Introduce schema component

src/Schema/Prompt.php

@@ -0,0 +1,89 @@
+<?php
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Schema;
+
+use Mcp\Exception\InvalidArgumentException;
+
+/**
+ * A prompt or prompt template that the server offers.
+ *
+ * @phpstan-import-type PromptArgumentData from PromptArgument
+ *
+ * @phpstan-type PromptData array{
+ *     name: string,
+ *     description?: string,
+ *     arguments?: PromptArgumentData[],
+ * }
+ *
+ * @author Kyrian Obikwelu <koshnawaza@gmail.com>
+ */
+class Prompt implements \JsonSerializable
+{
+    /**
+     * @param string                $name        the name of the prompt or prompt template
+     * @param string|null           $description an optional description of what this prompt provides
+     * @param PromptArgument[]|null $arguments   A list of arguments for templating. Null if not a template.
+     */
+    public function __construct(
+        public readonly string $name,
+        public readonly ?string $description = null,
+        public readonly ?array $arguments = null,
+    ) {
+        if (null !== $this->arguments) {
+            foreach ($this->arguments as $arg) {
+                if (!($arg instanceof PromptArgument)) {
+                    throw new InvalidArgumentException('All items in Prompt "arguments" must be PromptArgument instances.');
+                }
+            }
+        }
+    }
+
+    /**
+     * @param PromptData $data
+     */
+    public static function fromArray(array $data): self
+    {
+        if (empty($data['name']) || !\is_string($data['name'])) {
+            throw new InvalidArgumentException('Invalid or missing "name" in Prompt data.');
+        }
+        $arguments = null;
+        if (isset($data['arguments']) && \is_array($data['arguments'])) {
+            $arguments = array_map(fn (array $argData) => PromptArgument::fromArray($argData), $data['arguments']);
+        }
+
+        return new self(
+            name: $data['name'],
+            description: $data['description'] ?? null,
+            arguments: $arguments
+        );
+    }
+
+    /**
+     * @return array{
+     *     name: string,
+     *     description?: string,
+     *     arguments?: array<PromptArgument>
+     * }
+     */
+    public function jsonSerialize(): array
+    {
+        $data = ['name' => $this->name];
+        if (null !== $this->description) {
+            $data['description'] = $this->description;
+        }
+        if (null !== $this->arguments) {
+            $data['arguments'] = $this->arguments;
+        }
+
+        return $data;
+    }
+}