<?php

declare(strict_types=1);

namespace App\Form\Service\Abstract;

use App\BusProNet\Model\Booking;
use App\BusProNet\Model\Service;
use App\Form\Model\BookingDto;
use App\Form\Service\Contract\ParticipantFieldHandlerInterface;

/**
 * Abstract base class providing common functionality for participant field handlers.
 *
 * This class implements common patterns used across participant field handlers,
 * including default implementations for field state modification methods.
 * Reduces boilerplate code in concrete implementations.
 */
abstract class AbstractParticipantFieldHandler implements ParticipantFieldHandlerInterface
{
    /**
     * Returns the field names this handler depends on.
     *
     * Default implementation returns an empty array, meaning no dependencies.
     * Override this method in concrete handlers that depend on other fields
     * being processed first (e.g., a meal preference handler might depend on
     * the room assignment being processed first).
     *
     * @return string[] Array of field names that must be processed before this handler
     */
    public function getDependencies(): array
    {
        return [];
    }

    /**
     * Determines if this handler should process the field based on submitted data.
     *
     * Default implementation checks if the field exists in the submitted data.
     * Override this method for more complex processing conditions (e.g., only
     * process if certain other conditions are met, or skip processing in edit mode).
     *
     * @param array<string, mixed> $submittedData    The submitted participant form data
     * @param string               $mode             The booking mode (BookingDto::MODE_CREATE or MODE_EDIT)
     * @param int                  $participantIndex The index of the participant being processed
     *
     * @return bool True if the handler should process this field, false otherwise
     */
    public function shouldProcess(array $submittedData, string $mode, int $participantIndex): bool
    {
        return isset($submittedData[$this->getFieldName()]);
    }

    /**
     * Safely retrieves a participant object from the booking DTO.
     *
     * This helper method provides safe access to participant data by checking
     * if the participant exists at the given index. Returns null if the
     * participant doesn't exist, preventing array access errors.
     *
     * @param BookingDto $bookingDto       The booking DTO containing participants (create or edit)
     * @param int        $participantIndex The index of the participant to retrieve
     *
     * @return object|null The participant object, or null if not found
     */
    protected function getParticipant(BookingDto $bookingDto, int $participantIndex): ?object
    {
        $participants = $bookingDto->getParticipants();

        return $participants[$participantIndex] ?? null;
    }

    /**
     * Checks if the booking flow is in edit mode.
     *
     * Handlers may need to behave differently in edit mode, particularly when
     * dealing with data that isn't returned by the BPN API (like insurance selections).
     * In edit mode, missing data doesn't mean "clear this field" - it means the API
     * doesn't provide it and it should be preserved as-is.
     *
     * @param BookingDto $bookingDto The booking DTO to check
     *
     * @return bool True if in edit mode, false otherwise
     */
    protected function isEditMode(BookingDto $bookingDto): bool
    {
        return BookingDto::MODE_EDIT === $bookingDto->getMode();
    }

    /**
     * Checks if the booking flow is in create mode.
     *
     * @param BookingDto $bookingDto The booking DTO to check
     *
     * @return bool True if in create mode, false otherwise
     */
    protected function isCreateMode(BookingDto $bookingDto): bool
    {
        return BookingDto::MODE_CREATE === $bookingDto->getMode();
    }

    /**
     * Safely extracts a field value from submitted participant data.
     *
     * This helper method provides safe access to form field values using
     * the null coalescing operator. Useful for extracting field values
     * without worrying about undefined array keys.
     *
     * @param array<string, mixed> $submittedData The submitted participant form data
     * @param string               $fieldName     The name of the field to retrieve
     * @param mixed                $default       The default value to return if field is not set
     *
     * @return mixed The field value, or the default value if not found
     */
    protected function getFieldValue(array $submittedData, string $fieldName, mixed $default = null): mixed
    {
        return $submittedData[$fieldName] ?? $default;
    }

    /**
     * Normalizes empty string values to null.
     *
     * Form inputs often submit empty strings for unselected/empty fields.
     * This helper converts those empty strings to null values, which is
     * typically more appropriate for database storage and business logic.
     *
     * @param mixed $value The value to normalize
     *
     * @return mixed The normalized value (null if empty, original value otherwise)
     */
    protected function normalizeEmptyValue(mixed $value): mixed
    {
        return $this->isEmptyValue($value) ? null : $value;
    }

    /**
     * Converts and normalizes string values to integers.
     *
     * Form inputs submit all values as strings. This helper safely converts
     * string values to integers while handling empty strings and non-numeric
     * values gracefully by returning null.
     *
     * @param mixed $value The value to convert to integer
     *
     * @return int|null The integer value, or null if empty/non-numeric
     */
    protected function normalizeIntValue(mixed $value): ?int
    {
        if ($this->isEmptyValue($value)) {
            return null;
        }

        return is_numeric($value) ? (int) $value : null;
    }

    private function isEmptyValue(mixed $value): bool
    {
        return null === $value
            || false === $value
            || 0 === $value
            || 0.0 === $value
            || '' === $value
            || '0' === $value
            || [] === $value;
    }

