#!/usr/bin/env node
// Determines total battle counts per format since the beginning of stats
// collection in order to determine what the fallback dates for the importer's
// `STATISTICS` map should be.

'use strict';

const Dex = require('../../.sim-dist/dex').Dex;
global.toID = Dex.getId;

const smogon = require('smogon');
const importer = require('./importer');

const formats = new Map();
for (let gen = 1; gen <= 8; gen++) {
	for (const tier of importer.TIERS) {
		const format = Dex.formats.get(`gen${gen}${tier}`);
		if (format.exists) {
			formats.set(format.id, {});
		}
	}
}

(async () => {
	const index = await importer.fetch(smogon.Statistics.URL);
	const begin = new Date('Nov 2014');
	const end = new Date(smogon.Statistics.latest(index));
	end.setDate(end.getDate() + 1);
	for (const d = begin; d <= end; d.setMonth(d.getMonth() + 1)) {
		const month = `${d.getMonth() + 1}`.padStart(2, '0');
		const date = `${1900 + d.getYear()}-${month}`;
		for (const format of formats.keys()) {
			try {
				// The JSON files are quite large and needing to download and parse them to then
				// extract the 'number of battles' field is much slower than instead grabbing the
				// basic stats file and doing the comparatively cheap regex search.
				const url = smogon.Statistics.url(date, format, 0).replace('chaos/', '').replace('.json', '.txt');
				const usage = await importer.fetch(url);

				if (usage) {
					// https://www.smogon.com/stats/2016-10/cap-*.txt is invalid and doesn't match... *sigh*
					const m = usage.match(/^ Total battles: (.*)/);
					if (m) formats.get(format)[date] = Number(m[1]);
				}
			} catch (err) {
				if (!err.message.startsWith('HTTP 404')) throw err;
			}
		}
	}

	console.log(JSON.stringify(Array.from(formats.entries()), null, 2));
})().catch(err => console.error(err));
