initial commit

app/Services/Google/ApiAuthService.php

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+<?php
+
+namespace App\Services\Google;
+
+use Google\Client;
+
+class ApiAuthService
+{
+    /**
+     * @throws \Google\Exception
+     */
+    public function getAccessToken(): string
+    {
+        $client = new Client();
+        $serviceAccountKeyPath = env('GOOGLE_APPLICATION_CREDENTIALS');
+        $client->setAuthConfig($serviceAccountKeyPath);
+        $client->addScope('https://www.googleapis.com/auth/cloud-platform');
+        $client->fetchAccessTokenWithAssertion();
+
+        // todo - cache, refresh, etc
+        $accessToken = $client->getAccessToken();
+
+        return $accessToken['access_token'];
+    }
+}

app/Services/Google/DTO/ImageGenerationPrediction.php

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+<?php
+
+namespace App\Services\Google\DTO;
+
+class ImageGenerationPrediction
+{
+    public readonly string $bytesBase64Encoded;
+    public readonly string $mimeType;
+
+    public function __construct(string $bytesBase64Encoded, string $mimeType)
+    {
+        $this->bytesBase64Encoded = $bytesBase64Encoded;
+        $this->mimeType = $mimeType;
+    }
+}

app/Services/Google/DTO/ImageGenerationRequest.php

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+<?php
+
+namespace App\Services\Google\DTO;
+
+class ImageGenerationRequest
+{
+    public function __construct(
+        public readonly string $prompt,
+        public readonly ?string $negativePrompt = null,
+        public readonly ?int $sampleCount = null,
+        public readonly ?string $aspectRatio = null,
+        public readonly ?string $safetySetting = null,
+    )
+    {
+    }
+}

app/Services/Google/DTO/ImageGenerationResponse.php

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+<?php
+
+namespace App\Services\Google\DTO;
+
+use App\Services\Google\Error\APIError;
+
+class ImageGenerationResponse
+{
+    /**
+     * @var \App\Services\Google\DTO\ImageGenerationPrediction[]
+     */
+    public readonly array $predictions;
+    public readonly ?APIError $error;
+
+    public function __construct(array $rawResponse)
+    {
+        if (isset($rawResponse['predictions']) && count($rawResponse['predictions']) > 0) {
+            $predictions = [];
+            foreach ($rawResponse['predictions'] as $prediction) {
+                $predictions[] = new ImageGenerationPrediction($prediction['bytesBase64Encoded'], $prediction['mimeType']);
+            }
+            $this->predictions = $predictions;
+            $this->error = null;
+        }
+
+        if (isset($rawResponse['error'])) {
+            $error = $rawResponse['error'];
+            $this->error = new APIError($error['message'], $error['code']);
+        }
+
+        if (!isset($this->predictions) && !isset($this->error)) {
+            $this->error = new APIError('An unknown error occurred.', 0,);
+        }
+    }
+}

app/Services/Google/EndpointBuilderService.php

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+<?php
+
+namespace App\Services\Google;
+
+class EndpointBuilderService
+{
+    public function buildPredictionEndpoint(string $model): string
+    {
+        return $this->buildEndpoint($model, 'predict');
+    }
+
+    public function buildGenerationEndpoint(string $model): string
+    {
+        return $this->buildEndpoint($model, 'generateContent');
+    }
+
+    private function buildEndpoint(string $model, string $action): string
+    {
+        $projectId = env('GOOGLE_CLOUD_PROJECT');
+        $location = env('GOOGLE_LOCATION');
+        $modelPath = 'projects/' . $projectId .
+            '/locations/' . $location .
+            '/publishers/google/models/' . $model .
+            ':' . $action;
+
+        return 'https://' . $location . '-aiplatform.googleapis.com/v1/' . $modelPath;
+    }
+}

app/Services/Google/Error/APIError.php

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+<?php
+
+namespace App\Services\Google\Error;
+
+use Exception;
+
+class APIError extends Exception
+{
+    public $code;
+    public $message;
+
+    public function __construct(string $message, int $code)
+    {
+        parent::__construct($message);
+
+        $this->code = $code;
+        $this->message = $message;
+    }
+}

