<?php

function stemming_letter_de()
{
	return 'qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNMÄÖÜäöüß';
}

function stemming_stop_de($sWord)
{
	if (mb_strlen($sWord) < 2)
	{
		return false;
	}
	static $stop_list = false;
	if (!$stop_list)
	{
		$stop_list = [
			'QUOTE' => 0, 'HTTP' => 0, 'WWW' => 0, 'RU' => 0, 'IMG' => 0, 'GIF' => 0, 'aber' => 0,
			'alle' => 0, 'allem' => 0, 'allen' => 0, 'aller' => 0, 'alles' => 0,
			'als' => 0, 'also' => 0, 'am' => 0, 'an' => 0,
			'ander' => 0, 'andere' => 0, 'anderem' => 0, 'anderen' => 0, 'anderer' => 0,
			'anderes' => 0, 'anderm' => 0, 'andern' => 0, 'anderr' => 0, 'anders' => 0,
			'auch' => 0, 'auf' => 0, 'aus' => 0, 'bei' => 0, 'bin' => 0,
			'bis' => 0, 'bist' => 0, 'da' => 0, 'damit' => 0, 'dann' => 0,
			'der' => 0, 'den' => 0, 'des' => 0, 'dem' => 0, 'die' => 0, 'das' => 0,
			'daß' => 0,
			'derselbe' => 0, 'derselben' => 0, 'denselben' => 0, 'desselben' => 0, 'demselben' => 0,
			'dieselbe' => 0, 'dieselben' => 0, 'dasselbe' => 0,
			'dazu' => 0,
			'dein' => 0, 'deine' => 0, 'deinem' => 0, 'deinen' => 0, 'deiner' => 0, 'deines' => 0,
			'denn' => 0,
			'derer' => 0, 'dessen' => 0,
			'dich' => 0, 'dir' => 0, 'du' => 0,
			'dies' => 0, 'diese' => 0, 'diesem' => 0, 'diesen' => 0, 'dieser' => 0, 'dieses' => 0,
			'doch' => 0, 'dort' => 0,
			'durch' => 0,
			'ein' => 0, 'eine' => 0, 'einem' => 0, 'einen' => 0, 'einer' => 0, 'eines' => 0,
			'einig' => 0, 'einige' => 0, 'einigem' => 0, 'einigen' => 0, 'einiger' => 0, 'einiges' => 0,
			'einmal' => 0,
			'er' => 0, 'ihn' => 0, 'ihm' => 0,
			'es' => 0, 'etwas' => 0,
			'euer' => 0, 'eure' => 0, 'eurem' => 0, 'euren' => 0, 'eurer' => 0, 'eures' => 0,
			'für' => 0, 'gegen' => 0, 'gewesen' => 0, 'hab' => 0, 'habe' => 0,
			'haben' => 0, 'hat' => 0, 'hatte' => 0, 'hatten' => 0, 'hier' => 0,
			'hin' => 0, 'hinter' => 0,
			'ich' => 0, 'mich' => 0, 'mir' => 0,
			'ihr' => 0, 'ihre' => 0, 'ihrem' => 0, 'ihren' => 0, 'ihrer' => 0, 'ihres' => 0, 'euch' => 0,
			'im' => 0, 'in' => 0, 'indem' => 0, 'ins' => 0, 'ist' => 0,
			'jede' => 0, 'jedem' => 0, 'jeden' => 0, 'jeder' => 0, 'jedes' => 0,
			'jene' => 0, 'jenem' => 0, 'jenen' => 0, 'jener' => 0, 'jenes' => 0,
			'jetzt' => 0, 'kann' => 0,
			'kein' => 0, 'keine' => 0, 'keinem' => 0, 'keinen' => 0, 'keiner' => 0, 'keines' => 0,
			'können' => 0, 'könnte' => 0, 'machen' => 0, 'man' => 0,
			'manche' => 0, 'manchem' => 0, 'manchen' => 0, 'mancher' => 0, 'manches' => 0,
			'mein' => 0, 'meine' => 0, 'meinem' => 0, 'meinen' => 0, 'meiner' => 0, 'meines' => 0,
			'mit' => 0, 'muss' => 0, 'musste' => 0, 'nach' => 0, 'nicht' => 0,
			'nichts' => 0, 'noch' => 0, 'nun' => 0, 'nur' => 0, 'ob' => 0,
			'oder' => 0, 'ohne' => 0, 'sehr' => 0,
			'sein' => 0, 'seine' => 0, 'seinem' => 0, 'seinen' => 0, 'seiner' => 0, 'seines' => 0,
			'selbst' => 0, 'sich' => 0,
			'sie' => 0, 'ihnen' => 0,
			'sind' => 0, 'so' => 0,
			'solche' => 0, 'solchem' => 0, 'solchen' => 0, 'solcher' => 0, 'solches' => 0,
			'soll' => 0, 'sollte' => 0, 'sondern' => 0, 'sonst' => 0, 'über' => 0, 'um' => 0, 'und' => 0,
			'uns' => 0, 'unse' => 0, 'unsem' => 0, 'unsen' => 0, 'unser' => 0, 'unses' => 0,
			'unter' => 0, 'viel' => 0, 'vom' => 0, 'von' => 0, 'vor' => 0,
			'während' => 0, 'war' => 0, 'waren' => 0, 'warst' => 0, 'was' => 0,
			'weg' => 0, 'weil' => 0, 'weiter' => 0,
			'welche' => 0, 'welchem' => 0, 'welchen' => 0, 'welcher' => 0, 'welches' => 0,
			'wenn' => 0, 'werde' => 0, 'werden' => 0, 'wie' => 0, 'wieder' => 0,
			'will' => 0, 'wir' => 0, 'wird' => 0, 'wirst' => 0, 'wo' => 0,
			'wollen' => 0, 'wollte' => 0, 'würde' => 0, 'würden' => 0, 'zu' => 0,
			'zum' => 0, 'zur' => 0, 'zwar' => 0, 'zwischen' => 0,
		];
		if (defined('STEMMING_STOP_DE'))
		{
			foreach (explode(',', STEMMING_STOP_DE) as $word)
			{
				$word = trim($word);
				if ($word <> '')
				{
					$stop_list[$word] = 0;
				}
			}
		}
	}
	return !array_key_exists($sWord, $stop_list);
}

