<?php
/**
 * Integration lookup.
 *
 * @package FormPilot
 * @since   1.0.0
 */

declare( strict_types = 1 );

namespace FormPilot\Integrations;

use FormPilot\Integrations\Services\Discord;
use FormPilot\Integrations\Services\GoogleSheets;
use FormPilot\Integrations\Services\HubSpot;
use FormPilot\Integrations\Services\Mailchimp;
use FormPilot\Integrations\Services\Make;
use FormPilot\Integrations\Services\Slack;
use FormPilot\Integrations\Services\Zapier;
use FormPilot\Models\Form;
use FormPilot\Settings\Settings;
use FormPilot\Webhooks\Webhook;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Holds the available integrations and each form's configuration for them.
 *
 * @since 1.0.0
 */
final class IntegrationRegistry {

	/**
	 * Settings key holding the per form configuration.
	 */
	public const SETTING = 'integrations';

	/**
	 * Prefix marking a delivery that belongs to an integration.
	 */
	public const PREFIX = 'integration:';

	/**
	 * Integrations resolved for this request.
	 *
	 * @var array<string, Integration>|null
	 */
	private ?array $cache = null;

	/**
	 * Builds the site wide setting name of a shared credential.
	 *
	 * @param string $id  Integration slug.
	 * @param string $key Option name.
	 */
	public static function shared_key( string $id, string $key ): string {
		return 'integration_' . $id . '_' . $key;
	}

	/**
	 * Returns the integrations a site has switched on.
	 *
	 * An empty list means the setting has never been saved, which is different
	 * from a site that deliberately unticked everything — the first should show
	 * all of them, so a fresh install is not an empty screen with no explanation.
	 *
	 * @return array<string, Integration> Integrations keyed by slug.
	 */
	public function all(): array {
		$allowed = Settings::get( 'integrations_enabled' );

		if ( ! is_array( $allowed ) ) {
			return $this->registered();
		}

		return array_intersect_key( $this->registered(), array_flip( array_map( 'strval', $allowed ) ) );
	}

	/**
	 * Returns every integration that exists, whether switched on or not.
	 *
	 * The settings screen needs this: a service cannot be offered as a choice by
	 * a list that has already removed the ones nobody chose.
	 *
	 * @return array<string, Integration> Integrations keyed by slug.
	 */
	public function registered(): array {
		if ( null !== $this->cache ) {
			return $this->cache;
		}

		$services = array(
			new Slack(),
			new Discord(),
			new Zapier(),
			new Make(),
			new Mailchimp(),
			new HubSpot(),
			new GoogleSheets(),
		);

		$integrations = array();

		foreach ( $services as $service ) {
			$integrations[ $service->id() ] = $service;
		}

		/**
		 * Filters the available integrations.
		 *
		 * An add-on registers a service by adding one object implementing
		 * {@see Integration}; the editor, the storage and the delivery follow from
		 * its own description of itself.
		 *
		 * @since 1.0.0
		 *
		 * @param array<string, Integration> $integrations Integrations keyed by slug.
		 */
		$integrations = (array) apply_filters( 'formpilot_integrations', $integrations );

		$this->cache = array_filter(
			$integrations,
			static fn( $integration ): bool => $integration instanceof Integration
		);

		return $this->cache;
	}

	/**
	 * Returns one integration.
	 *
	 * @param string $id Integration slug, with or without the delivery prefix.
	 *
	 * @return Integration|null The integration, or null when nothing is registered under that slug.
	 */
	public function find( string $id ): ?Integration {
		if ( str_starts_with( $id, self::PREFIX ) ) {
			$id = substr( $id, strlen( self::PREFIX ) );
		}

		return $this->all()[ $id ] ?? null;
	}

	/**
	 * Returns a form's configuration for one integration.
	 *
	 * @param Form   $form Form to read.
	 * @param string $id   Integration slug.
	 *
	 * @return array<string, mixed> The stored values, empty when never configured.
	 */
	public function config( Form $form, string $id ): array {
		$stored = $form->setting( self::SETTING, array() );
		$stored = is_array( $stored ) ? $stored : array();
		$config = $stored[ $id ] ?? array();

		return is_array( $config ) ? $config : array();
	}

	/**
	 * Determines whether a form has switched an integration on and filled it in.
	 *
	 * @param Form        $form        Form to read.
	 * @param Integration $integration Integration to check.
	 *
	 * @return bool True when a submission should be delivered to it.
	 */
	public function is_enabled( Form $form, Integration $integration ): bool {
		$config = $this->config( $form, $integration->id() );

		return ! empty( $config['enabled'] ) && $integration->is_configured( $config );
	}

	/**
	 * Returns the integrations a form should deliver to.
	 *
	 * @param Form $form Form to read.
	 *
	 * @return array<string, Integration> Integrations keyed by slug.
	 */
	public function active( Form $form ): array {
		return array_filter(
			$this->all(),
			fn( Integration $integration ): bool => $this->is_enabled( $form, $integration )
		);
	}

	/**
	 * Rebuilds the endpoint of a delivery that is being retried.
	 *
	 * The log stores which integration a row belongs to, not where it was sent:
	 * an API key that has been rotated since should be picked up on the retry
	 * rather than replayed from a copy taken hours ago.
	 *
	 * @param Form   $form Form the delivery belongs to.
	 * @param string $key  Delivery key, including the prefix.
	 *
	 * @return Webhook|null The endpoint, or null when it can no longer be built.
	 */
	public function endpoint( Form $form, string $key ): ?Webhook {
		$integration = $this->find( $key );

		if ( ! $integration instanceof Integration || ! $this->is_enabled( $form, $integration ) ) {
			return null;
		}

		return $integration->endpoint( $form, $this->config( $form, $integration->id() ) );
	}

	/**
	 * Returns the shared secret an integration sends in its request body.
	 *
	 * Read live rather than replayed: the delivery log stores the body with
	 * credentials masked, so a retry asks for the value that is configured *now*.
	 *
	 * @param Form   $form Form the delivery belongs to.
	 * @param string $key  Delivery key, including the prefix.
	 *
	 * @return string The secret, or an empty string when there is none to give.
	 */
	public function secret_for( Form $form, string $key ): string {
		$integration = $this->find( $key );

		if ( ! $integration instanceof Integration || ! $this->is_enabled( $form, $integration ) ) {
			return '';
		}

		$config = $this->config( $form, $integration->id() );

		return isset( $config['secret'] ) && is_scalar( $config['secret'] ) ? trim( (string) $config['secret'] ) : '';
	}
}