<?php

class DecoderLine {

    private $length = 0;

    private $ring = "";
    private $ringlength = 0;

    private $patterns = array();

    public function __construct($len) {
        $this->length = $len;
    }

    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->ring .= $char;

        if ($this->ringlength < $this->length) {
            $this->ringlength++;
            if ($this->ringlength < $this->length) return;
        } else {
            $this->ring = substr($this->ring,1);
        }

        $key = "_" .$this->ring; // evita bug / comportamiento indocumentado de array_merge

        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");

for ($n = $minlen; $n <= $maxlen; $n++) {
    $decoder = new DecoderLine($n);
    $decoder->load($mensaje);
    $patrones = array_merge($patrones,$decoder->getPatterns());
}

arsort($patrones,SORT_NUMERIC);

$tally = 0;

foreach ($patrones as $patron => $num) {
    $p = substr($patron,1);
    echo "$num\t$p\n";
    if (++$tally == $numrank) break;
}