Rename Interfaces to Contracts to better match Laravel conventions

app/Contracts/Unit.php

@@ -0,0 +1,121 @@
+<?php
+
+namespace App\Contracts;
+
+use ArrayAccess;
+
+/**
+ * Class Unit
+ *
+ * @property mixed  $instance
+ * @property string $unit
+ * @property array  $units
+ */
+class Unit implements ArrayAccess
+{
+    /**
+     * The unit this is kept as
+     */
+    public $unit;
+
+    /**
+     * All of the units of this class
+     */
+    public $units;
+
+    /**
+     * Holds an instance of the PhpUnit type
+     */
+    protected $instance;
+
+    /**
+     * Units that are included as part of the REST response
+     */
+    public $responseUnits = [];
+
+    /**
+     * @return mixed
+     */
+    public function value()
+    {
+        return $this->__toString();
+    }
+
+    /**
+     * Just call toUnit() on the PhpUnitOfMeasure instance
+     *
+     * @param string $unit
+     *
+     * @return mixed
+     */
+    public function toUnit($unit)
+    {
+        return $this->instance->toUnit($unit);
+    }
+
+    /**
+     * Return all of the units that get sent back in a response
+     */
+    public function getResponseUnits(): array
+    {
+        $response = [];
+        foreach ($this->responseUnits as $unit) {
+            $response[$unit] = $this[$unit];
+        }
+
+        return $response;
+    }
+
+    /**
+     * Implements ArrayAccess
+     *
+     * @param $offset
+     *
+     * @return bool
+     */
+    public function offsetExists($offset)
+    {
+        return array_key_exists($offset, $this->units);
+    }
+
+    /**
+     * Implements ArrayAccess
+     *
+     * @param $offset
+     *
+     * @return mixed
+     */
+    public function offsetGet($offset)
+    {
+        return round($this->instance->toUnit($offset), 2);
+    }
+
+    /**
+     * Implements ArrayAccess
+     *
+     * @param $offset
+     * @param $value
+     */
+    public function offsetSet($offset, $value)
+    {
+        // $this->units[$offset] = $value;
+    }
+
+    /**
+     * Implements ArrayAccess
+     *
+     * @param $offset
+     */
+    public function offsetUnset($offset)
+    {
+        // $this->units[$offset] = null;
+    }
+
+    /**
+     * @return mixed
+     */
+    public function __toString()
+    {
+        return (string) $this->units[$this->unit];
+    }
+}