'use strict';

// Inspired in part by
// * https://www.npmjs.com/package/npmjs-api
// * https://github.com/kevva/npm-user-packages/blob/master/index.js

// Official docs at
// * https://github.com/npm/registry/blob/master/docs/REGISTRY-API.md#meta-endpoints
// * https://github.com/npm/registry/blob/master/docs/download-counts.md

var batchAsync = require('batchasync').batchAsync;
var request = require('@root/request');
request = require('util').promisify(request);

var hnai = exports;
hnai.packages = function(username) {
	// I didn't bother to implement paging because... I didn't
	return request({
		url: 'https://api.npms.io/v2/search?q=author:' + username + '&size=250&from=0',
		json: true
	}).then(function(resp) {
		// { total: 214, results: [ { package: { name: 'foobar' } } ] }
		if (resp.total > 250) {
			console.warn();
			console.warn("You have more than 250 published packages, but I haven't implemented paging.");
			console.warn("I'd say please open an issue, but you're ovbiously skilled, so please PR.");
			console.warn();
		}
		return resp.body.results.map(function(result) {
			return result.package.name;
		});
	});
};

hnai.downloads = function(pkgnames) {
	// https://github.com/npm/registry/blob/master/docs/download-counts.md#bulk-queries
	// FYI: Earliest date is January 10, 2015
	// * One-off: https://api.npmjs.org/downloads/range/{period}[/{package}]
	// * Bulk: https://api.npmjs.org/downloads/point/last-day/npm,express

	// All the batching logic
	var batches = [];
	var batch = [];
	pkgnames.forEach(function(pkgname) {
		if ('@' === pkgname[0]) {
			batches.push([pkgname]);
			return;
		}
		if (batch.length >= 128) {
			batches.push(batch);
			batch = [];
		}
		batch.push(pkgname);
	});
	if (batch.length) {
		batches.push(batch);
	}

	// do the batching
	return batchAsync(4, batches, function(batch) {
		if (1 === batch.length) {
			return one(batch[0]);
		} else {
			return many(batch);
		}
	}).then(function(results) {
		// transform the results
		var all = [];
		results.forEach(function(map) {
			//#console.debug('batch size:', Object.keys(map).length);
			Object.keys(map).forEach(function(key) {
				if (!map[key]) {
					// can be 'null' for just-published packages
					map[key] = { downloads: 0 };
				}
				all.push({
					package: key,
					downloads: map[key].downloads
				});
			});
		});

		// get back one big happy list
		return all;
	});
};

// these need to be simplified and transformed
function one(pkgname) {
	return request({
		url: 'https://api.npmjs.org/downloads/range/last-month/' + pkgname,
		json: true
	}).then(function(resp) {
		// { package: 'foobar', downloads: [{ downloads: 1, day: '2019-06-16' }] }
		var result = {};
		result[resp.body.package] = {
			package: resp.body.package,
			downloads: resp.body.downloads.reduce(function(sum, el) {
				return el.downloads;
			}, 0)
		};
		return result;
	});
}

// these are exactly what we want, pretty much
function many(pkgnames) {
	return request({
		url: 'https://api.npmjs.org/downloads/point/last-month/' + pkgnames.join(','),
		json: true
	}).then(function(resp) {
		// { foobar: { downloads: 12 } }
		return resp.body;
	});
}