"use strict";

const Promise = require("bluebird");
const execBinary = require("../exec-binary");
const parseIECBytes = require("../parse-bytes-iec");
const parseMountOptions = require("../parse-mount-options");
const createJsonParser = require("../text-parser-json");

// TODO: Should we replace this with a read from /proc/mounts directly?
//       Ref. https://unix.stackexchange.com/a/18067

function mapMountList(mounts) {
	return mounts.map((mount) => {
		// Some poorly-documented pseudo-filesystems were not worth investigating mount options for, yet. For those, we silently ignore missing/unknown entries.
		// TODO: FUSE, UDF should eventually be removed from this list
		let missingOptionsAllowed = ["cgroup", "cgroup2", "bpf", "pstore", "fuse", "udf"].includes(mount.fstype);

		let parsedOptions = parseMountOptions(mount.fstype, mount.options);

		// For dealing with bind mounts, which have a path suffix, like eg.:
		//    /dev/disk/by-uuid/692937db-d74c-4110-b55b-41a20f1b9342[/nix/store]
		let cleanSourceDevice = (mount.source.startsWith("/"))
			? mount.source.replace(/\[.+$/, "")
			: null; // Pseudo-filesystems

		if (missingOptionsAllowed || parsedOptions.missing.length === 0) {
			return {
				id: mount.id,
				sourceDevice: cleanSourceDevice,
				isBindMount: (cleanSourceDevice != null)
					? mount.source.includes("[") // FIXME: Is this actually correct? Can a square bracket ever appear in a device path legitimately?
					: false, // Pseudo-filesystems
				mountpoint: mount.target,
				filesystem: mount.fstype,
				options: parsedOptions.parsed,
				label: mount.label,
				uuid: mount.uuid,
				partitionLabel: mount.partlabel,
				partitionUUID: mount.partuuid,
				deviceNumber: mount["maj:min"],
				totalSpace: parseIECBytes(mount.size),
				freeSpace: parseIECBytes(mount.avail),
				usedSpace: parseIECBytes(mount.used),
				rootPath: mount.fsroot,
				taskID: mount.tid,
				optionalFields: mount["opt-fields"],
				propagationFlags: mount.propagation,
				children: (mount.children != null) ? mapMountList(mount.children) : []
			};
		} else {
			throw new Error(`Encountered unrecognized mount options for mount '${mount.target}': ${parsedOptions.missing.join(", ")}`);
		}
	});
}

let columns = [
	"SOURCE",
	"TARGET",
	"FSTYPE",
	"OPTIONS",
	"LABEL",
	"UUID",
	"PARTLABEL",
	"PARTUUID",
	"MAJ:MIN",
	"SIZE",
	"AVAIL",
	"USED",
	"FSROOT",
	"TID",
	"ID",
	"OPT-FIELDS",
	"PROPAGATION"
];

module.exports = function findmnt() {
	return Promise.try(() => {
		return execBinary("findmnt")
			.withFlags({
				json: true,
				o: columns.join(",")
			})
			.requireOnStdout(createJsonParser())
			.execute();
	}).then((output) => {
		return mapMountList(output.result.filesystems);
	});
};