<?php

/**
* This controller tells a client we provide OAI-PMH protocol and delivers oai-lom-data to harvest.
* Gets initialized due to requests. Validates metadata-prefix and used verb
* and calls a response-template with specified values.
*/
class Oer_OaiController extends StudipController
{

    public function before_filter(&$action, &$args)
    {
        parent::before_filter($action, $args);
        if (!Config::get()->OERCAMPUS_ENABLED) {
            throw new AccessDeniedException();
        }
    }
    public function index_action()
    {
        $this->set_content_type('text/xml;charset=utf-8');
        $this->request_url = Request::url();
        $this->currentDate = gmdate(DATE_ATOM);

        $allowed_verbs = ['GetRecord', 'Identify', 'ListIdentifiers', 'ListMetadataFormats', 'ListRecords', 'ListSets'];
        $allowed_prefix = ['oai_lom-de'];
        $request = Request::getInstance();
        URLHelper::setBaseUrl($GLOBALS['ABSOLUTE_URI_STUDIP']);
        $verb = $request->offsetGet('verb');
        if (!empty($verb) && in_array($verb, $allowed_verbs)) {
            $verb = lcfirst($verb);
            $this->verb = $verb;
        } else {
            $this->render_template("oer/oai/badVerb");
        }

        $metadataPrefix = $request->offsetGet('metadataPrefix');
        if (empty($metadataPrefix) || in_array($metadataPrefix, $allowed_prefix)) {
            $this->metadataPrefix = $metadataPrefix;
        } else {
            if (empty($this->response->body)) {
                $this->render_template("oer/oai/badPrefix");
            }
        }

        if ($this->verb && empty($this->response->body)) {
            $this->prepareRequest($request, $verb, $metadataPrefix);
        }
    }

    public function prepareRequest($request, $verb)
    {
        $this->from = $request->offsetGet('from');
        $set = $request->offsetGet('set');

        switch ($verb) {
            case 'getRecord':
                $this->prepareGetRecord($request);
                break;
            case 'identify':
                $this->prepareIdentifier();
                break;
            case 'listIdentifiers':
                $this->prepareListIdentifiers($set);
                break;
            case 'listMetadataFormats':
                $this->prepareListMetadataFormats($request, $verb);
                break;
            case 'listRecords':
                $this->prepareListRecords($set);
                break;
            case 'listSets':
                $this->prepareListSets();
                break;
        }
    }
    //Prepare responses
    public function prepareGetRecord($request)
    {
        $identifier = $request->offsetGet('identifier');

        if($targetMaterial = OERMaterial::find($identifier)) {
            $this->targetMaterial = $targetMaterial;
            $this->tags = $targetMaterial->getTopics();
            $this->vcard = vCard::export(User::find($targetMaterial->user_id));
            $this->renderResponse($this->verb);
        } else {
            $this->render_template("oer/oai/idNotExists");
        }
    }

    public function prepareListRecords($set)
    {

        $this->vcards = [];
        $tag_collection = [];
        if (!empty($set)) {

            if (empty($target_set = OERTag::findBySQL('name = ?', [$set]))){
                $this->render_template("oer/oai/noSets");
            }
            if ($this->records = OERMaterial::findByTag($set)) {
                foreach ($this->records as $key=>$value) {
                    $tags = $value->getTopics();
                    for($i=0; $i<sizeof($tags); $i++) {
                        $tag_collection[$key][$i] = $tags[$i]['name'];
                    }
                }
                $this->tags = $tags;
                $this->tag_collection = $tag_collection;
                $this->set = $set;
                $this->vcards[] = vCard::export(User::find($value->user_id));
                $this->renderResponse($this->verb);
            }

        } else {

            if ($this->records = OERMaterial::findBySQL('1')) {
                foreach ($this->records as $key=>$value) {
                    $tags = $value->getTopics();
                    for($i=0; $i<sizeof($tags); $i++) {
                        $tag_collection[$key][$i] = $tags[$i]['name'];
                    }
                }
                $this->vcards[] = vCard::export(User::find($value->user_id));
                $this->tag_collection = $tag_collection;
                $this->renderResponse($this->verb);
            } else {
                $this->render_template("oer/oai/noRecordsMatch");
            }

        }

    }

    public function prepareIdentifier()
    {
        $this->earliest_stamp = $this->getEarliestTime();

        if ($identifier = OERTag::findBySQL('1')) {
            $this->identifier = $identifier;
            $this->renderResponse($this->verb);
        } else {
            $this->render_template("oer/oai/noSets");
        }

    }

    public function prepareListIdentifiers($set)
    {
        if (!empty($set)) {
            $this->set = $set;
            $this->records = OERMaterial::findByTag($set);
            foreach ($this->records as $key=>$value) {
                $tags = $value->getTopics();
                for($i=0; $i<sizeof($tags); $i++) {
                    $tag_collection[$key][$i] = $tags[$i]['name'];
                }
            }
        } else {
            $tags = [];
            $tag_collection = [];
            $this->records = OERMaterial::findBySQL('1');
            foreach ($this->records as $key=>$value) {
                $tags = $value->getTopics();
                for($i=0; $i<sizeof($tags); $i++) {
                    $tag_collection[$key][$i] = $tags[$i]['name'];
                }
            }
        }
            $this->tag_collection = $tag_collection;
            $this->renderResponse($this->verb);

    }

    public function prepareListMetadataFormats($request)
    {

        //TODO: get the host of current material - meanwhile we take current host
        if ($identifier = $request->offsetGet('identifier')) {
            if($targetMaterial = OERMaterial::find($identifier)) {
                $this->identifier = $identifier;
                $this->targetMaterial = $targetMaterial;
                $this->renderResponse($this->verb);
            } else {
                $this->render_template("oer/oai/idNotExists");
            }
        } else {
            $this->renderResponse($this->verb);
        }
    }

    public function prepareListSets()
    {
        if ($tags = OERTag::findBySQL('1')) {
            $this->tags = $tags;
            $this->renderResponse($this->verb);
        } else {
            $this->render_template("oer/oai/noSets");
        }
    }
    //Render
    public function renderResponse($verb)
    {
        $this->render_template("oer/oai/".$verb);
    }
    //Helper
    public function getEarliestTime()
    {
        $entries = OERHost::findBySQL(
            '1=1 ORDER BY mkdate asc',
            []
        );
        $entry = $entries[0]->mkdate;
        return $earliest_stamp = gmdate(DATE_ATOM, $entry);
    }
}