feat(args): add cliApp() runner

Author: postspectacular

packages/args/src/api.ts

@@ -1,4 +1,5 @@
 import type { Fn, IDeref, IObjectOf } from "@thi.ng/api";
+import type { ILogger } from "@thi.ng/logger";
 
 export interface ArgSpecBase {
 	/**
@@ -196,3 +197,55 @@ export class Tuple<T> implements IDeref<T[]> {
 		return this.value;
 	}
 }
+
+export interface CLIAppConfig<OPTS extends object> {
+	/**
+	 * Shared args for all commands
+	 */
+	opts: Args<OPTS>;
+	/**
+	 * Command spec registry
+	 */
+	commands: IObjectOf<Command<any, OPTS>>;
+	/**
+	 * If true, the app will only use the single command entry in
+	 * {@link CLIAppConfig.commands} and not expect the first CLI args to be a
+	 * command name.
+	 */
+	single?: boolean;
+	/**
+	 * Usage options, same as {@link UsageOpts}. Usage will be shown
+	 * automatically in case of arg parse errors.
+	 */
+	usage: Partial<UsageOpts>;
+	/**
+	 * Arguments vector to use for arg parsing. If omitted, uses
+	 * `process.argv.slice(2)`
+	 */
+	argv?: string[];
+}
+
+export interface Command<T extends BASE, BASE extends object> {
+	/**
+	 * Command description (short, single line)
+	 */
+	desc: string;
+	/**
+	 * Command specific CLI arg specs
+	 */
+	opts: Args<Omit<T, keyof BASE>>;
+	/**
+	 * Number of required rest input value (after all options)
+	 */
+	inputs?: number;
+	/**
+	 * Actual command function/implementation.
+	 */
+	fn: Fn<CommandCtx<T, BASE>, Promise<void>>;
+}
+
+export interface CommandCtx<T extends BASE, BASE extends object> {
+	logger: ILogger;
+	opts: T;
+	inputs: string[];
+}

packages/args/src/cli.ts

@@ -0,0 +1,67 @@
+import { illegalArgs } from "@thi.ng/errors";
+import { ConsoleLogger } from "@thi.ng/logger/console";
+import type { CLIAppConfig, Command, UsageOpts } from "./api.js";
+import { parse } from "./parse.js";
+import { usage } from "./usage.js";
+import { padRight } from "@thi.ng/strings/pad-right";
+import type { IObjectOf } from "@thi.ng/api";
+
+export const cliApp = async <T extends object>(config: CLIAppConfig<T>) => {
+	const argv = config.argv || process.argv.slice(2);
+	let usageOpts = { prefix: "", ...config.usage };
+	try {
+		let cmdID: string;
+		let cmd: Command<any, T>;
+		let start = 0;
+		if (config.single) {
+			// single command mode, use 1st available name
+			cmdID = Object.keys(config.commands)[0];
+			if (!cmdID) illegalArgs("no command provided");
+			cmd = config.commands[cmdID];
+		} else {
+			start = 1;
+			cmdID = argv[0];
+			cmd = config.commands[cmdID];
+			usageOpts.prefix += __descriptions(config.commands);
+			if (!cmd) __usageAndExit(config, usageOpts);
+		}
+		const parsed = parse<T>({ ...config.opts, ...cmd.opts }, argv, {
+			showUsage: false,
+			usageOpts,
+			start,
+		});
+		const inputsOk =
+			parsed && cmd.inputs !== undefined
+				? cmd.inputs === parsed.rest.length
+				: true;
+		if (!(parsed && inputsOk)) {
+			process.stderr.write(`expected ${cmd.inputs || 0} input(s)\n`);
+			__usageAndExit(config, usageOpts);
+		}
+		await cmd.fn({
+			logger: new ConsoleLogger("app", "DEBUG"),
+			opts: parsed!.result,
+			inputs: parsed!.rest,
+		});
+	} catch (e) {
+		process.stderr.write((<Error>e).message + "\n\n");
+		__usageAndExit(config, usageOpts);
+	}
+};
+
+const __usageAndExit = <T extends object>(
+	config: CLIAppConfig<T>,
+	usageOpts: Partial<UsageOpts>
+) => {
+	process.stderr.write(usage(config.opts, usageOpts));
+	process.exit(1);
+};
+
+const __descriptions = (commands: IObjectOf<Command<any, any>>) =>
+	[
+		"\nAvailable commands:\n",
+		...Object.keys(commands).map(
+			(x) => `${padRight(16)(x)}: ${commands[x].desc}`
+		),
+		"\n\n",
+	].join("\n");

packages/args/src/index.ts

@@ -1,5 +1,6 @@
 export * from "./api.js";
 export * from "./args.js";
+export * from "./cli.js";
 export * from "./coerce.js";
 export * from "./parse.js";
 export * from "./usage.js";