<?php
/**
 * Application service for sending events to AdPix.
 *
 * @package AdPix\Analytics
 */

declare( strict_types = 1 );

namespace AdPix\Analytics\Service;

use AdPix\Analytics\Contracts\LoggerInterface;
use AdPix\Analytics\Contracts\QueueInterface;
use AdPix\Analytics\Contracts\SettingsRepositoryInterface;
use AdPix\Analytics\Contracts\VisitorContextInterface;
use AdPix\Analytics\Model\Event;
use AdPix\Analytics\Model\Identity;
use AdPix\Analytics\Model\Job;

defined( 'ABSPATH' ) || exit;

/**
 * The only way anything in this plugin sends an event.
 *
 * Every integration — WooCommerce, the user hooks, the form handlers — hands its event here and is
 * finished. This class enriches it with the visitor's cookies, applies the consent decision and puts
 * it on the queue. Nothing sends synchronously: a customer pressing Place Order must never wait on a
 * request to a third-party host, and must never see an error page because that host was slow.
 */
final class EventRecorder {

	/**
	 * @var SettingsRepositoryInterface
	 */
	private $settings;

	/**
	 * @var QueueInterface
	 */
	private $queue;

	/**
	 * @var VisitorContextInterface
	 */
	private $visitor;

	/**
	 * @var ConsentGate
	 */
	private $consent;

	/**
	 * @var LoggerInterface
	 */
	private $logger;

	/**
	 * @param SettingsRepositoryInterface $settings Configuration source.
	 * @param QueueInterface              $queue    Delivery queue.
	 * @param VisitorContextInterface     $visitor  The current request's visitor.
	 * @param ConsentGate                 $consent  Consent decision.
	 * @param LoggerInterface             $logger   Failure log.
	 */
	public function __construct(
		SettingsRepositoryInterface $settings,
		QueueInterface $queue,
		VisitorContextInterface $visitor,
		ConsentGate $consent,
		LoggerInterface $logger
	) {
		$this->settings = $settings;
		$this->queue    = $queue;
		$this->visitor  = $visitor;
		$this->consent  = $consent;
		$this->logger   = $logger;
	}

	/**
	 * Queue an event.
	 *
	 * @param Event                        $event    The event.
	 * @param string                       $category Consent category it falls under.
	 * @param VisitorContextInterface|null $visitor  Context to attribute it to; defaults to this
	 *                                               request's. An order passes the context frozen at
	 *                                               checkout so it is not attributed to whoever
	 *                                               happened to trigger the status change.
	 * @return bool Whether it was accepted for delivery.
	 */
	public function record( Event $event, string $category = ConsentGate::CATEGORY_STATISTICS, ?VisitorContextInterface $visitor = null ): bool {
		$visitor = null !== $visitor ? $visitor : $this->visitor;

		if ( ! $this->settings->load()->is_connected() ) {
			return false;
		}

		if ( ! $this->consent->allows( $category, $visitor ) ) {
			return false;
		}

		$enriched = $event
			->with_anonymous_id( $visitor->anonymous_id() )
			->with_context( $visitor->to_array() );

		if ( ! $enriched->is_identifiable() ) {
			// No identity and no cookie. The collector would accept it and create a user that can never
			// be matched to anything, which is worse than not sending it: it inflates the user count and
			// attributes the conversion to nobody.
			$this->logger->debug( 'Skipped an event with no way to identify the visitor', array( 'event' => $event->name() ) );

			return false;
		}

		return $this->enqueue( 'events', $enriched->to_array() );
	}

	/**
	 * Queue an identify call, which attaches an email or phone number to the visitor's profile.
	 *
	 * @param Identity                     $identity Who the visitor is.
	 * @param string                       $category Consent category it falls under.
	 * @param VisitorContextInterface|null $visitor  Context to attribute it to.
	 * @return bool
	 */
	public function identify( Identity $identity, string $category = ConsentGate::CATEGORY_STATISTICS, ?VisitorContextInterface $visitor = null ): bool {
		$visitor = null !== $visitor ? $visitor : $this->visitor;

		$settings = $this->settings->load();

		if ( ! $settings->is_connected() ) {
			return false;
		}

		// The collector rejects an identify with no external id, email or phone, so there is no point
		// spending a queued request and a retry cycle discovering that.
		if ( $identity->is_empty() ) {
			return false;
		}

		if ( ! $this->consent->allows( $category, $visitor ) ) {
			return false;
		}

		$payload = $identity->to_array();

		$anonymous = $visitor->anonymous_id();
		if ( null !== $anonymous ) {
			// This is the whole point of the call: it is what merges the anonymous browsing that led up
			// to the sign-up with the person who signed up.
			$payload['anonymous_id'] = $anonymous;
		}

		$traits = $identity->traits();
		if ( array() !== $traits ) {
			$payload['traits'] = $traits;
		}

		$context = $visitor->to_array();
		if ( array() !== $context ) {
			$payload['context'] = $context;
		}

		$default_cc = $settings->str( 'default_cc' );
		if ( '' !== $default_cc ) {
			// Lets a national phone number such as 09121234567 resolve to the same person as its
			// international form, on properties that have not set a calling code of their own.
			$payload['default_cc'] = $default_cc;
		}

		return $this->enqueue( 'identify', $payload );
	}

	/**
	 * Put a payload on the queue.
	 *
	 * @param string              $endpoint Endpoint suffix.
	 * @param array<string,mixed> $payload  Request body.
	 * @return bool
	 */
	private function enqueue( string $endpoint, array $payload ): bool {
		$accepted = $this->queue->push( new Job( $endpoint, $payload ) );

		if ( ! $accepted ) {
			$this->logger->error(
				'The delivery queue is full; an event was dropped',
				array(
					'endpoint' => $endpoint,
					'event'    => isset( $payload['event'] ) && is_scalar( $payload['event'] ) ? (string) $payload['event'] : $endpoint,
				)
			);
		}

		return $accepted;
	}
}