<?php
/**
 * Webhook payload builder.
 *
 * @package FormPilot
 * @since   1.0.0
 */

declare( strict_types = 1 );

namespace FormPilot\Webhooks;

use FormPilot\Database\Repositories\FieldRepository;
use FormPilot\Models\Form;
use FormPilot\Submissions\ValueFormatter;

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

/**
 * Builds the JSON body a webhook receives.
 *
 * Fields are sent keyed by field key with their label alongside, so the
 * receiving end can either address a value it knows by name or show the form the
 * way a person filled it in, without having to fetch anything back.
 *
 * @since 1.0.0
 */
final class WebhookPayload {

	/**
	 * Constructor.
	 *
	 * @param FieldRepository $fields    Repository reading fields.
	 * @param ValueFormatter  $formatter Decoder for stored values.
	 */
	public function __construct( private FieldRepository $fields, private ValueFormatter $formatter ) {}

	/**
	 * Builds the payload of a submission.
	 *
	 * @param Form                 $form          Form that was submitted.
	 * @param int                  $submission_id Stored submission ID.
	 * @param array<string, mixed> $values        Stored values keyed by field key.
	 *
	 * @return array<string, mixed> The payload.
	 */
	public function build( Form $form, int $submission_id, array $values ): array {
		$payload = array(
			'event'      => 'submission.created',
			'sent_at'    => gmdate( 'c' ),
			'site'       => array(
				'name' => wp_specialchars_decode( (string) get_bloginfo( 'name' ), ENT_QUOTES ),
				'url'  => home_url( '/' ),
			),
			'form'       => array(
				'id'    => $form->id(),
				'title' => $form->title(),
				'slug'  => $form->slug(),
			),
			'submission' => array(
				'id'     => $submission_id,
				'fields' => $this->fields( $form, $values ),
			),
		);

		/**
		 * Filters the payload sent to the webhooks of a form.
		 *
		 * @since 1.0.0
		 *
		 * @param array<string, mixed> $payload       Payload about to be encoded.
		 * @param Form                 $form          Form that was submitted.
		 * @param int                  $submission_id Stored submission ID.
		 * @param array<string, mixed> $values        Stored values keyed by field key.
		 */
		return (array) apply_filters( 'formpilot_webhook_payload', $payload, $form, $submission_id, $values );
	}

	/**
	 * Builds a payload with made up values, for a test delivery.
	 *
	 * @param Form $form Form the test belongs to.
	 *
	 * @return array<string, mixed> The payload.
	 */
	public function sample( Form $form ): array {
		$payload = $this->build( $form, 0, array() );

		$payload['event'] = 'webhook.test';
		$payload['test']  = true;

		return $payload;
	}

	/**
	 * Builds the field list.
	 *
	 * Every field of the form appears, including the ones with no answer, so the
	 * receiving end sees a stable shape rather than a payload whose keys change
	 * with what the visitor happened to fill in.
	 *
	 * @param Form                 $form   Form that was submitted.
	 * @param array<string, mixed> $values Stored values keyed by field key.
	 *
	 * @return array<int, array<string, mixed>> The fields.
	 */
	private function fields( Form $form, array $values ): array {
		$fields = array();

		foreach ( $this->fields->for_form( $form->id() ) as $field ) {
			$key = $field->field_key();

			if ( ! array_key_exists( $key, $values ) ) {
				// A page break carries no answer and neither does a field added
				// after this submission was stored.
				continue;
			}

			$fields[] = array(
				'key'   => $key,
				'label' => $field->label(),
				'type'  => $field->type(),
				'value' => $this->outbound( $this->formatter->decode( (string) $this->stringify( $values[ $key ] ) ) ),
			);
		}

		return $fields;
	}

	/**
	 * Removes what only this server can use from a value before it leaves.
	 *
	 * A stored upload records the absolute path it was written to, and the
	 * payload used to carry it verbatim - so every file field told a third-party
	 * endpoint where this site lives on disk, which no receiver can do anything
	 * with except learn the server's layout. The URL, name, type and size stay.
	 *
	 * @param mixed $value Decoded value.
	 *
	 * @return mixed The value, without a server path.
	 */
	private function outbound( mixed $value ): mixed {
		if ( $this->formatter->is_file_payload( $value ) ) {
			unset( $value['file'] );
		}

		return $value;
	}

	/**
	 * Returns a stored value as the string the formatter expects.
	 *
	 * @param mixed $value Stored value.
	 */
	private function stringify( mixed $value ): string {
		if ( is_scalar( $value ) ) {
			return (string) $value;
		}

		return (string) wp_json_encode( $value );
	}
}