"use strict";

const Promise = require("bluebird");
const memoizee = require("memoizee");
const fs = Promise.promisifyAll(require("fs"));
const treecutter = require("../../packages/treecutter");
const findmnt = require("../../packages/exec-findmnt");
const shallowMerge = require("../../packages/shallow-merge");
const All = require("../../packages/graphql-interface/symbols/all");

module.exports = function () {
	let findmntOnce = memoizee(() => {
		return Promise.try(() => {
			return findmnt();
		}).then((mounts) => {
			return treecutter.flatten(mounts);
		}).map((mount) => {
			if (mount.sourceDevice?.startsWith("/")) {
				return Promise.try(() => {
					return fs.realpathAsync(mount.sourceDevice);
				}).then((actualSourcePath) => {
					return shallowMerge(mount, {
						sourceDevice: actualSourcePath
					});
				});
			} else {
				return mount;
			}
		}).then((list) => {
			let tree = treecutter.rebuild(list);

			return {
				tree: tree,
				list: list
			};
		});
	});

	return function (mountpoints) {
		return Promise.try(() => {
			return findmntOnce();
		}).then(({tree, list}) => {
			return mountpoints.map((mountpoint) => {
				if (mountpoint === All) {
					return tree;
				} else {
					return list.find((mount) => mount.mountpoint === mountpoint);
				}
			});
		});
	};
};