<?php
abstract class Enigma_Rotor_Abstract implements Enigma_Encryptor_Asymmetric_Interface {
    private $_ringOffset;
    protected $_coreMapping;
    protected $_pegPositions=array();

    /**
     * Do we go ÒtickÓ here?
     * @return bool
     */
    public function hasPegAtPosition($position) {
        return(in_array($position,$this->_pegPositions));
    }

    public function setRingOffset ($offset)
    {
        if(preg_match('/^[A-Z]$/',$offset)) {
            $offset=$this->_charToAlphabetPosition($offset);
        } else if(!is_integer($offset) || ($offset<1) || ($offset>26)) {
            throw new Exception("Offset must be integer in range 1..26");
        }
        $this->_ringOffset = $offset;
    }

    public function getRingOffset ()
    {
        return $this->_ringOffset;
    }

    public function getCoreMapping ()
    {
        return $this->_coreMapping;
    }

    public function getOutputCharacterForInputCharacter ($inputCharacter)
    {
        $inputCharacter = strtoupper($inputCharacter);

        $coreInputCharacter = $this->_getCharacterOffsetBy(
        $inputCharacter, $this->_ringOffset-1
        );

        $coreOutputCharacter
        = $this->_coreMapping[$coreInputCharacter];

        $outputCharacter = $this->_getCharacterOffsetBy(
        $coreOutputCharacter, 0 - ($this->_ringOffset-1)
        );

        //        $outputCharacter= $this->_coreMapping[$inputCharacter];

        return ($outputCharacter);
    }

    public function getOutputCharacterForInputCharacterReverse ($inputCharacter)
    {
        $inputCharacter = strtoupper($inputCharacter);
        $coreInputCharacter = $this->_getCharacterOffsetBy($inputCharacter, $this->_ringOffset - 1);

        $flipMap=array_flip($this->_coreMapping);

        $coreOutputCharacter = $flipMap[$coreInputCharacter];
        $outputCharacter = $this->_getCharacterOffsetBy(
        $coreOutputCharacter, 0 - ($this->_ringOffset -1)
        );

        return ($outputCharacter);
    }


    private function _getCharacterOffsetBy ($character, $offset)
    {
        $charAsInt =
        $this->_charToAlphabetPosition($character);

        $newInteger = (26 + $charAsInt - $offset) % 26;

        if($newInteger==0) {
            $newInteger=26;
        }

        $newCharacter =
        $this-> _alphabetPositionToCharacter($newInteger);

        return ($newCharacter);
    }

    private function _charToAlphabetPosition ($char)
    {
        if(!preg_match('/^[A-Z]$/',$char)) {
            throw new Exception ("Bad Character '$char'");
        }
        $position= (ord($char)-64);

        return $position;
    }

    private function _alphabetPositionToCharacter ($position)
    {
        if(($position<1) || ($position>26)){
            throw new Exception ("Bad alphaoffset '$position'");
        }
        $char= (chr($position+64));

        return $char;
    }


}