refactor(Basic LLM Chain Node): Refactor Basic LLM Chain & add tests (#13850)

packages/@n8n/nodes-langchain/nodes/chains/ChainLLM/methods/imageUtils.ts

@@ -0,0 +1,99 @@
+import type { BaseLanguageModel } from '@langchain/core/language_models/base';
+import { HumanMessage } from '@langchain/core/messages';
+import { ChatGoogleGenerativeAI } from '@langchain/google-genai';
+import { ChatOllama } from '@langchain/ollama';
+import type { IExecuteFunctions, IBinaryData } from 'n8n-workflow';
+import { NodeOperationError, NodeConnectionType, OperationalError } from 'n8n-workflow';
+
+import type { MessageTemplate } from './types';
+
+export class UnsupportedMimeTypeError extends OperationalError {}
+
+/**
+ * Converts binary image data to a data URI
+ */
+export function dataUriFromImageData(binaryData: IBinaryData, bufferData: Buffer): string {
+	if (!binaryData.mimeType?.startsWith('image/')) {
+		throw new UnsupportedMimeTypeError(
+			`${binaryData.mimeType} is not a supported type of binary data. Only images are supported.`,
+		);
+	}
+	return `data:${binaryData.mimeType};base64,${bufferData.toString('base64')}`;
+}
+
+/**
+ * Creates a human message with image content from either binary data or URL
+ */
+export async function createImageMessage({
+	context,
+	itemIndex,
+	message,
+}: {
+	context: IExecuteFunctions;
+	itemIndex: number;
+	message: MessageTemplate;
+}): Promise<HumanMessage> {
+	// Validate message type
+	if (message.messageType !== 'imageBinary' && message.messageType !== 'imageUrl') {
+		throw new NodeOperationError(
+			context.getNode(),
+			'Invalid message type. Only imageBinary and imageUrl are supported',
+		);
+	}
+
+	const detail = message.imageDetail === 'auto' ? undefined : message.imageDetail;
+
+	// Handle image URL case
+	if (message.messageType === 'imageUrl' && message.imageUrl) {
+		return new HumanMessage({
+			content: [
+				{
+					type: 'image_url',
+					image_url: {
+						url: message.imageUrl,
+						detail,
+					},
+				},
+			],
+		});
+	}
+
+	// Handle binary image case
+	const binaryDataKey = message.binaryImageDataKey ?? 'data';
+	const inputData = context.getInputData()[itemIndex];
+	const binaryData = inputData.binary?.[binaryDataKey] as IBinaryData;
+
+	if (!binaryData) {
+		throw new NodeOperationError(context.getNode(), 'No binary data set.');
+	}
+
+	const bufferData = await context.helpers.getBinaryDataBuffer(itemIndex, binaryDataKey);
+	const model = (await context.getInputConnectionData(
+		NodeConnectionType.AiLanguageModel,
+		0,
+	)) as BaseLanguageModel;
+
+	try {
+		// Create data URI from binary data
+		const dataURI = dataUriFromImageData(binaryData, bufferData);
+
+		// Some models need different image URL formats
+		const directUriModels = [ChatGoogleGenerativeAI, ChatOllama];
+		const imageUrl = directUriModels.some((i) => model instanceof i)
+			? dataURI
+			: { url: dataURI, detail };
+
+		return new HumanMessage({
+			content: [
+				{
+					type: 'image_url',
+					image_url: imageUrl,
+				},
+			],
+		});
+	} catch (error) {
+		if (error instanceof UnsupportedMimeTypeError)
+			throw new NodeOperationError(context.getNode(), error.message);
+		throw error;
+	}
+}