Google Vertex AI: Gemini: チャット

const MAX_IMAGE_SIZE = 20971520; // Gemini のインラインファイルの制限。1 ファイルにつき 20 MB まで

function main() {
    ////// == 工程コンフィグ・ワークフローデータの参照 / Config & Data Retrieving ==
    const auth = configs.getObject('conf_Auth');

    const region = retrieveRegion();
    const projectId = configs.get('conf_ProjectId');
    const model = retrieveModel();
    const maxTokens = retrieveMaxTokens();
    const temperature = retrieveTemperature();
    const stopSequences = retrieveStopSequences();
    const message = configs.get('conf_Message1');
    if (message === '') {
        throw new Error('User Message is empty.');
    }
    const inlineImages = retrieveImages();

    ////// == 演算 / Calculating ==
    const answer = invokeModel(
        auth,
        region,
        projectId,
        model,
        maxTokens,
        temperature,
        stopSequences,
        message,
        inlineImages
    );

    ////// == ワークフローデータへの代入 / Data Updating ==
    saveData('conf_Answer1', answer);
}

/**
 * config からリージョンコードを読み出す
 * リージョンコードの形式として不正な場合はエラー
 * @return {String}
 */
function retrieveRegion() {
    const region = configs.get('conf_Region');
    // 今後リージョンが増えることも考えて、文字数には余裕をみている
    const reg = new RegExp('^[a-z]{2,20}-[a-z]{2,20}[1-9]{1,2}$');
    if (!reg.test(region)) {
        throw new Error('Region Code is invalid.');
    }
    return region;
}

/**
 * config からモデル ID を読み出す
 * モデル ID として不正な文字が含まれている場合はエラー
 * @return {String}
 */
function retrieveModel() {
    const model = configs.get('conf_Model');
    const reg = new RegExp('^[a-z0-9.-]+$');
    if (!reg.test(model)) {
        throw new Error('Model includes an invalid character.');
    }
    return model;
}

/**
 * config から最大トークン数を読み出す
 * 未定義の場合、null を返す
 * @returns {Number}
 */
const retrieveMaxTokens = () => {
    const maxTokens = configs.get('conf_MaxTokens');
    if (maxTokens === '') {
        return null;
    }
    const regExp = new RegExp(/^[1-9][0-9]*$/);
    if (!regExp.test(maxTokens)) {
        throw new Error('Maximum number of tokens must be a positive integer.');
    }
    return parseInt(maxTokens, 10);
};

/**
 * config から温度を読み出す
 * 未定義の場合、null を返す
 * @returns {Number}
 */
const retrieveTemperature = () => {
    const temperature = configs.get('conf_Temperature');
    if (temperature === '') {
        return null;
    }
    const regExp = /^([0-1](\.\d+)?|2(\.0+)?)$/;
    if (!regExp.test(temperature)) {
        throw new Error('Temperature must be a number from 0 to 2.');
    }
    return parseFloat(temperature);
};

/**
 * config から停止シーケンスを読み出す
 * @returns {Array<String>}
 */
const retrieveStopSequences = () => {
    const stopSequencesStr = configs.get('conf_StopSequences');
    if (stopSequencesStr === '') {
        return [];
    }
    const stopSequences = stopSequencesStr.split('\n').filter((s) => s !== '');
    if (stopSequences.length > 5) {
        throw new Error('Too many stop sequences. The maximum number is 5.');
    }
    return stopSequences;
};

/**
 * config から画像・動画を読み出す
 * 以下の場合はエラー
 * - 添付ファイルの総数が多すぎる場合
 * - ファイルサイズが大きすぎる場合
 * - 画像でも動画でもないファイルが添付されている場合
 * @returns {Array<Object>} インライン画像・動画オブジェクトの配列
 */
const retrieveImages = () => {
    const imagesDef = configs.getObject('conf_Images1');
    if (imagesDef === null) {
        return [];
    }
    const images = engine.findData(imagesDef);
    if (images === null) {
        return [];
    }
    const inlineImages = [];
    images.forEach((image) => {
        if (image.getLength() > MAX_IMAGE_SIZE) {
            throw new Error(
                `Attached file "${image.getName()}" is too large. Each file must be less than ${MAX_IMAGE_SIZE} bytes.`
            );
        }
        const contentType = image.getContentType();
        if (
            !contentType.startsWith('image/') &&
            !contentType.startsWith('video/') &&
            !contentType.startsWith('audio/') &&
            !contentType.startsWith('application/pdf') &&
            !contentType.startsWith('text/plain')
        ) {
            throw new Error(
                `Attached file "${image.getName()}" is neither an image, video, audio, PDF, nor text.`
            );
        }
        const inlineImage = {
            mimeType: image.getContentType(),
            data: base64.encodeToString(fileRepository.readFile(image)),
        };
        inlineImages.push(inlineImage);
    });
    return inlineImages;
};

const SCOPE = 'https://www.googleapis.com/auth/cloud-platform';
const URL_TOKEN_REQUEST = 'https://oauth2.googleapis.com/token';

