<?php
class ZLibStream {
    var $s;
    var $head;
    var $type;
    var $filter;

    function ZLibStream($type)
    {
        $this->type = $type;
        $this->s = array( FALSE, FALSE );
        $this->filter = FALSE;
    }

    static function create($type)
    {
        if ($type == 'plain')
            return (FALSE);

        if (($thiz = new ZLibStream($type)) == FALSE)
            return (FALSE);

        for ($i = 0 ; $i < 2 ; $i++)
            $thiz->s[$i] = FALSE;
        if (($thiz->s = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP)) == FALSE)
            return (FALSE);

        for ($i = 0 ; $i < 2 ; $i++)
            stream_set_blocking  ( $thiz->s[$i], 0); // 0 -> not blocking
        
        if ($type == 'gzip') {
            $params = array('level' => 6, 'window' => -15, 'memory' => 9);
            
            if (($thiz->filter = stream_filter_append($thiz->s[1], "zlib.deflate", STREAM_FILTER_READ, $params)) == FALSE) {
                return (FALSE);
            }
            $thiz->head = "\037\213\010\000\000\000\000\000\000\003";
        }
        else if ($type  == 'deflate') {
            if (($thiz->filter = stream_filter_append($thiz->s[1], "zlib.deflate", STREAM_FILTER_READ)) == FALSE) {
                return (FALSE);
            }
        }
        return ($thiz);
    }

    function destroy()
    {
        if ($this->filter != FALSE) {
            stream_filter_remove($this->filter);
        }

        for ($i = 0 ; $i < 2 ; $i++) {
            if ($this->s[$i] != FALSE)
                fclose($this->s[$i]);
        }
    }

        /*
          too many actors, an explanation is needed to clarify:

          - fwrite: all data MUST be passed to write with success
          - fflush: probably reduntant
          - fread: all reads after successfull writes must go well, 
          
         */
    function compress_chunk($s_in)
    {
        $s_in_l = mb_strlen($s_in, 'ASCII');

        if ($this->head != FALSE) {
            $s_out = $this->head;
            $this->head = FALSE;
        }
        else {
            $s_out = "";
        }

        for ($to_be_proc = $s_in_l, $max_fail = 0 ; $to_be_proc > 0 && $max_fail < 2 ; $max_fail++) {
            if ($to_be_proc > 0) {
                $max_fail = 0;
                if (($ct = fwrite($this->s[0], $s_in)) == FALSE) 
                    return FALSE;
                
                $to_be_proc -= $ct;
            }
            fflush($this->s[0]); // maybe reduntant but light so ...
        
            while (($ret = fread($this->s[1],  8192)) != FALSE) {
                $s_out .= $ret;
            }
        }

        if ($max_fail < 2)
            return ($s_out);
        else
            return (FALSE);
    }

    static function compress($enc, $s)
    {
        // fprintf(STDERR, "compress: [%s][%s]\n", $enc, $s);

        if ($enc == 'gzip') {
            return (gzencode($s, -1, FORCE_GZIP));
        }
        else if ($enc == 'deflate') {
            return (gzencode($s, -1, FORCE_DEFLATE));
        }
        else
            return $s;
    }
} // class ZLibStream 


function zlibstream_test()
{
    $cont = array( "pippo", "pluto", "paperino");

    for ($f = 0 ; $f < 2 ; $f++) {
        if (($zls = ZLibStream::create('gzip')) == FALSE) {
            printf("ZLibStream Creation failed\n");
            exit(1);
        }
        
        if (($fp = fopen("../../test/zlibstream".$f.".gz", "w")) == FALSE) {
            printf("ZLibStream test output file failed\n");
            exit(2);
        }   
        
        for ($i = 0 ; $i < 9 ; $i++) {
            $idx = $i % 3;
            
            $comp = $zls->compress_chunk($cont[$idx]);
            
            fwrite($fp, $comp);
            fflush($fp);
            sleep(3);
        }
        fclose($fp);
        $zls->destroy();
    }
}

// zlibstream_test();

?>