add an id<->alpha convertion library #143

application/helpers/alphaid_helper.php

@@ -0,0 +1,156 @@
+<?php
+/**
+ * Translates a number to a short alhanumeric version
+ *
+ * Translated any number up to 9007199254740992
+ * to a shorter version in letters e.g.:
+ * 9007199254740989 --> PpQXn7COf
+ *
+ * specifiying the second argument true, it will
+ * translate back e.g.:
+ * PpQXn7COf --> 9007199254740989
+ *
+ * this function is based on any2dec && dec2any by
+ * fragmer[at]mail[dot]ru
+ * see: http://nl3.php.net/manual/en/function.base-convert.php#52450
+ *
+ * If you want the alphaID to be at least 3 letter long, use the
+ * $pad_up = 3 argument
+ *
+ * In most cases this is better than totally random ID generators
+ * because this can easily avoid duplicate ID's.
+ * For example if you correlate the alpha ID to an auto incrementing ID
+ * in your database, you're done.
+ *
+ * The reverse is done because it makes it slightly more cryptic,
+ * but it also makes it easier to spread lots of IDs in different
+ * directories on your filesystem. Example:
+ * $part1 = substr($alpha_id,0,1);
+ * $part2 = substr($alpha_id,1,1);
+ * $part3 = substr($alpha_id,2,strlen($alpha_id));
+ * $destindir = "/".$part1."/".$part2."/".$part3;
+ * // by reversing, directories are more evenly spread out. The
+ * // first 26 directories already occupy 26 main levels
+ *
+ * more info on limitation:
+ * - http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/165372
+ *
+ * if you really need this for bigger numbers you probably have to look
+ * at things like: http://theserverpages.com/php/manual/en/ref.bc.php
+ * or: http://theserverpages.com/php/manual/en/ref.gmp.php
+ * but I haven't really dugg into this. If you have more info on those
+ * matters feel free to leave a comment.
+ *
+ * The following code block can be utilized by PEAR's Testing_DocTest
+ * <code>
+ * // Input //
+ * $number_in = 2188847690240;
+ * $alpha_in  = "SpQXn7Cb";
+ *
+ * // Execute //
+ * $alpha_out  = alphaID($number_in, false, 8);
+ * $number_out = alphaID($alpha_in, true, 8);
+ *
+ * if ($number_in != $number_out) {
+ *	 echo "Conversion failure, ".$alpha_in." returns ".$number_out." instead of the ";
+ *	 echo "desired: ".$number_in."\n";
+ * }
+ * if ($alpha_in != $alpha_out) {
+ *	 echo "Conversion failure, ".$number_in." returns ".$alpha_out." instead of the ";
+ *	 echo "desired: ".$alpha_in."\n";
+ * }
+ *
+ * // Show //
+ * echo $number_out." => ".$alpha_out."\n";
+ * echo $alpha_in." => ".$number_out."\n";
+ * echo alphaID(238328, false)." => ".alphaID(alphaID(238328, false), true)."\n";
+ *
+ * // expects:
+ * // 2188847690240 => SpQXn7Cb
+ * // SpQXn7Cb => 2188847690240
+ * // aaab => 238328
+ *
+ * </code>
+ *
+ * @author	Kevin van Zonneveld <[email protected]>
+ * @author	Simon Franz
+ * @author	Deadfish
+ * @author  SK83RJOSH
+ * @copyright 2008 Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+ * @license   http://www.opensource.org/licenses/bsd-license.php New BSD Licence
+ * @version   SVN: Release: $Id: alphaID.inc.php 344 2009-06-10 17:43:59Z kevin $
+ * @link	  http://kevin.vanzonneveld.net/
+ *
+ * @param mixed   $in	  String or long input to translate
+ * @param boolean $to_num  Reverses translation when true
+ * @param mixed   $pad_up  Number or boolean padds the result up to a specified length
+ * @param string  $pass_key Supplying a password makes it harder to calculate the original ID
+ *
+ * @return mixed string or long
+ */
+function alphaID($in, $to_num = false, $pad_up = 10)
+{
+	$out   =   '';
+	$index = 'abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
+	$base  = strlen($index);
+
+  $pass_key = getenv("ALPHAID_HASH");
+
+	if ($pass_key !== null) {
+		// Although this function's purpose is to just make the
+		// ID short - and not so much secure,
+		// with this patch by Simon Franz (http://blog.snaky.org/)
+		// you can optionally supply a password to make it harder
+		// to calculate the corresponding numeric ID
+
+		for ($n = 0; $n < strlen($index); $n++) {
+			$i[] = substr($index, $n, 1);
+		}
+
+		$pass_hash = hash('sha256',$pass_key);
+		$pass_hash = (strlen($pass_hash) < strlen($index) ? hash('sha512', $pass_key) : $pass_hash);
+
+		for ($n = 0; $n < strlen($index); $n++) {
+			$p[] =  substr($pass_hash, $n, 1);
+		}
+
+		array_multisort($p, SORT_DESC, $i);
+		$index = implode($i);
+	}
+
+	if ($to_num) {
+		// Digital number  <<--  alphabet letter code
+		$len = strlen($in) - 1;
+
+		for ($t = $len; $t >= 0; $t--) {
+			$bcp = bcpow($base, $len - $t);
+			$out = $out + strpos($index, substr($in, $t, 1)) * $bcp;
+		}
+
+		if (is_numeric($pad_up)) {
+			$pad_up--;
+
+			if ($pad_up > 0) {
+				$out -= pow($base, $pad_up);
+			}
+		}
+	} else {
+		// Digital number  -->>  alphabet letter code
+		if (is_numeric($pad_up)) {
+			$pad_up--;
+
+			if ($pad_up > 0) {
+				$in += pow($base, $pad_up);
+			}
+		}
+
+		for ($t = ($in != 0 ? floor(log($in, $base)) : 0); $t >= 0; $t--) {
+			$bcp = bcpow($base, $t);
+			$a   = floor($in / $bcp) % $base;
+			$out = $out . substr($index, $a, 1);
+			$in  = $in - ($a * $bcp);
+		}
+	}
+
+	return $out;
+}

application/tests/helpers/Alphaid_herlper_test.php

@@ -0,0 +1,24 @@
+<?php
+
+class Alphaid_helper_test extends TestCase {
+
+  public static $stringId;
+
+  public function setUp() {
+		$this->CI = &get_instance();
+
+		$this->CI->load->helper("alphaid_helper");
+	}
+
+  public function test_intToString() {
+
+    self::$stringId = alphaID(1);
+
+    $this->assertEquals(is_string(self::$stringId), true);
+  }
+
+  public function test_stringToInt(){
+      $this->assertEquals(1, alphaID(self::$stringId, true));
+  }
+
+}