implement Link class

src/Link.php

@@ -0,0 +1,122 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Yggverse\Gemtext;
+
+class Link
+{
+    private string $_address;
+
+    private ?string $_alt;
+    private ?string $_date;
+
+    public function __construct(
+         string $address,
+        ?string $alt = null,
+        ?string $date = null
+    ) {
+        $this->setAddress(
+            $address
+        );
+
+        $this->setAlt(
+            $alt
+        );
+
+        $this->setDate(
+            $date
+        );
+    }
+
+    public function setAddress(
+        string $address
+    ): void
+    {
+        $address = trim(
+            $address
+        );
+
+        if (empty($address))
+        {
+            throw new \Exception(
+                _('Address required')
+            );
+        }
+
+        $this->_address = $address;
+    }
+
+    public function getAddress(): string
+    {
+        return $this->_address;
+    }
+
+    public function setAlt(
+        ?string $alt
+    ): void
+    {
+        if ($alt)
+        {
+            $alt = trim(
+                $alt
+            );
+        }
+
+        $this->_alt = $alt;
+    }
+
+    public function getAlt(): ?string
+    {
+        return $this->_alt;
+    }
+
+    public function setDate(
+        ?string $date
+    ): void
+    {
+        if ($date)
+        {
+            $date = trim(
+                $date
+            );
+
+            if (!preg_match('/^\d{4}-\d{2}-\d{2}$/'))
+            {
+                throw new \Exception(
+                    _('Date does not match format YYYY-MM-DD')
+                );
+            }
+        }
+
+        $this->_date = $date;
+    }
+
+    public function getDate(): ?string
+    {
+        return $this->_date;
+    }
+
+    public function toString(): string
+    {
+        $parts = [
+            '=>',
+            $this->getAddress()
+        ];
+
+        if ($date = $this->getDate())
+        {
+            $parts[] = $date;
+        }
+
+        if ($alt = $this->getAlt())
+        {
+            $parts[] = $alt;
+        }
+
+        return implode(
+            ' ',
+            $parts
+        );
+    }
+}