LangChain for JavaScript part 3: Create Dall-E images

import { promises as fsp } from 'fs';
import { DallEAPIWrapper } from "@langchain/openai";
import { PromptTemplate } from "@langchain/core/prompts";
import { Buffer } from 'buffer';
import { v4 as generateUUID } from 'uuid';

function generateFilename() {
    return `${generateUUID()}.png`;
}

const headline = `LangChain for JavaScript part 1`;

const imagePrompt = PromptTemplate.fromTemplate(`
To generate a creative header image using Dall-E based on your blog post's headline and body text, we can design a flexible prompt that incorporates key elements of your blog. Here's how you can structure your prompt, making it adaptable to any blog post by substituting your specific headlines and text:

### Dall-E Prompt Template

**Title of the Blog Post**: {headline}

**Preferred Color Scheme and Art Style**: Bright and vibrant colors to emphasize growth and sustainability; a blend of digital art and watercolor styles for a modern yet organic feel

**Mood or Atmosphere of the Image**: Inspiring and uplifting, showcasing harmony between urban life and nature

Make sure to not include the Title of the Blog Post in the image. The image should be a visual representation of the blog post's content and theme.
`);

async function main() {
    const tool = new DallEAPIWrapper({
        n: 1, // Default
        modelName: "dall-e-3", // Default
        openAIApiKey: process.env.OPENAI_API_KEY, 
        size: "1792x1024"
    });
      
    const prompt = await imagePrompt.format({ headline }); 
    const imageURL = await tool.invoke(prompt);
    const filename = generateFilename();
    const arrayBuf = await fetch(imageURL).then(res => res.arrayBuffer());
    await fsp.writeFile(filename, Buffer.from(arrayBuf));
}

main().catch(console.error);

/**
 * An interface for the Dall-E API Wrapper.
 */
export interface DallEAPIWrapperParams extends ToolParams {
    /**
     * The OpenAI API key
     */
    openAIApiKey?: string;
    /**
     * The model to use.
     * @params "dall-e-2" | "dall-e-3"
     * @default "dall-e-3"
     */
    modelName?: string;
    /**
     * The style of the generated images. Must be one of vivid or natural.
     * Vivid causes the model to lean towards generating hyper-real and dramatic images.
     * Natural causes the model to produce more natural, less hyper-real looking images.
     * @default "vivid"
     */
    style?: "natural" | "vivid";
    /**
     * The quality of the image that will be generated. ‘hd’ creates images with finer
     * details and greater consistency across the image.
     * @default "standard"
     */
    quality?: "standard" | "hd";
    /**
     * The number of images to generate.
     * Must be between 1 and 10.
     * For dall-e-3, only `n: 1` is supported.
     * @default 1
     */
    n?: number;
    /**
     * The size of the generated images.
     * Must be one of 256x256, 512x512, or 1024x1024 for DALL·E-2 models.
     * Must be one of 1024x1024, 1792x1024, or 1024x1792 for DALL·E-3 models.
     * @default "1024x1024"
     */
    size?: "256x256" | "512x512" | "1024x1024" | "1792x1024" | "1024x1792";
    /**
     * The format in which the generated images are returned.
     * Must be one of "url" or "b64_json".
     * @default "url"
     */
    responseFormat?: "url" | "b64_json";
    /**
     * A unique identifier representing your end-user, which will help
     * OpenAI to monitor and detect abuse.
     */
    user?: string;
    /**
     * The organization to use
     */
    organization?: string;
}

const tool = new DallEAPIWrapper({
    openAIApiKey: process.env.OPENAI_API_KEY
    modelName: "dall-e-3",
    style: "vivid",
    quality: "standard",
    n: 1,
    size: "1024x1024",
    responseFormat: "url"
});