Refactory Writer Styles to match new code organization (#433)

Decomposed old StyleHelper into StyleManager, StyleRegistry and StyleMerger.

src/Spout/Writer/Common/Manager/Style/StyleManager.php

@@ -0,0 +1,92 @@
+<?php
+
+namespace Box\Spout\Writer\Common\Manager\Style;
+
+use Box\Spout\Writer\Common\Entity\Style\Style;
+
+/**
+ * Class StyleManager
+ * Manages styles to be applied to a cell
+ *
+ * @package Box\Spout\Writer\Common\Manager\Style
+ */
+class StyleManager implements StyleManagerInterface
+{
+    /** @var StyleRegistry Registry for all used styles */
+    protected $styleRegistry;
+
+    /**
+     * @param StyleRegistry $styleRegistry
+     */
+    public function __construct(StyleRegistry $styleRegistry)
+    {
+        $this->styleRegistry = $styleRegistry;
+    }
+
+    /**
+     * Returns the default style
+     *
+     * @return Style Default style
+     */
+    protected function getDefaultStyle()
+    {
+        // By construction, the default style has ID 0
+        return $this->styleRegistry->getRegisteredStyles()[0];
+    }
+
+    /**
+     * Registers the given style as a used style.
+     * Duplicate styles won't be registered more than once.
+     *
+     * @param Style $style The style to be registered
+     * @return Style The registered style, updated with an internal ID.
+     */
+    public function registerStyle($style)
+    {
+        return $this->styleRegistry->registerStyle($style);
+    }
+
+    /**
+     * Apply additional styles if the given row needs it.
+     * Typically, set "wrap text" if a cell contains a new line.
+     *
+     * @param Style $style The original style
+     * @param array $dataRow The row the style will be applied to
+     * @return Style The updated style
+     */
+    public function applyExtraStylesIfNeeded($style, $dataRow)
+    {
+        $updatedStyle = $this->applyWrapTextIfCellContainsNewLine($style, $dataRow);
+        return $updatedStyle;
+    }
+
+    /**
+     * Set the "wrap text" option if a cell of the given row contains a new line.
+     *
+     * @NOTE: There is a bug on the Mac version of Excel (2011 and below) where new lines
+     *        are ignored even when the "wrap text" option is set. This only occurs with
+     *        inline strings (shared strings do work fine).
+     *        A workaround would be to encode "\n" as "_x000D_" but it does not work
+     *        on the Windows version of Excel...
+     *
+     * @param Style $style The original style
+     * @param array $dataRow The row the style will be applied to
+     * @return Style The eventually updated style
+     */
+    protected function applyWrapTextIfCellContainsNewLine($style, $dataRow)
+    {
+        // if the "wrap text" option is already set, no-op
+        if ($style->hasSetWrapText()) {
+            return $style;
+        }
+
+        foreach ($dataRow as $cell) {
+            if (is_string($cell) && strpos($cell, "\n") !== false) {
+                $style->setShouldWrapText();
+                break;
+            }
+        }
+
+        return $style;
+    }
+}