<?php declare(strict_types=1);
/*
 * This file is part of ANIS SERVER API.
 *
 * (c) François Agneray <francois.agneray@lam.fr>
 * (c) Chrystel Moreau <chrystel.moreau@lam.fr>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace App\Action\Search;

use Psr\Log\LoggerInterface;
use Doctrine\ORM\EntityManagerInterface;
use Doctrine\DBAL\Platforms\PostgreSQL94Platform;
use Doctrine\DBAL\Query\QueryBuilder;
use Doctrine\DBAL\Query\Expression\CompositeExpression;
use Psr\Http\Message\ServerRequestInterface as Request;
use Psr\Http\Message\ResponseInterface as Response;
use PDO;

use App\Utils\ActionTrait;
use App\Utils\DBALConnectionFactory;
use App\Utils\SearchException;
use App\Utils\Operator\IOperatorFactory;
use App\Entity\Dataset;
use App\Entity\Attribute;

/**
 * Get anis data or meta search (GET)
 *
 * @author François Agneray <francois.agneray@lam.fr>
 * @package App\Action\Search
 */
final class SearchAction
{
    use ActionTrait;

    /**
     * The logger interface is the central access point to log anis information
     *
     * @var LoggerInterface
     */
    private $logger;

    /**
     * The EntityManager is the central access point to Doctrine ORM functionality (metadata database)
     *
     * @var EntityManagerInterface
     */
    private $em;

    /**
     * Factory method used to retrieve a PDO connection object to the business database
     *
     * @var DBALConnectionFactory
     */
    private $dcf;

    /**
     *
     * @var IOperatorFactory
     */
    private $operatorFactory;

    /**
     * The encryption key used by anis to encrypt and decrypt sensitive data like passwords
     * This key is provided by configuration (see the config file)
     *
     * @var string
     */
    private $encryptionKey;
  
    /**
     * This class is creates before call __invoke to execute the action
     *
     * @param LoggerInterface         $logger
     * @param EntityManagerInterface  $em
     * @param DBALConnectionFactory   $dcf
     * @param IOperatorFactory        $operatorFactory
     * @param string                  $encryptionKey
     */
    public function __construct(
        LoggerInterface $logger,
        EntityManagerInterface $em,
        DBALConnectionFactory $dcf,
        IOperatorFactory $operatorFactory,
        string $encryptionKey
    ) {
        $this->logger = $logger;
        $this->em = $em;
        $this->dcf = $dcf;
        $this->operatorFactory = $operatorFactory;
        $this->encryptionKey = $encryptionKey;
    }

    /**
     * This action returns data from an anis request
     *
     * @param ServerRequestInterface $request   This object contains the HTTP request
     * @param ResponseInterface      $response  This object represents the HTTP response
     * @param string[]               $args      This table contains information transmitted in the URL (see routes.php)
     *
     * @return ResponseInterface
     */
    public function __invoke(Request $request, Response $response, array $args): Response
    {
        $this->logger->info('Search meta action dispatched');

        if ($request->isOptions()) {
            return $response->withHeader('Access-Control-Allow-Methods', 'GET, OPTIONS');
        }

        $dataset = $this->em->find('App\Entity\Dataset', $args['dname']);

        if (is_null($dataset)) {
            return $this->dispatchHttpError(
                $response,
                'Invalid request',
                'Dataset with id ' . $args['dname'] . ' is not found'
            )->withStatus(404);
        }

        $queryParams = $request->getQueryParams();
        if (!array_key_exists('a', $queryParams)) {
            return $this->dispatchHttpError(
                $response,
                'Invalid request',
                'Param a is required for this request'
            )->withStatus(400);
        }

        $database = $dataset->getProject()->getDatabase();
        $decryptedPassword = $this->decryptData($database->getPassword());
        $connection = $this->dcf->create($database, $decryptedPassword);
        $this->operatorFactory->setDatabasePlatform($connection->getDatabasePlatform());
        
        $queryBuilder = $connection->createQueryBuilder();
        $queryBuilder->from($dataset->getTableRef());

        try {
            $searchType = $this->getAndVerifySearchType($args['type']);

            if (array_key_exists('c', $queryParams)) {
                $this->where($queryBuilder, $dataset, explode(';', $queryParams['c']));
            }
    
            $listOfIds = explode(';', $queryParams['a']);
    
            if ($searchType === 'data') {
                $attributes = $this->select($queryBuilder, $dataset, $listOfIds);
    
                if (array_key_exists('o', $queryParams)) {
                    $this->order($queryBuilder, $dataset, explode(';', $queryParams['o']));
                }
    
                if (array_key_exists('p', $queryParams)) {
                    $this->limit($queryBuilder, $queryParams['p']);
                }
    
                $result = $this->fetchAll($queryBuilder, $attributes);
            } elseif ($searchType === 'meta') {
                $queryBuilder->select('COUNT(*) as nb');
                $stmt = $queryBuilder->execute();
                $count = $stmt->fetchAll();
                $result = array();
                $result['dataset_selected'] = $dataset->getLabel();
                $attributesSelected = array();
                foreach ($listOfIds as $id) {
                    $attribute = $this->getAttribute($dataset, (int) $id);
                    $attributesSelected[] = array(
                        'name' => $attribute->getName(),
                        'label' => $attribute->getLabel()
                    );
                }
                $result['attributes_selected'] = $attributesSelected;
                $result['total_items'] = $count[0]['nb'];
            }
        } catch (SearchException $e) {
            return $this->dispatchHttpError(
                $response,
                'Invalid request',
                $e->getMessage()
            )->withStatus(400);
        }

