class.ilTestRandomQuestionSetBuilderWithAmountPerPool.php

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<?php
/* Copyright (c) 1998-2013 ILIAS open source, Extended GPL, see docs/LICENSE */

require_once 'Modules/Test/classes/class.ilTestRandomQuestionSetBuilder.php';

class ilTestRandomQuestionSetBuilderWithAmountPerPool extends ilTestRandomQuestionSetBuilder
{
        public function checkBuildable()
        {
                $questionStage = $this->getQuestionStageForSourcePoolDefinitionList($this->sourcePoolDefinitionList);
                return $this->isQuestionSetFetchable($this->sourcePoolDefinitionList, $questionStage);
        }

        private function isQuestionSetFetchable(ilTestRandomQuestionSetSourcePoolDefinitionList $sourcePoolDefinitionList, $questionStage)
        {
                $requiredAmount = $this->getRequiredQuestionAmountForDefinitionList($sourcePoolDefinitionList);
                $possibleAmount = count($questionStage);

                return ( $possibleAmount >= $requiredAmount );
        }

        public function performBuild(ilTestSession $testSession)
        {
                $questionSet = array();

                foreach($this->sourcePoolDefinitionList as $definition)
                {
                        $requiredQuestionAmount = $definition->getQuestionAmount();

                        $potentialQuestionStage = $this->getQuestionStageForSourcePoolDefinition($definition);

                        $actualQuestionStage = $this->getUniqueQuestionCollectionFromPotentialQuestionCollection(
                                $potentialQuestionStage, $questionSet
                        );

                        if( $this->questionCollectionGreaterThanRequiredAmount($actualQuestionStage, $requiredQuestionAmount) )
                        {
                                $questions = $this->fetchQuestionsFromStageRandomly($actualQuestionStage, $requiredQuestionAmount);
                        }
                        else
                        {
                                $questions = $actualQuestionStage;
                        }

                        $questionSet = $this->mergeQuestionCollections($questionSet, $questions);
                }

                $requiredQuestionAmount = self::getRequiredQuestionAmountForDefinitionList($this->sourcePoolDefinitionList);

                if( $this->questionCollectionSmallerThanRequiredAmount($questionSet, $requiredQuestionAmount) )
                {
                        $missingQuestionCount = $this->getMissingQuestionCount($questionSet, $requiredQuestionAmount);
                        $questionStage = $this->getQuestionStageForSourcePoolDefinitionList($this->sourcePoolDefinitionList);
                        $questions = $this->fetchQuestionsFromStageRandomly($questionStage, $missingQuestionCount);

                        $questionSet = $this->mergeQuestionCollections($questionSet, $questions);
                }

                $questionSet = $this->handleQuestionOrdering($questionSet);

                $this->storeQuestionSet($testSession, $questionSet);
        }

        private function getUniqueQuestionCollectionFromPotentialQuestionCollection($potentialQuestionCollection, $otherQuestionCollection)
        {
                $uniqueQuestionCollection = array_diff($potentialQuestionCollection, $otherQuestionCollection);
                return $uniqueQuestionCollection;
        }

        private function questionCollectionGreaterThanRequiredAmount($questionCollection, $requiredAmount)
        {
                return count($questionCollection) > $requiredAmount;
        }

        private function questionCollectionSmallerThanRequiredAmount($questionCollection, $requiredAmount)
        {
                return count($questionCollection) < $requiredAmount;
        }

        private function mergeQuestionCollections($questionSet, $questions)
        {
                return array_merge($questionSet, $questions);
        }

        private function getMissingQuestionCount($questionSet, $requiredQuestionAmount)
        {
                return ( $requiredQuestionAmount - count($questionSet) );
        }

        public static function getRequiredQuestionAmountForDefinitionList(ilTestRandomQuestionSetSourcePoolDefinitionList $sourcePoolDefinitionList)
        {
                $requiredQuestionAmountPerTest = 0;

                foreach($sourcePoolDefinitionList as $definition)
                {
                        $requiredQuestionAmountPerTest += $definition->getQuestionAmount();
                }

                return $requiredQuestionAmountPerTest;
        }
}