scroll/src/common/runtime.ts

import { getTermios } from './termios.ts';
import { ctrlKey, noop } from './utils.ts';
import { ITestBase } from './types.ts';
import { KeyCommand } from './ansi.ts';
import { IRuntime } from './runtime_types.ts';
export type * from './runtime_types.ts';

/**
 * Which Typescript runtime is currently being used
 */
export enum RunTimeType {
	Bun = 'bun',
	Deno = 'deno',
	Unknown = 'common',
}

const decoder = new TextDecoder();
let scrollRuntime: IRuntime | null = null;

// ----------------------------------------------------------------------------
// Misc runtime functions
// ----------------------------------------------------------------------------

/**
 * Convert input from ANSI escape sequences into a form
 * that can be more easily mapped to editor commands
 *
 * @param raw - the raw chunk of input
 */
export function readKey(raw: Uint8Array): string {
	if (raw.length === 0) {
		return '';
	}
	const parsed = decoder.decode(raw);

	// Return the input if it's unambiguous
	if (parsed in KeyCommand) {
		return parsed;
	}

	// Some keycodes have multiple potential inputs
	switch (parsed) {
		case '\x1b[1~':
		case '\x1b[7~':
		case '\x1bOH':
		case '\x1b[H':
			return KeyCommand.Home;

		case '\x1b[4~':
		case '\x1b[8~':
		case '\x1bOF':
		case '\x1b[F':
			return KeyCommand.End;

		case '\n':
		case '\v':
			return KeyCommand.Enter;

		case ctrlKey('l'):
			return KeyCommand.Escape;

		case ctrlKey('h'):
			return KeyCommand.Backspace;

		default:
			return parsed;
	}
}

/**
 * Append information to the scroll.log logfile
 */
export function logToFile(s: unknown) {
	importForRuntime('file_io').then((f) => {
		const raw = typeof s === 'string' ? s : JSON.stringify(s, null, 2);
		const output = raw + '\n';

		f.appendFile('./scroll.log', output).then(noop);
	});
}

/**
 * Kill program, displaying an error message
 * @param s
 */
export function die(s: string | Error): void {
	getTermios().then((t) => {
		t.disableRawMode();
		t.cleanup();
		console.error(s);

		getRuntime().then((r) => r.exit());
	});
}

/**
 * Determine which Typescript runtime we are operating under
 */
export function runtimeType(): RunTimeType {
	let runtime = RunTimeType.Unknown;

	if ('Deno' in globalThis) {
		runtime = RunTimeType.Deno;
	}
	if ('Bun' in globalThis) {
		runtime = RunTimeType.Bun;
	}

	return runtime;
}

/**
 * Get the adapter object for the current Runtime
 */
export async function getRuntime(): Promise<IRuntime> {
	if (scrollRuntime === null) {
		const runtime = runtimeType();
		const path = `../${runtime}/mod.ts`;

		const pkg = await import(path);
		if ('default' in pkg) {
			scrollRuntime = pkg.default;
		}
	}

	return Promise.resolve(scrollRuntime!);
}

/**
 * Get the common test interface object
 */
export async function getTestRunner(): Promise<ITestBase> {
	const runtime = runtimeType();
	const path = `../${runtime}/test_base.ts`;
	const pkg = await import(path);
	if ('default' in pkg) {
		return pkg.default;
	}

	return pkg;
}

/**
 * Import a runtime-specific module
 *
 * e.g. to load "src/bun/mod.ts", if the runtime is bun,
 * you can use like so `await importForRuntime('index')`;
 *
 * @param path - the path within the runtime module
 */
export const importForRuntime = async (path: string) => {
	const runtime = runtimeType();
	const suffix = '.ts';
	const base = `../${runtime}/`;

	const pathParts = path
		.split('/')
		.filter((part) => part !== '' && part !== '.' && part !== suffix)
		.map((part) => part.replace(suffix, ''));

	const cleanedPath = pathParts.join('/');
	const importPath = base + cleanedPath + suffix;

	const pkg = await import(importPath);
	if ('default' in pkg) {
		return pkg.default;
	}

	return pkg;
};