<?php

declare(strict_types=1);

namespace App\Form\Service;

use App\BusProNet\Constants;
use App\BusProNet\Model\Service;
use App\Form\Model\BookingDtoInterface;
use App\Form\Service\Abstract\AbstractParticipantFieldHandler;

/**
 * Handles processing of the courses field for booking participants.
 *
 * This handler manages course selections for participants in the booking
 * creation process. It processes the courses field from form submissions,
 * filters out age-inappropriate courses, and updates the participant DTO with only
 * valid selections.
 *
 * Key responsibilities:
 * - Validates course selections against age constraints
 * - Removes courses that are no longer available due to age changes
 * - Maintains data consistency during HTMX form updates
 * - Prevents form validation errors from stale course selections
 *
 * Dependencies: dateOfBirth (must be processed first for age evaluation)
 */
class ParticipantCoursesFieldHandler extends AbstractParticipantFieldHandler
{
    /**
     * Returns the form field name this handler processes.
     *
     * @return string The field name 'courses'
     */
    public function getFieldName(): string
    {
        return 'courses';
    }

    /**
     * Returns the field dependencies for proper processing order.
     *
     * This handler depends on dateOfBirth being processed first because
     * age evaluation requires the participant's birth date to be available.
     *
     * @return string[] Array containing 'dateOfBirth' dependency
     */
    public function getDependencies(): array
    {
        return ['dateOfBirth'];
    }

    /**
     * Determines if this handler should process the field based on submitted data.
     *
     * For service selection fields like courses, we always need to process
     * to handle cases where all selections are cleared (field not present in data).
     * This ensures the participant DTO is updated with an empty array when no
     * services are selected.
     *
     * @param array<string, mixed> $submittedData    The submitted participant form data
     * @param int                  $participantIndex The index of the participant being processed
     *
     * @return bool Always returns true for service selection fields
     */
    public function shouldProcess(array $submittedData, int $participantIndex): bool
    {
        return true; // Always process to handle deselection cases
    }

    /**
     * Processes the courses field for a specific participant.
     *
     * This method extracts course selections from submitted form data,
     * validates each selection against the participant's age constraints, and
     * updates the participant DTO with only valid selections. Courses that are
     * no longer appropriate for the participant's age are automatically removed.
     *
     * @param array<string, mixed> $submittedData    The submitted participant form data
     * @param BookingDtoInterface  $bookingDto       The booking DTO to update (create or edit)
     * @param int                  $participantIndex The index of the participant being processed
     */
    public function processField(array $submittedData, BookingDtoInterface $bookingDto, int $participantIndex): void
    {
        // Safely get the participant object, returning early if not found
        $participant = $this->getParticipant($bookingDto, $participantIndex);
        if (null === $participant) {
            return;
        }

        // Extract current course selections from submitted data
        $selectedCourses = $this->getFieldValue($submittedData, $this->getFieldName()) ?? [];

        // Get available courses from travel data
        $availableCourses = $bookingDto->travel->getAdditionalServicesBySubTypes(Constants::TOKEN_COURSES);

        // Filter selections to keep only age-appropriate courses
        $validSelections = $this->filterValidServiceSelections(
            $selectedCourses,
            $availableCourses,
            $bookingDto,
            $participantIndex
        );

        // Update participant with validated selections
        $participant->courses = $validSelections;
    }

    /**
     * Filters course selections to keep only those valid for the participant's age.
     *
     * @param array               $selectedServices  List of currently selected courses
     * @param array               $availableServices List of all available courses
     * @param BookingDtoInterface $bookingDto        The booking DTO for context
     * @param int                 $participantIndex  The participant index for age evaluation
     *
     * @return array Filtered array of valid course selections
     */
    private function filterValidServiceSelections(
        array $selectedServices,
        array $availableServices,
        BookingDtoInterface $bookingDto,
        int $participantIndex,
    ): array {
        $validSelections = [];

        foreach ($selectedServices as $selectedService) {
            if ($this->isServiceValidForParticipant($selectedService, $availableServices, $bookingDto, $participantIndex)) {
                $validSelections[] = $selectedService;
            }
        }

        return $validSelections;
    }

    /**
     * Validates if a selected course is still valid for the participant.
     *
     * @param mixed               $selectedService   The selected course to validate
     * @param array               $availableServices Array of available courses
     * @param BookingDtoInterface $bookingDto        The booking DTO for context
     * @param int                 $participantIndex  The participant index for age evaluation
     *
     * @return bool True if the course is valid for the participant, false otherwise
     */
    private function isServiceValidForParticipant(
        mixed $selectedService,
        array $availableServices,
        BookingDtoInterface $bookingDto,
        int $participantIndex,
    ): bool {
        // Find the service in available services
        $service = $this->findServiceInAvailableServices($selectedService, $availableServices);

        if (null === $service) {
            return false; // Service not found in available services
        }

        // Check if service has age constraints
        $ageEvaluator = new ServiceAgeEvaluator();
        if (false === $ageEvaluator->canEvaluate($service)) {
            return true; // No age restrictions, service is valid
        }

        // Validate service against participant's age
        return $ageEvaluator->isServiceAvailableForParticipant($service, $bookingDto, $participantIndex);
    }

    /**
     * Finds a selected course in the list of available courses.
     *
     * @param mixed $selectedService   The selected course to find
     * @param array $availableServices Array of available Service objects
     *
     * @return Service|null The found service or null if not found
     */
    private function findServiceInAvailableServices(mixed $selectedService, array $availableServices): ?Service
    {
        foreach ($availableServices as $availableService) {
            if ($this->servicesMatch($selectedService, $availableService)) {
                return $availableService;
            }
        }

        return null;
    }

    /**
     * Determines if a selected course matches an available course.
     *
     * @param mixed   $selectedService  The selected course from form data
     * @param Service $availableService The available course to compare against
     *
     * @return bool True if the courses match, false otherwise
     */
    private function servicesMatch(mixed $selectedService, Service $availableService): bool
    {
        // Direct object comparison
        if ($selectedService === $availableService) {
            return true;
        }

        // ID comparison for Service objects
        if ($selectedService instanceof Service) {
            return $selectedService->id === $availableService->id;
        }

        // ID comparison for numeric values
        if (is_numeric($selectedService)) {
            return (int) $selectedService === $availableService->id;
        }

        // String ID comparison
        if (is_string($selectedService)) {
            return $selectedService === (string) $availableService->id;
        }

        return false;
    }
}