function stemming_de($word)
{
	$vowels = 'AEIOUYÄÖÜ';
	//First, replace ß by ss
	$word = str_replace('ß', 'SS', $word); //Actually ß in uppercase is already SS
	//put u and y between vowels into lower case
	$word = preg_replace('/([' . $vowels . '])U([' . $vowels . '])/', "\\1u\\2", $word);
	$word = preg_replace('/([' . $vowels . '])Y([' . $vowels . '])/', "\\1y\\2", $word);
	$word_len = mb_strlen($word);

	//In any word, R1 is the region after the first non-vowel following a vowel,
	//or the end of the word if it contains no such a non-vowel.
	$R1 = 0;
	while ( ($R1 < $word_len) && (mb_strpos($vowels, mb_substr($word, $R1, 1)) === false))
	{
		$R1++;
	}
	while ( ($R1 < $word_len) && (mb_strpos($vowels, mb_substr($word, $R1, 1)) !== false))
	{
		$R1++;
	}
	if ($R1 < $word_len)
	{
		$R1++;
	}

	//R2 is the region after the first non-vowel following a vowel in R1,
	//or is the null region at the end of the word if there is no such non-vowel.
	$R2 = $R1;
	while ( ($R2 < $word_len) && (mb_strpos($vowels, mb_substr($word, $R2, 1)) === false))
	{
		$R2++;
	}
	while ( ($R2 < $word_len) && (mb_strpos($vowels, mb_substr($word, $R2, 1)) !== false))
	{
		$R2++;
	}
	if ($R2 < $word_len)
	{
		$R2++;
	}

	//R1 is adjusted so that the region before it contains at least 3 letters.
	if ($R1 < 3)
	{
		$R1 = 3;
	}

