#!/usr/bin/env node
import { dirname, join } from "node:path";
import { parseArgs } from "node:util";
import { lstat, readFile } from "node:fs/promises";
import { z } from "zod";
import { PROVIDERS_OR_POLICIES } from "@huggingface/inference";
import { Agent } from "@huggingface/mcp-client";
import { version as packageVersion } from "../package.json";
import { ServerConfigSchema } from "./lib/types";
import { debug, error } from "./lib/utils";
import { mainCliLoop } from "./lib/mainCliLoop";

const USAGE_HELP = `
Usage:
  tiny-agents [flags]
  tiny-agents run   "agent/id"
  tiny-agents serve "agent/id"

Available Commands:
  run         Run the Agent in command-line
  serve       Run the Agent as an OpenAI-compatible HTTP server

Flags:
  -h, --help      help for tiny-agents
  -v, --version   Show version information
`.trim();

const CLI_COMMANDS = ["run", "serve"] as const;
function isValidCommand(command: string): command is (typeof CLI_COMMANDS)[number] {
	return (CLI_COMMANDS as unknown as string[]).includes(command);
}

const FILENAME_CONFIG = "agent.json";
// eslint-disable-next-line @typescript-eslint/no-unused-vars
const FILENAME_PROMPT = "PROMPT.md";

async function loadConfigFrom(loadFrom: string): Promise<{ configJson: string; prompt?: string }> {
	try {
		/// First try it as a local file path, then as a local directory, then we will try as a path inside the repo itself
		return {
			configJson: await readFile(loadFrom, { encoding: "utf8" }),
		};
	} catch {
		if ((await lstat(loadFrom)).isDirectory()) {
			/// local directory
			try {
				let prompt: string | undefined;
				try {
					prompt = await readFile(join(loadFrom, FILENAME_PROMPT), { encoding: "utf8" });
				} catch {
					debug(`PROMPT.md not found in ${loadFrom}, continuing without prompt template`);
				}
				return {
					configJson: await readFile(join(loadFrom, FILENAME_CONFIG), { encoding: "utf8" }),
					prompt,
				};
			} catch {
				error(`Config file not found in specified local directory.`);
				process.exit(1);
			}
		}
		const srcDir = dirname(__filename);
		const configDir = join(srcDir, "agents", loadFrom);
		try {
			let prompt: string | undefined;
			try {
				prompt = await readFile(join(configDir, FILENAME_PROMPT), { encoding: "utf8" });
			} catch {
				debug(`PROMPT.md not found in ${configDir}, continuing without prompt template`);
			}
			return {
				configJson: await readFile(join(configDir, FILENAME_CONFIG), { encoding: "utf8" }),
				prompt,
			};
		} catch {
			error(`Config file not found in tiny-agents repo! Loading from the HF Hub is not implemented yet`);
			process.exit(1);
		}
	}
}

async function main() {
	const {
		values: { help, version },
		positionals,
	} = parseArgs({
		options: {
			help: {
				type: "boolean",
				short: "h",
			},
			version: {
				type: "boolean",
				short: "v",
			},
		},
		allowPositionals: true,
	});
	if (version) {
		console.log(packageVersion);
		process.exit(0);
	}
	const command = positionals[0];
	const loadFrom = positionals[1];
	if (help) {
		console.log(USAGE_HELP);
		process.exit(0);
	}
	if (positionals.length !== 2 || !isValidCommand(command)) {
		error(`You need to call run or serve, followed by an agent id (local path or Hub identifier).`);
		console.log(USAGE_HELP);
		process.exit(1);
	}

	const { configJson, prompt } = await loadConfigFrom(loadFrom);

	const ConfigSchema = z
		.object({
			model: z.string(),
			provider: z.enum(PROVIDERS_OR_POLICIES).optional(),
			endpointUrl: z.string().optional(),
			apiKey: z.string().optional(),
			servers: z.array(ServerConfigSchema),
		})
		.refine((data) => data.provider !== undefined || data.endpointUrl !== undefined, {
			message: "At least one of 'provider' or 'endpointUrl' is required",
		});

	let config: z.infer<typeof ConfigSchema>;
	try {
		const parsedConfig = JSON.parse(configJson);
		config = ConfigSchema.parse(parsedConfig);
	} catch (err) {
		error("Invalid configuration file:", err instanceof Error ? err.message : err);
		process.exit(1);
	}

	const agent = new Agent(
		config.endpointUrl
			? {
					endpointUrl: config.endpointUrl,
					model: config.model,
					apiKey: config.apiKey ?? process.env.API_KEY ?? process.env.HF_TOKEN,
					servers: config.servers,
					prompt,
			  }
			: {
					// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
					provider: config.provider!,
					model: config.model,
					apiKey: config.apiKey ?? process.env.API_KEY ?? process.env.HF_TOKEN,
					servers: config.servers,
					prompt,
			  }
	);

	if (command === "serve") {
		error(`Serve is not implemented yet, coming soon!`);
		process.exit(1);
	} else {
		debug(agent);
		// main loop from mcp-client/cli.ts
		await mainCliLoop(agent);
	}
}

main();