app/Services/Google/ImageAspectRatios.php

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+<?php
+
+namespace App\Services\Google;
+
+/**
+ * "aspectRatio": "1:1, 9:16, 16:9, 3:4, or 4:3. default 1:1",
+ */
+enum ImageAspectRatios: string
+{
+    case _1_1 = '1:1';
+    case _9_16 = '9:16';
+    case _16_9 = '16:9';
+    case _3_4 = '3:4';
+    case _4_3 = '4:3';
+}

app/Services/Google/ImageGenerationSafetySettings.php

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+<?php
+
+namespace App\Services\Google;
+
+/**
+ * "safetySetting": "block_none, block_only_high, block_medium_and_above, block_low_and_above. default block_medium_and_above"
+ */
+enum ImageGenerationSafetySettings: string
+{
+    case BLOCK_NONE = 'block_none';
+    case BLOCK_ONLY_HIGH = 'block_only_high';
+    case BLOCK_MEDIUM_AND_ABOVE = 'block_medium_and_above';
+    case BLOCK_LOW_AND_ABOVE = 'block_low_and_above';
+}

app/Services/Google/ImageGenerationService.php

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+<?php
+
+namespace App\Services\Google;
+
+use App\Services\Google\DTO\ImageGenerationRequest;
+use App\Services\Google\DTO\ImageGenerationResponse;
+
+/**
+ * ref: https://cloud.google.com/vertex-ai/generative-ai/docs/model-reference/imagen-api
+ */
+class ImageGenerationService
+{
+    private readonly string $imagenModel;
+
+    public function __construct(
+        private readonly ApiAuthService $apiAuthService,
+        private readonly EndpointBuilderService $endpointBuilderService,
+    )
+    {
+        $this->imagenModel = env('GOOGLE_IMAGEN_MODEL');
+    }
+
+    /**
+     * @throws \Exception
+     */
+    public function generateImage(ImageGenerationRequest $request): ImageGenerationResponse
+    {
+        $requestBody = $this->buildRequestBody($request);
+
+        return $this->sendGenerationRequest($requestBody);
+    }
+
+    private function buildRequestBody(ImageGenerationRequest $request): string {
+        $instance = [
+            'prompt' => $request->prompt,
+        ];
+        if ($request->negativePrompt) {
+            $instance['negativePrompt'] = $request->negativePrompt;
+        }
+
+        $parameters = [
+            'sampleCount' => 1,
+        ];
+
+        if ($request->sampleCount) {
+            $parameters['sampleCount'] = $request->sampleCount;
+        }
+        if ($request->aspectRatio) {
+            $parameters['aspectRatio'] = $request->aspectRatio;
+        }
+        if ($request->safetySetting) {
+            $parameters['safetySetting'] = $request->safetySetting;
+        }
+
+        $requestBody = [
+            'instances' => [$instance],
+            'parameters' => $parameters
+        ];
+
+        return json_encode($requestBody);
+    }
+
+    /**
+     * @throws \Google\Exception
+     * @throws \Exception
+     */
+    private function sendGenerationRequest(string $requestBody): ImageGenerationResponse
+    {
+        $endpoint = $this->endpointBuilderService->buildPredictionEndpoint($this->imagenModel);
+        $accessToken = $this->apiAuthService->getAccessToken();
+
+        $ch = curl_init($endpoint);
+        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+        curl_setopt($ch, CURLOPT_POST, true);
+        curl_setopt($ch, CURLOPT_POSTFIELDS, $requestBody);
+        curl_setopt($ch, CURLOPT_HTTPHEADER, [
+            'Authorization: Bearer ' . $accessToken,
+            'Content-Type: application/json',
+        ]);
+
+        $response = curl_exec($ch);
+        if (curl_errno($ch) || $response === false) {
+            throw new \Exception(curl_error($ch));
+        }
+        curl_close($ch);
+
+        $responseArray = json_decode($response, true);
+
+        return new ImageGenerationResponse($responseArray);
+    }
+}