<?php

function convert_number_to_latvian_words($num)
{
	if ( ! is_numeric($num))
		return false;

	if (($num >= 0 && (int) $num < 0) OR (int) $num < 0 - PHP_INT_MAX) {
		// overflow
		trigger_error('convert_number_to_latvian_words only accepts numbers between -' . PHP_INT_MAX . ' and ' . PHP_INT_MAX, E_USER_WARNING);
		return false;
	}

	$dict = [
		0 => 'nulle',
		1 => 'viens',
		2 => 'divi',
		3 => 'trīs',
		4 => 'četri',
		5 => 'pieci',
		6 => 'seši',
		7 => 'septiņi',
		8 => 'astoņi',
		9 => 'deviņi',
		10 => 'desmit',
		11 => 'vienpadsmit',
		12 => 'divpadsmit',
		13 => 'trīspadsmit',
		14 => 'četrpadsmit',
		15 => 'piecpadsmit',
		16 => 'sešpadsmit',
		17 => 'septiņpadsmit',
		18 => 'astoņpadsmit',
		19 => 'deviņpadsmit',
		20 => 'divdesmit',
		30 => 'trīsdesmit',
		40 => 'četrdesmit',
		50 => 'piecdesmit',
		60 => 'sešdesmit',
		70 => 'septiņdesmit',
		80 => 'astoņdesmit',
		90 => 'deviņdesmit',
		100 => 'simts',
		1000 => 'tūkstotis',
		1000000 => 'miljons',
		1000000000 => 'miljards',
    ];

	$pre = [
		1 => 'vien',
		2 => 'div',
		3 => 'trīs',
		4 => 'četr',
		5 => 'piec',
		6 => 'seš',
		7 => 'septiņ',
		8 => 'astoņ',
		9 => 'deviņ',
    ];

	if ($num < 0) {
		return 'mīnus '.convert_number_to_latvian_words(abs($num));
	}

	switch ($num) {
		case 0:
		case 100:
		case 1000:
		case 1000000:
		case 1000000000:
			return $dict[$num];
	}

	if ($num < 21) {
		return $dict[$num];
	}

	if ($num < 100) {
		$x10 = ((int) ($num / 10)) * 10;
		$rem = $num % 10;

		$str = $dict[$x10];

		if ($rem > 0) {
			$str .= ' '.$dict[$rem];
		}

		return $str;
	}

	if ($num < 1000) {
		$x100 = intval($num / 100);
		$rem = $num % 100;

		$str = ($x100 === 1 ? 'simtu' : $pre[$x100].'simt');

		if ($rem > 0) {
			$str .= ' '.convert_number_to_latvian_words($rem);
		}

		return $str;
	}

	if ($num < 1000000) {
		$val = intval($num / 1000);
		$rem = $num % 1000;

		$str = convert_number_to_latvian_words($val);
		$str .= ($val === 1 ? ' tūkstotis' : ' tūkstoši');

		if ($rem > 0) {
			$str .= ' '.convert_number_to_latvian_words($rem);
		}

		return $str;
	}

	throw new Exception('Maximum number that can be converted to words exceeded');
}