        $this->logger->info('SQL: ' . $queryBuilder->getSQL());

        return $response->withJson($result, 200, JSON_NUMERIC_CHECK | JSON_UNESCAPED_SLASHES);
    }

    /**
     * Returns one of two accepted search types (meta or data)
     * Or throw an Exception
     *
     * @throws SearchException Bad type of search
     * @param string $type Type of search
     */
    private function getAndVerifySearchType(string $type): string
    {
        if ($type !== 'data' && $type !== 'meta') {
            throw SearchException::typeOfSearchDoesNotExist($type);
        }
        return $type;
    }

    /**
     * Adds the select clause to the request
     *
     * @param QueryBuilder $queryBuilder Represents the query being built
     * @param Dataset      $dataset      Represents the requested dataset
     * @param string[]     $listOfIds    The substring of the url (parameter a)
     */
    private function select(QueryBuilder $queryBuilder, Dataset $dataset, array $listOfIds): array
    {
        $columns = array();
        $attributes = array();
        foreach ($listOfIds as $id) {
            $attribute = $this->getAttribute($dataset, (int) $id);
            $columns[] = $attribute->getTableName() . '.' . $attribute->getName() . ' as ' . $attribute->getLabel();
            $attributes[] = $attribute;
        }
        $queryBuilder->select($columns);

        return $attributes;
    }

    /**
     * Adds the where clause to the request
     *
     * @param QueryBuilder $queryBuilder Represents the query being built
     * @param Dataset      $dataset      Represents the requested dataset
     * @param string[]     $criteria     The substring of the url (parameter c)
     */
    private function where(QueryBuilder $queryBuilder, Dataset $dataset, array $criteria): void
    {
        $expressions = array();
        foreach ($criteria as $criterion) {
            $params = $params = explode('::', $criterion);
            $attribute = $this->getAttribute($dataset, (int) $params[0]);
            $column = $attribute->getTableName() . '.' . $attribute->getName();
            $columnType = $attribute->getType();
            if (array_key_exists(2, $params)) {
                $values = explode('|', $params[2]);
            } else {
                $values = array();
            }
            $operator = $this->operatorFactory->create(
                $params[1],
                $queryBuilder->expr(),
                $column,
                $columnType,
                $values
            );
            $expressions[] = $operator->getExpression();
        }
        $queryBuilder->where(new CompositeExpression(CompositeExpression::TYPE_AND, $expressions));
    }

    /**
     * Adds the order clause to the request
     *
     * @param QueryBuilder $queryBuilder Represents the query being built
     * @param Dataset      $dataset      Represents the requested dataset
     * @param string[]     $orders       The substring of the url (parameter o)
     */
    private function order(QueryBuilder $queryBuilder, Dataset $dataset, array $orders): void
    {
        foreach ($orders as $order) {
            $o = explode(':', $order);
            if (count($o) != 2) {
                throw SearchException::badNumberOfParamsForOrder();
            }
            $attribute = $this->getAttribute($dataset, (int) $o[0]);
            if ($o[1] === 'a') {
                $aord = 'ASC';
            } elseif ($o[1] === 'd') {
                $aord = 'DESC';
            } else {
                throw SearchException::typeOfOrderDoesNotExist($o[1]);
            }
            $queryBuilder->orderBy($attribute->getTableName() . '.' . $attribute->getName(), $aord);
        }
    }

    /**
     * Adds the limit clause to the request
     *
     * @param QueryBuilder $queryBuilder Represents the query being built
     * @param string       $param        The substring of the url (parameter p)
     */
    private function limit(QueryBuilder $queryBuilder, string $param): void
    {
        $p = explode(':', $param);
        if (count($p) != 2) {
            throw SearchException::badNumberOfParamsForLimit();
        }
        $limit = $p[0];
        $offset = ($p[1] - 1) * $limit;
        $queryBuilder
            ->setFirstResult($offset)
            ->setMaxResults($limit);
    }

    private function fetchAll(QueryBuilder $queryBuilder, array $attributes): array
    {
        $jsonAttributes = $this->getAttributesOfTypeJson($attributes);
        $stmt = $queryBuilder->execute();
        $rows = $stmt->fetchAll();
        foreach ($rows as &$row) {
            foreach ($row as $key => &$column) {
                if (array_search($key, $jsonAttributes)) {
                    if (!is_null($column)) {
                        $row[$key] = json_decode($column, true);
                    }
                }
            }
        }
        return $rows;
    }

    private function getAttributesOfTypeJson(array $attributes): array
    {
        return array_map(function ($attribute) {
            return $attribute->getLabel();
        }, array_filter($attributes, function ($attribute) {
            return $attribute->getType() === 'json';
        }));
    }

    /**
     * Returns the Attribute object of a dataset based on its ID (primary key)
     *
     * @throws SearchException Attribute with ID not found into the selected dataset
     * @return Attribute
     */
    private function getAttribute(Dataset $dataset, int $id): Attribute
    {
        $attributes = $dataset->getAttributes();
        foreach ($attributes as $attribute) {
            if ($attribute->getId() === $id) {
                return $attribute;
            }
        }
        throw SearchException::attributeNotFound($id, $dataset->getLabel());
    }
}