<?php
/**
 * Mailchimp integration.
 *
 * @package FormPilot
 * @since   1.0.0
 */

declare( strict_types = 1 );

namespace FormPilot\Integrations\Services;

use FormPilot\Integrations\Integration;
use FormPilot\Integrations\IntegrationContext;
use FormPilot\Models\Form;
use FormPilot\Webhooks\Webhook;

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

/**
 * Adds the person who submitted to a Mailchimp audience.
 *
 * The API key carries the data centre after a dash — `…-us21` — and that is the
 * subdomain the request has to go to, so the endpoint is derived from the key
 * rather than asked for separately.
 *
 * @since 1.0.0
 */
final class Mailchimp extends Integration {

	/**
	 * Returns the slug the configuration is stored under.
	 */
	public function id(): string {
		return 'mailchimp';
	}

	/**
	 * Returns the name shown in the editor.
	 */
	public function label(): string {
		return __( 'Mailchimp', 'devplugins-custom-form-builder' );
	}

	/**
	 * Returns the sentence explaining what to fill in.
	 */
	public function description(): string {
		return __( 'Needs an API key from your Mailchimp account and the Audience ID from Audience settings. Only submissions with a valid email address are sent.', 'devplugins-custom-form-builder' );
	}

	/**
	 * Returns the settings this integration takes, per form.
	 *
	 * @return array<int, array<string, mixed>> The option definitions.
	 */
	public function options(): array {
		return array(
			array(
				'key'         => 'api_key',
				'type'        => 'password',
				'label'       => __( 'API key', 'devplugins-custom-form-builder' ),
				'required'    => true,
				// One account key for the site, overridable per form.
				'shared'      => true,
				'description' => __( 'Leave empty to use the key from the Integrations settings.', 'devplugins-custom-form-builder' ),
			),
			array(
				'key'         => 'list_id',
				'type'        => 'text',
				'label'       => __( 'Audience ID', 'devplugins-custom-form-builder' ),
				'description' => __( 'A short code such as a1b2c3d4e5.', 'devplugins-custom-form-builder' ),
				'required'    => true,
			),
			array(
				'key'      => 'email_field',
				'type'     => 'field',
				'label'    => __( 'Email address comes from', 'devplugins-custom-form-builder' ),
				'required' => true,
			),
			array(
				'key'   => 'first_name_field',
				'type'  => 'field',
				'label' => __( 'First name comes from', 'devplugins-custom-form-builder' ),
			),
			array(
				'key'   => 'last_name_field',
				'type'  => 'field',
				'label' => __( 'Last name comes from', 'devplugins-custom-form-builder' ),
			),
			array(
				'key'         => 'tags',
				'type'        => 'text',
				'label'       => __( 'Tags', 'devplugins-custom-form-builder' ),
				'description' => __( 'Comma separated, applied to everyone added through this form.', 'devplugins-custom-form-builder' ),
			),
			array(
				'key'         => 'double_optin',
				'type'        => 'checkbox',
				'label'       => __( 'Ask for confirmation by email', 'devplugins-custom-form-builder' ),
				'description' => __( 'Adds the person as pending until they confirm. Leave this on unless the form itself made the consent explicit.', 'devplugins-custom-form-builder' ),
			),
		);
	}

	/**
	 * Returns where a submission should be delivered.
	 *
	 * @param Form                 $form   Form being submitted.
	 * @param array<string, mixed> $config Stored values for that form.
	 *
	 * @return Webhook|null The endpoint, or null when there is nothing to send to.
	 */
	public function endpoint( Form $form, array $config ): ?Webhook {
		$key    = $this->option( $config, 'api_key' );
		$centre = $this->data_centre( $key );
		$list   = $this->option( $config, 'list_id' );

		if ( '' === $centre || '' === $list ) {
			return null;
		}

		return $this->target(
			sprintf( 'https://%1$s.api.mailchimp.com/3.0/lists/%2$s/members', $centre, rawurlencode( $list ) ),
			array(
				// Mailchimp accepts any username with the key as the password.
				'Authorization' => 'Basic ' . base64_encode( 'formpilot:' . $key ),
			)
		);
	}

	/**
	 * Determines whether the stored configuration is usable.
	 *
	 * @param array<string, mixed> $config Stored values for one form.
	 *
	 * @return bool True when a submission can be sent.
	 */
	public function is_configured( array $config ): bool {
		return parent::is_configured( $config ) && '' !== $this->data_centre( $this->option( $config, 'api_key' ) );
	}

	/**
	 * Builds the member record.
	 *
	 * @param IntegrationContext   $context Submission being delivered.
	 * @param array<string, mixed> $config  Stored values for the form.
	 *
	 * @return array<string, mixed> The payload.
	 */
	public function payload( IntegrationContext $context, array $config ): array {
		$merge = array();

		$first = $context->value( $this->option( $config, 'first_name_field' ) );
		$last  = $context->value( $this->option( $config, 'last_name_field' ) );

		if ( '' !== $first ) {
			$merge['FNAME'] = $first;
		}

		if ( '' !== $last ) {
			$merge['LNAME'] = $last;
		}

		$payload = array(
			'email_address' => $context->email( $this->option( $config, 'email_field' ) ),
			'status'        => empty( $config['double_optin'] ) ? 'subscribed' : 'pending',
		);

		if ( array() !== $merge ) {
			$payload['merge_fields'] = $merge;
		}

		$tags = array_filter( array_map( 'trim', explode( ',', $this->option( $config, 'tags' ) ) ) );

		if ( array() !== $tags ) {
			$payload['tags'] = array_values( $tags );
		}

		return $payload;
	}

	/**
	 * Returns whether a submission has anything worth sending.
	 *
	 * @param IntegrationContext   $context Submission being delivered.
	 * @param array<string, mixed> $config  Stored values for the form.
	 *
	 * @return bool True when the submission carries a usable address.
	 */
	public function should_send( IntegrationContext $context, array $config ): bool {
		return '' !== $context->email( $this->option( $config, 'email_field' ) );
	}

	/**
	 * Returns the data centre an API key belongs to.
	 *
	 * @param string $key API key.
	 *
	 * @return string The subdomain, or an empty string when the key has no suffix.
	 */
	private function data_centre( string $key ): string {
		if ( ! str_contains( $key, '-' ) ) {
			return '';
		}

		$centre = substr( strrchr( $key, '-' ) ?: '', 1 );

		return 1 === preg_match( '/^[a-z0-9]+$/i', $centre ) ? strtolower( $centre ) : '';
	}
}