a cron run or a shop manager
 * clicking Complete in wp-admin. Reading cookies at that point reads whoever is there instead, which
 * is how an order ends up attributed to the shop manager's own session, or to nobody at all.
 *
 * So the context is captured at checkout, stored on the order, and replayed from here when the event
 * is finally sent.
 */
final class StoredVisitorContext implements VisitorContextInterface {

	/**
	 * @var string
	 */
	private $anonymous_id;

	/**
	 * @var array<string,mixed>
	 */
	private $context;

	/**
	 * @var bool
	 */
	private $opted_out;

	/**
	 * Consent decision per category, as it stood at capture time.
	 *
	 * @var array<string,bool>
	 */
	private $consent;

	/**
	 * @param string              $anonymous_id Tracker anonymous id.
	 * @param array<string,mixed> $context      S2S context object.
	 * @param bool                $opted_out    Whether the visitor had opted out.
	 * @param array<string,bool>  $consent      Consent decision per category.
	 */
	private function __construct( string $anonymous_id, array $context, bool $opted_out, array $consent ) {
		$this->anonymous_id = $anonymous_id;
		$this->context      = $context;
		$this->opted_out    = $opted_out;
		$this->consent      = $consent;
	}

	/**
	 * Freeze what a live context currently says.
	 *
	 * @param VisitorContextInterface $live       The request's own context.
	 * @param string[]                $categories Consent categories worth remembering.
	 * @return array<string,mixed> Storable form.
	 */
	public static function capture( VisitorContextInterface $live, array $categories ): array {
		$consent = array();

		foreach ( $categories as $category ) {
			$consent[ $category ] = $live->allows( $category );
		}

		return array(
			'anonymous_id' => (string) $live->anonymous_id(),
			'context'      => $live->to_array(),
			'opted_out'    => $live->has_opted_out(),
			'consent'      => $consent,
		);
	}

	/**
	 * Rebuild from its stored form.
	 *
	 * @param mixed $stored Stored value.
	 * @return self|null Null when nothing usable was stored.
	 */
	public static function from_array( $stored ): ?self {
		if ( ! is_array( $stored ) ) {
			return null;
		}

		$context = isset( $stored['context'] ) && is_array( $stored['context'] ) ? $stored['context'] : array();
		$consent = isset( $stored['consent'] ) && is_array( $stored['consent'] ) ? $stored['consent'] : array();

		$normalised = array();
		foreach ( $consent as $category => $allowed ) {
			$normalised[ (string) $category ] = (bool) $allowed;
		}

		return new self(
			isset( $stored['anonymous_id'] ) && is_scalar( $stored['anonymous_id'] ) ? (string) $stored['anonymous_id'] : '',
			$context,
			! empty( $stored['opted_out'] ),
			$normalised
		);
	}

	/**
	 * The anonymous id captured at the time.
	 *
	 * @return string|null
	 */
	public function anonymous_id(): ?string {
		return '' !== $this->anonymous_id ? $this->anonymous_id : null;
	}

	/**
	 * The context captured at the time.
	 *
	 * @return array<string,mixed>
	 */
	public function to_array(): array {
		return $this->context;
	}

	/**
	 * Whether the visitor had opted out.
	 *
	 * @return bool
	 */
	public function has_opted_out(): bool {
		return $this->opted_out;
	}

	/**
	 * Whether a category was permitted at the time.
	 *
	 * A category nobody thought to record is treated as permitted, matching how a live context reads a
	 * site with no consent banner: absence of a decision is not a refusal.
	 *
	 * @param string $category Consent category.
	 * @return bool
	 */
	public function allows( string $category ): bool {
		return ! array_key_exists( $category, $this->consent ) || $this->consent[ $category ];
	}
}