    /**
     * Normalizes a checkbox/form toggle value to a boolean.
     *
     * Form checkboxes may submit true, false, 1, 0, '1', '0', or be absent.
     * This method treats only true, 1, and '1' as checked; everything else as unchecked.
     *
     * @param mixed $value The raw value from form submission
     *
     * @return bool True if the checkbox is considered checked, false otherwise
     */
    protected function normalizeCheckboxValue(mixed $value): bool
    {
        return true === $value || 1 === $value || '1' === $value;
    }

    /**
     * Returns field state modifications that should be applied after processing.
     *
     * Default implementation returns no state modifications. Override this method
     * in concrete handlers that need to modify field states based on their
     * processing results.
     *
     * @param array<string, mixed> $submittedData    The submitted participant form data
     * @param BookingDto           $bookingDto       The booking DTO (potentially modified by processing)
     * @param int                  $participantIndex The participant index being processed
     *
     * @return array<string, array<string, mixed>> Empty array (no state modifications by default)
     */
    public function getFieldStateModifications(array $submittedData, BookingDto $bookingDto, int $participantIndex): array
    {
        return [];
    }

    /**
     * Returns field names whose state is affected by this handler's processing.
     *
     * Default implementation returns an empty array, meaning this handler doesn't
     * affect the state of any fields. Override this method in concrete handlers
     * that modify field states.
     *
     * @return string[] Empty array (no affected fields by default)
     */
    public function getAffectedFieldNames(): array
    {
        return [];
    }

    /**
     * Finds an item by ID from an array of objects.
     *
     * Generic helper for validating a selected ID against an array of available
     * items and returning the matching object. Used by handlers that need to
     * validate service, pickup, or other selections against available options.
     *
     * Normalizes the input ID to integer before comparison since Service, Pickup,
     * and Room models all use integer IDs.
     *
     * @param mixed    $selectedId The submitted ID to find (string or int)
     * @param object[] $items      Array of objects with an `id` property (must be int)
     *
     * @return object|null The matching item, or null if not found or invalid ID
     */
    protected function findItemById(mixed $selectedId, array $items): ?object
    {
        $id = $this->normalizeIntValue($selectedId);

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

        foreach ($items as $item) {
            if ($item->id === $id) {
                return $item;
            }
        }

        return null;
    }

    /**
     * Finds a Service in available services by matching the selected value.
     *
     * Handles various input types that may come from form submissions:
     * - Service object: matches by object identity or ID
     * - Integer/numeric string: matches by ID
     *
     * @param mixed     $selectedService   The selected service (Service object, int, or numeric string)
     * @param Service[] $availableServices Array of available Service objects
     *
     * @return Service|null The matching Service, or null if not found
     */
    protected function findServiceInAvailableServices(mixed $selectedService, array $availableServices): ?Service
    {
        foreach ($availableServices as $availableService) {
            if ($this->servicesMatch($selectedService, $availableService)) {
                return $availableService;
            }
        }

        return null;
    }

    /**
     * Checks if a selected service matches an available service.
     *
     * Compares services by object identity first, then by ID. Handles Service objects,
     * integers, and numeric strings from form submissions.
     *
     * @param mixed   $selectedService  The selected service to compare
     * @param Service $availableService The available service to compare against
     *
     * @return bool True if the services match, false otherwise
     */
    protected 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 (int or numeric string from form)
        if (is_numeric($selectedService)) {
            return (int) $selectedService === $availableService->id;
        }

        return false;
    }

    /**
     * Retrieves available services from travel data, merged with booked services in edit mode.
     *
     * In edit mode, services that were previously booked for the participant are included
     * even if they're no longer available in travel data. This prevents booked services
     * from being dropped during form validation when the travel catalog has changed.
     *
     * @param BookingDto $bookingDto              The booking DTO containing travel and booking data
     * @param int        $participantIndex        The participant index to retrieve booked services for
     * @param mixed      $serviceGroup            The service group(s) to filter by (e.g., TOKEN_RENTALS)
     * @param bool       $filterByTravelDateRange Whether to filter travel services by date range
     *
     * @return Service[] Array of available services keyed by service ID
     */
    protected function getAvailableServicesWithBooked(
        BookingDto $bookingDto,
        int $participantIndex,
        mixed $serviceGroup,
        bool $filterByTravelDateRange = false,
    ): array {
        $availableServices = $bookingDto->travel->getAdditionalServicesBySubTypes($serviceGroup, $filterByTravelDateRange);

        if ($this->isEditMode($bookingDto) && null !== $bookingDto->booking) {
            $availableServices = $this->mergeBookedServices(
                $availableServices,
                $bookingDto->booking,
                $participantIndex,
                $serviceGroup
            );
        }

        return $availableServices;
    }

    /**
     * Merges booked services into the available services array.
     *
     * @param Service[] $availableServices The services available from travel data
     * @param Booking   $booking           The booking containing previously booked services
     * @param int       $participantIndex  The participant index to retrieve booked services for
     * @param mixed     $serviceGroup      The service group(s) to filter by
     *
     * @return Service[] Merged array of services keyed by service ID
     */
    private function mergeBookedServices(
        array $availableServices,
        Booking $booking,
        int $participantIndex,
        mixed $serviceGroup,
    ): array {
        $bookedServices = $booking->getAdditionalServicesForParticipantByGroup($participantIndex, $serviceGroup);

        foreach ($bookedServices as $bookedService) {
            if (false === isset($availableServices[$bookedService->id])) {
                $availableServices[$bookedService->id] = $bookedService;
            }
        }

        return $availableServices;
    }
}