import { env } from 'node:process';
import { dirname, join } from 'node:path';
import { existsSync, mkdirSync } from 'node:fs';

import { writable } from 'empathic/access';
import * as find from 'empathic/find';

/**
 * Find the closest "package.json" file while walking parent directories.
 * @returns The absolute path to a "package.json", if found.
 */
export function up(options?: find.Options): string | undefined {
	return find.up('package.json', options);
}

/**
 * Construct a path to a `node_modules/.cache/<name>` directory.
 *
 * This may return `undefined` if:
 *   1. no "package.json" could be found
 *   2. the nearest "node_modules" directory is not writable
 *   3. the "node_modules" parent directory is not writable
 *
 * > [NOTE]
 * > You may define a `CACHE_DIR` environment variable, which will be
 * > used (as defined) instead of traversing the filesystem for the
 * > closest "package.json" and inferring a "node_modules" location.
 *
 * @see find-cache-dir for more information.
 *
 * @param name The name of your module/cache.
 * @returns The absolute path of the cache directory, if found.
 */
export function cache(
	name: string,
	options?: find.Options & { create?: boolean },
): string | undefined {
	options = options || {};

	let dir = env.CACHE_DIR;

	if (!dir || /^(1|0|true|false)$/.test(dir)) {
		let pkg = up(options);

		if (dir = pkg && dirname(pkg)) {
			let mods = join(dir, 'node_modules');
			let exists = existsSync(mods);

			// exit cuz exists but not writable
			// or cuz missing but parent not writable
			if (!writable(exists ? mods : dir)) return;

			dir = join(mods, '.cache');
		}
	}

	if (dir) {
		dir = join(dir, name);
		if (options.create && !existsSync(dir)) {
			mkdirSync(dir, { recursive: true });
		}
		return dir;
	}
}