<?php

declare(strict_types=1);

namespace App\Form\Service;

use App\Form\Model\BookingDto;
use App\Form\Model\ParticipantDto;
use App\Form\Service\Abstract\AbstractParticipantFieldHandler;

/**
 * Handles the email field, pre-filling the applicant's address for under-16 participants.
 *
 * BusPro requires a Mail-Adresse for every participant once a room is present and rejects the
 * step-3 Anfrage with 650 otherwise, children included. It does accept an address identical to
 * the Anmelder's, so children inherit the applicant's rather than being asked for one they
 * typically do not have. The value stays editable and stays mandatory. This happens in the
 * create flow only; in edit mode the handler just stores what was submitted.
 *
 * The copy only ever fills a blank, so an address somebody typed is never overwritten. A later
 * correction to the applicant's own address therefore does not propagate to children who already
 * inherited the previous one.
 *
 * Depends on dateOfBirth: whether a participant counts as a child is only known once their date
 * of birth has been processed.
 */
class ParticipantEmailFieldHandler extends AbstractParticipantFieldHandler
{
    public function getFieldName(): string
    {
        return 'email';
    }

    /**
     * @return string[]
     */
    public function getDependencies(): array
    {
        return ['dateOfBirth'];
    }

    /**
     * @param array<string, mixed> $submittedData    The submitted participant form data
     * @param BookingDto           $bookingDto       The booking DTO to update (create or edit)
     * @param int                  $participantIndex The index of the participant being processed
     */
    public function processField(array $submittedData, BookingDto $bookingDto, int $participantIndex): void
    {
        $participant = $this->getParticipant($bookingDto, $participantIndex);

        if (false === $participant instanceof ParticipantDto) {
            return;
        }

        $submitted = $this->getFieldValue($submittedData, $this->getFieldName());

        if (true === is_string($submitted)) {
            $participant->email = '' !== trim($submitted) ? trim($submitted) : null;
        }

        $this->applyApplicantEmail($bookingDto, $participant);
    }

    /**
     * Copies the applicant's address onto a child who has none of their own.
     */
    public function applyApplicantEmail(BookingDto $bookingDto, ParticipantDto $participant): void
    {
        // Create mode only. An existing booking already carries whatever BusPro accepted, a
        // blank may be intended where personal data is optional, and participant[0] is not
        // reliably the applicant there.
        if (BookingDto::MODE_CREATE !== $bookingDto->getMode()) {
            return;
        }

        if (false === $participant->isChild()) {
            return;
        }

        $applicantEmail = $this->resolveApplicantEmail($bookingDto);

        if (null === $applicantEmail) {
            return;
        }

        // The applicant themselves never inherits, and on an ordinary booking that is participant[0].
        if (true === $participant->isApplicant() && true === $bookingDto->applicantTravels) {
            return;
        }

        if (null === $participant->email || '' === trim($participant->email)) {
            $participant->email = $applicantEmail;
        }
    }

    private function resolveApplicantEmail(BookingDto $bookingDto): ?string
    {
        $applicant = $bookingDto->applicantTravels
            ? ($bookingDto->participants[0] ?? null)
            : $bookingDto->applicant;

        $email = $applicant?->email;

        if (null === $email || '' === trim($email)) {
            return null;
        }

        return trim($email);
    }
}