🛀 data mode rework

src/Data/QRDataModeAbstract.php

@@ -0,0 +1,101 @@
+<?php
+/**
+ * Class QRDataModeAbstract
+ *
+ * @filesource   QRDataModeAbstract.php
+ * @created      19.11.2020
+ * @package      chillerlan\QRCode\Data
+ * @author       smiley <smiley@chillerlan.net>
+ * @copyright    2020 smiley
+ * @license      MIT
+ */
+
+namespace chillerlan\QRCode\Data;
+
+use chillerlan\QRCode\Helpers\BitBuffer;
+
+/**
+ */
+abstract class QRDataModeAbstract implements QRDataModeInterface{
+
+	/**
+	 * the current data mode: Num, Alphanum, Kanji, Byte
+	 */
+	protected int $datamode;
+
+	/**
+	 * mode length bits for the version breakpoints 1-9, 10-26 and 27-40
+	 *
+	 * ISO/IEC 18004:2000 Table 3 - Number of bits in Character Count Indicator
+	 */
+	protected array $lengthBits = [0, 0, 0];
+
+	/**
+	 * The data to write
+	 */
+	protected string $data;
+
+	/**
+	 * a BitBuffer instance
+	 */
+	protected BitBuffer $bitBuffer;
+
+	/**
+	 * QRDataModeAbstract constructor.
+	 *
+	 * @throws \chillerlan\QRCode\Data\QRCodeDataException
+	 */
+	public function __construct(BitBuffer $bitBuffer, string $data){
+		// do we need this here? we check during write anyways.
+#		if(!static::validateString($data)){
+#			throw new QRCodeDataException('invalid data string');
+#		}
+
+		$this->bitBuffer = $bitBuffer;
+		$this->data      = $data;
+	}
+
+	/**
+	 * returns the character count of the $data string
+	 */
+	protected function getLength():int{
+		return strlen($this->data);
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function getLengthBits(int $k):int{
+		return $this->lengthBits[$k] ?? 0;
+	}
+
+	/**
+	 * returns the length bits for the version breakpoints 1-9, 10-26 and 27-40
+	 *
+	 * @throws \chillerlan\QRCode\Data\QRCodeDataException
+	 * @codeCoverageIgnore
+	 */
+	protected function getLengthBitsForVersion(int $version):int{
+
+		foreach([9, 26, 40] as $key => $breakpoint){
+			if($version <= $breakpoint){
+				return $this->getLengthBits($key);
+			}
+		}
+
+		throw new QRCodeDataException(sprintf('invalid version number: %d', $version));
+	}
+
+	/**
+	 *
+	 */
+	protected function writeSegmentHeader(int $version):void{
+
+		$this->bitBuffer
+			->put($this->datamode, 4)
+			->put($this->getLength(), $this->getLengthBitsForVersion($version))
+		;
+
+	}
+
+}