<?php

declare (strict_types=1);
namespace PoP\ComponentModel\Response;

use PoP\ComponentModel\App;
use PoP\ComponentModel\TypeResolvers\RelationalTypeResolverInterface;
use PoP\GraphQLParser\Spec\Parser\Ast\FieldInterface;
use PoP\Root\Services\AbstractBasicService;
use SplObjectStorage;
/** @internal */
class DatabaseEntryManager extends AbstractBasicService implements \PoP\ComponentModel\Response\DatabaseEntryManagerInterface
{
    public final const PRIMARY_DBNAME = 'primary';
    public final const HOOK_DBNAME_TO_FIELDNAMES = __CLASS__ . ':dbName-to-fieldNames';
    /**
     * @var array<string,string[]>|null
     */
    protected ?array $dbNameFieldNames = null;
    /**
     * @param array<string|int,SplObjectStorage<FieldInterface,mixed>> $entries
     * @return array<string,array<string|int,SplObjectStorage<FieldInterface,mixed>>>
     */
    public function moveEntriesWithIDUnderDBName(array $entries, RelationalTypeResolverInterface $relationalTypeResolver) : array
    {
        if (!$entries) {
            return [];
        }
        /** @var array<string,array<string|int,SplObjectStorage<FieldInterface,mixed>>> */
        $dbNameEntries = $this->getEntriesUnderPrimaryDBName($entries);
        $dbNameToFieldNames = $this->getDBNameFieldNames($relationalTypeResolver);
        foreach ($dbNameEntries[self::PRIMARY_DBNAME] as $id => $fieldValues) {
            $fields = \iterator_to_array($fieldValues);
            foreach ($dbNameToFieldNames as $dbName => $fieldNames) {
                $fields_to_move = \array_filter($fields, fn(FieldInterface $field) => \in_array($field->getName(), $fieldNames));
                /** @var SplObjectStorage<FieldInterface,mixed> */
                $idDBNameEntries = $dbNameEntries[$dbName][$id] ?? new SplObjectStorage();
                foreach ($fields_to_move as $field) {
                    $idDBNameEntries[$field] = $dbNameEntries[self::PRIMARY_DBNAME][$id][$field];
                    $dbNameEntries[self::PRIMARY_DBNAME][$id]->offsetUnset($field);
                }
                $dbNameEntries[$dbName][$id] = $idDBNameEntries;
            }
        }
        return $dbNameEntries;
    }
    /**
     * Place all entries under dbName "primary"
     *
     * @param SplObjectStorage<FieldInterface,mixed>|array<string|int,SplObjectStorage<FieldInterface,mixed>> $entries
     * @return array<string,SplObjectStorage<FieldInterface,mixed>>|array<mixed,array<int|string,SplObjectStorage<FieldInterface,mixed>>>
     */
    protected function getEntriesUnderPrimaryDBName(array|SplObjectStorage $entries) : array
    {
        return [self::PRIMARY_DBNAME => $entries];
    }
    /**
     * Allow to inject what data fields must be placed under what dbNames
     *
     * @return array<string,string[]> Array of key: dbName, values: field names
     */
    protected function getDBNameFieldNames(RelationalTypeResolverInterface $relationalTypeResolver) : array
    {
        if ($this->dbNameFieldNames === null) {
            $this->dbNameFieldNames = App::applyFilters(self::HOOK_DBNAME_TO_FIELDNAMES, [], $relationalTypeResolver) ?? [];
        }
        return $this->dbNameFieldNames;
    }
    /**
     * @param SplObjectStorage<FieldInterface,mixed> $entries
     * @return array<string,SplObjectStorage<FieldInterface,mixed>>
     */
    public function moveEntriesWithoutIDUnderDBName(SplObjectStorage $entries, RelationalTypeResolverInterface $relationalTypeResolver) : array
    {
        if ($entries->count() === 0) {
            return [];
        }
        // By default place everything under "primary"
        /** @var array<string,SplObjectStorage<FieldInterface,mixed>> */
        $dbNameEntries = $this->getEntriesUnderPrimaryDBName($entries);
        $dbNameToFieldNames = $this->getDBNameFieldNames($relationalTypeResolver);
        $fields = \iterator_to_array($entries);
        foreach ($dbNameToFieldNames as $dbName => $fieldNames) {
            // Move these data fields under "meta" DB name
            $fields_to_move = \array_filter($fields, fn(FieldInterface $field) => \in_array($field->getName(), $fieldNames));
            foreach ($fields_to_move as $field) {
                /** @var SplObjectStorage<FieldInterface,mixed> */
                $dbEntries = $dbNameEntries[$dbName] ?? new SplObjectStorage();
                $dbEntries[$field] = $dbNameEntries[self::PRIMARY_DBNAME][$field];
                $dbNameEntries[self::PRIMARY_DBNAME]->offsetUnset($field);
                $dbNameEntries[$dbName] = $dbEntries;
            }
        }
        return $dbNameEntries;
    }
}
