<?php
/**
 *
 *
 *
 * @author Christian Weiske (original version)
 */
class Erfurt_Sparql_ResultRenderer_Array implements SparqlEngineDb_ResultRenderer {
	
	private $model;
	private $cls;
	
	/**
	 *   Defines the methods needed to create the types
	 *   in $arVarAssignments.
	 *   Key is the type (e.g. "s" for subject), and
	 *   value the method's name.
	 *
	 *   @see $arVarAssignments
	 *
	 *   @var array
	 */
	protected $arCreationMethods = array(
		's' => 'createSubjectFromDbRecordSetPart',
		'p' => 'createPredicateFromDbRecordSetPart',
		'o' => 'createObjectFromDbRecordSetPart'
	);

	public function __construct($model, $class = null) {

		$this->model = $model;
		$this->cls = $class;
		
		if (is_string($this->cls)) $this->cls = strtolower($this->cls);
	}
	
	/**
	*   Converts the database results into the desired output format
    *   and returns the result.
    *
    *   @param array $arRecordSets  Array of (possibly several) SQL query results.
    *   @param Query $query     SPARQL query object
    *   @param SparqlEngineDb $engine   Sparql Engine to query the database
    *   @return mixed   The result as rendered by the result renderers.
    */
    public function convertFromDbResults($arRecordSets, Query $query, SparqlEngineDb $engine) {
	
		$this->query    = $query;
        $this->engine   = $engine;
        $this->sg       = $engine->getSqlGenerator();

        $strResultForm = $this->query->getResultForm();
        switch ($strResultForm) {
            case 'select':
            case 'select distinct':
                $arResult = $this->getVariableArrayFromRecordSets($arRecordSets, $strResultForm);
                return $arResult;

			case 'construct':
            case 'count':
            case 'ask':
           	case 'describe':
            default:
                throw new Exception('Unsupported result form: ' . $strResultForm);
        }
    }

	protected function getVariableArrayFromRecordSets($arRecordSets, $strResultForm) {
		
        $arResult = array();
        foreach ($arRecordSets as $dbRecordSet) {
            $arResult = array_merge(
                $arResult,
                $this->getVariableArrayFromRecordSet($dbRecordSet, $strResultForm)
            );
        }

        return $arResult;
    }

	/**
    *   Converts a ADORecordSet object into an array of "rows" that
    *   are subarrays of variable => value pairs.
    *
    *   @param ADORecordSet $dbRecordSet    Anything ADOConnection::Execute() can return
    *   @return array
    */
    protected function getVariableArrayFromRecordSet(ADORecordSet $dbRecordSet, $strResultForm) {

        $arResult       = array();
        $arResultVars = $this->query->getResultVars();
        
        if (in_array('*', $arResultVars)) {
            $arResultVars   = array_keys($this->sg->arVarAssignments);
        }

        //work around bug in adodb:
        // ADORecordSet_empty does not implement php5 iterators
        if ($dbRecordSet->RowCount() <= 0) {
           return array();
        }



        foreach ($dbRecordSet as $row) {
            $arResultRow = array();
            foreach ($arResultVars as $strVarName) {
                if (!isset($this->sg->arVarAssignments[$strVarName])) {
                    //variable is in select, but not in result (test: q-select-2)
                    $arResultRow[$strVarName] = '';
                } else {
                    $arVarSettings  = $this->sg->arVarAssignments[$strVarName];
                    $strMethod      = $this->arCreationMethods[$arVarSettings[1]];
                    $node = $this->$strMethod($dbRecordSet, $arVarSettings[0], $strVarName);

					if ($node instanceof RDFSResource) $arResult[$node->getURI()] = $node;
					else if ($node instanceof BlankNode) $arResult[$node->getLabel()] = $node;
					else if ($node instanceof RDFSLiteral) $arResult['"'.$node->getLabel().'"@'.$node->getLanguage().'^^'.$node->getDatatype()] = $node;

                }
            }
        }
        return $arResult;
    }

	/**
    *   Creates an RDF Statement object for one of the variables
    *   contained in the given $dbRecordSet object.
    *
    *   @see convertFromDbResult() to understand $strVarBase necessity
    *
    *   @param ADORecordSet $dbRecordSet    Record set returned from ADOConnection::Execute()
    *   @param string       $strVarBase     Prefix of the columns the recordset fields have.
    *
    *   @return Statement   RDF statement object
    */
    protected function createStatementFromDbRecordSetPart(ADORecordSet $dbRecordSet, $strVarBase) {

        return new Statement(
            $this->createSubjectFromDbRecordSetPart  ($dbRecordSet, $strVarBase),
            $this->createPredicateFromDbRecordSetPart($dbRecordSet, $strVarBase),
            $this->createObjectFromDbRecordSetPart   ($dbRecordSet, $strVarBase)
        );
    }

