<?php

declare(strict_types=1);

namespace App\Form\Service;

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

/**
 * Handles processing of the dateOfBirth field for booking participants.
 *
 * This handler manages date of birth processing for participants in the booking creation
 * and edit processes. It processes the dateOfBirth field from form submissions and updates
 * the participant DTO with the provided date. This is crucial for age-based field visibility
 * and service filtering during HTMX form updates.
 *
 * Field Processing:
 * - Extracts date of birth from submitted form data
 * - Converts form date strings to DateTimeImmutable objects
 * - Handles empty selections (converting them to null)
 * - Updates the participant's dateOfBirth property
 *
 * Dependencies: None (this is a base field that other handlers may depend on)
 */
class ParticipantDateOfBirthFieldHandler extends AbstractParticipantFieldHandler
{
    /**
     * Returns the form field name this handler processes.
     *
     * This handler is responsible for the 'dateOfBirth' field, which contains
     * the birth date for each participant in the booking form.
     *
     * @return string The field name 'dateOfBirth'
     */
    public function getFieldName(): string
    {
        return 'dateOfBirth';
    }

    /**
     * Processes the dateOfBirth field for a specific participant.
     *
     * This method extracts the date of birth from the submitted form data and
     * updates the corresponding participant in the booking DTO. It handles the
     * conversion from form date strings to DateTimeImmutable objects and properly
     * handles empty selections.
     *
     * Processing steps:
     * 1. Safely retrieves the participant object from the DTO
     * 2. Extracts the dateOfBirth value from submitted data
     * 3. Normalizes the value (empty string → null, date string → DateTimeImmutable)
     * 4. Updates the participant's dateOfBirth property
     *
     * @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
    {
        // Safely get the participant object, returning early if not found
        $participant = $this->getParticipant($bookingDto, $participantIndex);

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

        // Extract the date of birth from form data (defaults to null if not present)
        $dateOfBirth = $this->getFieldValue($submittedData, $this->getFieldName());

        // Convert form date to DateTimeImmutable, handling empty selections as null
        $participant->dateOfBirth = $this->normalizeDateValue($dateOfBirth);
    }

    /**
     * Normalizes a date value from form submission to DateTimeImmutable or null.
     *
     * This method handles the conversion of form date values to proper DateTimeImmutable
     * objects. It gracefully handles empty strings, null values, and invalid date formats.
     *
     * @param mixed $value The raw value from form submission
     *
     * @return \DateTimeImmutable|null The normalized date or null if empty/invalid
     */
    private function normalizeDateValue(mixed $value): ?\DateTimeImmutable
    {
        // Handle null or empty string (no date selected)
        if (null === $value || '' === trim((string) $value)) {
            return null;
        }

        // If already a DateTimeInterface, convert to DateTimeImmutable
        if ($value instanceof \DateTimeInterface) {
            return \DateTimeImmutable::createFromInterface($value);
        }

        // Try to parse string date
        if (is_string($value)) {
            try {
                return new \DateTimeImmutable($value);
            } catch (\Exception $e) {
                // Invalid date format, return null
                return null;
            }
        }

        // Unsupported type, return null
        return null;
    }
}