#!/usr/bin/node

const cmp = require('../lib/www/server/lib/comparisons');

async function purgeComparisons () {
	const groups = await cmp.groups();
	const comparisons = await cmp.getGroup();

	const pids = new Set(Object.values(groups).flat().map( p => p.pid ));
	const comparison_pids = new Set(comparisons.map( c => [ c.baseline_pid, c.monitor_pid ] ).flat());

	for (const pid of comparison_pids) {
		if (!pids.has(pid)) {
			console.log(`${pid} no longer par of a group. Deleting comparisons`);

			staleComps = comparisons.filter( c => c.baseline_pid == pid || c.monitor_pid == pid );
			for (c of staleComps) {
				console.log(`Deleting comparison ${c.baseline_pid} → ${c.monitor_pid}`);
				await cmp.remove(c.baseline_pid, c.monitor_pid);
			}
		}
	}
}


async function main () {

	console.log("Looking for unreferenced comparisons to purge");
	await purgeComparisons();

	console.log("Retrieving project groups");
	const groups = await cmp.groups();

	if (!Object.keys(groups??{})?.length) {
		console.log("No groups found");
		return 0;
	}

	console.log(`Found ${Object.keys(groups)?.length} groups: ${Object.keys(groups).join(", ")}`);

	for (const groupName of Object.keys(groups)) {
		const projects = groups[groupName];

		console.log(`Fetching saved comparisons for ${groupName}`);

		const comparisons = await cmp.getGroup(groupName);

		if (!comparisons || !comparisons.length) {
			console.log(`No comparisons found for ${groupName}`);
			continue;
		}

		// Check if there are any projects that have been modified since last comparison
		// or if there are any pairs that are no longer part of the group

		const outdated = comparisons.filter( c => {
			const baseline_tstamp = projects.find( p => p.pid === c.baseline_pid )?.tstamp;
			const monitor_tstamp = projects.find( p => p.pid === c.monitor_pid )?.tstamp;
			return (c.tstamp < baseline_tstamp) || (c.tstamp < monitor_tstamp) ||
				baseline_tstamp == null || monitor_tstamp == null;
		});

		for (const comparison of outdated) {
			console.log(`Removing stale comparison: ${comparison.baseline_pid} → ${comparison.monitor_pid}`);
			await cmp.remove(comparison.baseline_pid, comparison.monitor_pid);
		}

		if (projects?.length < 2) {
			console.log(`Group ${groupName} has less than two projects. No comparisons are possible`);
			continue;
		}

		// Re-run the comparisons that are not in the database. They may
		// be missing either beacause they were not there to start with
		// or because we just removed them due to being stale

		console.log(`Recalculating group ${groupName}`);
		await cmp.saveGroup(groupName);
	}

	console.log("Comparisons update done");
	return 0;
}

if (require.main === module) {
	main();
} else {
	module.exports = main;
}