<?php
    /*
    0  1  2  3
    4  5  6  7
    8  9  10 11
    12 13 14 15

    */
    //$letters = "scktaramgkpbniel";
    $letters = "icwiuhvlwarylree";
    $matrix = str_split($letters);
    $lettercount = sizeOf($matrix); 
    $columns = $rows = sqrt($lettercount);
    $letterstartindex = array();
    $usedletterindex = array(); // used to mark off boxes that are already used in constructing the word
    for($i=0;$i<$lettercount;$i++){
        $usedletterindex[$i]=0;
    }

    $handle = @fopen("dictionary.txt", "r");
    if ($handle) {
        $currentletter = "";
        while (($buffer = fgets($handle, 4096)) !== false) {
            if($buffer[0] !== $currentletter){
                $currentletter = $buffer[0];
                $letterstartindex[$currentletter] = ftell($handle);
            }
        }

        foreach($matrix AS $k=>$v){
            $currentletter = $v;
            fseek($handle,$letterstartindex[$currentletter]);
            while (($buffer = fgets($handle, 4096)) !== false && $currentletter === $buffer[0]) {
                if(strlen($buffer) <= 4) continue; // 2 letter words are in the dictionary file but not in scramble
                $word = substr($buffer,0,-1);
                if(wordsearch($word,$k,$usedletterindex)){
                    echo $word."\n";
                }
            }
        }
        fclose($handle);
    }

    function wordsearch($word,$matrixStartIndex,$usedletterindex){
        global $matrix;
        $found = 1;
        if($word[0] === $matrix[$matrixStartIndex]){
            $usedletterindex[$matrixStartIndex] = 1; // mark off first letter
            $found = crawlsearch($word,1,$matrixStartIndex,$usedletterindex);
        }
        else{
            $found = 0;
        }
        return $found;
    }

    function crawlsearch($word,$wordindex,$matrixstartindex,$usedletterindex){
        global $matrix,$columns,$lettercount;
        $usedletterindex[$matrixstartindex] = 1;
        if(strlen($word)==$wordindex+1){
            // word has been found
            return 1;
        }

        $n = $s = $e = $w = 0;
        if($matrixstartindex >= $columns){
            // check north 
            $n = 1;
            $target = $matrixstartindex - $columns;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
        if($matrixstartindex % $columns){
            // check west
            $w = 1;
            $target = $matrixstartindex - 1;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
        if(($matrixstartindex % $columns) != $columns-1){
            // check east
            $e = 1;
            $target = $matrixstartindex + 1;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
        if($matrixstartindex < ($lettercount-$columns)){
            // check south
            $s = 1;
            $target = $matrixstartindex + $columns;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
        if($n && $e){
            // check northeast
            $target = ($matrixstartindex-$columns)+1;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
        if($n && $w){
            // check northwest
            $target = ($matrixstartindex-$columns)-1;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
        if($s && $e){
            // check southeast
            $target = ($matrixstartindex+$columns)+1;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
        if($s && $w){
            // check southwest
            $target = ($matrixstartindex+$columns)-1;
            if(!$usedletterindex[$target] && ($matrix[$target] === $word[$wordindex])){
                // found
                $status = crawlsearch($word,$wordindex+1,$target,$usedletterindex);
                if($status == 1) return $status;
            }
        }
    }
?>