<?php

namespace Packback\Lti1p3;

class LtiAssignmentsGradesService extends LtiAbstractService
{
    public const CONTENTTYPE_SCORE = 'application/vnd.ims.lis.v1.score+json';
    public const CONTENTTYPE_LINEITEM = 'application/vnd.ims.lis.v2.lineitem+json';
    public const CONTENTTYPE_LINEITEMCONTAINER = 'application/vnd.ims.lis.v2.lineitemcontainer+json';
    public const CONTENTTYPE_RESULTCONTAINER = 'application/vnd.ims.lis.v2.resultcontainer+json';

    public function getScope(): array
    {
        return $this->getServiceData()['scope'];
    }

    // https://www.imsglobal.org/spec/lti-ags/v2p0#assignment-and-grade-service-claim
    // When an LTI message is launching a resource associated to one and only one lineitem,
    // the claim must include the endpoint URL for accessing the associated line item;
    // in all other cases, this property must be either blank or not included in the claim.
    public function getResourceLaunchLineItem(): ?LtiLineitem
    {
        $serviceData = $this->getServiceData();
        if (empty($serviceData['lineitem'])) {
            return null;
        }

        return LtiLineitem::new()->setId($serviceData['lineitem']);
    }

    public function putGrade(LtiGrade $grade, ?LtiLineitem $lineitem = null)
    {
        $this->validateScopes([LtiConstants::AGS_SCOPE_SCORE]);

        $lineitem = $this->ensureLineItemExists($lineitem);
        $scoreUrl = $this->appendLineItemPath($lineitem, '/scores');

        $request = new ServiceRequest(
            ServiceRequest::METHOD_POST,
            $scoreUrl,
            ServiceRequest::TYPE_SYNC_GRADE
        );
        $request->setBody($grade);
        $request->setContentType(static::CONTENTTYPE_SCORE);

        return $this->makeServiceRequest($request);
    }

    public function findLineItem(LtiLineitem $newLineItem): ?LtiLineitem
    {
        $lineitems = $this->getLineItems();

        foreach ($lineitems as $lineitem) {
            if ($this->isMatchingLineitem($lineitem, $newLineItem)) {
                return new LtiLineitem($lineitem);
            }
        }

        return null;
    }

    public function updateLineitem(LtiLineitem $lineitemToUpdate): LtiLineitem
    {
        $request = new ServiceRequest(
            ServiceRequest::METHOD_PUT,
            $lineitemToUpdate->getId(),
            ServiceRequest::TYPE_UPDATE_LINEITEM
        );

        $request->setBody($lineitemToUpdate)
            ->setContentType(static::CONTENTTYPE_LINEITEM)
            ->setAccept(static::CONTENTTYPE_LINEITEM);

        $updatedLineitem = $this->makeServiceRequest($request);

        return new LtiLineitem($updatedLineitem['body']);
    }

    public function createLineitem(LtiLineitem $newLineItem): LtiLineitem
    {
        $request = new ServiceRequest(
            ServiceRequest::METHOD_POST,
            $this->getServiceData()['lineitems'],
            ServiceRequest::TYPE_CREATE_LINEITEM
        );
        $request->setBody($newLineItem)
            ->setContentType(static::CONTENTTYPE_LINEITEM)
            ->setAccept(static::CONTENTTYPE_LINEITEM);
        $createdLineItem = $this->makeServiceRequest($request);

        return new LtiLineitem($createdLineItem['body']);
    }

    public function deleteLineitem(): array
    {
        $request = new ServiceRequest(
            ServiceRequest::METHOD_DELETE,
            $this->getServiceData()['lineitem'],
            ServiceRequest::TYPE_DELETE_LINEITEM
        );

        return $this->makeServiceRequest($request);
    }

    public function findOrCreateLineitem(LtiLineitem $newLineItem): LtiLineitem
    {
        return $this->findLineItem($newLineItem) ?? $this->createLineitem($newLineItem);
    }

    public function getGrades(?LtiLineitem $lineitem = null)
    {
        $lineitem = $this->ensureLineItemExists($lineitem);
        $resultsUrl = $this->appendLineItemPath($lineitem, '/results');

        $request = new ServiceRequest(
            ServiceRequest::METHOD_GET,
            $resultsUrl,
            ServiceRequest::TYPE_GET_GRADES
        );
        $request->setAccept(static::CONTENTTYPE_RESULTCONTAINER);

        return $this->getAll($request);
    }

    public function getLineItems(): array
    {
        $this->validateScopes([LtiConstants::AGS_SCOPE_LINEITEM, LtiConstants::AGS_SCOPE_LINEITEM_READONLY]);

        $request = new ServiceRequest(
            ServiceRequest::METHOD_GET,
            $this->getServiceData()['lineitems'],
            ServiceRequest::TYPE_GET_LINEITEMS
        );
        $request->setAccept(static::CONTENTTYPE_LINEITEMCONTAINER);

        $lineitems = $this->getAll($request);

        // If there is only one item, then wrap it in an array so the foreach works
        if (isset($lineitems['body']['id'])) {
            $lineitems['body'] = [$lineitems['body']];
        }

        return $lineitems;
    }

    public function getLineItem(string $url): LtiLineitem
    {
        $this->validateScopes([LtiConstants::AGS_SCOPE_LINEITEM, LtiConstants::AGS_SCOPE_LINEITEM_READONLY]);

        $request = new ServiceRequest(
            ServiceRequest::METHOD_GET,
            $url,
            ServiceRequest::TYPE_GET_LINEITEM
        );
        $request->setAccept(static::CONTENTTYPE_LINEITEM);

        $response = $this->makeServiceRequest($request)['body'];

        return new LtiLineitem($response);
    }

    private function ensureLineItemExists(?LtiLineitem $lineitem = null): LtiLineitem
    {
        // If no line item is passed in, attempt to use the one associated with
        // this launch.
        if (!isset($lineitem)) {
            $lineitem = $this->getResourceLaunchLineItem();
        }

        // If none exists still, create a default line item.
        if (!isset($lineitem)) {
            $defaultLineitem = LtiLineitem::new()
                ->setLabel('default')
                ->setScoreMaximum(100);
            $lineitem = $this->createLineitem($defaultLineitem);
        }

        // If the line item does not contain an ID, find or create it.
        if (empty($lineitem->getId())) {
            $lineitem = $this->findOrCreateLineitem($lineitem);
        }

        return $lineitem;
    }

    private function isMatchingLineitem(array $lineitem, LtiLineitem $newLineItem): bool
    {
        return $newLineItem->getTag() == ($lineitem['tag'] ?? null) &&
            $newLineItem->getResourceId() == ($lineitem['resourceId'] ?? null) &&
            $newLineItem->getResourceLinkId() == ($lineitem['resourceLinkId'] ?? null);
    }

    private function appendLineItemPath(LtiLineitem $lineItem, string $suffix): string
    {
        $url = $lineItem->getId();
        $pos = strpos($url, '?');

        if ($pos === false) {
            $url = $url.$suffix;
        } else {
            $url = substr_replace($url, $suffix, $pos, 0);
        }

        return $url;
    }
}