/**
 * @param auth HTTP 認証設定
 * @returns {any} アクセストークンを含むオブジェクト
 */
const getAccessToken = (auth) => {
    const privateKeyId = auth.getPrivateKeyId();
    const privateKey = auth.getPrivateKey();
    const serviceAccount = auth.getCustomSecret1();
    const scope = auth.getScope();
    if (scope === null || !scope.split(' ').includes(SCOPE)) {
        throw new Error(`Scope ${SCOPE} must be included in the scope.`);
    }
    if (privateKeyId === '') {
        throw new Error('Private Key ID is required.');
    }
    if (privateKey === '') {
        throw new Error('Private Key is required.');
    }
    if (serviceAccount === '') {
        throw new Error('Service Account must be set to Custom Secret 1.');
    }
    const header = {
        alg: 'RS256',
        typ: 'at+jwt',
        kid: privateKeyId,
    };
    const now = Math.floor(Date.now() / 1000);
    const payload = {
        iss: serviceAccount,
        aud: URL_TOKEN_REQUEST,
        sub: '',
        iat: now,
        exp: now + 3600,
        /**
         * https://developers.google.com/identity/protocols/oauth2/service-account#jwt-auth
         * "without OAuth" の話だが、OAuth でも 1 hour になるようだ。
         * 1 hour より長ければエラー。短ければ、1 hour のトークンが返ってくる。
         */
        scope,
    };
    const keyB = rsa.readKeyFromPkcs8(privateKey);
    const assertion = jwt.build(header, payload, keyB);

    const response = httpClient
        .begin()
        .formParam('grant_type', 'urn:ietf:params:oauth:grant-type:jwt-bearer')
        .formParam('assertion', assertion)
        .post(URL_TOKEN_REQUEST);
    const responseText = response.getResponseAsString();
    if (response.getStatusCode() !== 200) {
        engine.log(responseText);
        throw new Error(`Failed to get Access token. status: ${response.getStatusCode()}`);
    }
    const result = JSON.parse(response.getResponseAsString());
    if (result.access_token === undefined) {
        engine.log(responseText);
        throw new Error(`Failed to get Access token. access token not found.`);
    }
    return result;
};

/**
 * モデルの実行
 * @param region
 * @param projectId
 * @param model
 * @param maxTokens
 * @param temperature
 * @param stopSequences
 * @param message
 * @param inlineImages
 * @returns {String} answer
 */
const invokeModel = (
    auth,
    region,
    projectId,
    model,
    maxTokens,
    temperature,
    stopSequences,
    message,
    inlineImages
) => {
    const URL = `https://${region}-aiplatform.googleapis.com/v1/projects/${projectId}/locations/${region}/publishers/google/models/${model}:streamGenerateContent`;

    const generation_config = {};
    if (maxTokens !== null) {
        generation_config.maxOutputTokens = maxTokens;
    }
    if (temperature !== null) {
        generation_config.temperature = temperature;
    }
    generation_config.stopSequences = stopSequences;
    const payload = {
        contents: {
            role: 'user',
            parts: [
                {
                    text: message,
                },
            ],
        },
        safety_settings: {
            category: 'HARM_CATEGORY_SEXUALLY_EXPLICIT',
            threshold: 'BLOCK_LOW_AND_ABOVE',
        },
        generation_config,
    };
    inlineImages.forEach((inlineImage) => {
        payload.contents.parts.push({
            inlineData: inlineImage,
        });
    });

    const response = httpClient
        .begin()
        .oauth2JwtBearer(auth, () => getAccessToken(auth))
        .body(JSON.stringify(payload), 'application/json')
        .post(URL);

    const status = response.getStatusCode();
    const respTxt = response.getResponseAsString();
    if (status !== 200) {
        engine.log(respTxt);
        throw new Error(`Failed to invoke model. status: ${status}`);
    }
    const json = JSON.parse(respTxt);
    let answers = [];

    for (const { candidates, usageMetadata } of json) {
        if (candidates[0].content === undefined) {
            engine.log('No content in the candidate.');
        } else {
            answers.push(candidates[0].content.parts[0].text);
        }
        const finishReason = candidates[0].finishReason;
        if (finishReason !== undefined) {
            engine.log(`Finish Reason: ${finishReason}`);
        }
        if (usageMetadata !== undefined) {
            if (usageMetadata.promptTokenCount !== undefined) {
                engine.log(`Prompt Token Count: ${usageMetadata.promptTokenCount}`);
            }
            if (usageMetadata.candidatesTokenCount !== undefined) {
                engine.log(`Candidates Token Count: ${usageMetadata.candidatesTokenCount}`);
            }
        }
    }

    if (answers.length === 0 || answers.join('') === '') {
        throw new Error(`No response content generated.`);
    }

    return answers.join('');
};

/**
 * データ項目への保存
 * @param configName
 * @param data
 */
const saveData = (configName, data) => {
    const def = configs.getObject(configName);
    if (def === null) {
        return;
    }
    engine.setData(def, data);
};