<?php

class DecoderFactory {

    private $minlen = 0;
    private $maxlen = 0;

    private $line = "";
    private $linelength = 0;

    private $patterns = array();

    public function __construct($minlen,$maxlen) {
        $this->minlen = $minlen;
        $this->maxlen = $maxlen;
    }

    public function load($msg) {
        foreach (str_split($msg) as $m) $this->push($m);
    }

    public function getPatterns() {
        return $this->patterns;
    }

    public function push($char) {
        $l = strlen($char);
        if ($l == 0) return;
        if ($l != 1) $char = $char[0];

        $this->line .= $char;
        $this->linelength ++;

        for ($n=$this->minlen; $n <= $this->maxlen; $n++) {
            if ($n > $this->linelength) break;
            $key = substr($this->line,-$n);

            if (!isset($this->patterns[$key]))
                $this->patterns[$key] = 1;
            else
                $this->patterns[$key]++;

        }

    }
}

// --------------

if ($argc != 5) die ("uso: $argv[0] minlen maxlen num_rank mensaje\n");

$patrones = array();

$minlen = intval($argv[1]);
$maxlen = intval($argv[2]);
$numrank = intval($argv[3]);
$mensaje = $argv[4];

if ($minlen < 1) die ("minlen incorrecto\n");
if ($maxlen < $minlen) die ("maxlen incorrecto\n");

if ($maxlen > strlen($mensaje) || $numrank < 1) die ("no hay patrones\n");

$decoder = new DecoderFactory($minlen,$maxlen);
$decoder->load($mensaje);
$patrones = $decoder->getPatterns();

arsort($patrones,SORT_NUMERIC);

$tally = 0;

foreach ($patrones as $patron => $num) {
    echo "$num\t$patron\n";
    if (++$tally == $numrank) break;
}