src/lib/server/endpoints/google/endpointVertex.ts

import {
	VertexAI,
	HarmCategory,
	HarmBlockThreshold,
	type Content,
	type TextPart,
} from "@google-cloud/vertexai";
import type { Endpoint } from "../endpoints";
import { z } from "zod";
import type { Message } from "$lib/types/Message";
import type { TextGenerationStreamOutput } from "@huggingface/inference";

export const endpointVertexParametersSchema = z.object({
	weight: z.number().int().positive().default(1),
	model: z.any(), // allow optional and validate against emptiness
	type: z.literal("vertex"),
	location: z.string().default("europe-west1"),
	project: z.string(),
	apiEndpoint: z.string().optional(),
	safetyThreshold: z
		.enum([
			HarmBlockThreshold.HARM_BLOCK_THRESHOLD_UNSPECIFIED,
			HarmBlockThreshold.BLOCK_LOW_AND_ABOVE,
			HarmBlockThreshold.BLOCK_MEDIUM_AND_ABOVE,
			HarmBlockThreshold.BLOCK_NONE,
			HarmBlockThreshold.BLOCK_ONLY_HIGH,
		])
		.optional(),
});

export function endpointVertex(input: z.input<typeof endpointVertexParametersSchema>): Endpoint {
	const { project, location, model, apiEndpoint, safetyThreshold } =
		endpointVertexParametersSchema.parse(input);

	const vertex_ai = new VertexAI({
		project,
		location,
		apiEndpoint,
	});

	return async ({ messages, preprompt, generateSettings }) => {
		const generativeModel = vertex_ai.getGenerativeModel({
			model: model.id ?? model.name,
			safetySettings: safetyThreshold
				? [
						{
							category: HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT,
							threshold: safetyThreshold,
						},
						{
							category: HarmCategory.HARM_CATEGORY_HARASSMENT,
							threshold: safetyThreshold,
						},
						{
							category: HarmCategory.HARM_CATEGORY_HATE_SPEECH,
							threshold: safetyThreshold,
						},
						{
							category: HarmCategory.HARM_CATEGORY_SEXUALLY_EXPLICIT,
							threshold: safetyThreshold,
						},
						{
							category: HarmCategory.HARM_CATEGORY_UNSPECIFIED,
							threshold: safetyThreshold,
						},
				  ]
				: undefined,
			generationConfig: {
				maxOutputTokens: generateSettings?.max_new_tokens ?? 4096,
				stopSequences: generateSettings?.stop,
				temperature: generateSettings?.temperature ?? 1,
			},
		});

		// Preprompt is the same as the first system message.
		let systemMessage = preprompt;
		if (messages[0].from === "system") {
			systemMessage = messages[0].content;
			messages.shift();
		}

		const vertexMessages = messages.map(({ from, content }: Omit<Message, "id">): Content => {
			return {
				role: from === "user" ? "user" : "model",
				parts: [
					{
						text: content,
					},
				],
			};
		});

		const result = await generativeModel.generateContentStream({
			contents: vertexMessages,
			systemInstruction: systemMessage
				? {
						role: "system",
						parts: [
							{
								text: systemMessage,
							},
						],
				  }
				: undefined,
		});

		let tokenId = 0;
		return (async function* () {
			let generatedText = "";

			for await (const data of result.stream) {
				if (!data?.candidates?.length) break; // Handle case where no candidates are present

				const candidate = data.candidates[0];
				if (!candidate.content?.parts?.length) continue; // Skip if no parts are present

				const firstPart = candidate.content.parts.find((part) => "text" in part) as
					| TextPart
					| undefined;
				if (!firstPart) continue; // Skip if no text part is found

				const isLastChunk = !!candidate.finishReason;

				const content = firstPart.text;
				generatedText += content;
				const output: TextGenerationStreamOutput = {
					token: {
						id: tokenId++,
						text: content,
						logprob: 0,
						special: isLastChunk,
					},
					generated_text: isLastChunk ? generatedText : null,
					details: null,
				};
				yield output;

				if (isLastChunk) break;
			}
		})();
	};
}
export default endpointVertex;