'use strict';

const Gauge = require('../gauge');
const linuxVariant = require('./osMemoryHeapLinux');
const safeMemoryUsage = require('./helpers/safeMemoryUsage');

const PROCESS_RESIDENT_MEMORY = 'process_resident_memory_bytes';

function notLinuxVariant(registry, config = {}) {
	const namePrefix = config.prefix ? config.prefix : '';
	const labels = config.labels ? config.labels : {};
	const labelNames = Object.keys(labels);

	new Gauge({
		name: namePrefix + PROCESS_RESIDENT_MEMORY,
		help: 'Resident memory size in bytes.',
		registers: registry ? [registry] : undefined,
		labelNames,
		collect() {
			const memUsage = safeMemoryUsage();

			// I don't think the other things returned from `process.memoryUsage()` is relevant to a standard export
			if (memUsage) {
				this.set(labels, memUsage.rss);
			}
		},
	});
}

module.exports = (registry, config) =>
	process.platform === 'linux'
		? linuxVariant(registry, config)
		: notLinuxVariant(registry, config);

module.exports.metricNames =
	process.platform === 'linux'
		? linuxVariant.metricNames
		: [PROCESS_RESIDENT_MEMORY];