commit 075fede0344fa79e65cb59d9a1f5bcc201d85952
Author: Chintan <chintan@wezbyte.com>
Date:   Thu Feb 18 06:17:52 2021 +0000

    Initial commit

diff --git a/cdesai_tff.info.yml b/cdesai_tff.info.yml
new file mode 100644
index 0000000..9cf36ff
--- /dev/null
+++ b/cdesai_tff.info.yml
@@ -0,0 +1,7 @@
+name: CDesai - Text Formatter Demo Challenge
+type: module
+description: 'Demo of custom text formatters based on Unleashed Technologies challenge.'
+core_version_requirement: ^8.9 || ^9
+package: 'Demo'
+dependencies:
+  - drupal:node
diff --git a/composer.json b/composer.json
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index 0000000..a429dfc
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+++ b/composer.json
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+{
+    "name": "drupal/cdesai_tff",
+    "description": "Demo of custom text formatters based on Unleashed Technologies challenge.",
+    "type": "drupal-module",
+    "homepage": "https://wezbyte.com/tff-demo",
+    "keywords": ["Drupal", "Chintan", "Desai","Text", "Formatter", "Demo"],
+    "minimum-stability": "dev",
+    "authors": [
+        {
+            "name": "Chintan Desai",
+            "email": "chintan@wezbyte.com"
+        }
+    ],
+    "require": {
+        "drupal/core": "^8.0 || ^9.0",
+        "cocur/slugify": "^4.0"
+    }
+}
diff --git a/src/DesaiTextFormatterBase.php b/src/DesaiTextFormatterBase.php
new file mode 100644
index 0000000..803188c
--- /dev/null
+++ b/src/DesaiTextFormatterBase.php
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+<?php
+
+
+namespace Drupal\cdesai_tff;
+
+use Drupal\Core\Field\FieldItemInterface;
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Field\FormatterBase;
+
+abstract class DesaiTextFormatterBase extends FormatterBase {
+
+  /**
+   * Generates a string to be used a CSS class.
+   *
+   * @return string
+   *   The formatted string.
+   */
+  abstract function getCssClassId();
+
+  /**
+   * Formats the given item.
+   *
+   * @param \Drupal\Core\Field\FieldItemInterface $item
+   *   Field item object that needs to be converted.
+   *
+   * @return string
+   *   The formatted string.
+   */
+  abstract function getValue(FieldItemInterface $item);
+
+  /**
+   * @inheritDoc
+   */
+  public function viewElements(FieldItemListInterface $items, $langcode) {
+    $elements = [];
+    foreach ($items as $delta => $item) {
+      $elements[$delta] = [
+        '#type' => 'html_tag',
+        '#tag' => 'span',
+        '#attributes' => [
+          'class' => [$this->getCssClassId()],
+        ],
+        '#value' => $this->getValue($item),
+      ];
+    }
+
+    return $elements;
+  }
+
+}
diff --git a/src/Plugin/Field/FieldFormatter/Rot13TextFormatter.php b/src/Plugin/Field/FieldFormatter/Rot13TextFormatter.php
new file mode 100644
index 0000000..8d42ef1
--- /dev/null
+++ b/src/Plugin/Field/FieldFormatter/Rot13TextFormatter.php
@@ -0,0 +1,102 @@
+<?php
+
+
+namespace Drupal\cdesai_tff\Plugin\Field\FieldFormatter;
+
+use Drupal\cdesai_tff\DesaiTextFormatterBase;
+use Drupal\Core\Field\FieldItemInterface;
+
+/**
+ * Implementation of custom Rot13 text formatter.
+ *
+ * @FieldFormatter(
+ *   id = "cdesai_tff_rot13",
+ *   label = @Translation("Custom Rot13 Formatter"),
+ *   field_types = {
+ *     "string",
+ *     "text"
+ *   }
+ * )
+ */
+class Rot13TextFormatter extends DesaiTextFormatterBase {
+
+  private static $DECIMAL_A_UPPER = 65;
+  private static $DECIMAL_A_LOWER = 97;
+  private static $NUM_ALPHABET = 26;
+  private static $ROT_CONSTANT = 13;
+
+  /**
+   * @inheritDoc
+   */
+  function getCssClassId() {
+    return 'cdesai-tff-rot13';
+  }
+
+  /**
+   * @inheritDoc
+   */
+  function getValue(FieldItemInterface $item) {
+    return $this->convertToRot13($item);
+  }
+
+  /**
+   * Converts the given item to Rot13 format.
+   *
+   * @param \Drupal\Core\Field\FieldItemInterface $item
+   *   Field item object that needs to be converted.
+   *
+   * @return string
+   *   The converted string.
+   */
+  protected function convertToRot13(FieldItemInterface $item) {
+    $origString = $item->getString();
+    $converted = '';
+
+    for ($i = 0; $i < strlen($origString); $i++ ) {
+      $decimalValue = ord($origString{$i});
+
+      if (self::isUpperCase($decimalValue)) {
+        $newValue = self::$DECIMAL_A_UPPER + ($decimalValue - self::$DECIMAL_A_UPPER + self::$ROT_CONSTANT) % self::$NUM_ALPHABET;
+        $converted .= chr($newValue);
+      }
+      elseif (self::isLowerCase($decimalValue)) {
+        $newValue = self::$DECIMAL_A_LOWER + ($decimalValue - self::$DECIMAL_A_LOWER + self::$ROT_CONSTANT) % self::$NUM_ALPHABET;
+        $converted .= chr($newValue);
+      }
+      else {
+        $converted .= $origString{$i};
+      }
+    }
+
+    return $converted;
+  }
+
+  /**
+   * Checks whether the given decimal value is of an upper case letter.
+   *
+   * @param int $decimal_value
+   *  Decimal value of a character.
+   *
+   * @return bool
+   *   Returns TRUE if the condition matches; FALSE otherwise.
+   */
+  private static function isUpperCase($decimal_value) {
+    return $decimal_value >= self::$DECIMAL_A_UPPER
+      && $decimal_value < (self::$DECIMAL_A_UPPER + self::$NUM_ALPHABET);
+  }
+
+  /**
+   * Checks whether the given decimal value is of a lower case letter.
+   *
+   * @param int $decimal_value
+   *  Decimal value of a character.
+   *
+   * @return bool
+   *   Returns TRUE if the condition matches; FALSE otherwise.
+   */
+  private static function isLowerCase($decimal_value) {
+    return $decimal_value >= self::$DECIMAL_A_LOWER
+      && $decimal_value < (self::$DECIMAL_A_LOWER + self::$NUM_ALPHABET);
+  }
+
+}