src/lib/server/models.ts

import { HF_ACCESS_TOKEN, MODELS, OLD_MODELS, TASK_MODEL } from "$env/static/private";
import type { ChatTemplateInput } from "$lib/types/Template";
import { compileTemplate } from "$lib/utils/template";
import { z } from "zod";

type Optional<T, K extends keyof T> = Pick<Partial<T>, K> & Omit<T, K>;

const sagemakerEndpoint = z.object({
	host: z.literal("sagemaker"),
	url: z.string().url(),
	accessKey: z.string().min(1),
	secretKey: z.string().min(1),
	sessionToken: z.string().optional(),
});

const tgiEndpoint = z.object({
	host: z.union([z.literal("tgi"), z.undefined()]),
	url: z.string().url(),
	authorization: z.string().min(1).default(`Bearer ${HF_ACCESS_TOKEN}`),
});

const commonEndpoint = z.object({
	weight: z.number().int().positive().default(1),
});

const endpoint = z.lazy(() =>
	z.union([sagemakerEndpoint.merge(commonEndpoint), tgiEndpoint.merge(commonEndpoint)])
);

const combinedEndpoint = endpoint.transform((data) => {
	if (data.host === "tgi" || data.host === undefined) {
		return tgiEndpoint.merge(commonEndpoint).parse(data);
	} else if (data.host === "sagemaker") {
		return sagemakerEndpoint.merge(commonEndpoint).parse(data);
	} else {
		throw new Error(`Invalid host: ${data.host}`);
	}
});

const modelsRaw = z
	.array(
		z.object({
			/** Used as an identifier in DB */
			id: z.string().optional(),
			/** Used to link to the model page, and for inference */
			name: z.string().min(1),
			displayName: z.string().min(1).optional(),
			description: z.string().min(1).optional(),
			websiteUrl: z.string().url().optional(),
			modelUrl: z.string().url().optional(),
			datasetName: z.string().min(1).optional(),
			datasetUrl: z.string().url().optional(),
			userMessageToken: z.string().default(""),
			userMessageEndToken: z.string().default(""),
			assistantMessageToken: z.string().default(""),
			assistantMessageEndToken: z.string().default(""),
			messageEndToken: z.string().default(""),
			preprompt: z.string().default(""),
			prepromptUrl: z.string().url().optional(),
			chatPromptTemplate: z
				.string()
				.default(
					"{{preprompt}}" +
						"{{#each messages}}" +
						"{{#ifUser}}{{@root.userMessageToken}}{{content}}{{@root.userMessageEndToken}}{{/ifUser}}" +
						"{{#ifAssistant}}{{@root.assistantMessageToken}}{{content}}{{@root.assistantMessageEndToken}}{{/ifAssistant}}" +
						"{{/each}}" +
						"{{assistantMessageToken}}"
				),
			promptExamples: z
				.array(
					z.object({
						title: z.string().min(1),
						prompt: z.string().min(1),
					})
				)
				.optional(),
			endpoints: z.array(combinedEndpoint).optional(),
			parameters: z
				.object({
					temperature: z.number().min(0).max(1),
					truncate: z.number().int().positive(),
					max_new_tokens: z.number().int().positive(),
					stop: z.array(z.string()).optional(),
				})
				.passthrough()
				.optional(),
		})
	)
	.parse(JSON.parse(MODELS));

export const models = await Promise.all(
	modelsRaw.map(async (m) => ({
		...m,
		userMessageEndToken: m?.userMessageEndToken || m?.messageEndToken,
		assistantMessageEndToken: m?.assistantMessageEndToken || m?.messageEndToken,
		chatPromptRender: compileTemplate<ChatTemplateInput>(m.chatPromptTemplate, m),
		id: m.id || m.name,
		displayName: m.displayName || m.name,
		preprompt: m.prepromptUrl ? await fetch(m.prepromptUrl).then((r) => r.text()) : m.preprompt,
		parameters: { ...m.parameters, stop_sequences: m.parameters?.stop },
	}))
);

// Models that have been deprecated
export const oldModels = OLD_MODELS
	? z
			.array(
				z.object({
					id: z.string().optional(),
					name: z.string().min(1),
					displayName: z.string().min(1).optional(),
				})
			)
			.parse(JSON.parse(OLD_MODELS))
			.map((m) => ({ ...m, id: m.id || m.name, displayName: m.displayName || m.name }))
	: [];

export type BackendModel = Optional<(typeof models)[0], "preprompt" | "parameters">;
export type Endpoint = z.infer<typeof endpoint>;

export const defaultModel = models[0];

export const smallModel = models.find((m) => m.name === TASK_MODEL) || defaultModel;

export const validateModel = (_models: BackendModel[]) => {
	// Zod enum function requires 2 parameters
	return z.enum([_models[0].id, ..._models.slice(1).map((m) => m.id)]);
};