Add streaming chat session

Author: erdemkose

README.md

@@ -23,6 +23,7 @@ _This library is not developed or endorsed by Google._
   - [Chat Session (Multi-Turn Conversations)](#chat-session-multi-turn-conversations)
   - [Chat Session with history](#chat-session-with-history)
   - [Streaming responses](#streaming-responses)
+  - [Streaming Chat Session](#streaming-chat-session)
   - [Tokens counting](#tokens-counting)
   - [Listing models](#listing-models)
 
@@ -153,6 +154,8 @@ This code will print "Hello World!" to the standard output.
 
 ### Streaming responses
 
+> Requires `curl` extension to be enabled
+
 In the streaming response, the callback function will be called whenever a response is returned from the server.
 
 Long responses may be broken into separate responses, and you can start receiving responses faster using a content stream.
@@ -178,6 +181,55 @@ $client->geminiPro()->generateContentStream(
 //  its simple syntax and rich library of functions.
 ```
 
+### Streaming Chat Session
+
+> Requires `curl` extension to be enabled 
+
+```php
+$client = new GeminiAPI\Client('GEMINI_API_KEY');
+
+$history = [
+    Content::text('Hello World in PHP', Role::User),
+    Content::text(
+        <<<TEXT
+        <?php
+        echo "Hello World!";
+        ?>
+        
+        This code will print "Hello World!" to the standard output.
+        TEXT,
+        Role::Model,
+    ),
+];
+$chat = $client->geminiPro()
+    ->startChat()
+    ->withHistory($history);
+
+$callback = function (GenerateContentResponse $response): void {
+    static $count = 0;
+
+    print "\nResponse #{$count}\n";
+    print $response->text();
+    $count++;
+};
+
+$chat->sendMessageStream($callback, new TextPart('in Go'));
+```
+
+```text
+Response #0
+package main
+
+import "fmt"
+
+func main() {
+
+Response #1
+    fmt.Println("Hello World!")
+}
+
+This code will print "Hello World!" to the standard output.
+```
 
 ### Embed Content
 

src/ChatSession.php

@@ -45,6 +45,37 @@ public function sendMessage(PartInterface ...$parts): GenerateContentResponse
         return $response;
     }
 
+    /**
+     * @param callable(GenerateContentResponse): void $callback
+     * @param PartInterface ...$parts
+     * @return void
+     */
+    public function sendMessageStream(
+        callable $callback,
+        PartInterface ...$parts,
+    ): void {
+        $this->history[] = new Content($parts, Role::User);
+
+        $parts = [];
+        $partsCollectorCallback = function (GenerateContentResponse $response) use ($callback, &$parts) {
+            if(!empty($response->candidates)) {
+                array_push($parts, ...$response->parts());
+            }
+
+            $callback($response);
+        };
+
+        $config = (new GenerationConfig())
+            ->withCandidateCount(1);
+        $this->model
+            ->withGenerationConfig($config)
+            ->generateContentStreamWithContents($partsCollectorCallback, $this->history);
+
+        if (!empty($parts)) {
+            $this->history[] = new Content($parts, Role::Model);
+        }
+    }
+
     /**
      * @return Content[]
      */

src/GenerativeModel.php

@@ -72,9 +72,21 @@ public function generateContentStream(
     ): void {
         $content = new Content($parts, Role::User);
 
+        $this->generateContentStreamWithContents($callback, [$content]);
+    }
+
+    /**
+     * @param callable(GenerateContentResponse): void $callback
+     * @param Content[] $contents
+     * @return void
+     */
+    public function generateContentStreamWithContents(callable $callback, array $contents): void
+    {
+        $this->ensureArrayOfType($contents, Content::class);
+
         $request = new GenerateContentStreamRequest(
             $this->modelName,
-            [$content],
+            $contents,
             $this->safetySettings,
             $this->generationConfig,
         );