add anthropic driver

Author: tobimori

classes/Ai/Drivers/Anthropic.php

@@ -0,0 +1,103 @@
+<?php
+
+namespace tobimori\Seo\Ai\Drivers;
+
+use Generator;
+use tobimori\Seo\Ai\Chunk;
+use tobimori\Seo\Ai\Driver;
+use tobimori\Seo\Ai\SseStream;
+
+class Anthropic extends Driver
+{
+	protected const string DEFAULT_ENDPOINT = 'https://api.anthropic.com/v1/messages';
+	protected const string DEFAULT_MODEL = 'claude-4-5-haiku';
+
+	/**
+	 * @inheritDoc
+	 */
+	public function stream(
+		string $prompt,
+		string|null $model = null,
+	): Generator {
+		$apiKey = $this->config('apiKey', required: true);
+		$headers = [
+			'Content-Type: application/json',
+			'Accept: text/event-stream',
+			"x-api-key: {$apiKey}",
+			'anthropic-version: 2023-06-01',
+		];
+
+		$payload = [
+			'model' => $model ?? $this->config('model', static::DEFAULT_MODEL),
+			'messages' => [
+				['role' => 'user', 'content' => $prompt]
+			],
+			'max_tokens' => 4096,
+			'stream' => true,
+		];
+
+		$stream = new SseStream($this->config('endpoint', static::DEFAULT_ENDPOINT), $headers, $payload, (int)$this->config('timeout', 120));
+		yield from $stream->stream(function (array $event): Generator {
+			$type = $event['type'] ?? null;
+
+			// handle message start event
+			if ($type === 'message_start') {
+				yield Chunk::streamStart($event);
+				return;
+			}
+
+			// handle content block start (beginning of text output)
+			if ($type === 'content_block_start') {
+				$contentBlock = $event['content_block'] ?? [];
+				if (($contentBlock['type'] ?? null) === 'text') {
+					yield Chunk::textStart($event);
+				}
+				return;
+			}
+
+			// handle content block delta (text chunks)
+			if ($type === 'content_block_delta') {
+				$delta = $event['delta'] ?? [];
+				if (($delta['type'] ?? null) === 'text_delta') {
+					$text = $delta['text'] ?? '';
+					if ($text !== '') {
+						yield Chunk::textDelta($text, $event);
+					}
+				}
+				return;
+			}
+
+			// handle content block stop (end of text block)
+			if ($type === 'content_block_stop') {
+				yield Chunk::textComplete($event);
+				return;
+			}
+
+			// handle message stop (end of stream)
+			if ($type === 'message_stop') {
+				yield Chunk::streamEnd($event);
+				return;
+			}
+
+			// handle ping events (keep-alive)
+			if ($type === 'ping') {
+				// ignore ping events
+				return;
+			}
+
+			// handle error events
+			if ($type === 'error') {
+				$error = $event['error'] ?? [];
+				$message = $error['message'] ?? 'Unknown Anthropic streaming error.';
+				yield Chunk::error($message, $event);
+				return;
+			}
+
+			// handle message delta (contains usage info)
+			if ($type === 'message_delta') {
+				// we could extract usage info here if needed
+				return;
+			}
+		});
+	}
+}