	/**
    *   Creates an RDF subject object
    *   contained in the given $dbRecordSet object.
    *
    *   @see convertFromDbResult() to understand $strVarBase necessity
    *
    *   @param ADORecordSet $dbRecordSet    Record set returned from ADOConnection::Execute()
    *   @param string       $strVarBase     Prefix of the columns the recordset fields have.
    *
    *   @return Resource   RDF triple subject resource object
    */
    protected function createSubjectFromDbRecordSetPart(ADORecordSet $dbRecordSet, $strVarBase, $strVarName) {

        if ($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']] === null) {
            //FIXME: should be NULL, but doesn't pass test
            return '';
        }

        if ($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_is']] == 'r'
            //null should be predicate which is always a resource
         || $dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_is']] === null
        ) {
            $subject    = $this->createResource($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']]);
        } else {
            $subject    = $this->createBlankNode($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']]);
        }
        return $subject;
    }

	/**
    *   Creates an RDF predicate object
    *   contained in the given $dbRecordSet object.
    *
    *   @see convertFromDbResult() to understand $strVarBase necessity
    *
    *   @param ADORecordSet $dbRecordSet    Record set returned from ADOConnection::Execute()
    *   @param string       $strVarBase     Prefix of the columns the recordset fields have.
    *
    *   @return Resource   RDF triple predicate resource object
    */
    protected function createPredicateFromDbRecordSetPart(ADORecordSet $dbRecordSet, $strVarBase, $strVarName) {

        if ($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']] === null) {
            //FIXME: should be NULL, but doesn't pass test
            return '';
        }
        $predicate      = $this->createResource($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']]);
        return $predicate;
    }

    /**
    *   Creates an RDF object object
    *   contained in the given $dbRecordSet object.
    *
    *   @see convertFromDbResult() to understand $strVarBase necessity
    *
    *   @param ADORecordSet $dbRecordSet    Record set returned from ADOConnection::Execute()
    *   @param string       $strVarBase     Prefix of the columns the recordset fields have.
    *
    *   @return Resource   RDF triple object resource object
    */
    protected function createObjectFromDbRecordSetPart(ADORecordSet $dbRecordSet, $strVarBase, $strVarName) {

        if ($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']] === null) {
            //FIXME: should be NULL, but doesn't pass test
            return '';
        }
        switch ($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_is']]) {
            case 'r':
                $object = $this->createResource($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']]);
                break;
            case 'b':
                $object = $this->createBlankNode($dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']]);
                break;
            default:
                $object = $this->createLiteral(
                    $dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_value']],
                    $dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_lang']],
					$dbRecordSet->fields[$strVarBase . '.' . $this->sg->arVarAssignments[$strVarName]['sql_type']]
                );
        }
        return $object;
    }

    

	/**
	 *
	 *
	 * @param string $uri
	 * @return RDFSResource  
	 */
	private function createResource($uri) {

		if ($this->cls === null) return $this->model->resourceF($uri);

		else {
			switch ($this->cls) {
				case 'instance':
					return $this->model->instanceF($uri);
				case 'class':
					return $this->model->classF($uri);
				case 'property':
					return $this->model->propertyF($uri);
				default:
					return $this->model->resourceF($uri);
			}
		}
	}
	
	/**
	 *
	 *
	 * @param string $uri
	 * @return RDFSResource  
	 */
	private function createBlankNode($id) {
		
		if ($this->cls === null) return new BlankNode($id);
		else {
			switch ($this->cls) {
				case 'instance':
					return $this->model->instanceF($id);
				case 'class':
					
					return $this->model->classF($id);
				case 'property':
					return $this->model->propertyF($id);
				default:
					return new BlankNode($id);
			}
		}
	}
	
	/**
	 *
	 *
	 * @param string $uri
	 * @return RDFSResource  
	 */
	private function createLiteral($label, $language = null, $datatype = null) {
		
		return $this->model->literalF($label, $language, $datatype);
	}
}
?>