	//Define a valid s-ending as one of b, d, f, g, h, k, l, m, n, r or t.
	$s_ending = 'BDFGHKLMNRT';

	//Define a valid st-ending as the same list, excluding letter r.
	$st_ending = 'BDFGHKLMNT';

	$word_r1 = mb_substr($word, $R1);

	//Step 1:
	//Search for the longest among the following suffixes
	//(a) em   ern   er
	//and delete if in R1
	if (preg_match('/(ERN|EM|ER)$/', $word_r1, $match))
	{
		$word = mb_substr($word, 0, -mb_strlen($match[1]));
	}
	//(b) e   en   es
	//If an ending of group (b) is deleted, and the ending is preceded by niss, delete the final s
	elseif (preg_match('/(ES|EN|E)$/', $word_r1, $match))
	{
		$word = mb_substr($word, 0, -mb_strlen($match[1]));
		if (preg_match('/NISS$/', $word))
		{
			$word = mb_substr($word, 0, -1);
		}
	}
	//(c) s (preceded by a valid s-ending)
	//the letter of the valid s-ending is not necessarily in R1
	elseif (mb_substr($word_r1, -1) == 'S' && preg_match('/[' . $s_ending . ']S$/', $word))
	{
		$word = mb_substr($word, 0, -1);
	}

	$word_r1 = mb_substr($word, $R1);
	//Step 2:
	//Search for the longest among the following suffixes,
	//(a) en   er   est
	//and delete if in R1.
	if (preg_match('/(EST|EN|ER)$/', $word_r1, $match))
	{
		$word = mb_substr($word, 0, -mb_strlen($match[1]));
	}
	//(b) st (preceded by a valid st-ending, itself preceded by at least 3 letters)
	elseif (preg_match('/ST$/', $word_r1) && preg_match('/.{3,}[' . $st_ending . ']ST$/', $word))
	{
		$word = mb_substr($word, 0, -2);
	}

	//Step 3: d-suffixes (*)
	//Search for the longest among the following suffixes, and perform the action indicated.

	$word_r2 = mb_substr($word, $R2);
	//keit
	//    delete if in R2
	//    if preceded by lich or ig, delete if in R2
	if (preg_match('/KEIT$/', $word_r2))
	{
		$word = mb_substr($word, 0, -4);
		$word_r2 = mb_substr($word, $R2);
		if (preg_match('/(LICH|IG)$/', $word_r2, $match))
		{
			$word = mb_substr($word, 0, -mb_strlen($match[1]));
		}
	}
	// lich   heit
	//     delete if in R2
	//     if preceded by er or en, delete if in R1
	elseif (preg_match('/(LICH|HEIT)$/', $word_r2))
	{
		$word = mb_substr($word, 0, -4);
		$word_r1 = mb_substr($word, $R1);
		if (preg_match('/(ER|EN)$/', $word_r1))
		{
			$word = mb_substr($word, 0, -2);
		}
	}
	// end   ung
	//     delete if in R2
	//     if preceded by ig, delete if in R2 and not preceded by e
	elseif (preg_match('/(END|UNG)$/', $word_r2))
	{
		$word = mb_substr($word, 0, -3);
		$word_r2 = mb_substr($word, $R2);
		if (preg_match('/(^|[^E])(IG)$/', $word_r2))
		{
			$word = mb_substr($word, 0, -2);
		}
	}
	// ig   ik   isch
	//     delete if in R2 and not preceded by e
	elseif (preg_match('/(^|[^E])(IG|IK|ISCH)$/', $word_r2, $match))
	{
		$word = mb_substr($word, 0, -mb_strlen($match[2]));
	}

	//Finally,
	//turn U and Y back into lower case, and remove the umlaut accent from a, o and u.
	$word = str_replace(['u', 'y', 'Ä', 'Ö', 'Ü'], ['U', 'Y', 'A', 'O', 'U'], $word);

	return $word;
}

function stemming_upper_de($sText)
{
	return str_replace(['Ä', 'Ö', 'Ü'], ['A', 'O', 'U'], mb_strtoupper($sText));
}