Chat session support

README.md

@@ -14,6 +14,15 @@ _This library is not developed or endorsed by Google._
 
 - Erdem Köse - **[github.com/erdemkose](https://github.com/erdemkose)**
 
+## Table of Contents
+- [Installation](#installation)
+- [How to use](#how-to-use)
+  - [Basic text generation](#basic-text-generation)
+  - [Multimodal input](#multimodal-input)
+  - [Chat Session (Multi-Turn Conversations)](#chat-session-multi-turn-conversations)
+  - [Tokens counting](#tokens-counting)
+  - [Listing models](#listing-models)
+
 ## Installation
 
 > You need an API key to gain access to Google Generative AI services.
@@ -67,6 +76,40 @@ print $response->text();
 // The image is set against a starry background.
 ```
 
+### Chat Session (Multi-Turn Conversations)
+
+```php
+$client = new GenerativeAI\Client('YOUR_GEMINI_PRO_API_TOKEN');
+
+$chat = $client->GeminiPro()->startChat();
+
+$response = $chat->sendMessage(new TextPart('Hello World in PHP'));
+print $response->text();
+
+$response = $chat->sendMessage(new TextPart('in Go'));
+print $response->text();
+```
+
+```text
+<?php
+echo "Hello World!";
+?>
+
+This code will print "Hello World!" to the standard output.
+```
+
+```text
+package main
+
+import "fmt"
+
+func main() {
+    fmt.Println("Hello World!")
+}
+
+This code will print "Hello World!" to the standard output.
+```
+
 ### Tokens counting
 
 ```php

src/ChatSession.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace GenerativeAI;
+
+use GenerativeAI\Enums\Role;
+use GenerativeAI\Resources\Content;
+use GenerativeAI\Resources\Parts\PartInterface;
+use GenerativeAI\Responses\GenerateContentResponse;
+use Psr\Http\Client\ClientExceptionInterface;
+
+class ChatSession
+{
+    /** @var Content[] */
+    private array $history;
+
+    public function __construct(
+        private readonly GenerativeModel $model,
+    ) {
+    }
+
+    /**
+     * @throws ClientExceptionInterface
+     */
+    public function sendMessage(PartInterface ...$parts): GenerateContentResponse
+    {
+        $this->history[] = new Content($parts, Role::User);
+
+        $config = (new GenerationConfig())
+        ->withCandidateCount(1);
+        $response = $this->model
+            ->withGenerationConfig($config)
+            ->generateContentWithContents($this->history);
+
+        if(!empty($response->candidates)) {
+            $parts = $response->candidates[0]->content->parts;
+            $this->history[] = new Content($parts, Role::Model);
+        }
+
+        return $response;
+    }
+}

src/GenerativeModel.php

@@ -12,10 +12,13 @@
 use GenerativeAI\Responses\GenerateContentResponse;
 use GenerativeAI\Resources\Content;
 use GenerativeAI\Resources\Parts\PartInterface;
+use GenerativeAI\Traits\ArrayTypeValidator;
 use Psr\Http\Client\ClientExceptionInterface;
 
 class GenerativeModel
 {
+    use ArrayTypeValidator;
+
     /** @var SafetySetting[] */
     private array $safetySettings = [];
 
@@ -33,16 +36,33 @@ public function __construct(
     public function generateContent(PartInterface ...$parts): GenerateContentResponse
     {
         $content = new Content($parts, Role::User);
+
+        return $this->generateContentWithContents([$content]);
+    }
+
+    /**
+     * @param Content[] $contents
+     * @throws ClientExceptionInterface
+     */
+    public function generateContentWithContents(array $contents): GenerateContentResponse
+    {
+        $this->ensureArrayOfType($contents, Content::class);
+
         $request = new GenerateContentRequest(
             $this->modelName,
-            [$content],
+            $contents,
             $this->safetySettings,
             $this->generationConfig,
         );
 
         return $this->client->generateContent($request);
     }
 
+    public function startChat(): ChatSession
+    {
+        return new ChatSession($this);
+    }
+
     /**
      * @throws ClientExceptionInterface
      */